Permafrost Monthly Alerts (PMAs)

2016042860 Liu Yeyi (Chinese Academy of Sciences, Institute of Atmospheric Physics, Beijing, China) and Jiang Dabang. Last glacial maximum permafrost in China from CMIP5 simulations: Palaeogeography, Palaeoclimatology, Palaeoecology, 447, p. 12-21, illus. incl. 3 tables, sketch maps, 46 ref., April 1, 2016.

The distributions of frozen ground and active layer thickness (ALT) during the last glacial maximum (LGM) and pre-industrial periods in China were investigated using Coupled Model Intercomparison Project Phase 5 (CMIP5) model experiments. Compared to the pre-industrial period, the LGM climate was ~ 5 °C colder and featured significantly higher freezing indices on the Tibetan Plateau and in Northeast China. Frozen ground expanded widely in the LGM. The extents of permafrost and seasonally frozen ground in China were 4.11 ´ 10⁶ km² and 4.97 ´ 10⁶ km², respectively, which are 2.42 ´ 10⁶ km² larger and 1.45 ´ 10⁶ km² smaller, respectively, than the pre-industrial levels. Moreover, the colder climate and longer duration also resulted in LGM ALT values that were 1.3 m less than the pre-industrial values in the permafrost areas common to both periods. Altitudinal permafrost was present mainly on the Tibetan Plateau and adjacent mountains in West China between 28°N and 41°30'N and covered an area of ~ 2.63 ´ 10⁶ km². Latitudinal permafrost was present mainly in Northeast China and occupied an area of 1.48 ´ 10⁶ km². The southern limit of latitudinal permafrost was located ~ 10° of latitude farther south during the LGM than during the pre-industrial period. The LGM simulation results agree reasonably well with previous reconstructions, with the exception of an underestimation in the permafrost extent. Although relatively high-level disagreement exists between the models in terms of the exact locations of the southern limits, the ensemble average is still able to represent the large-scale spatial pattern of frozen ground remarkably well. Abstract Copyright (2016) Elsevier, B.V.

DOI: 10.1016/j.palaeo.2016.01.042

2016040793 Andrieux, Eric (University of Bordeaux, PACEA, Pessac, France); Bertran, Pascal and Saito, Kazuyuki. Spatial analysis of the French Pleistocene permafrost by a GIS database: in Paleoenvironment special issue (Vandenberghe, Jef, editor; et al.), Permafrost and Periglacial Processes, 27(1), p. 17-30, illus. incl. sketch maps, 40 ref., March 2016.

GIS analysis of the French database of Pleistocene periglacial features allows an improved evaluation of the maximum extent of past permafrost. The distribution of typical ice-wedge pseudomorphs does not extend south of 47°N and therefore suggests that widespread discontinuous permafrost did not affect the regions south of the Paris Basin. The exclusive presence of sand wedges with primary infill between 45 and 47°N, mainly in the periphery of covers and areas, suggests that thermal contraction cracking of the ground occurred together with sand drifting in a context of deep seasonal frost or sporadic discontinuous permafrost, unfavorable for the growth of significant ground-ice bodies. The latitudinal variation of the wedge dimensions clearly shows that the sand wedges were located in the southern margin of the area affected by thermal contraction. The proposed map of Pleistocene permafrost in France partially reconciles field data with paleoclimatic simulations. The remaining discrepancies may arise primarily from the time lag between the Last Permafrost Maximum (c. 31-24 ka) and the Last Glacial Maximum (21 ka). Copyright Copyright 2015 John Wiley & Sons, Ltd.

DOI: 10.1002/ppp.1856

2016040794 Kitover, D. C. (VU University Amsterdam, Department of Earth Sciences, Amsterdam, Netherlands); van Balen, R. T.; Vandenberghe, Jef; Roche, D. M. and Renssen, H. LGM permafrost thickness and extent in the Northern Hemisphere derived from the Earth system model iLOVECLIM: in Paleoenvironment special issue (Vandenberghe, Jef, editor; et al.), Permafrost and Periglacial Processes, 27(1), p. 31-42, illus. incl. 1 table, sketch map, 34 ref., March 2016.

