Permafrost Monthly Alerts (PMAs)

12052238 DeConto, Robert M. (University of Massachusetts, Amherst, Department of Geosciences, Amherst, MA); Galeotti, Simone; Pagani, Mark; Tracy, David; Schaefer, Kevin; Zhang, Tingjun; Pollard, David and Beerling, David J. Past extreme warming events linked to massive carbon release from thawing permafrost: Nature (London), 484(7392), p. 87-91, illus. incl. 2 tables, sketch maps, 31 ref., April 5, 2012. Supplemental information/data is available in the online version of this article.

DOI: 10.1038/nature10929

12056440 Kabala, C. (University of Environmental and Life Sciences, Institute of Soil Science and Environmental Protection, Wroclaw, Poland) and Zapart, J. Initial soil development and carbon accumulation on moraines of the rapidly retreating Werenskiold Glacier, SW Spitsbergen, Svalbard Archipelago: Geoderma, 175-176, p. 9-20, illus. incl. 4 tables, sketch map, 61 ref., April 2012.

The rapid retreat of the Werenskiold Glacier (the Svalbard Archipelago, High Arctic) is leading to an extensive broadening of the proglacial zone covered with recent moraine till on older glacigenic deposits or directly on bedrock schists. To study the type and intensity of initial soil development under a harsh periglacial climate, a chronosequence of six soils was established between the glacier front and its terminal moraine on 1 to about 80 year-old moraines. Although the surface layer over the entire area of study is frost-active, the patterned features are not well developed. The succession of vegetation, mainly Saxifraga sp. and lichens, starts 5-6 years after deglaciation, successively covering up to 30% of the soil surface, then stagnating. Present-day soil-forming processes within the uppermost soil layer comprise initial weathering of primary minerals (chlorites and amphiboles), carbonate dissolution and base cation leaching associated with pH lowering, accumulation of organic matter and nitrogen, and an increase in pedogenically-derived Fe. Soil development measures are time-related and, in general, fit a logarithmic model. The intensity of transformation, including organic carbon and nitrogen accumulation, started at high rates comparable to those reported in Low Arctic and Alpine environments; however, in the fourth/fifth decade after deglaciation it reached a quasi steady-state. Low annual precipitation is probably a crucial factor that controls plant succession and leaching of carbonates, thus limiting mineral weathering, organic matter accumulation and soil development on the Werenskiold moraines.

DOI: 10.1016/j.geoderma.2012.01.025

12056621 Toutanji, Houssam (University of Alabama in Huntsville, Department of Civil and Environmental Engineering, Huntsville, AL); Goff, Christopher M.; Ethridge, Edwin and Stokes, Eric. Gas permeability and flow characterization of simulated lunar regolith: Advances in Space Research, 49(8), p. 1271-1276, illus. incl. 1 table, 12 ref., April 15, 2012.

DOI: 10.1016/j.asr.2012.02.002

12052221 Wetterich, Sebastian (Alfred Wegener Institute for Polar and Marine Research, Department of Periglacial Research, Potsdam, Germany); Grosse, Guido; Schirrmeister, Lutz; Andreev, Andrei A.; Bobrov, Anatoly A.; Kienast, Frank; Bigelow, Nancy H. and Edwards, Mary E. Late Quaternary environmental and landscape dynamics revealed by a pingo sequence on the northern Seward Peninsula, Alaska: Quaternary Science Reviews, 39, p. 26-44, illus. incl. 2 tables, sketch map, 144 ref., April 16, 2012.

A terrestrial sediment sequence exposed in an eroding pingo provides insights into the late-Quaternary environmental history of the northern Seward Peninsula, Alaska. We have obtained the first radiocarbon-dated evidence for a mid-Wisconsin thermokarst lake, demonstrating that complex landscape dynamics involving cyclic permafrost aggradation and thermokarst lake formation occurred over stadial-interstadial as well as glacial-interglacial time periods. High values of Picea pollen and the presence of Larix pollen in sediments dated to 50-40 ka BP strongly suggest the presence of forest or woodland early in MIS 3; the trees grew within a vegetation matrix dominated by grass and sedge, and there is indirect evidence of grazing animals. Thus the interstadial ecosystem was different in structure and composition from the Holocene or from the preceding Last Interglacial period. An early Holocene warm period is indicated by renewed thermokarst lake formation and a range of fossil taxa. Multiple extralimital plant taxa suggest mean July temperatures above modern values. The local presence of spruce during the early Holocene warm interval is evident from a radiocarbon-dated spruce macrofossil remain and indicates significant range extension far beyond the modern tree line. The first direct evidence of spruce in Northwest Alaska during the early Holocene has implications for the presence of forest refugia in Central Beringia and previously assumed routes and timing of post-glacial forest expansion in Alaska.

DOI: 10.1016/j.quascirev.2012.01.027

12052181 Johnsson, A. (University of Gothenburg, Department of Earth Sciences, Goteborg, Sweden); Reiss, D.; Hauber, E.; Zanetti, M.; Hiesinger, H.; Johansson, L. and Olvmo, M. Periglacial mass-wasting landforms on Mars suggestive of transient liquid water in the recent past; insights from solifluction lobes on Svalbard: Icarus, 218(1), p. 489-505, illus. incl. 1 table, sketch map, 126 ref., March 2012.

DOI: 10.1016/j.icarus.2011.12.021

12051633 Heil, K. (Technische Universität München, Freising, Germany) and Schmidhalter, U. Characterisation of soil texture variability using the apparent soil electrical conductivity at a highly variable site: Computers & Geosciences, 39, p. 98-110, illus. incl. 7 tables, 49 ref., February 2012.

The characterisation of the spatial distribution of clay, silt, and sand/gravel is one of the main objectives of soil surveys. Researchers as well as producers have an interest in characterising soil texture variability. The objective of our study was the development of models to derive the clay, silt, and sand/gravel content from the variables apparent electrical conductivity (EC_a), the boundary depth between Quaternary and Tertiary sediments, the terrain parameters, and the cultivation (organic vs integrated and type of fertiliser). The investigation site made it possible to include a wide range of soil types within the geological area under investigation. The apparent electrical conductivity and the soil properties texture and digital terrain attributes were densely mapped onto approximately 17 ha. Soil sampling was carried out in a 50´50-m grid. Clay and sand/gravel were most closely related to the EC_a, whereas silt showed a stronger dependency on the boundary depth. R² values ranged between 0.67 and 0.76 in this hilly landscape. However, some weaknesses of the applied procedure were observed: on layered soils with clay lenses covered with sandy, gravelly material, too much clay, and too little sand/gravel were predicted. In some subareas with distinct differences at the field boundaries, breaks in the EC_a were observed. The latter was likely due to fertilising effects that caused enhanced EC_a levels. In conclusion, the EC_a, in combination with the boundary depth between Quaternary and Tertiary sediments, the elevation, the terrain aspect, and the cultivation parameters represent a useful and robust surveying technique to predict soil texture for the Tertiary hill country in southern Germany.

DOI: 10.1016/j.cageo.2011.06.017

12049946 Stumpp, Christine (University of California at Riverside, Department of Environmental Sciences, Riverside, CA); Stichler, W.; Kandolf, M. and Simunek, J. Effects of land cover and fertilization method on water flow and solute transport in five lysimeters; a long-term study using stable water isotopes: Vadose Zone Journal, 11(1), unpaginated, illus. incl. 5 tables, 63 ref., February 2012.

Land cover and agricultural management practices can significantly influence soil structure. However, little is known about how fertilizer applications and land cover affect soil hydrology and groundwater recharge over long time periods. The objective of this study was to use stable water isotopes as environmental tracers to provide additional information required for better understanding of water flow and solute transport processes in the unsaturated zone influenced by land cover and type of fertilizer applications. Five lysimeters containing undisturbed soil monoliths from the same agricultural field site were investigated over a period of 5 yr. Liquid cattle slurry and solid animal manure were applied to the maize (Zea mays L.) and winter rye (Secale cereale L.) lysimeters. The grass-clover lysimeter was treated with mineral fertilizer. Quantitative influence of land cover and type of fertilizer application on water flow and solute transport was evaluated for all lysimeters using a modified version of HYDRUS-1D. The highest drainage was observed in the maize lysimeter treated with cattle slurry, and the lowest in the grass lysimeter treated with mineral fertilizer. Pronounced differences in water contents and estimated saturated hydraulic conductivities between the lysimeters were restricted to the upper 25 to 30 cm of the soil. In particular, the lysimeters treated with animal manure had higher porosities, indicating a higher content of organic matter. Main differences in discharge between the lysimeters were observed in spring and during the plant growth periods, indicating the importance of nonuniform, patchy infiltration patterns during snow melt and of root water uptake, respectively. Mean water flow velocities, transit times, and effective water contents were estimated from the stable water isotope data, providing evidence on the impact of land cover and type of fertilizer application. We found smaller mean transit times in the maize lysimeters and for soils with liquid cattle slurry applications. Simulations indicate that numerical modeling can reproduce the general trend of water flow and isotope transport. Despite differences in mean transit times, fitted dispersivities were all in the same range, suggesting similar soil structures in the five lysimeters. However, more data for calibration and more information about heterogeneous infiltration would be required to improve the model accuracy. In general, stable water isotopes clearly contributed an added value, elucidating differences in mean flow parameters between the lysimeters. Thus, they provided evidence of the impacts of land cover and fertilizer applications, which are not obvious from water balance and mean discharge rates alone.

DOI: 10.2136/vzj2011.0075

12050066 Henley, David C. (University of Calgary, Department of Geoscience, CREWES, Calgary, AB, Canada). Interferometric application of static corrections: Geophysics, 77(1), p. Q1-Q13, illus., 17 ref., January 1, 2012.

Correcting reflection seismic data for the effects of near-surface irregularities is a persistent problem usually addressed at least partly by static corrections applied to traces. However, there are areas where static corrections are ineffective because basic assumptions are violated. The assumptions which fail most often are surface consistency and stationarity, which are central to the concept of static corrections. To address this failure, I mapped raw seismic traces into the radial trace domain and gathered the radial traces by common surface angle. Then I imposed a more general constraint, raypath consistency, which simultaneously introduces nonstationarity. Conventional static correction also assumes implicitly that reflection events consist of single discrete arrivals. This is not true, however, in regions where near-surface multipathing and scattering complicate reflection event waveforms. Borrowing from recent work in seismic inferometry, I removed the single-arrival assumption by using trace crosscorrelations to estimate and deconvolve surface functions from traces, rather than applying time shifts. The entire crosscorrelation function is used in every case, so both timing and waveform variations are removed by the deconvolution. The operation is applied in the common-angle domain, so it is raypath consistent and nonstationary. The method, dubbed "raypath interferometry", was applied successfully to a set of 2D Arctic field data with serious surface consistency and multipath problems, and to a set of 3C 2D land data with very large S-wave receiver statics. Although intended primarily for use on seismic data for which conventional statics corrections fail, raypath interferometry can be used on any seismic data; its assumptions include single-arrival events and surface consistency as special cases.

DOI: 10.1190/geo2011-0082.1

12054504 Huggel, Christian (University of Zurich, Departmet of Glaciology, Geomorphodynamics and Geochronology, Zurich, Switzerland); Clague, John J. and Korup, Oliver. Is climate change responsible for changing landslide activity in high mountains?: Earth Surface Processes and Landforms, 37(1), p. 77-91, illus. incl. 1 table, 150 ref., January 2012.

Climate change, manifested by an increase in mean, minimum, and maximum temperatures and by more intense rainstorms, is becoming more evident in many regions. An important consequence of these changes may be an increase in landslides in high mountains. More research, however, is necessary to detect changes in landslide magnitude and frequency related to contemporary climate, particularly in alpine regions hosting glaciers, permafrost, and snow. These regions not only are sensitive to changes in both temperature and precipitation, but are also areas in which landslides are ubiquitous even under a stable climate. We analyze a series of catastrophic slope failures that occurred in the mountains of Europe, the Americas, and the Caucasus since the end of the 1990s. We distinguish between rock and ice avalanches, debris flows from de-glaciated areas, and landslides that involve dynamic interactions with glacial and river processes. Analysis of these events indicates several important controls on slope stability in high mountains, including: the non-linear response of firn and ice to warming; three-dimensional warming of subsurface bedrock and its relation to site geology; de-glaciation accompanied by exposure of new sediment; and combined short-term effects of precipitation and temperature. Based on several case studies, we propose that the following mechanisms can significantly alter landslide magnitude and frequency, and thus hazard, under warming conditions: (1) positive feedbacks acting on mass movement processes that after an initial climatic stimulus may evolve independently of climate change; (2) threshold behavior and tipping points in geomorphic systems; (3) storage of sediment and ice involving important lag-time effects. Abstract Copyright (2010), John Wiley & Sons, Ltd.

DOI: 10.1002/esp.2223

12054318 Haldorsen, Sylvi (Norwegian University of Life Sciences, Department of Plants and Environmental Science, As, Norway); Heim, Michael and van der Ploeg, Martine. Impacts of climate change on groundwater in permafrost areas; case study from Svalbard, Norway: in Climate change effects on groundwater resources; a global synthesis of findings and recommendations (Treidel, Holger, editor; et al.), International Association of Hydrogeologists, 27, p. 324-338, illus. incl. sketch map, 82 ref., 2012.