An estimate of permafrost extent and thickness in the northern hemisphere during the Last Glacial Maximum (LGM, ~ 21 ka) has been produced using the VU University Amsterdam Permafrost Snow (VAMPERS) model, forced by iLOVECLIM, an Earth System Model of Intermediate Complexity. We present model results that give both permafrost thickness and extent. In the northern hemisphere, permafrost is estimated to have extended southwards to approximately 50°N in Asia and have achieved 1500 m thickness in Russia. The simulated distribution is compared with a reconstruction of Northern Hemisphere permafrost extent (Vandenberghe et al., [Vandenberghe, J., 2014]). We contend that the areas which agree with Vandenberghe et al. ([Vandenberghe, J., 2014]) are the approximate areas of continuous permafrost during the LGM. In Asia, the model results agree well until approximately 50°N, which is also the approximate 0°C mean annual ground temperature isotherm estimated by iLOVECLIM. South of this limit, therefore, were likely the areas of discontinuous, sporadic and isolated permafrost during the LGM. However, it becomes difficult to model these more sensitive areas of permafrost extent since formation is dependent on local factors that are too fine for our grid's spatial resolution. In Europe, the model results disagree with the reconstruction but this was to be expected since iLOVECLIM is known to carry a warm bias in this region. For permafrost thickness, we compare our estimates with previous research and find that we have reasonably close approximations but there is a wide range of uncertainty since the subsurface parameters of lithology and water content are generalized. Copyright Copyright 2015 John Wiley & Sons, Ltd.

DOI: 10.1002/ppp.1861

2016040796 Lenz, Josefine (Alfred Wegener Institute, Department of Periglacial Research, Potsdam, Germany); Grosse, Guido; Jones, Benjamin M.; Walter Anthony, Katey M.; Bobrov, Anatoly; Wulf, Sabine and Wetterich, Sebastian. Mid-Wisconsin to Holocene permafrost and landscape dynamics based on a drained lake basin core from the northern Seward Peninsula, northwest Alaska: in Paleoenvironment special issue (Vandenberghe, Jef, editor; et al.), Permafrost and Periglacial Processes, 27(1), p. 56-75, illus. incl. 3 tables, sketch map, 36 ref., March 2016.

Permafrost-related processes drive regional landscape dynamics in the Arctic terrestrial system. A better understanding of past periods indicative of permafrost degradation and aggradation is important for predicting the future response of Arctic landscapes to climate change. Here, we used a multi-proxy approach to analyze a ~ 4 m long sediment core from a drained thermokarst lake basin on the northern Seward Peninsula in western Arctic Alaska (USA). Sedimentological, biogeochemical, geochronological, micropaleontological (ostracoda, testate amoebae) and tephra analyses were used to determine the long-term environmental early Wisconsin to Holocene history preserved in our core for central Beringia. Yedoma accumulation dominated throughout the early to late Wisconsin but was interrupted by wetland formation from 44.5 to 41.5 ka BP. The latter was terminated by the deposition of 1 m of volcanic tephra, most likely originating from the South Killeak Maar eruption at about 42 ka BP. Yedoma deposition continued until 22.5 ka BP and was followed by a depositional hiatus in the sediment core between 22.5 and 0.23 ka BP. We interpret this hiatus as due to intense thermokarst activity in the areas surrounding the site, which served as a sediment source during the late Wisconsin to Holocene climate transition. The lake forming the modern basin on the upland initiated around 0.23 ka BP and drained catastrophically in spring 2005. The present study emphasizes that Arctic lake systems and periglacial landscapes are highly dynamic and that permafrost formation as well as degradation in central Beringia was controlled by regional to global climate patterns as well as by local disturbances. Copyright Copyright 2015 John Wiley & Sons, Ltd.

DOI: 10.1002/ppp.1848

2016040792 Lindgren, Amelie (Stockholm University, Department of Physical Geography, Stockholm, Sweden); Hugelius, Gustaf; Kuhry, Peter; Christensen, Torben R. and Vandenberghe, Jef. GIS-based maps and area estimates of Northern Hemisphere permafrost extent during the last glacial maximum: in Paleoenvironment special issue (Vandenberghe, Jef, editor; et al.), Permafrost and Periglacial Processes, 27(1), p. 6-16, illus. incl. 2 tables, sketch maps, 60 ref., March 2016.