12054488 Moore, Jeffrey R. (ETH Zürich, Department of Earth Sciences, Zurich, Switzerland); Gischig, Valentin; Katterbach, Maren and Loew, Simon. Air circulation in deep fractures and the temperature field of an alpine rock slope: Earth Surface Processes and Landforms, 36(15), p. 1985-1996, illus. incl. 1 table, sketch map, 26 ref., December 2011.

The subsurface temperature field of a rock slope is a key variable influencing both bedrock fracturing and slope stability. However, significant unknowns remain relating to the effect of air and water fracture flow, which can rapidly transmit temperature changes to appreciable depths. In this work, we analyze a unique set of temperature measurements from an alpine rock slope at ~2400 m a.s.l. in southern Switzerland. The monitored area encompasses part of an active slope instability above the village of Randa (VS) and is traversed by a network of open cracks, some of which have been traced to >80 m depth. We first describe distributed temperature measurements and borehole profiles, highlighting deep steady temperatures and different transient effects, and then use these data to approximate the conductive temperature field at the site. In a second step, we analyze the impact of air and water circulation in deep open fractures on the subsurface thermal field. On multiple visits to the study site in winter, we consistently noted the presence of warm air vents in the snowpack following the trace of deep tension cracks. Measurements showed that venting air changed temperature gradually from ~3 to 2 °C between December and May, which is similar to the rock temperature at around 50 m depth. Comparison with ambient air temperature suggests that winter conditions favor buoyancy-driven convective air flow in these fractures, which acts to cool the deep subsurface as the rock gives up heat to incoming air. The potential impact of this process on the local thermal field is revealed by a disturbed temperature profile in one borehole and transient signals observed at depths well below the thermal active layer. Seasonal water infiltration during snowmelt appears to have little impact on the temperature field in the monitored area. Abstract Copyright (2010), John Wiley & Sons, Ltd.

DOI: 10.1002/esp.2217

12054492 Ridefelt, Hanna (Uppsala University, Department of Social and Economic Geography, Uppsala, Sweden); Boelhouwers, Jan and Etzelmuller, Bernd. Local variations of solifluction activity and environment in the Abisko Mountains, northern Sweden: Earth Surface Processes and Landforms, 36(15), p. 2042-2053, illus. incl. 7 tables, sketch map, 46 ref., December 2011.

Seven sites within the mountain region of Abisko, northern Sweden, were selected for measurement of solifluction movement rates and correlation with the local environmental factors. Grids with sizes from 20 m ´ 30 m to 50 m ´ 100 m included both solifluction landforms and adjacent ground. Positions of movement markers and the terrain were recorded and the grid areas were digitally reconstructed. This allowed topography, vegetation and soil texture (fraction of fine material) surfaces to be interpolated and used together with data on soil moisture in statistical analyses. Significant correlations differ from site to site indicating that environmental factors have varying importance and inter-relations depending on the local setting. Geomorphic work was also assessed within the grids. The results indicate measurable geomorphic work where no landforms are present. These areas may make larger contributions to sediment displacement than where solifluction landforms exist. Solifluction is an important denudational agent in the region and has its greatest impact on landscape development in the western part of the region. Abstract Copyright (2010), John Wiley & Sons, Ltd.

DOI: 10.1002/esp.2225

12054479 Parsekian, Andrew D. (Rutgers, the State University of New Jersey, Department of Earth and Environmental Sciences, Newark, NJ); Jones, Benjamin M.; Jones, Miriam; Grosse, Guido; Walter Anthony, Katey M. and Slater, Lee. Expansion rate and geometry of floating vegetation mats on the margins of thermokarst lakes, northern Seward Peninsula, Alaska, USA: Earth Surface Processes and Landforms, 36(14), p. 1889-1897, illus. incl. sketch map, 57 ref., November 2011.

Investigations on the northern Seward Peninsula in Alaska identified zones of recent (<50 years) permafrost collapse that led to the formation of floating vegetation mats along thermokarst lake margins. The occurrence of floating vegetation mat features indicates rapid degradation of near-surface permafrost and lake expansion. This paper reports on the recent expansion of these collapse features and their geometry is determined using geophysical and remote sensing measurements. The vegetation mats were observed to have an average thickness of 0.57 m and petrophysical modeling indicated that gas content of 1.5-5% enabled floatation above the lake surface. Furthermore, geophysical investigation provides evidence that the mats form by thaw and subsidence of the underlying permafrost rather than terrestrialization. The temperature of the water below a vegetation mat was observed to remain above freezing late in the winter. Analysis of satellite and aerial imagery indicates that these features have expanded at maximum rates of 1-2 m yr^-1 over a 56 year period. Including the spatial coverage of floating 'thermokarst mats' increases estimates of lake area by as much as 4% in some lakes. Abstract Copyright (2010), John Wiley & Sons, Ltd.

DOI: 10.1002/esp.2210

12049164 Waller, Richard (Keele University, Keele, School of Physical and Geographical Sciences, Keele, United Kingdom); Phillips, Emrys; Murton, Julian; Lee, Jonathan and Whiteman, Colin. Sand intraclasts as evidence of subglacial deformation of middle Pleistocene permafrost, north Norfolk, UK: Quaternary Science Reviews, 30(23-24), p. 3481-3500, illus. incl. 1 table, sketch map, 73 ref., November 2011.

Sand intraclasts are common within the Bacton Green Till Member, a glacitectonic melange subjected to polyphase deformation during the Middle Pleistocene in North Norfolk, UK. The intraclasts range from a few tens of centimetres to >10 m in length and have sharp contacts with the surrounding till. Sand within the intraclasts is unconsolidated and contains well-preserved primary stratification. The wrapping of glacitectonic foliation around the intraclasts and the development of folds relating to mechanical instabilities indicate that the intraclasts acted as competent masses within a more easily deformable fine-grained till that accommodated the majority of the strain. Sharp contacts and distinctive heavy-mineral assemblages indicate little intermixing between the sand and till. Five hypotheses about the entrainment and evolution of the intraclasts are tested against sedimentological, structural and mineralogical observations. The most reasonable hypothesis attributes the intraclasts to glacitectonic deformation of "warm" permafrost. Initial ice advance caused large-scale thrusting of proglacial permafrost that led to the stacking of pre-glacial and ice-marginal sediments that were subsequently deformed sub-marginally to generate the intraclasts. Preservation of primary stratification within the intraclasts is attributed to deformation at temperatures slightly below the pressure-melting point, when pore ice cemented the intraclasts as rigid bodies. At the same time deformation was concentrated into the surrounding finer-grained till because of its significant liquid water content and ductile rheology. It is concluded that the intraclasts provide a criterion to identify past glacier-permafrost interactions and a potential means of differentiating between subglacial deformation under unfrozen and partially-frozen conditions.

DOI: 10.1016/j.quascirev.2011.07.011

12053868 Bauer, Ilka E. (University of Alberta, Department of Biological Sciences, Edmonton, AB, Canada) and Vitt, Dale H. Peatland dynamics in a complex landscape; development of a fen-bog complex in the sporadic discontinuous permafrost zone of northern Alberta, Canada: Boreas, 40(4), p. 714-726, illus. incl. strat. cols., 2 tables, sketch map, 62 ref., October 2011.

The development of a peatland complex in the Sporadic Discontinuous Permafrost zone of northwestern Alberta, Canada was reconstructed using a series of dated profiles. Peat-forming communities first established c. 10 230 cal. a BP, and by 8000 cal. a BP the site supported monocot fens or marshes in several isolated topographic depressions. Most of the current peatland area initiated between c. 8000 and 4000 cal. a BP, and involved the replacement of upland habitats by shrubby or treed fen and, in some areas, the establishment of Sphagnum on mineral terrain. Ombrotrophic hummock communities had established by c. 7000 cal. a BP, and permafrost was present at 6800 cal. a BP in at least some peat plateau areas. Macrofossil-based reconstructions show considerable local diversity in vegetation succession and permafrost dynamics, with cyclic collapse and aggradation in at least one profile and relative stability in others. Lichen-rich peat is rare in deep-peat plateau cores, and where charcoal was recovered, fire effects on vegetation trajectories varied between cores. Organic matter accumulation was high in the early Holocene and declined after permafrost formation, with low rates especially over the past 4000 years. The site was burned in a wildfire in 1971, and by 1998 permafrost had disappeared from almost all peat plateau areas. In this part of the discontinuous permafrost zone, peat plateaus are likely to be unsustainable under a warming climate. The hydrology and carbon dynamics of former plateau areas following large-scale permafrost degradation require further investigation.

DOI: 10.1111/j.1502-3885.2011.00210.x

12051263 Blinnikov, Mikhail S. (St. Cloud State University, Department of Geography, Saint Clound, MN); Gaglioti, Benjamin V.; Walker, Donald A.; Wooller, Matthew J. and Zazula, Grant D. Pleistocene graminoid-dominated ecosystems in the Arctic: Quaternary Science Reviews, 30(21-22), p. 2906-2929, illus. incl. 5 tables, sketch map, 251 ref., October 2011.

We review evidence obtained from analyses of multiple proxies (floristics, mammal remains, paleoinsects, pollen, macrofossils, plant cuticles, phytoliths, stable isotopes, and modeling) that elucidate the composition and character of the graminoid-dominated ecosystems of the Pleistocene Arctic. The past thirty years have seen a renewed interest in this now-extinct biome, sometimes referred to as "tundra-steppe" (steppe-tundra in North American sources). While many questions remain, converging evidence from many new terrestrial records and proxies coupled with better understanding of paleoclimate dynamics point to the predominance of xeric and cold adapted grassland as the key former vegetation type in the Arctic confirming earlier conjectures completed in the 1960s-1980s. A variety of still existing species of grasses and forbs played key roles in the species assemblages of the time, but their mixtures were not analogous to the tundras of today. Local mosaics based on topography, proximity to the ice sheets and coasts, soil heterogeneity, animal disturbance, and fire regimes were undoubtedly present. However, inadequate coverage of terrestrial proxies exist to resolve this spatial heterogeneity. These past ecosystems were maintained by a combination of dry and cold climate and grazing pressure/disturbance by large (e.g., mammoth and horse) and small (e.g., ground squirrels) mammals. Some recent studies from Eastern Beringia (Alaska) suggest that more progress will be possible when analyses of many proxies are combined at local scales.

DOI: 10.1016/j.quascirev.2011.07.002

12051270 de Klerk, Pim (Ernst Moritz Arndt University, Institute of Botany and Landscape Ecology, Greifswald, Germany); Donner, Norman; Karpov, Nikolay S.; Minke, Merten and Joosten, Hans. Short-term dynamics of a low-centred ice-wedge polygon near Chokurdakh (NE Yakutia, NE Siberia) and climate change during the last ca 1250 years: Quaternary Science Reviews, 30(21-22), p. 3013-3031, illus. incl. sect., 1 table, sketch map, 156 ref., October 2011.

Palaeoecological studies (including analysis of pollen, macrofossils, geochemistry, and AMS radiocarbon dates) of four peat sections from one low-centred ice-wedge polygon in NE Yakutia (NE Siberia) allow the three-dimensional reconstruction of polygon development during the last ca 1250 years. After drainage of a lake, peat forming vegetation invaded rapidly. Comparison with palaeotemperature data shows that the initial formation of mature ridges coincided with a period of high summer temperatures around AD 1400. The ridges persisted and expanded during the subsequent colder ca 200 years. Partial collapse of various ridges at the end of the 18th century corresponded to a phase with low summer temperatures. During the warm, 20th century one collapsed ridge regenerated, whereas another persisted in its collapsed state. Ice-wedge polygons are, thus, complex and highly dynamic ecosystems, in which changes in temperature and precipitation may induce rapid ecological changes by the complex interplay of water, ice and vegetation. Our study indicates that global warming associated with a decrease in summer precipitation may initially result in enhanced polygon ridge formation. The combination of longer summers and increased winter precipitation, as predicted for high latitudes will, however, eventually result in larger meltwater input in the polygon mires, which may cause the (partial) collapse of polygon ridges and underlying ice-wedges.

DOI: 10.1016/j.quascirev.2011.06.016

12051279 Wetterich, Sebastian (Alfred Wegener Institute for Polar and Marine Research, Department of Periglacial Research, Potsdam, Germany); Rudaya, Natalia; Tumskoy, Vladimir; Andreev, Andrei A.; Opel, Thomas; Schirrmeister, Lutz and Meyer, Hanno. Last glacial maximum records in permafrost of the east Siberian Arctic: Quaternary Science Reviews, 30(21-22), p. 3139-3151, illus. incl. 4 tables, sketch map, 74 ref., October 2011.

Palaeontological proxy data and cryolithological information from Siberian Arctic permafrost preserves records of late Quaternary climate and environmental conditions in West Beringia and their variability which results from interglacial-glacial and interstadial-stadial dynamics. To date, the Last Glacial Maximum (LGM) period has been rather poorly represented in East Siberian permafrost records. Here, we present pollen, sediment, and ground-ice stable water isotope data obtained from coastal exposures on Bol'shoy Lyakhovsky Island (New Siberian Archipelago, Arctic Ocean) that mirror the coldest conditions during the Sartan period between about 26 and 22 ka BP, using pollen and sediment data for summer conditions and stable water isotope data for winter conditions. The pollen record revealed a cold tundra-steppe vegetation with characteristic predominance of grass pollen over sedge pollen while the stable isotope ice-wedges data indicate extremely cold winter temperatures with mean values of d¹⁸O of about -37 ppm, dD of about -290 ppm. Combined with available regional LGM permafrost records that extend from the Taymyr Peninsula in the west to the Yana River lowland in the east, the new data set from Bol'shoy Lyakhovsky Island indicate that the regional appearance of LGM conditions depended on atmospheric circulation patterns that were influenced by the extent of the Northern Hemisphere glaciation.