This study presents GIS-based estimates of permafrost extent in the northern circumpolar region during the Last Glacial Maximum (LGM), based on a review of previously published maps and compilations of field evidence in the form of ice-wedge pseudomorphs and relict sand wedges. We focus on field evidence localities in areas thought to have been located along the past southern border of permafrost. We present different reconstructions of permafrost extent, with areal estimates of exposed sea shelf, ice sheets and glaciers, to assess areas of minimum, likely and maximum permafrost extents. The GIS-based mapping of these empirical reconstructions allows us to estimate the likely area of northern permafrost during the LGM as 34.5 million km² (which includes 4.7 million km² of permafrost on exposed coastal sea shelves). The minimum estimate is 32.7 million km² and the maximum estimate is 35.3 million km². The extent of LGM permafrost is estimated to have been between c. 9.1 to 11.7 million km² larger than its current extent on land (23.6 million km²). However, 2.4 million km² of the lost land area currently remains as subsea permafrost on the submerged coastal shelves. The LGM permafrost extent in the northern circumpolar region during the LGM was therefore about 33 percent larger than at present. The net loss of northern permafrost since the LGM is due to its disappearance in large parts of Eurasia, which is not compensated for by gains in North America in areas formerly covered by the Laurentide ice sheet. Copyright Copyright 2015 John Wiley & Sons, Ltd.

DOI: 10.1002/ppp.1851

2016040795 Saito, Kazuyuki (University of Alaska Fairbanks, International Arctic Research Center, Fairbanks, AK); Trombotto Liaudat, Darío; Yoshikawa, Kenji; Mori, Junko; Sone, Toshio; Marchenko, Sergey; Romanovsky, Vladimir; Walsh, John; Hendricks, Amy and Bottegal, Estefanía. Late Quaternary permafrost distributions downscaled for South America; examinations of GCM-based maps with observations: in Paleoenvironment special issue (Vandenberghe, Jef, editor; et al.), Permafrost and Periglacial Processes, 27(1), p. 43-55, illus. incl. 3 tables, sketch map, 40 ref., March 2016.

High-resolution maps of potential frozen ground distribution in South America have been produced for the present day (0 ka) and the Last Glacial Maximum (21 ka). Surface air temperature outputs from global climate models (GCMs) of the recent Paleoclimate Model Intercomparison Project were used for the reconstructions, and then downscaled from regional to local scales, with the help of a 1 arc-minute digital elevation model. Their validity was examined using fieldwork-based evidence and knowledge. The downscaled map for the present day successfully reproduces the presence of permafrost in the Andes, a task at which original coarse-resolution GCM output maps failed. The map also shows close correspondence with instrumental observations. Similarly, the downscaled distribution of 21 ka frozen ground shows overall consistency with geomorphological and/or palaeoenvironmental reconstructions. Areal coverage of potential permafrost for all of South America is estimated at 139,000 km² for today and 435,000 km² for 21 ka, mostly along the Andean mountain ranges. Regional inspections, however, show divergence from field-observed features, attributed to microclimatic effects and past permafrost conditions. For southern Patagonia, and especially the eastern lowlands, the diagnosed lower limit for permafrost is about 1000 m asl, whereas field evidence at lower altitudes indicates the presence of either permafrost or deep seasonal frost. Copyright Copyright 2015 John Wiley & Sons, Ltd.

DOI: 10.1002/ppp.1863

2016040801 Vandenberghe, Jef (VU University, Institute of Earth Sciences, Amsterdam, Netherlands); Wang, X. and Vandenberghe, D. Very large cryoturbation structures of last permafrost maximum age at the foot of the Qilian Mountains (NE Tibet Plateau, China): in Paleoenvironment special issue (Vandenberghe, Jef, editor; et al.), Permafrost and Periglacial Processes, 27(1), p. 138-143, illus. incl. sketch map, 22 ref., March 2016.

Unusually large cryoturbation structures (4-4.5 m amplitude), developed in channel gravels and overbank fine-grained deposits of a river terrace on the NE Tibet Plateau, China, were formed by loadcasting as late Pleistocene-age permafrost degraded. It is suggested that the oversaturation and liquefaction of the thawed sediments could have been achieved only if the amount of ice in the upper 4-4.5 m of terrace sediments had been very high. The structures, dated at around 26-20 ka by OSL, point to the presence of a massive icy layer existing within a permafrost body during the Last Permafrost Maximum. Copyright Copyright 2015 John Wiley & Sons, Ltd.

DOI: 10.1002/ppp.1847

2016047360 Dafflon, Baptiste (Lawrence Berkeley National Laboratory, Earth Science Division, Berkeley, CA); Hubbard, Susan; Ulrich, Craig; Peterson, John; Wu, Yuxin; Wainwright, Haruko and Kneafsey, Timothy J. Geophysical estimation of shallow permafrost distribution and properties in an ice-wedge polygon-dominated Arctic tundra region: Geophysics, 81(1), p. WA247-WA263, illus., 94 ref., January 2016.

Shallow permafrost distribution and characteristics are important for predicting ecosystem feedbacks to a changing climate over decadal to century timescales because they can drive active layer deepening and land surface deformation, which in turn can significantly affect hydrologic and biogeochemical responses, including greenhouse gas dynamics. As part of the U.S. Department of Energy Next-Generation Ecosystem Experiments-Arctic, we have investigated shallow Arctic permafrost characteristics at a site in Barrow, Alaska, with the objective of improving our understanding of the spatial distribution of shallow permafrost, its associated properties, and its links with landscape microtopography. To meet this objective, we have acquired and integrated a variety of information, including electric resistance tomography data, frequency-domain electromagnetic induction data, laboratory core analysis, petrophysical studies, high-resolution digital surface models, and color mosaics inferred from kite-based landscape imaging. The results of our study provide a comprehensive and high-resolution examination of the distribution and nature of shallow permafrost in the Arctic tundra, including the estimation of ice content, porosity, and salinity. Among other results, porosity in the top 2 m varied between 85% (besides ice wedges) and 40%, and was negatively correlated with fluid salinity. Salinity directly influenced ice and unfrozen water content and indirectly influenced the soil organic matter content. A relatively continuous but depth-variable increase in salinity led to a partially unfrozen saline layer (cryopeg) located below the top of the permafrost. The cryopeg environment could lead to year-round microbial production of greenhouse gases. Results also indicated a covariability between topography and permafrost characteristics including ice-wedge and salinity distribution. In addition to providing insight about the Arctic ecosystem, through integration of lab-based petrophysical results with field data, this study also quantified the key controls on electric resistivity at this Arctic permafrost site, including salinity, porosity, water content, ice content, soil organic matter content, and lithologic properties.

DOI: 10.1190/geo2015-0175.1

2016047359 Dou, Shan (Lawrence Berkeley National Laboratory, Earth and Environmental Sciences, Berkeley, CA); Nakagawa, Seiji; Dreger, Douglas and Ajo-Franklin, Jonathan. A rock-physics investigation of unconsolidated saline permafrost; P-wave properties from laboratory ultrasonic measurements: Geophysics, 81(1), p. WA233-WA245, illus., 52 ref., January 2016. Includes appendices.

Saline permafrost is sensitive to thermal disturbances and is prone to subsidence, which renders it a major source of geohazard in Arctic coastal environments. Seismic methods could be used to map and monitor saline permafrost at scales of geotechnical interests because of the ice-content dependencies of seismic properties. We have developed a comprehensive study of the ultrasonic P-wave properties (i.e., velocity and attenuation) of synthetic saline permafrost samples for a range of salinities and temperatures, and measurements conducted on a fine-grained permafrost core obtained from Barrow, Alaska. The resulting data consist of P-wave properties presented as functions of temperature and salinity. Notable observations include the following: P-wave velocities showed marked reductions in the presence of dissolved salts and complex variations resulting from the water-to-ice phase transitions; strong P-wave attenuation was present in the temperature intervals in which the samples were partially frozen. When presented as functions of ice saturation, the data sets lead us to two key findings: (1) neither a purely cementing nor a purely pore-filling model of the pore-scale distributions of ice could adequately fit the observed velocity data and (2) although the velocities increase monotonically with increasing ice saturations, P-wave attenuation reaches a maximum at intermediate ice saturations-contrary to the ordinary expectation of decreasing attenuation with increasing velocities. The observed ice-content dependencies of P-wave properties, along with the implications on the probable pore-scale distributions of ice, provide a valuable basis for rock-physics modeling, which in turn could facilitate seismic characterizations of saline permafrost.