DOI: 10.1016/j.quascirev.2011.07.020

12053867 Winterfeld, Maria (Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany); Schirrmeister, Lutz; Grigoriev, Mikhail N.; Kunitsky, Viktor V.; Andreev, Andrei; Murray, Andrew and Overduin, Pier Paul. Coastal permafrost landscape development since the late Pleistocene in the western Laptev Sea, Siberia: Boreas, 40(4), p. 697-713, illus. incl. strat. cols., 1 table, sketch maps, 73 ref., October 2011.

The palaeoenvironmental development of the western Laptev Sea is understood primarily from investigations of exposed cliffs and surface sediment cores from the shelf. In 2005, a core transect was drilled between the Taymyr Peninsula and the Lena Delta, an area that was part of the westernmost region of the non-glaciated Beringian landmass during the late Quaternary. The transect of five cores, one terrestrial and four marine, taken near Cape Mamontov Klyk reached 12 km offshore and 77 m below sea level. A multiproxy approach combined cryolithological, sedimentological, geochronological (14C-AMS, OSL on quartz, IR-OSL on feldspars) and palaeoecological (pollen, diatoms) methods. Our interpretation of the proxies focuses on landscape history and the transition of terrestrial into subsea permafrost. Marine interglacial deposits overlain by relict terrestrial permafrost within the same offshore core were encountered in the western Laptev Sea. Moreover, the marine interglacial deposits lay unexpectedly deep at 64 m below modern sea level 12 km from the current coastline, while no marine deposits were encountered onshore. This implies that the position of the Eemian coastline presumably was similar to today's. The landscape reconstruction suggests Eemian coastal lagoons and thermokarst lakes, followed by Early to Middle Weichselian fluvially dominated terrestrial deposition. During the Late Weichselian, this fluvial landscape was transformed into a poorly drained accumulation plain, characterized by widespread and broad ice-wedge polygons. Finally, the shelf plain was flooded by the sea during the Holocene, resulting in the inundation and degradation of terrestrial permafrost and its transformation into subsea permafrost.

DOI: 10.1111/j.1502-3885.2011.00203.x

12049323 Bing Hui (Chinese Academy of Sciences, State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China) and He Ping. Experimental investigations on the influence of cyclical freezing and thawing on physical and mechanical properties of saline soil: Environmental Earth Sciences, 64(2), p. 431-436, illus. incl. 2 tables, 12 ref., September 2011.

Uniaxial compressive strength experiments were performed on saline loess different water and salt contents, and multiple freeze/thaw cycles at room temperature. The experiments revealed changes to the stress-strain curve and the failure mode of the saline loess. The results indicated that soil strength is intensified or weakened during freezing and thawing due to the injection of sodium sulfate solute. Cyclical freezing and thawing is a process to get a new dynamic equilibrium, and under these experimental conditions, six freeze-thaw cycles are need for loess with sodium sulfate to reach a new dynamic equilibrium. Copyright 2010 Springer-Verlag

DOI: 10.1007/s12665-010-0858-y

12049293 Chen Youliang (University of Shanghai for Science and Technology, Department of Civil Engineering, Shanghai, China); Azzam, Rafig; Wang Ming; Xu Shan and Chang Lequn. The uniaxial compressive and tensile tests of frozen saturated clay in Shanghai area: Environmental Earth Sciences, 64(1), p. 29-36, illus. incl. 8 tables, 8 ref., September 2011.

The compressive and tensile strengths of frozen clay are important parameters for frozen wall design in artificial freezing excavation of tunnels and foundation pits. Up to now, nobody has conducted the compressive and tensile test of frozen clays in the Shanghai area. In this paper, the unconfined compressive and tensile tests of frozen clay specimens drilled from the soil horizons 3-5 in the Shanghai area were conducted in Zwick-Z020kN High-low Temperature Materials Testing Machine and Frozen Soil Triaxial Testing Machine, the corresponding constitutive equations were suggested; the temperature-unconfined uniaxial compressive strength relation was discussed; the strain rate-unconfined uniaxial compressive strength and strain rate-uniaxial tensile strength relations were studied. The relation between moisture content, dry density and unconfined uniaxial compressive strength was analyzed, too. In addition, the uniaxial compressive elastic modulus of Shanghai frozen clays and its influence factors were discussed. The research work of the current paper is very helpful for the design and theoretical studies of artificial freezing excavation in soft soil areas. Copyright 2010 Springer-Verlag

DOI: 10.1007/s12665-010-0813-y

12049313 Ye Weimin (Tongji University, Key Laboratory of Geotechnical and Underground Engineering, Shanghai, China); Qi Ziyuan; Chen Bao; Xie Ji; Huang Yu; Lu Yaoru and Cui, Yu-Jun. Mechanism of cultivation soil degradation in rocky desertification areas under dry/wet cycles: Environmental Earth Sciences, 64(1), p. 269-276, illus. incl. 5 tables, 35 ref., September 2011.

Karst rocky desertification is a process of land degradation involving serious soil erosion, extensive exposure of basement rocks. It leads to drastic decrease in soil productivity and formation of a desert-like landscape. In this regard, changes in climatic conditions are the main origin of the soils degradation. Indeed, soils subjected to successive dry/wet cycling processes caused by climate change develop swelling and shrinkage deformations which can modify their water retention properties, thus inducing the degradation of soil-water capacity. The ecological characteristics of cultivation soils in karst areas, Southwest of China, are extremely easy to be affected by external environmental factors due to its shallow bedding and low vegetation coverage. Based on the analysis of the climate (precipitation) of this region during the past decades, an experimental study has been conducted on a cultivated soil obtained from the typical karst area in southwestern China. Firstly, the soil-water properties have been investigated. The measured soil-water retention curve shows that the air-entry value of the soil is between 50 and 60 kPa, while the residual saturation is about 12%. Based on the experimental results, three identifiable stages of de-saturation have been defined. Secondly, a special apparatus was developed to investigate the volume change behavior of the soil with controlled suction cycles. The vapor equilibrium technique was used for the suction control. The obtained results show that under the effect of dry/wet cycles, (1) the void ratio of the cultivated soil is continuously decreasing, leading to a gradual soil compaction. (2) The permeability decreases, giving rise to a deterioration of water transfer ability as well as a deterioration of soil-water retention capacity. It is then obvious that the long-term dry/wet cycling process caused by the climate change induce a continuously compaction and degradation of the cultivated soil in karst rocky desertification areas. Copyright 2010 Springer-Verlag

DOI: 10.1007/s12665-010-0846-2

12053826 Manz, Lorraine. Frost heave: Geo News, 38(2), p. 18-24, illus., 17 ref., July 2011.

12049274 Cao Wei (Chinese Academy of Sciences, State Key Laboratory of Frozen Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Sheng Yu; Qin, Yinghong; Li Jing and Wu Jichun. An application of a new method in permafrost environment assessment of Muli mining area in Qinghai-Tibet Plateau, China: Environmental Earth Sciences, 63(3), p. 609-616, illus. incl. 3 tables, sketch map, 18 ref., June 2011.

The permafrost environment in the Muli mining area, an opencast mining site in the Qinghai-Tibet Plateau, China, is now undergoing significant degradation because of the ongoing mining activities. The permafrost environment in this mining site had already been evaluated by previous study, in which analytic hierarchy process was applied. Although this method can roughly characterize the permafrost environment of this mining site, it has limitations by being easily affected by man-made factors. In view of this limitation, this study attempts to employ a new method, the catastrophe progression method, to estimate the current stage of the permafrost environment in this mining area. The results show that, by catastrophe progression method, currently the calculated indexes of the permafrost freezing-thawing disintegration, permafrost thermal stability, permafrost ecological fragility, and the permafrost environment are 0.43 (general situation), 0.77 (general situation), 0.71 (bad situation) and 0.83 (general situation), respectively. These values imply that the permafrost environment has been damaged by anthropologic activities to a certain degree and potentially may be further degenerated. However, at this degree, a new equilibrium stage of permafrost environment could be achieved if the current state of environmental degradation is stabilized and treatments are constructed against further damages. Copyright 2010 Springer-Verlag

DOI: 10.1007/s12665-010-0728-7

12055781 Guo Donglin (Chinese Academy of Sciences, Institute of Atmospheric Physics, Nansen-Zhu International Research Center, Beijing, China); Yang Meixue and Wang Huijun. Sensible and latent heat flux response to diurnal variation in soil surface temperature and moisture under different freeze/thaw soil conditions in the seasonal frozen soil region of the central Tibetan Plateau: Environmental Earth Sciences, 63(1), p. 97-107, illus. incl. 6 tables, sketch map, 31 ref., May 2011.

The relationship between sensible and latent heat flux and diurnal variation in soil surface temperature and moisture under four freeze/thaw soil conditions was investigated using observed soil temperature and moisture and simulated sensible and latent heat flux. The diurnal range of latent heat flux had a similar temporal change pattern as that of unfrozen soil water at depths of 0-3 cm during the freezing stage. Also, there was a better relationship with the diurnal range of unfrozen soil water at depths of 3-6 cm during the thawing stage. Diurnal variation in latent heat flux was significant and depended mostly on solar radiation during the completely thawed stage. However, while diurnal variation in solar radiation during the completely frozen stage was significant, for latent heat flux it was quite weak due to low unfrozen soil water content. Thus, diurnal variation in latent heat flux depended mostly on unfrozen soil water content during this stage. During the freezing and thawing stages, diurnal variation in latent heat flux was also significant and depended mostly on diurnal variation in unfrozen soil water content. However, the impacts of air temperature change from solar radiation on latent heat flux could not be ignored. Copyright 2010 Springer-Verlag

DOI: 10.1007/s12665-010-0672-6

12051145 Melles, Martin (University of Cologne, Institute of Geology and Mineralogy, Cologne, Germany); Brigham-Grette, Julie; Minyuk, Pavel; Koeberl, Christian; Andreev, Andrei; Cook, Timothy; Fedorov, Grigory; Gebhardt, Catalina; Haltia-Hovi, Eeva; Kukkonen, Maaret; Nowaczyk, Norbert; Schwamborn, Georg and Wennrich, Volker. The Lake El'gygytgyn Scientific Drilling Project; conquering Arctic challenges through continental drilling: Scientific Drilling, 11, p. 29-40, illus. incl. sects., 1 table, sketch map, 35 ref., March 2011.

DOI: 10.2204/iodp.sd.11.03.2011

12049220 Berrittella, Cinzia (Vrije Universiteit, Department of Hydrology and Geo-Environmental Sciences, Amsterdam, Netherlands) and van Huissteden, J. Uncertainties in modelling CH₄ emissions from northern wetlands in glacial climates; the role of vegetation parameters: Climate of the Past, 7(4), p. 1075-1087, illus. incl. 4 tables, sketch map, 75 ref., 2011. Published in Climate of the Past Discussion: 9 December 2010, URL: http://www.clim-past-discuss.net/6/2651/2010/cpd-6-2651-2010.html; accessed in Feb., 2012.

Marine Isotope Stage 3 (MIS 3) interstadials are marked by a sharp increase in the atmospheric methane (CH₄) concentration, as recorded in ice cores. Wetlands are assumed to be the major source of this CH₄, although several other hypotheses have been advanced. Modelling of CH₄ emissions is crucial to quantify CH₄ sources for past climates. Vegetation effects are generally highly generalized in modelling past and present-day CH₄ fluxes, but should not be neglected. Plants strongly affect the soil-atmosphere exchange of CH₄ and the net primary production of the vegetation supplies organic matter as substrate for methanogens. For modelling past CH₄ fluxes from northern wetlands, assumptions on vegetation are highly relevant since paleobotanical data indicate large differences in Last Glacial (LG) wetland vegetation composition as compared to modern wetland vegetation. Besides more cold-adapted vegetation, Sphagnum mosses appear to be much less dominant during large parts of the LG than at present, which particularly affects CH₄ oxidation and transport. To evaluate the effect of vegetation parameters, we used the PEATLAND-VU wetland CO₂/CH₄ model to simulate emissions from wetlands in continental Europe during LG and modern climates. We tested the effect of parameters influencing oxidation during plant transport (f_ox), vegetation net primary production (NPP, parameter symbol P_max), plant transport rate (V_transp), maximum rooting depth (Z_root) and root exudation rate (f_ex). Our model results show that modelled CH₄ fluxes are sensitive to f_ox and Z_root in particular. The effects of P_max, V_transp and f_ex are of lesser relevance. Interactions with water table modelling are significant for V_transp. We conducted experiments with different wetland vegetation types for Marine Isotope Stage 3 (MIS 3) stadial and interstadial climates and the present-day climate, by coupling PEATLAND-VU to high resolution climate model simulations for Europe. Experiments assuming dominance of one vegetation type (Sphagnum vs. Carex vs. Shrubs) show that Carex-dominated vegetation can increase CH₄ emissions by 50% to 78% over Sphagnum-dominated vegetation depending on the modelled climate, while for shrubs this increase ranges from 42% to 72%. Consequently, during the LG northern wetlands may have had CH₄ emissions similar to their present-day counterparts, despite a colder climate. Changes in dominant wetland vegetation, therefore, may drive changes in wetland CH₄ fluxes, in the past as well as in the future.

URL: http://www.clim-past.net/7/1075/2011/cp-7-1075-2011.pdf

12049228 Levavasseur, Guillaume (Laboratoire des Sciences du Climat et de L'Environnement, Gif-sur-Yvette, France); Vrac, Mathieu; Roche, Didier M.; Paillard, Didier; Martin, A. and Vandenberghe, Jef. Present and LGM permafrost from climate simulations; contribution of statistical downscaling: Climate of the Past, 7(4), p. 1225-1246, illus. incl. 4 tables, sketch maps, 77 ref., 2011. Includes supplement, URL: http://www.clim-past.net/7/1247/2011/cp-7-1247-2011-supplement.zip; published in Climate of the Past Discussion: 25 May 2011, URL: http://www.clim-past-discuss.net/7/1647/2011/cpd-7-1647-2011.html; accessed in Feb., 2012.

We quantify the agreement between permafrost distributions from PMIP2 (Paleoclimate Modeling Intercomparison Project) climate models and permafrost data. We evaluate the ability of several climate models to represent permafrost and assess the variability between their results. Studying a heterogeneous variable such as permafrost implies conducting analysis at a smaller spatial scale compared with climate models resolution. Our approach consists of applying statistical downscaling methods (SDMs) on large- or regional-scale atmospheric variables provided by climate models, leading to local-scale permafrost modelling. Among the SDMs, we first choose a transfer function approach based on Generalized Additive Models (GAMs) to produce high-resolution climatology of air temperature at the surface. Then we define permafrost distribution over Eurasia by air temperature conditions. In a first validation step on present climate (CTRL period), this method shows some limitations with non-systematic improvements in comparison with the large-scale fields. So, we develop an alternative method of statistical downscaling based on a Multinomial Logistic GAM (ML-GAM), which directly predicts the occurrence probabilities of local-scale permafrost. The obtained permafrost distributions appear in a better agreement with CTRL data. In average for the nine PMIP2 models, we measure a global agreement with CTRL permafrost data that is better when using ML-GAM than when applying the GAM method with air temperature conditions. In both cases, the provided local information reduces the variability between climate models results. This also confirms that a simple relationship between permafrost and the air temperature only is not always sufficient to represent local-scale permafrost. Finally, we apply each method on a very different climate, the Last Glacial Maximum (LGM) time period, in order to quantify the ability of climate models to represent LGM permafrost. The prediction of the SDMs (GAM and ML-GAM) is not significantly in better agreement with LGM permafrost data than large-scale fields. At the LGM, both methods do not reduce the variability between climate models results. We show that LGM permafrost distribution from climate models strongly depends on large-scale air temperature at the surface. LGM simulations from climate models lead to larger differences with LGM data than in the CTRL period. These differences reduce the contribution of downscaling.

URL: http://www.clim-past.net/7/1225/2011/cp-7-1225-2011.pdf

12055537 Woillez, Marie-Noelle (Institute Pierre Simon Laplace, Laboratoire des Sciences du Climat et de l'Environnement, Gif-sur-Yvette, France); Kageyama, Masa; Krinner, Gerhard; de Noblet-Ducoudré, Nathalie; Viovy, Nicolas and Mancip, M. Impact of CO₂ and climate on the last glacial maximum vegetation; results from the ORCHIDEE/IPSL models: Climate of the Past, 7(2), p. 557-577, illus. incl. 3 tables, 49 ref., 2011. Published in Climate of the Past Discussion: 3 January 2011, URL: http://www.clim-past-discuss.net/7/1/2011/cpd-7-1-2011.html; accessed in Nov., 2011.

Vegetation reconstructions from pollen data for the Last Glacial Maximum (LGM), 21 ky ago, reveal lanscapes radically different from the modern ones, with, in particular, a massive regression of forested areas in both hemispheres. Two main factors have to be taken into account to explain these changes in comparison to today's potential vegetation: a generally cooler and drier climate and a lower level of atmospheric CO₂. In order to assess the relative impact of climate and atmospheric CO₂ changes on the global vegetation, we simulate the potential modern vegetation and the glacial vegetation with the dynamical global vegetation model ORCHIDEE, driven by outputs from the IPSL_CM4_v1 atmosphere-ocean general circulation model, under modern or glacial CO₂ levels for photosynthesis. ORCHIDEE correctly reproduces the broad features of the glacial vegetation. Our modelling results support the view that the physiological effect of glacial CO₂ is a key factor to explain vegetation changes during glacial times. In our simulations, the low atmospheric CO₂ is the only driver of the tropical forests regression, and explains half of the response of temperate and boreal forests to glacial conditions. Our study shows that the sensitivity to CO₂ changes depends on the background climate over a region, and also depends on the vegetation type, needleleaf trees being much more sensitive than broadleaf trees in our model. This difference of sensitivity leads to a dominance of broadleaf types in the remaining simulated forests, which is not supported by pollen data, but nonetheless suggests a potential impact of CO₂ on the glacial vegetation assemblages. It also modifies the competitivity between the trees and makes the amplitude of the response to CO₂ dependent on the initial vegetation state.

URL: http://www.clim-past.net/7/557/2011/cp-7-557-2011.pdf

12055533 Zech, Roland (Brown University, Geological Sciences, Providence, RI); Huang, Yongsong; Zech, Michael; Tarozo, Rafael and Zech, Wolfgang. High carbon sequestration in Siberian permafrost loess-paleosols during glacials: Climate of the Past, 7(2), p. 501-509, illus. incl. strat. col., sketch map, 55 ref., 2011. Includes supplement: URL: http://www.clim-past.net/7/501/2011/cp-7-501-2011-supplement.pdf; published in Climate of the Past Discussion: 15 October 2010, URL: http://www.clim-past-discuss.net/6/2199/2010/cpd-6-2199-2010.html; accessed in Nov., 2011.

Recent findings show that the amount of organic carbon stored in high-latitude permafrost regions has been greatly underestimated. While concerns are rising that thawing permafrost and resultant CO₂ and methane emissions are a positive feedback mechanism at times of anthropogenic global warming, the potential role of permafrost carbon dynamics on glacial-interglacial timescales has received little attention. Here we present new results from a well-studied permafrost loess-paleosol sequence in north-east Siberia that almost spans two glacial cycles (~220 ka). We analysed the deuterium/hydrogen isotopic ratios (dD) of alkanes, which serve as proxy for paleo-temperature. Thus circumventing difficulties to obtain exact age control for such sequences, the results corroborate our previous notion that more soil organic carbon was sequestered during glacials than during interglacials. This fact highlights the role of permafrost in favouring preservation of soil organic matter. Reduced biomass production during glacials may have been of second-order importance on these timescales. Although future studies are needed to evaluate existing large estimates of carbon dioxide releases from thawing permafrost during the last termination (>1000 Pg C), we suggest that permafrost carbon dynamics contributed to the observed glacial-interglacial variation in atmospheric CO₂ and need to be included in carbon cycle and climate models.

URL: http://www.clim-past.net/7/501/2011/cp-7-501-2011.pdf

12050597 Reyes, Alberto V. (University of Alberta, Department of Earth and Atmospheric Sciences, Edmonton, AB, Canada); Froese, Duane G. and Jensen, Britta J. L. Permafrost response to last interglacial warming; field evidence from non-glaciated Yukon and Alaska: Quaternary Science Reviews, 29(23-24), p. 3256-3274, illus. incl. sects., strat. cols., 2 tables, sketch map, 114 ref., November 2010.

We present stratigraphic observations from three sites in eastern Beringia - Ch'ijee's Bluff in northern Yukon and nearby exposures on the Old Crow River, the Palisades on the Yukon River in Alaska, and placer mining exposures at Thistle Creek in west-central Yukon - which provide insight into the response of permafrost to regional warming during the last interglaciation. Chronology is based on the presence of Old Crow tephra, an important regional stratigraphic marker that dates to late Marine Isotope Stage 6, supplemented by paleoecology and non-finite ¹⁴C ages on wood-rich organic silts. Old Crow tephra overlies several relict ice wedges at the Palisades and Thistle Creek, indicating that permafrost at these sites did not thaw completely during the last interglaciation. Prominent deposits of last interglacial wood-rich organic silt are present at multiple sites in eastern Beringia, and probably represent accumulations of reworked forest vegetation due to thaw slumping or deposition into thermokarst ponds or depressions. Consistent stratigraphic relations between these deposits, Old Crow tephra, and ice wedge pseudomorphs at our three study sites, and at least six other sites in eastern Beringia, suggest that thaw of shallow permafrost was widespread during the last interglaciation. Limited stratigraphic evidence suggests that thaw was probably on the order of meters, rather than 10s of meters. The ubiquity of shallow permafrost degradation during the last interglaciation suggests that current ground warming may foreshadow widespread near-surface thaw under even modest future warming scenarios. However, the persistence of relict pre-last interglacial ice wedges highlights the potential for the regional antiquity of discontinuous permafrost, and provides compelling field evidence for the long-term resilience of deep permafrost during sustained periods of warmer-than-present climate.

DOI: 10.1016/j.quascirev.2010.07.013

12048695 Fischer, Luzia (University of Zurich, Department of Geography, Glaciology, Geomorphodynamics and Geochronology, Zurich, Switzerland); Amann, Florian; Moore, Jeffrey R. and Huggel, Christian. Assessment of periglacial slope stability for the 1988 Tschierva rock avalanche (Piz Morteratsch, Switzerland): Engineering Geology, 116(1-2), p. 32-43, illus., October 27, 2010. Based on Publisher-supplied data.

The Tschierva rock avalanche occurred on October 29, 1988 in the area of the Piz Morteratsch, Switzerland. Releasing a total volume of ~ 300,000 m³, the avalanche ran out over 1 km destroying a hiking trail before stopping on the Tschierva Glacier. We analyze the setting of this periglacial slope failure, combining geomechanical and cryosphere investigations to identify the primary factors contributing to the rock avalanche. An approach to slope stability assessment is presented that copes with existing data limitations in an inaccessible alpine terrain. Results from the analyses of morphology, geology, glaciation history, permafrost, hydrology, and meteorological data allowed preliminary inferences to be made regarding the influence of these factors on slope stability. Conceptual kinematic and numerical slope stability modeling critically analyzed the role of kinematic degrees of freedom, glacier retreat, and water infiltration from above the detachment zone. Results highlight the strong influence of discontinuity orientation with respect to the slope face, the role of a fault zone with increased joint density, and long-term progressive development of persistent discontinuities induced by glacier retreat and groundwater loading cycles in leading to the rock avalanche. The role of permafrost could not be clearly assessed, however observations and analyses indicate that permafrost had no dominant influence on the slope failure. Extraordinary precipitation prior to the event is suggested to have played a role in triggering the rock avalanche, especially in combination with observed superficial ice that could have sealed the rock face generating high water pressures. Our results emphasize the importance of analyzing multiple contributing factors when assessing alpine rock slope failures, with careful consideration of data limitations prevailing in such areas.

DOI: 10.1016/j.enggeo.2010.07.005

12050537 Nordvik, Trond (Geological Survey of Norway, Trondheim, Norway); Blikra, Lars Harald; Nyrnes, Erik and Derron, Marc-Henri. Statistical analysis of seasonal displacements at the Nordnes rockslide, northern Norway: Engineering Geology, 114(3-4), p. 228-237, illus., August 10, 2010. Based on Publisher-supplied data.

The Nordnes rockslide in northern Norway poses a threat to local settlements along the nearby fjord due to its potential of generating tsunamis. Therefore, a monitoring program was initiated in 2007. Evaluation of the resulting monitoring data is expected to provide important contributions to the understanding of the sliding mechanisms. This paper focuses on statistical analyses of continuous laser and crackmeter measurements at the Nordnes rockslide during a period of 16 months. Annual linear displacements and seasonal fluctuations were estimated from time series of 3 lasers and 10 crackmeters. Results from the analyses show that the north-westernmost part of the area has the largest movement of more than 5 cm per year, which makes this part the most critical in terms of generation of a rapid rockslide. The amplitudes of the seasonal fluctuations estimated from crackmeter time series were approximately 0.5 mm. The largest displacements clearly occur in autumn and early winter with a stagnation or retreat phase in spring and summer. Thus, the movements are not increased during snowmelt which is a normal seasonal characteristic elsewhere. Although the temperature changes have a significant effect on the observed displacements, the seasonal variations could not fully be modelled with temperature terms in the regression models suggesting that there are other additional controlling factors. The rockslide is localized in arctic and periglacial conditions, and the documented seasonal variations are interpreted to be linked to effects of deformations caused by seasonal frost and permafrost. Prediction intervals for future displacements were also derived from the current time series. These prediction intervals are considered useful for the evaluation of future measurements and may serve as basis for defining alert thresholds for possible future early warning systems.

DOI: 10.1016/j.enggeo.2010.04.019

12050533 Sun Binxiang (Shaoxing University, Department of Civil Engineering, Shaoxing Zhejiang, China); Yang Lijun; Liu Qi and Xu Xu. Numerical modelling for crushed rock layer thickness of highway embankments in permafrost regions of the Qinghai-Tibet Plateau: Engineering Geology, 114(3-4), p. 181-190, illus., August 10, 2010. Based on Publisher-supplied data.