DOI: 10.1190/geo2015-0176.1

2016047372 Douglas, Thomas A. (United States Army Corps of Engineers, Cold Regions Research and Engineering Laboratory, Fort Wainwright, AK); Jorgenson, M. Torre; Brown, Dana R. N.; Campbell, Seth W.; Hiemstra, Christopher A.; Saari, Stephanie P.; Bjella, Kevin and Liljedahl, Anna K. Degrading permafrost mapped with electrical resistivity tomography, airborne imagery and LiDAR, and seasonal thaw measurements: Geophysics, 81(1), p. WA71-WA85, illus. incl. 3 tables, 85 ref., January 2016.

Accurate identification of the relationships between permafrost extent and landscape patterns can help to develop airborne geophysical or remote sensing tools to map permafrost in remote locations or across large areas. These tools will be particularly applicable in discontinuous permafrost where climate warming or disturbances such as human development or fire can lead to rapid permafrost degradation. We have linked field-based geophysical, point-scale, and imagery surveying measurements to map permafrost at five fire scars (1930, 1975, 1988, 2001, and 2010) on the Tanana Flats in central Alaska. Ground-based elevation surveys, seasonal thaw-depth profiles, and electrical resistivity tomography (ERT) measurements were combined with airborne imagery and light detection and ranging (LiDAR) to identify relationships between permafrost geomorphology and elapsed time since fire disturbance. ERT proved to be a robust technique for mapping the presence or absence of permafrost because of the marked difference in resistivity values for frozen versus unfrozen material. There was no clear relationship between elapsed time since fire and permafrost extent at our sites. However, we have found that the transition zone boundaries between permafrost soils and unfrozen soils in the collapse-scar bogs at our sites had complex and unpredictable morphologies. This result suggested that attempts to quantify the presence or absence of permafrost using aerial measurements alone could lead to incomplete results. Taken in total, the results from our study indicated that although ground-based ERT measurements were the most rapid means of mapping permafrost, we were still limited in being able to apply airborne surveying measurements at the landscape scale toward accurately estimating permafrost extent.

DOI: 10.1190/geo2015-0149.1

2016044123 Xie Changwei (Chinese Academy of Sciences, Cold & Arid Regions Environmental and Engineering Research Institute, Cryosphere Research Station on the Qinghai-Tibet Plateau, Lanzhou, China); Gough, William A.; Zhao Lin; Wu Tonghua and Liu Wenhui. Temperature-dependent adjustments of the permafrost thermal profiles on the Qinghai-Tibet Plateau, China: Arctic, Antarctic, and Alpine Research, 47(4), p. 719-728, illus. incl. 2 tables, sketch maps, 46 ref., November 2015.

Using continuous data obtained from 17 monitoring sites, the permafrost temperature profiles and the depths of zero annual amplitude (DZAA) on the Qinghai-Tibet Plateau are examined. Permafrost thermal trumpet curves are generally narrow and the DZAAs are generally shallow in warm permafrost regions, especially at sites where the permafrost temperature is close to 0°C. The observed DZAAs in warm permafrost regions are indeed generally less than 7.0 m and for three sites less than 4.0 m. In low-temperature permafrost areas, the situation is reversed: the thermal trumpet curves are generally wide and the DZAAs are generally deep. Theoretical and numerical analyses clearly show there is a causal relationship between permafrost warming and the decrease of the DZAA. Latent heat effects are buffering the increase of permafrost temperature and result in narrow thermal trumpet curves and shallow DZAAs. Based on observations and numerical analyses, this research suggests that most of the permafrost on the Qinghai-Tibet Plateau is undergoing internal thaw and the latent heat effects have important implications on the permafrost thermal regime. The temperature-dependent adjustments in permafrost will promote both the downward and upward degradation of permafrost as a result of climate warming.

DOI: 10.1657/AAAR00C-13-128

2016037543 Overduin, Pier P. (Alfred Wegener Institute Helmholtz, Center for Polar and Marine Research, Potsdam, Germany); Haberland, Christian; Ryberg, Trond; Kneier, Fabian; Jacobi, Tim; Grigoriev, Mikhail. N. and Ohrnberger, Matthias. Submarine permafrost depth from ambient seismic noise: Geophysical Research Letters, 42(18), p. 7581-7588, illus. incl. 1 table, sketch map, 40 ref., September 28, 2015.