Under the warm and ice-rich nature of permafrost and the scenarios of climate warming on the Qinghai-Tibet Plateau, it will be necessary to employ new techniques of cooling the ground temperature in the construction of the proposed Qinghai-Tibet Express Highway. Research indicates that including of a coarsely crushed rock layer may produce enhanced cooling of the embankment and underlying foundation soils, due to natural convection during winter months. As compared with a railway embankment, a highway embankment has a much wider driving surface which consists of asphalt and cement-stabilized sand-gravel layers above the crushed rock layer, thus resulting in increasing of yearly mean surface temperatures and decreasing of temperature differences between the lower and upper boundaries of the crushed rock layer during winter months. For this type of the highway embankment, successful application of natural convection cooling concept to the crushed rock embankment of the proposed Qinghai-Tibet Express Highway still has many problems, such as thickness of the crushed rock layer filled in the embankment to trigger winter-time natural convection. Development of winter-time natural convection in the crushed rock highway embankment was studied by the numerical simulations. The results indicate that natural convection in the highway embankment begins to occur in the side slope regions and gradually develops from two side slope regions to the middle portion with lowering of yearly harmonic surface temperatures. The dependence of the natural convection index on thickness of the crushed rock layer in the highway embankment exhibits three regions, i.e., with increasing of the crushed rock layer thickness, a zero region in which there is no obvious development of winter-time natural convection, a rapid-increase region in which there is a significant increase in the cooling capability of winter-time natural convection and a no-appreciable-increase region in which there is no appreciable increase in the cooling capability of natural convection. Crushed rock layer thicknesses in the highway embankment, corresponding to the initial point and end point of the rapid-increase region, are defined as minimum and maximum thicknesses of the crushed rock layer, which would trigger winter-time natural convection. The choice of the temperature difference across the crushed rock layer is a key in applying the natural convection index successfully to evaluating critical thicknesses of the crushed rock layer in the highway embankment. Evaluation of crushed rock layer thicknesses, with various grain sizes, was also performed.

DOI: 10.1016/j.enggeo.2010.04.014

12050667 Desilets, Darin (Sandia National Laboratories, Albuquerque, NM); Zreda, Marek and Ferre, Ty P. A. Nature's neutron probe; land surface hydrology at an elusive scale with cosmic rays: Water Resources Research, 46(11), Citation W11505, illus., 22 ref., 2010. Includes appendices.

Fast neutrons are generated naturally at the land surface by energetic cosmic rays. These "background" neutrons respond strongly to the presence of water at or near the land surface and represent a hitherto elusive intermediate spatial scale of observation that is ideal for land surface studies and modeling. Soil moisture, snow, and biomass each have a distinct influence on the spectrum, height profile, and directional intensity of neutron fluxes above the ground, suggesting that different sources of water at the land surface can be distinguished with neutron data alone. Measurements can be taken at fixed sites for long-term monitoring or in a moving vehicle for mapping over large areas. We anticipate applications in many previously problematic contexts, including saline environments, wetlands and peat bogs, rocky soils, the active layer of permafrost, and water and snow intercepted by vegetation, as well as calibration and validation of data from spaceborne sensors.

DOI: 10.1029/2009WR008726

12055241 Vonk, J. E. (Stockholm University, Department of Applied Environmental Science, Stockhom, Sweden); Sánchez-García, L.; Semiletov, I.; Dudarev, O.; Eglinton, T.; Andersson, A. and Gustafsson, Orjan. Molecular and radiocarbon constraints on sources and degradation of terrestrial organic carbon along the Kolyma paleoriver transect, East Siberian Sea: Biogeosciences, 7(10), p. 3153-3166, illus. incl. 3 tables, sketch maps, 79 ref., 2010. Part of special issue no. 76, Land-shelf-basin interactions of the Siberian Arctic, edited by Gustafsson, O, et al., URL: http://www.biogeosciences.net/special_issue76.html; includes supplement, URL: http://www.biogeosciences.net/7/3153/2010/bg-7-3153-2010-supplement.pdf; published in Biogeosciences Discussion: 2 July 2010, URL: http://www.biogeosciences-discuss.net/7/5191/2010/bgd-7-5191-2010.html; accessed in Dec., 2011.

Climate warming in northeastern Siberia may induce thaw-mobilization of the organic carbon (OC) now held in permafrost. This study investigated the composition of terrestrial OC exported to Arctic coastal waters to both obtain a natural integration of terrestrial permafrost OC release and to further understand the fate of released carbon in the extensive Siberian Shelf Seas. Application of a variety of elemental, molecular and isotopic (d¹³C and D¹⁴C) analyses of both surface water suspended particulate matter and underlying surface sediments along a 500 km transect from Kolyma River mouth to the mid-shelf of the East Siberian Sea yielded information on the sources, degradation status and transport processes of thaw-mobilized soil OC. A three end-member dual-carbon-isotopic mixing model was applied to deduce the relative contributions from riverine, coastal erosion and marine sources. The mixing model was solved numerically using Monte Carlo simulations to obtain a fair representation of the uncertainties of both end-member composition and the end results. Riverine OC contributions to sediment OC decrease with increasing distance offshore (35±15 to 13±9%), whereas coastal erosion OC exhibits a constantly high contribution (51±11 to 60±12%) and marine OC increases offshore (9±7 to 36±10%). We attribute the remarkably strong imprint of OC from coastal erosion, extending up to ~500 km from the coast, to efficient offshoreward transport in these shallow waters presumably through both the benthic boundary layer and ice-rafting. There are also indications of simultaneous selective preservation of erosion OC compared to riverine OC. Molecular degradation proxies and radiocarbon contents indicated a degraded but young (D¹⁴C ca. -60 per mil or ca. 500 ¹⁴C years) terrestrial OC pool in surface water particulate matter, underlain by a less degraded but old (D¹⁴C ca. -500 per mil or ca. 5500 ¹⁴C years) terrestrial OC pool in bottom sediments. We suggest that the terrestrial OC fraction in surface water particulate matter is mainly derived from surface soil and recent vegetation fluvially released as buoyant organic-rich aggregates (e.g., humics), which are subjected to extensive processing during coastal transport. In contrast, terrestrial OC in the underlying sediments is postulated to originate predominantly from erosion of mineral-rich Pleistocene coasts (i.e., yedoma) and inland mineral soils. Sorptive association of this organic matter with mineral particles protects the OC from remineralization and also promotes rapid settling (ballasting) of the OC. Our findings corroborate recent studies by indicating that different Arctic surface soil OC pools exhibit distinguishing susceptibilities to degradation in coastal waters. Consequently, the general postulation of a positive feedback to global warming from degradation of permafrost carbon may be both attenuated (by reburial of one portion) and geographically displaced (degradation of released terrestrial permafrost OC far out over the Arctic shelf seas).

URL: http://www.biogeosciences.net/7/3153/2010/bg-7-3153-2010.pdf

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12052215 O'Donnell, Jonathan A. The effects of permafrost degradation on soil carbon dynamics in Alaska's boreal region: 214 p., Doctoral, 2010, University of Alaska at Fairbanks, Fairbanks, AK. ISBN: 978-1-124-56145-5 Available from: Univ. Microfilms.

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12056371 Allard, Michel (University Laval, Centre d'Etudes Nordiques, Quebec, QC, Canada); Fortier, Richard; Calmels, Fabrice; Gagnon, O. and L'Hérault, Emmanuel. Ground ice conditions in Salluit, northern Quebec [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C54A-02, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

Salluit in Northern Quebec (ca. 1300 inhabitants) faces difficult ground ice conditions for its development. The village is located in a U-shaped valley, along a fjord that was deglaciated around 8000 cal BP. The post-glacial marine limit is at the current elevation of 150 m ASL. Among the mapped surficial geology units, three contain particularly ice-rich permafrost: marine clays, till and silty colluviums. A diamond drill was used to extract 10 permafrost cores down to 23 m deep. In addition, 18 shallow cores (to 5 m deep) were extracted with a portable drill. All the frozen cores were shipped to Quebec city where ground ice contents were measured and cryostructures were imaged by CT-Scanning. Water contents, grain-size and pore water salinity were measured. Refraction seismic profiles were run to measure the depth to bedrock. GPR and electrical resistivity surveys helped to map ice-rich areas. Three cone penetration tests (CPT) were run in the frozen clays to depths ranging from 8 to 21 m. Maximum clay thickness is ca. 50 m deep near the shoreline. The cone penetration tests and all the cores in clays revealed large amounts of both segregated and aggradational ice (volumetric contents up to 93% over thicknesses of one meter) to depths varying between 2.5 and 4 m, below which the ice content decreases and the salinity increases (values measured up to 42 gr/L between 4.5 and 6 m deep). Chunks of organic matter buried below the actual active layer base indicate past cryoturbations under a somewhat warmer climate, most probably associated with intense frost boil action, as widely observed today. The stony till has developed large quantities of segregation ice which can be seen in larger concentrations and as thicker lenses under boulders and in matrix rich (>&eq;50% sand and silt) parts of the glacial sediment. As digging for a sewage pond was undertaken in winter 2008 by blasting, the clast-influenced cryostructure of the till could be observed in cuts and in large chunks of permafrost. Volumetric ice contents between 30 and 70% were measured in the till. In addition, low lying areas where till thickness exceeds ca 5 m contain polygons with ice wedges up to 2 m wide. Colluviums on slopes laid by sheet flow have been accumulating on two sectors of the study area, the source material being eroded clay at higher elevations; these slope sediments contain alternating layers of buried organics (C-14 date of 2300 BP at base of the sequence), silt and lenses of aggradational ice. Although the surface geophysical methods (electrical resistivity, GPR) were essential for mapping ice rich permafrost, the detailed appraisal of ground ice conditions was made truly possible by drilling and extracting intact cores. The use of the Cat-scan method proved very efficient for the precise and rapid measurement of ground ice contents and for imaging cryostructures on a large number of samples, thus providing exact information on permafrost composition and for interpreting permafrost history. The Salluit study also involves climate monitoring, thermal analysis and modeling, and intense community consultations.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056377 Bennett, K. E. (University of Alaska Fairbanks, International Arctic Research Center, Fairbanks, AK); Hinzman, L. D.; Cherry, J. E.; Walsh, J. E.; Hiemstra, Christopher A.; Balk, Ben C. and Lindsey, Scott. Hydro-climatology of a discontinuous permafrost watershed in interior Alaska [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C54A-08, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

Hydrologic modeling in the northern interior region of Alaska is particularly challenging owing to the properties of the discontinuous permafrost underlying watersheds and the complex interaction between topography, permafrost, vegetation, and hydro-climate. Notwithstanding the difficulty in modeling frozen soil moisture interactions in discontinuous permafrost basins and simulating the inputs of moisture into the soil profile via snow melt; hydro-climatologic data sets in the high latitudes are often short, discontinuous, and require rigorous validation to ensure data quality prior to their use in forcing models. This work presents results from the first phase of a broader modeling project in the Chena River basin, a 6500 km² watershed located in interior Alaska near the town of Fairbanks. This basin has been the stage of several costly and damaging flood events that led to development of flood control structures by the US Army Corps of Engineers. The focus of the initial examination is on the relationships between basin aspect, permafrost, vegetation and climate (temperature, precipitation and snow pack) observed in historical records and satellite imagery. The goal of the work is to improve permafrost processing and snow cover observations within the River Forecast Center's hydrologic modeling framework (CHPS; SAC-SMA and SNOW17). The improved models will eventually be used to investigate changes in historical and future patterns of extreme hydro-climate events. North and south facing aspects are a distinct control on snow melt in this watershed, which is related to the regional hydro-climate via physiographic and vegetation controls. Identifying these relationships in the historical record provides important context for modeling future changes as projected by regional climate models, as future temperature and precipitation regimes and possible threshold responses in permafrost could shift these relationships and result in changes in extremes. These findings and the exploration intended for the broader project are anticipated to be valuable for both engineers and forecasters who are interested in extreme hydro-climate impacts in this region of the north.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056366 Endrizzi, Stefano (University of Zurich, Department of Glaciology and Geomorphodynamics, Zurich, Switzerland). The GEOtop model as a tool to describe the strongly coupled energy and water balance in permafrost or seasonally-frozen soils [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C53G-04, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

GEOtop is a small scale grid-based model that couples the soil heat and water budgets, represents the energy exchange with the atmosphere considering the radiative and turbulent fluxes, and describes the subsurface water flow in its fully three-dimensional nature. In particular, the model reproduces the strong coupling between water and energy balance during soil freezing and thawing processes, considering the highly non-linear heat capacity effect resulting from phase change. In addition, it describes the water and energy budgets in the snow cover, represents blowing snow, and models the temporal evolution of the snow depth and, therefore, its effect on soil temperature. Infiltration in frozen soil and runoff are also represented. Vegetation effects are considered, in particular as regards snow interception, trapping, and the interactions with turbulent and radiative heat exchange. GEOtop is therefore a very useful tool in several applications that involve permafrost and seasonally-frozen soils, both in high altitude and latitude regions. In particular, GEOtop allows evaluating the effects of water lateral transport in the freezing/thawing process, effects that are often neglected, but may be significant. Applications are shown for i) a typical peat-covered arctic environment, where the position of the frost table controls the runoff production rate, due to the strong decrease of the soil hydraulic conductivity with depth; and ii) an alpine site, where borehole data are used to test the model and the effect of the upslope drainage distance is studied.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056364 Frampton, Andrew (Stockholm University, Physical Geography & Quaternary Geology, Stockholm, Sweden); Painter, S.; Lyon, Steve W.; Sjoberg, Ylva and Destouni, Georgia. Transient modeling of permafrost dynamics in a changing climate [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C53G-02, illus., December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