Permafrost inundated since the last glacial maximum is degrading, potentially releasing trapped or stabilized greenhouse gases, but few observations of the depth of ice-bonded permafrost (IBP) below the seafloor exist for most of the arctic continental shelf. We use spectral ratios of the ambient vibration seismic wavefield, together with estimated shear wave velocity from the dispersion curves of surface waves, for estimating the thickness of the sediment overlying the IBP. Peaks in spectral ratios modeled for three-layered 1-D systems correspond with varying thickness of the unfrozen sediment. Seismic receivers were deployed on the seabed around Muostakh Island in the central Laptev Sea, Siberia. We derive depths of the IBP between 3.7 and 20.7 m ± 15%, increasing with distance from the shoreline. Correspondence between expected permafrost distribution, modeled response, and observational data suggests that the method is promising for the determination of the thickness of unfrozen sediment. Abstract Copyright (2015), . American Geophysical Union. All Rights Reserved.

DOI: 10.1002/2015GL065409

2016046207 Serov, Pavel (UiT The Arctic University of Norway, Department of Geology, Tromso, Norway); Portnov, Alexey; Mienert, Jurgen; Semenov, Peter and Ilatovskaya, Polina. Methane release from pingo-like features across the south Kara Sea shelf, an area of thawing offshore permafrost: Journal of Geophysical Research: Earth Surface, 120(8), p. 1515-1529, illus. incl. sketch map, 30 ref., August 2015.

The Holocene marine transgression starting at »19 ka flooded the Arctic shelves driving extensive thawing of terrestrial permafrost. It thereby promoted methanogenesis within sediments, the dissociation of gas hydrates, and the release of formerly trapped gas, with the accumulation in pressure of released methane eventually triggering blowouts through weakened zones in the overlying and thinned permafrost. Here we present a range of geophysical and chemical scenarios for the formation of pingo-like formations (PLFs) leading to potential blowouts. Specifically, we report on methane anomalies from the South Kara Sea shelf focusing on two PLFs imaged from high-resolution seismic records. A variety of geochemical methods are applied to study concentrations and types of gas, its character, and genesis. PLF 1 demonstrates ubiquitously low-methane concentrations (14.2-55.3 ppm) that are likely due to partly unfrozen sediments with an ice-saturated internal core reaching close to the seafloor. In contrast, PLF 2 reveals anomalously high-methane concentrations of >120,000 ppm where frozen sediments are completely absent. The methane in all recovered samples is of microbial and not of thermogenic origin from deep hydrocarbon sources. However, the relatively low organic matter content (0.52-1.69%) of seafloor sediments restricts extensive in situ methane production. As a consequence, we hypothesize that the high-methane concentrations at PLF 2 are due to microbial methane production and migration from a deeper source. Abstract Copyright (2015), American Geophysical Union. All Rights Reserved.

DOI: 10.1002/2015JF003467

2016039658 Scapozza, Cristian (Scuola Uniersitaria Professionale della Svizzera Italiana, Istituto Scienze della Terra, Canobbio, Switzerland). Evolution des glaciers et du pergélisol depuis le dernier maximum glaciaire dans la région du mont gelémont fort (Alpes Valaisannes, Suisse); chronologie, modalités de la dernière déglaciation et datations des âges d'exposition à l'aide du Marteau de Schmidt [Glacier and permafrost evolution since the last glacial maximum in the Mont Gele-Mont Fort region (Valais Alps, Switzerland); chronology, modalities of the last deglaciation, and Schmidt hammer exposure age dating]: Quaternaire (Paris), 26(2), p. 141-173 (English sum.), illus. incl. 16 tables, geol. sketch maps, 92 ref., June 2015.