Analysis of permafrost dynamics is conducted with a recently developed numerical model which is capable of handling a three-phase, two-component flow system coupled to heat transport. This approach enables a thorough physically-based description of permafrost flow dynamics. It can further utilize classical water-retention curves for unsaturated media under non-freezing conditions, which have been complied for many soil types and are readily available in the literature Here we consider simulation configurations representing small-scale subsurface domains with various soil textures relevant for high-latitude arctic and subarctic discontinuous permafrost environments. These are evaluated in terms of how they exhibit control on the formation and development of permafrost, together with dynamics of water flow and transients in groundwater discharge, subject to both seasonal temperature variability and warming climate scenarios. Previous results have indicated a reduction in temporal variability of groundwater flow for a moderate temperature trend over a long time period of warming. Recent results indicate similar behavior also for larger rates-of-change, i.e., faster temperature increases over shorter time periods. This implies that greater warming trends yield relatively fast changes in annual flow variability, which may serve as early indicators for permafrost degradation rather than solely relying on long-term changes in mean flows. This is advantageous to performing multiple direct in-situ--and often costly--local measurements of permafrost degradation, since detection of changes in hydrological signals is easier to establish, and hydrological time series exist for relatively long time periods and encompass integrated catchment scale behavior.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056370 French, H. Cryostratigraphy, paleocryostratigraphy and previously frozen ground [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C54A-01, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

Cryostratigraphy differs from traditional stratigraphy by explicitly recognizing that perennially frozen sediment and rock (permafrost) contain structures that are different to those found in unfrozen sediment and rock. These differences are usually related to either the nature of the ice contained within the frozen sediment or to weathering processes and chemical precipitates that are associated with freezing and thawing. Paleocryostratigraphy attempts to infer the previous freezing history of currently-frozen sediment and rock. In areas where frozen ground no longer exists, as in the mid-latitudes today, Pleistocene periglacial reconstruction employs a variety of cryostratigraphic and paleocryostratigraphic principles.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056374 Gilichinsky, D. (Russian Academy of Sciences, Soil Cryology Laboratory, Pushchino, Russian Federation). Terrestrial permafrost models of Martian habitats and inhabitants [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C54A-05, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

The terrestrial permafrost is the only rich depository of viable ancient microorganisms on Earth, and can be used as a bridge to possible Martian life forms and shallow subsurface habitats where the probability of finding life is highest. Since there is a place for water, the requisite condition for life, the analogous models are more or less realistic. If life ever existed on Mars, traces might have been preserved and could be found at depth within permafrost. The age of the terrestrial isolates corresponds to the longevity of the frozen state of the embedding strata, with the oldest known dating back to the late Pliocene in Arctic and late Miocene in Antarctica. Permafrost on Earth and Mars vary in age, from a few million years on Earth to a few billion years on Mars. Such a difference in time scale would have a significant impact on the possibility of preserving life on Mars, which is why the longevity of life forms preserved within terrestrial permafrost can only be an approximate model for Mars. 1. A number of studies indicate that the Antarctic cryosphere began to develop on the Eocene-Oligocene boundary, after the isolation of the continent. Permafrost degradation is only possible if mean annual ground temperature, -28°C now, rise above freezing, i.e., a significant warming to above 25°C is required. There is no evidence of such sharp temperature increase, which indicates that the climate and geological history was favorable to persistence of pre-Pliocene permafrost. These oldest relics (~30 Myr) are possibly to be found at high hypsometric levels of ice-free areas (Dry Valleys and nearby mountains). It is desirable to test the layers for the presence of viable cells. The limiting age, if one exists, within this ancient permafrost, where the viable organisms were no longer present, could be established as the limit for life preservation below 0°C. Positive results will extend the known temporal limits of life in permafrost. 2. Even in this case, the age of Martian permafrost is still 100 times older. Only one terrestrial environment is close to Mars in age - volcanoes in permafrost areas. The age of volcanic deposits frozen after eruption is much younger than the age of surrounding permafrost. Culture- and culture-independent methods show the presence of viable thermophiles and their genes within pyroclastic frozen material on Deception Island, Antarctica and Kamchatka peninsula. These bacteria and archeae have not been found in permafrost outside the volcanic areas. The only way for thermophiles to get into frozen soil is through deposition during eruption, i.e. the catastrophic geological events transport microbes from the depths to the surface and they survive at subzero temperatures. The past activity of Martian volcanoes periodically burned through the frozen strata and products of eruptions rose from the depths to the surface and froze. Images taken by the Stereo Camera on board the Mars Express discovered volcanoes 2-15 Myr old that date back to ages close to permafrost on Earth. Terrestrial communities might serve as a model of inhabitants for these young volcanoes. 3. The only opportunity for free water on Mars is the overcooled water brines, and halo/psychrophilc community of Arctic cryopegs, sandwiched within permafrost, represents a plausible prototype for Martian microbial life.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056372 Hauber, Ernst (German Aerospace Centre (DLR), Department of Planetary Geology, Berlin, Germany); Ulrich, Mathias; Reiss, Dennis; Hiesinger, H.; Balme, Matt R. and Gallagher, Colman J. Towards climate reconstruction on Mars using landscape analysis; insights from terrestrial analogues [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C54A-03, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

Many very young landforms on Mars resemble terrestrial glacial and periglacial surface features in permafrost regions and show a latitude-dependent geographic distribution. They include surface mantling, viscous flow features, polygonally fractured ground, patterned ground, fractured mounds, and gullies. Collectively, these landforms are hypothesized to represent the geomorphological surface record of Martian ice ages that were triggered by astronomical forcing and associated climate changes. Many previous studies of possible cold-climate features on Mars considered just one of them in isolation, e.g., polygons or fractured mounds. Such approaches do not consider the geomorphologic context of the landforms, and thus interpretations can be ambiguous due to the possible effect of equifinality. A more comprehensive investigation of the full assemblage of associated landforms (landscape analysis) has the potential to reduce this ambiguity. We use the permafrost landscape of Spitsbergen (Svalbard, Norway) as an analogue for the assemblage of cold-climate landforms that is typically found in mid-latitudes on Mars. Although relatively warm and wet as compared to other cold-climate analogues on Earth, Spitsbergen is a particularly instructive morphological analogue to Mars as it offers many surface features in a close spatial context that are strikingly similar to those on Mars. Based on this comparison, which uses remote sensing and field data from Svalbard, we identify similarities as well as differences, both of which are important in the use of analogues as a means to establish testable hypotheses. We then propose possible scenarios which may help to understand the evolution of Martian landforms into their present state. Of particular interest with respect to the habitability of Martian permafrost is whether liquid water was involved or not. Most phenomena on Mars, but not Svalbard, can plausibly be explained by "dry" permafrost scenarios without the need to invoke freeze/thaw. Examples of such processes are the slow creep of ice-debris mixtures in permafrost, such as rock glaciers or debris-covered glaciers, or the aggradation and degradation of niveo-aeolian deposits. Other landforms could be explained with and without the availability of liquid water. Examples are thermal contraction polygons, which could form as ice-wedge polygons indicating thaw and liquid water, or, alternatively, as sublimation polygons. Former glaciers could have either been warm-based or cold-based, and therefore do not provide constraints on the history of liquid water. Some landforms such as gullies, however, seem to definitely require at least transient liquid water sometimes in the last ~10 Ma. We conclude that liquid water is unlikely to have a significant effect in the last few million years, but could have been more important before ~5 Ma.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056376 Henkemans, Emily (University of Waterloo, Department of Earth Science, Waterloo, ON, Canada); Frape, Shaun; Ruskeeniemi, Timo; Claesson-Liljedahl, Lillemor; Lehtinen, Anne and Annable, W. K. Hydrogeochemistry of groundwater as part of the Greenland analogue project in an area of continuous permafrost adjacent to the Greenland ice sheet, Kangerlussuaq, West Greenland [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C54A-07, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

Studying groundwater in areas of continuous permafrost is often limited to studies of springs and open pingos (e.g. Pollard et al. 1999 and Allen et al. 1976). Boreholes in such locations are expensive, risky and logistically challenging (e.g. Stotler et al. 2011) resulting in a limited understanding of the interaction between continental scale ice sheets and groundwater. Continental ice sheet models are often coupled to groundwater flow systems; however, there is a lack of modern field data with which to compare the results of models and their treatment of groundwater flow systems under the influence of glaciation. The Greenland Analogue Project (GAP) aims to eliminate some of the uncertainties in modeling ice sheets by using the Greenland ice sheet as a modern analogue for past glaciations. Since 2009, 3 boreholes have been drilled, 2 of which contain sampling systems. DH-GAP01 is a 191 m deep borehole drilled at an angle into a talik and has been sampled and studied since 2009. DH-GAP04 is a 632 m deep, angled borehole that intersects the groundwater flow system directly beneath Isunguata Sermia and is producing preliminary groundwater samples. Additional information on groundwater in the Kangerlussuaq area comes from a spring located directly in front of the Leverett ice lobe. Geochemical and isotopic (d18O, d2H, d37Cl, 87Sr/86Sr, and d34S and d18O of SO4) tools are used to interpret geochemical processes acting on groundwaters and provide insight into groundwater flow. Analyses of d18O and d2H in groundwaters from DH-GAP01 show the borehole waters fall along the Global Meteoric Water Line (GMWL). Evaporation is an important process affecting the d18O-d2H of surface waters in the region causing lakes to plot along a local evaporation line (Leng and Anderson, 2003). The waters from the Leverett spring plot to the right of the GMWL as possibly a mixture of groundwater and surface evaporated fluids. However, both the waters from DH-GAP01 and the Leverett spring show depletion relative to surface waters and precipitation in the region. DH-GAP01 and the Leverett spring differ from each other both in chemical and isotopic composition. This reveals a difference in geochemical processes that may be related to the presence of what is likely more than 100 m of glacial sediment beneath the Leverett Spring. The 87Sr/86Sr ratio of DH-GAP01 waters (0.7075) is similar to that of waters extracted from crush and leach experiments, ranging from 0.7061 to 0.7135, performed on sections of drill core from DH-GAP01 and a second borehole located 6 km away and supports water-rock interaction as the source of salinity in these dilute (<900 mS/cm) groundwaters. The strontium ratio in the Leverett spring waters falls within the range described by surface waters in the area. Surface waters found closest to the ice sheet are strongly radiogenic (up to 0.7574) compared to less radiogenic signatures (0.7298) further from the ice margin which may reflect more mature weathering profiles in areas further from the ice.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056378 Jin, D. (Korea Polar Research Institute, Incheon, South Korea); Kim, Seong and Lee, H. Research activity and infrastructure of Korea Polar Research Institute; current and future perspectives [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C54B-01, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

The Korea Polar Research Institute (KOPRI) opened the Antarctic King Sejong research station in 1988 at the King George Island off the Antarctic Peninsula and started the polar research mainly in the fields of biology and geology with some atmosphere observations. To extend the view of polar research, the KOPRI opened the Arctic Dasan research station at Ny-Alesund, Spitsbergen Island in 2002 and has studied the rapid climate change diagnostics and some microbiological observation. The KOPRI is now expanding the Arctic research into Alaska and Canada under the international collaboration, and planning to outreach to Russia to monitor the change in permafrost and to understand its impact on global warming. To deepen the views of polar research including the ice covered oceans in both poles, the ice-breaking vessel, the ARAON of about 7000 ton, was launched recently and successfully finished the Arctic and Antarctic cruises for research activity on all perspectives of ocean sciences and support for the King Sejong station. The KOPRI is now building another Antarctic research station, called Jangbogo, at the Terra Nova Bay off the Ross Sea and plan to open the station at the March of 2014. By building the second Antarctic station together with the ARAON, the KOPRI will focus its research on understanding the rapid climate change in west Antarctica such as to monitor the calving of the Larsen Ice shelf, rapid melting of Pine Island Glacier, and upper atmosphere, to study the sea ice and ecosystem change in the Amundsen Sea and the role of the southern annular mode in the west Antarctic warming, upper atmosphere and climate change, to reconstruct paleoclimate records from ice and sediment cores.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056368 Lawrence, D. M. (National Center for Atmospheric Research, Boulder, CO); Swenson, S. C.; Slater, A. G. and Lee, Hanna. Advances in modeling interactions between thermal, hydrologic, and ecosystem states in permafrost-affected zones in the community land model [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C53G-06, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

Thermal, hydrologic, and ecosystem processes are intricately coupled in permafrost-affected environments and are challenging processes to model. We describe a set of improvements to the Community Land Model (CLM), the land model used in the Community Earth System Model, that expand the model's capability to represent cold region hydrological processes and which resolve several critical biases in the model's high latitude ecosystem simulation. The improvements include changes to the parameterization of vertical soil water flow into and through icy/frozen soils, a representation of the active layer water table position, the introduction of a surface water storage pool that permits a prognostic simulation of wetland distribution, and the introduction of a simple river flooding model. Together, these improvements result in a substantial improvement of the hydrologic, thermal, and ecosystem simulation in permafrost-affected zones, yielding more realistic active layer soil moisture levels which supports more realistic vegetation growth, improved river discharge hydrographs of the Arctic rivers. Prognostic wetland distribution enables a more direct and integrated coupling with a methane emissions model that has recently been developed for CLM. We assess the impact of the more realistic hydrologic simulation on simulations of soil thermal (e.g., active layer thickness and deep ground temperature) and vegetation states. Additionally, we examine how the improved hydrology alters projected permafrost degradation rates.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056369 Lebedeva, Lyudmila (Saint Petersburg State University, St. Petersburg, Russian Federation) and Semenova, O. Long-term data of the Kolyma water-balance station; results of upscaling the process comprehension to basins with limited observations [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C53G-07, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

Most basins in permafrost environment possess very limited information available and are indeed a challenge for hydrological modelling. Long-term datasets of detailed process observations are essential for processes comprehension, model conceptualization and parameters assessment, validation of developed approaches. The Kolyma water balance station (KWBS) may be considered as the world oldest research watershed in permafrost environment being established in 1948. It is located in the North-Eastern Russia within the upstreams of the Kolyma River. The station was intended for long-term collection of observations and investigation of runoff, variable states, water balance components, etc. Such, within a territory of 22 km2 about 30 precipitation, 7 runoff gauges, and more than 20 cryopedometers had been operating at the KWBS with records from 3 to 25 years. Active layer depth varies widely from 0.5 to 2 m depending on a landscape and location on the slope. The previous studies have proved that this research watershed is representative for a large territory of the Russian North-East covered by permafrost. The goal of this continuous study is the analysis of the KWBS observational dataset in terms of assessment, development and validation of hydrological concepts and estimation of hydrological model parameters. The Hydrograph, which is a distributed process-based runoff formation model developed in Russia, is applied. The model describes all essential components of land hydrological cycle specific for permafrost environment including snow processes, soil moisture/heat dynamics and phase change processes in thawing and frozen soils. It has been successfully tested in various geographic regions, including temperate and tropical climates but most extensively in snow-dominated basins of Eastern Siberia and Northwestern Canada. Two major types of active layer depth formation were derived. The deepest one, up to the 1.6 m, forms at the rock debris landscape. Minimum depth of thawing (0.6 m) is observed in swamped forest. Maximum simulated thawing depth during summer period is coincident with the observed values at both landscapes while simulated process of soil freezing is delayed in comparison with the observed data. Maximum within-year deviation of calculated runoff from observed values occurs during snowmelt. Simulated and observed hydrographs agree reasonably well for the period of late summer and autumn. To validate the developed model and test estimated values of the model parameters the upscaling was conducted from the research watershed to larger scales. Runoff formation processes were simulated for four basins in the upstreams of Upper Kolyma River with area of several thousands square kilometers. The results of the Hydrograph model algorithm advancement based on the KWBS data and its application at large-scale basins would be presented including simulations of soil active depths at different landscapes and runoff.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056363 Lyon, Steve W. (Stockholm University, Physical Geography & Quaternar, Stockholm, Sweden); Sjoberg, Ylva; Jantze, Elin J. and Destouni, Georgia. Estimating permafrost changes via storage-discharge dynamics [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C53G-01, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

Permafrost influences the hydrologic response of a catchment. As such, it makes sense to use hydrologic changes at the catchment-scale to estimate changes in permafrost condition and distribution. This talk highlights recent advancements on relating catchment-scale storage-discharge dynamics to long-term permafrost changes. Results are considered from across a variety of settings spanning arctic to alpine permafrost environments. The strength of this approach is that it requires only observations of streamflow to reflect changes on much larger measurement support scales than the local scales of direct permafrost observations. In addition, by relying on a hydrologic process function change, rather than an absolute flow change, detection of permafrost changes are made independently of absolute streamflow changes that integrate various subsystems and thus may mask different subsystem flow changes within a catchment. This provides information that forms a basis for development of physically-based models capable of representing groundwater-permafrost interactions and biogeochemical fluxes under climatic changes.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056365 Quinton, W. L. (Wilfrid Laurier University, Cold Regions Research Centre, Waterloo, ON, Canada) and Hayashi, M. Runoff from wetland-dominated terrains with thawing permafrost [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C53G-03, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

This study was conducted in the wetland-dominated, southern margin of continental permafrost at Scotty Creek, NWT, Canada over the period 2001-2010 to improve the understanding and model-representation of the key water flow and storage processes that control the hydrological response of catchments in the region. This study contributes to resolving some of the difficult challenges in understanding and modelling the storage and routing functions of wetlands-dominated basins underlain by discontinuous permafrost that typify the southern boundary of permafrost, and provides insights into how the wide-spread permafrost thaw in this environment may alter stream flows. Permafrost thaw is one of the most important and dramatic manifestations of climate warming in Canada, and has the potential to alter the volume and timing of runoff to downstream ecosystems. While permafrost thaw occurs in varying degrees throughout the North, the discontinuous permafrost zone of the subarctic is where the most dramatic thaw and resulting landscape transformations are currently observed. Forecasted dramatic changes in temperature and moisture are expected to affect the processes governing the flux and storage of water in this region where little is known about the interactions between thawing permafrost and hydrology. A major challenge to northern water resources management in the 21st century therefore lies in predicting stream flows dynamically in the context of widely-occurring permafrost thaw. This study draws on 10-years of field observation at Scotty Creek, NWT to explain: 1) a conceptual model of the hydrological interactions among the major terrain types of wetland-dominated discontinuous permafrost that typify the southern margin of permafrost; 2) soil thaw and re-freezing processes that control runoff generation from permafrost plateaus; 3) the importance of vertical and horizontal heat flows in thawing permafrost; and 4) how thaw-induced land-cover changes can alter basin runoff production in this region. Annual and seasonal runoff from a thawing permafrost plateau is simulated using the Cold Regions Hydrological Model and computed from the water balance for the period 2001-2010.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056373 Stoker, Carol (NASA, Ames Research Center, Space Science Division, Moffett Field, CA). Permafrost as a habitable environment on Mars; insights from the Phoenix Mars Mission [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C54A-04, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

The Phoenix mission landed in the northern plains of Mars (68.2°N, 234.3°E) in May 2009, at a location with ground ice within 10 cm of the surface (1). A mission objective was to determine whether conditions at the surface or near subsurface could supporting living organisms with capabilities similar to terrestrial microbes, either at present or in the recent past (2). The lander carried a robotic arm with digging scoop to collect soil and icy material and performed volatile mineral and organic analysis (3) and wet chemical analysis (4). Results from Phoenix along with theoretical modeling and other previous mission results can be used to evaluate the habitability of the landing site (2). Factors that characterize the environments' ability to support life as we know it are the presence of liquid water, the presence of an energy source to support metabolism, the presence of nutrients containing the fundamental building blocks of life, and the absence of environmental conditions that are toxic to or preclude life. Phoenix observational evidence for the presence of liquid water (past or present) includes clean segregated ice (1), chemical etching of soil grains (2), calcite minerals in the soil (3), and variable concentrations of soluble salts (5). The present maximum surface temperature measured is 260K (6) so unfrozen water can form only in adsorbed films or saline brines but warmer climates occur cyclically on geologically short time scales due to variations in orbital parameters. During the most clement periods, temperatures allowing metabolism extend nearly a meter into the subsurface (7). Energy to drive metabolism is available from sunlight, beneath semi-transparent soil grains that can provide shielding from UV radiation. Phoenix also discovered perchlorate (4), a chemical energy source utilized by a wide range of microbes, occurs in high soil concentrations. Biologically available C, H, N, O, P and S compounds are supplied by known atmospheric sources or global dust. Environmental conditions are within growth tolerance for terrestrial microbes. Summer daytime temperatures are sufficient for metabolic activity, the pH is 7.8 and is well buffered (4), and the projected water activity of a wet soil will allow growth. In summary, martian permafrost in the north polar region is a viable location for modern life. Future missions to search for modern life on Mars could target permafrost on Mars.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056367 Ulrich, Mathias (Alfred Wegener Institute for Polar and Marine Research, Potsdam, Germany); Schirrmeister, Lutz and Hauber, Ernst. Permafrost landform studies on Earth; implications for periglacial landscape evolution and habitability on Mars [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract C53G-05, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

Periglacial landforms on Earth reflect cold-climate conditions in connection with permafrost (i.e. ground-ice-related) dynamics. Many geomorphological features, which are interpreted to be periglacial landforms, are in particular distributed in Martian mid-latitudes. In this study we modeled geological and geomorphological evolution of Martian periglacial landscapes using terrestrial analogous environments as reference, and it aimed at reconstructing processes and environmental conditions responsible for their formation. Therefore, spatial analyses of periglacial key regions on Earth and Mars using high-resolution remote-sensing data were supported by detailed terrestrial field investigations in NE Siberia (Russia) and on Svalbard (Norway). Morphometric analyses, modeling of process-controlling factors, and multivariate statistics were conducted with focus on specific periglacial relief features, i.e. depressions formed by permafrost degradation and polygonal patterned ground. Based on our findings, the potential of permafrost environments on Mars to be habitable are discussed in particular for Utopia Planitia in the Martian northern hemisphere. In this context, the influence of liquid water in periglacial landscape evolution on Mars during its recent geological history is of special importance as liquid water is the major requirement for the existence, evolution, and preservation of any kind of life. The insights obtained from terrestrial analogue studies are summarized to discuss past and present subsurface and climate conditions in relation to periglacial landscape evolution on Mars. Specific climate periods are identified for the most recent Martian history (<10 million years), which meet the requirements of distinct orbital configurations (high obliquity (>35°), high eccentricity (>0.1), and northern summer at perihelion) during which thaw processes and liquid water could have had an influence on periglacial landscape evolution in Martian mid-latitudes. Liquid water involved in the evolution of permafrost landforms in Utopia Planitia might have allowed the development of habitable micro-climatic niches, which are strongly related to specific permafrost landform morphology.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12056306 Ziolkowski, L. A. (McMaster University, Origins Institute, Hamilton, ON, Canada); Mykytczuk, Nadia C.; Whyte, Lyle and Slater, G. F. Contemporary microbes in hypersaline springs that contain fossil carbon [abstr.]: in AGU 2011 fall meeting, American Geophysical Union Fall Meeting, 2011, Abstract B54B-07, December 2011. Meeting: American Geophysical Union 2011 fall meeting, Dec. 5-9, 2011, San Francisco, CA.

On Axel Heiberg Island, near 80°N in the Canadian Arctic, perennial hypersaline springs provide a unique environment for cold-active microbes. The neutral pH Gypsum Hill springs originate in a gypsum diaper and flow through 600 m of continuous permafrost before reaching the surface at ~6°C, 7.5% NaCl, low dissolved inorganic carbon and rich in both sulfate and sulfide (Pollard et al., 2009). In the first part of the year, when ambient temperatures dip as low as -40°C, filamentous streamers are abundant under the snow covered run-off channels. These microbial assemblages are not present during the summer, when the snow cover has melted. Culture- and molecular-based analyses of the 16S rRNA gene indicated that the streamers are dominated by a chemolithoautotrophic sulfur-oxidizing Thiomicrospira species and under in situ conditions the streamers oxidized sulfide and thiosulfate and also fixed CO₂ (Perreault et al., 2008). We characterized the isotopic composition (¹³C and ¹⁴C) of the microbial community biomarkers as phospholipid fatty acid (PLFA) and glycolipid fatty acid (GLFA) methyl esters. These components represent the cell membranes of the viable microbial community, which are quickly hydrolyzed after cell death and provide insight into the carbon cycling of the organisms. Even though isotopic measurements of the bulk biomass indicate carbon and nitrogen limitation within the system, the streamers are rich in biomass with greater than 10⁹ cells/g. While the PLFA and GLFA profiles were similar, indicating a predominantly gram-negative bacteria community, the ¹³C composition of these two lipid types was different. The PLFA d¹³C indicated a dominant autotrophic signal, while the d¹³C of the GLFA had a more heterotrophic signal. While the streamers grow yearly, their ¹⁴C age based on the lipid results was 6400 years, indicating utilization of a carbon source that is ¹⁴C depleted. We hypothesize that these microbes are using ¹⁴C depleted dissolved inorganic carbon carried by the groundwater. This is a unique system where the C utilized by a surface microbial community is in fact not from the atmosphere. These results indicate that communities in extreme environments may be using geologically derived substrates.

URL: http://www.agu.org/cgi-bin/SFgate/SFgate?language=English&verbose=0&listenv=tabl ...

12053774 Douglas, T. A. (U. S. Army Cold Regions Research and Engineering Laboratory, Fort Wainwright, AK); Jacobson, A. D.; McClelland, J. W.; Barker, A. J.; Khosh, M. S. and Lehn, G. O. Permafrost active layer dynamics inferred from major element geochemical signatures in six Arctic Alaskan rivers [abstr.]: in Goldschmidt 2011 abstract volume, Mineralogical Magazine, 75(3), p. 777, June 2011. WWW. Meeting: Goldschmidt2011, Aug. 8-14, 2011, Prague, Czech Republic.

Arctic climate warming is expected to degrade permafrost and affect watershed hydrogeology and biogeochemistry. Increasing temperatures could lead to the downward migration of the seasonally thawed (active) layer into previously frozen soil. This could create a unique weathering signal in surface waters during late summer and early fall when the active layer is at its deepest extent. The response of permafrost to climate warming may not lead to a simple, homogeneous increase in active layer depths. Ice lenses, peat layers, and heterogeneous soil ice (water) contents will respond differently to warming. Our study was initiated to determine whether geochemical tracers can provide a proxy for these active layer dynamics in Arctic watersheds. We collected up to 65 surface water samples from six Arctic Alaskan rivers from melt to freeze-up in 2009 and 2010. Watershed areas range from 1.6 to 610 km². Two rivers were underlain by organic rich permafrost, two rivers drained mountainous bedrock, and two rivers were underlain by both bedrock and organic rich permafrost. We measured the major ion geochemistry of the water samples. For most of the rivers, Na, Ca, Mg, and SO₄ concentrations are lower during melt runoff and steadily increase throughout the summer into the fall. Potassium values are greatest in early melt waters and then decrease through the summer into the fall. Nitrate concentrations increase steadily in the late fall in bedrock dominated streams, suggesting a decrease in N assimilation rates in the bedrock soils during late summer and fall. Our results suggest river chemistry is driven by flow paths that deepen from surface to mineral soils as the melt season progresses.

URL: http://minmag.geoscienceworld.org/content/75/3/712.full.pdf+html

12055667 Ford, Derek (McMaster University, School of Geography and Earth Sciences, Hamilton, ON, Canada). From the plains of Abraham to Dodo Canyon; remarkable dolomite karst in permafrost in the Mackenzie Mountains, Northwest Territories, Canada [abstr.]: in 21st British Cave Research Association Cave science symposium, Cave and Karst Science, 37(1), p. 25, 2010. Meeting: 21st British Cave Research Association Cave science symposium, March 6, 2010, Bristol, United Kingdom.

12052899 Oliva, Marc (University of Lisbon, Institute of Geography, Lisbon, Portugal). Climate variability and periglacial processes during the mid-late Holocene in Sierra Nevada (southern Iberian Peninsula) [abstr.]: in European Geosciences Union general assembly 2010, Geophysical Research Abstracts, 12, EGU2010-2561, 2010. Meeting: European Geosciences Union general assembly 2010, May 2-7, 2010, Vienna, Austria.

12054450 Teodoro, L. F. A. (NASA, Ames Research Center, Moffett Field, CA); Elphic, R. C.; Sigler, M. and Eke, V. R. Realistic models of ice distribution on the lunar sub-surface [abstr.]: in Annual meeting of the Lunar Exploration Analysis Group (Shearer, Charles K., convener; et al.), LPI Contribution, Rep. No. 1595, p. 69, illus., 5 ref., 2010. Meeting: Annual meeting of the Lunar Exploration Analysis Group, Sept. 14-16, 2010, Washington, DC. Accessed on April 27, 2012.

URL: http://www.lpi.usra.edu/meetings/leag2010/pdf/3080.pdf

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12051482 Hill, P. R. and Mate, D. J., compilers. Five municipal case studies on adapting to climate change for professional planners--Cinq études de cas sur les moyens d'adaptation au changement climatique à l'intention des urbanistes: Open-File Report - Geological Survey of Canada, Rep. No. 6180, 190 p., (English, French), illus., 2011. WWW. Accessed on May 16, 2012.

From 2002 to 2006, the Earth Sciences Sector of Natural Resources Canada implemented a program entitled "Reducing Canada's Vulnerability to Climate Change". Within this program, one project, "Municipal Case Studies: the planning process and climate change" aimed to generate scientific knowledge on a sample of the major climate change impacts facing Canadian communities. One of the desired outcomes of this project was that professional planners would use geoscientific information in planning for climate change. The case studies were selected to address issues such as water resource depletion, coastal erosion due to higher sea levels, and permafrost melting. In order to make the results of the case studies accessible to the planning community, City Spaces Consulting Ltd., a planning consulting firm based in Victoria, British Columbia, was contracted to produce summary reports of the five case studies and draw out the planning implications of the results. This Open File presents these summary reports in both official languages. We would like to acknowledge the contributions of the numerous scientific collaborators and community participants in these studies that are listed in the individual reports. Natural Resources Canada scientists led two of the case studies (Calgary: Steve Grasby; Delta: Phil Hill). The other three were led by the University of Victoria (Graham Island: Ian Walker), Universite Laval (Salluit: Michel Allard) and Environment Canada (New Brunswick coast: Real Daigle) with NRCan scientist participation.

URL: http://geopub.nrcan.gc.ca/moreinfo_e.php?id=289255

12051596 Leblanc, A. M.; Allard, M.; Carbonneau, A. S.; Oldenborger, G. A.; L'Hérault, E.; Sladen, W. E.; Gosselin, P. and Mate, D. Assessing permafrost conditions and landscape hazards in support of climate change adaptation in Pangnirtung, Nunavut: Open-File Report - Geological Survey of Canada, Rep. No. 6868, 65 p., illus., 40 ref., 2011. WWW. Accessed on May 16, 2012.

URL: http://geopub.nrcan.gc.ca/moreinfo_e.php?id=289548

12051602 Short, S.; Stevens, C. W. and Wolfe, S. A. Seasonal surface displacement derived from InSAR, Yellowknife and surrounding area, Northwest Territories: Open-File Report - Geological Survey of Canada, Rep. No. 7030, 11 p., tables; physiographic map, 1:15,000, 1 ref., 2011. compact disc, WWW. Accessed on May 16, 2012.

Seasonal surface displacement was mapped by the Canada Centre for Remote Sensing and the Geological Survey of Canada for Yellowknife and the surrounding area using satellite interferometric synthetic aperture radar (InSAR). RADARSAT-2 ultra-fine scenes acquired on May 21, July 8, August 1, August 25 and September 18, 2010, were interferometrically stacked and the total amount of summer vertical displacement was calculated. This open file presents the relative surface displacement in both map and digital ArcGIS form. The calculated values are portrayed in terms of relative displacement that has been classified as stable, low and medium downward displacement and upward displacement. At some locations a significant change in surface characteristics results in a loss of interferometric coherence and no values were calculated. Surface displacement may be from natural and human-induced processes. This dataset provides spatial context for the variability and relative magnitude of seasonal surface displacement within the Yellowknife area.

URL: http://geopub.nrcan.gc.ca/moreinfo_e.php?id=289578

12051196 Smith, I. R. The seismic shothole drillers' log database and GIS for Northwest Territories and northern Yukon; an archive of near-surface lithostratigraphic surficial and bedrock geology data: Open-File Report - Geological Survey of Canada, Rep. No. 6833, 1 disc, illus. incl. tables, 2011. DVD, WWW. Accessed on May 16, 2012.

The seismic shothole drillers' log database provides baseline, near-surface (3-90 m; average 18.6 m) lithostratigraphic geoscience information on surficial, bedrock, hydro-, and permafrost geology. The revised and updated version 3 database contains 343,989 individual augered, or air-rotary drilled seismic shothole drillers' log records collected from 1952 to present. Originally published in 2007 as Open File 5465 (75,783 records) then updated in 2010 as Open File 6049 (275,871 records), the present database represents the sum total of all available archival holdings from Industry. Compiled in a Microsoft Access database, and graphically rendered in a GIS, the shothole data span the length and breadth of the Mackenzie corridor, Mackenzie Delta, and adjoining petroleum exploration regions of continental Northwest Territories and northern Yukon. The data, and numerous derivative thematic GIS and models stemming from this publication, provide an unparalleled and unique source of information that will benefit a wide variety of users (e.g., aboriginal organizations, communities, government, industry, land and water boards, regulators, and scientists), and applications (e.g., environmental assessments, infrastructure development, land use planning, resource management, and seismic exploration).

URL: http://geoscan.ess.nrcan.gc.ca/cgi-bin/starfinder/0?path=geoscan.fl&id=fastlink& ...

12051599 Stevens, C. W.; Palmer, M.; Wolfe, S. A.; Kokelj, S. and Smith, S. L. Permafrost and environmental conditions at stream crossing sites in the northern Mackenzie Corridor, Northwest Territories: Open-File Report - Geological Survey of Canada, Rep. No. 6976, 65 p., illus. incl. tables, 16 ref., 2011. compact disc, WWW (Northwest Territories Geoscience Office, NWT Open Report 2011-12). Accessed on May 16, 2012.

Aboriginal Affairs and Northern Development Canada (AANDC) and the Geological Survey of Canada established ground temperature monitoring sites at three stream crossings along the northern Mackenzie Corridor in order to examine the impact of local environmental conditions on permafrost. Ground temperatures were measured between August of 2009 and August of 2010 at hilltop, north and south facing slopes and valley bottom sites. Water and ground temperatures beneath the stream were also measured to provide information on the thermal influence of tundra streams on permafrost. Surface layer measurements consisting of vegetation height, active layer thaw depth and snow depth were acquired along cross valley transects. In addition, ground penetrating radar surveys were conducted to determine winter stream conditions at each site. This dataset improves the characterization of permafrost and environmental conditions at stream crossing sites where significant geotechnical challenges exist and provides useful baseline information necessary for the planning, design and regulation of infrastructure along the potential development corridor.

URL: http://geopub.nrcan.gc.ca/moreinfo_e.php?id=289554

12051603 Wolfe, S. A.; Duchesne, C.; Gaanderse, A.; Houben, A. J.; D'Onofrio, R. E.; Kokelj, S. V. and Stevens, C. W. Report on 2010-11 permafrost investigations in the Yellowknife area, Northwest Territories: Open-File Report - Geological Survey of Canada, Rep. No. 6983, 75 p., illus. incl. tables, 2011. compact disc, WWW (Northwest Territories Geoscience Office, NWT Open File 2011-009). Accessed on May 16, 2012.

This open file reports on recent geoscience data collected and monitoring sites installed by the Geological Survey of Canada (GSC) in collaboration with Aboriginal Affairs and Northern Development Canada (AANDC), Northwest Territories Geoscience Office (NTGO), Government of the Northwest Territories (GNWT) Environment and Natural Resources (ENR) and the Department of Transport (DOT), BGC Engineering Inc., Carleton University, and the University of Ottawa. The report represents the first of several co-published GSC/NTGO Open File reports under the Climate Change Geoscience Program. A 2010-11 field program under the Transportation Risk in the Arctic to Climatic Sensitivity (TRACS) activity in the Climate Change Geoscience Program included extensive fieldwork in the Yellowknife area between June and September, 2010. Field data collection by the Geological Survey of Canada and Carleton University included 14 CRREL-cored boreholes and ecological descriptions at 48 sites. An additional 20 ecological site descriptions were made by University of Ottawa students. Collaborative work with BGC Engineering Inc. included field observations and soil analysis (grain size and Atterberg limits) at test pits along Highway 3, and 15 water-jet drilled holes for subsequent temperature cable installations. Numerous temperature measurement sites were also established with AANDC along a 170 km transect between Behchoko and Tibbitt Lake including six air temperature sites, six multi-channel near-surface temperature sites and seven water temperature sites. In March 2011, additional field data were collected including snow depths at 45 sites, densities at 18 sites, and ice thicknesses at eight pond sites. Snow depth transect surveys were also conducted at 11 sites along Highway 3, across the highway embankments and right-of-ways. These data were collected in order to provide baseline information regarding the nature and properties of permafrost in the Yellowknife area.

URL: http://geopub.nrcan.gc.ca/moreinfo_e.php?id=289596

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12051479 Bednarski, J. M., compiler. Surficial geology, Kwokullie Lake, British Columbia: Open-File Report - Geological Survey of Canada, Geological Survey of Canada, Calgary, AB, Canada, Rep. No. 6562, 1 disc or 1 sheet, surficial geology map, 1:50,000, 2011. compact disc, WWW. Accessed on May 16, 2012.

Kwokullie Lake map area (NTS 94P/07) covers the northeast part of the Etsho Plateau whose northern boundary is defined by a large meltwater channel that is now occupied by Kimea lake and creek at about 460 m above sea level (asl). The Kimea meltwater channel was cut by an ancestral Petitot River that flowed westward during deglaciation when the retreating Laurentide Ice Sheet still covered the land to the north. Prior to this time (ca. 25 000-11 000 years ago), the Laurentide Ice Sheet covered the entire map area with a dominant ice flow from the northeast. Etsho Plateau gradually rises to 720 m asl in the southeast quadrant of the map area and, although it offers some relief, most of the area is underlain by poorly-drained clayey till that is mantled by extensive organic deposits. Hummocky organic deposits containing ground various amounts of ground ice are common on the upper plateau, especially around Kwokullie and Desan lakes, where recent disturbances have led to thermokarst terrain. Glacial flutings and drumlins concentrated on the upstream flank of the Etsho Plateau indicate that at least two distinct ice lobes emanated from the ice sheet at some time after the glacial maximum. A persistent northern lobe was responsible for the widespread northeast ice flow however, in the southeast quadrant of the map area, it was deflected by a second lobe flowing westward up the plateau. A southwest-trending moraine system appears to mark the interlobate boundary. Subsequent episodic retreat of the two lobes is marked by groups of recessional moraines to the north and east. There are at least two main concentrations of recessional moraines on the northern flank of the plateau. Within these moraine concentrations, cross-cutting relationships are common, indicating that many stillstands and minor readvances of the northern lobe occurred as it thinned and retreated to the north. In general the end moraines are thin and rise above the boggy terrain with only a few metres of relief. They are composed mainly of till but, in places, they also contain discontinuous deposits of stratified material, with minor amounts of ice-thrust glaciofluvial and glaciolacustrine sediment.

URL: http://apps1.gdr.nrcan.gc.ca/mirage/mirage_list_e.php?id=289249

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