Knowledge about the morphoclimatic evolution of the Alps during the Lateglacial and the Holocene considerably evolved during the last century in particular in the eastern part of the Alps, even if little interest was accorded to the periglacial zone. This latter being located above the upper limit of the forest, it is very difficult to find organic remains for absolute time calibrations. Subject of many studies during the seventies and the eighties, the Valais Alps have lost in interest in studies concerning the deglaciation, probably because of the difficulties in defining a complete deglaciation sequence encompassing the entire Lateglacial and of the limited number of available numerical dates. In the first part, the evolution of glaciers and rock glaciers in five glacial basins of the Mont Gele-Mont Fort region since the end of the last glaciation was reconstructed on the basis of a palaeoenvironmental approach. The reconstruction of the glacier's equilibrium line altitude depression and of the permafrost depression allowed 16 local stadials, regrouped in five regional glacial stadials and three generations of rock glaciers, to be defined. Palaeotemperatures and palaeo-precipitations calculated at the equilibrium line altitude and at the lower limit of permafrost allowed a palaeoclimatic chronology, on which the glacial and periglacial history of the region was correlated, to be composed. Thereafter, this chronology was refined thanks to Schmidt hammer exposure-age dating. Twelve rock glaciers, two protalus ramparts, three talus slopes, thirteen morainic ridges and three roches moutonnees have been dated applying this method. The measured R-values (adimensional) are comprised between 43 on a morainic ridge of the end of the Oldest Dryas and 59 on a morainic ridge of 1861 AD. Thanks to the relative dating of glacial landforms with the palaeogeographic method, it was possible to use the R-values measured on surfaces of known age to calibrate the exposure-ages of the studied landforms. According to the dating carried out, it follows that the oldest relict rock glaciers would have developed from the end of the Oldest Dryas and would have inactivated during the Preboreal. The following generation of relict rock glaciers would have developed from the Younger Dryas and would have inactivated during the Mid-Holocene Climate Optimum. Currently active/inactive rock glaciers have started to develop just before or during the Mid-Holocene Climate Optimum. For the studied talus slopes, the obtained minimal ages indicate that rockwall erosion rates after the end of the Mid-Holocene Climate Optimum were very low. Therefore, rockwall erosion rates during the talus slope development period had been very important.

2016044111 Willeit, M. (Potsdam Institute for Climate Impact Research, Potsdam, Germany) and Ganopolski, A. Coupled Northern Hemisphere permafrost-ice-sheet evolution over the last glacial cycle: Climate of the Past, 11(9), p. 1165-1180, illus. incl. 1 table, 51 ref., 2015. Includes appendices.

Permafrost influences a number of processes which are relevant for local and global climate. For example, it is well known that permafrost plays an important role in global carbon and methane cycles. Less is known about the interaction between permafrost and ice sheets. In this study a permafrost module is included in the Earth system model CLIMBER-2, and the coupled Northern Hemisphere (NH) permafrost-ice-sheet evolution over the last glacial cycle is explored. The model performs generally well at reproducing present-day permafrost extent and thickness. Modeled permafrost thickness is sensitive to the values of ground porosity, thermal conductivity and geothermal heat flux. Permafrost extent at the Last Glacial Maximum (LGM) agrees well with reconstructions and previous modeling estimates. Present-day permafrost thickness is far from equilibrium over deep permafrost regions. Over central Siberia and the Arctic Archipelago permafrost is presently up to 200-500 m thicker than it would be at equilibrium. In these areas, present-day permafrost depth strongly depends on the past climate history and simulations indicate that deep permafrost has a memory of surface temperature variations going back to at least 800 ka. Over the last glacial cycle permafrost has a relatively modest impact on simulated NH ice sheet volume except at LGM, when including permafrost increases ice volume by about 15 m sea level equivalent in our model. This is explained by a delayed melting of the ice base from below by the geothermal heat flux when the ice sheet sits on a porous sediment layer and permafrost has to be melted first. Permafrost affects ice sheet dynamics only when ice extends over areas covered by thick sediments, which is the case at LGM.

URL: http://www.clim-past.net/11/1165/2015/cp-11-1165-2015.pdf

2016040797 Teltewskoi, Annette (Ernst Moritz Arndt University, Institute of Botany and Landscape Ecology, Greifswald, Germany); Beermann, Fabian; Beil, Ilka; Bobrov, Anatoly; De Klerk, Pim; Lorenz, Sebastian; Lüder, Arne; Michaelis, Dierk and Joosten, Hans. 4000 years of changing wetness in a permafrost polygon peatland (Kytalyk, NE Siberia); a comparative high-resolution multi-proxy study: in Paleoenvironment special issue (Vandenberghe, Jef, editor; et al.), Permafrost and Periglacial Processes, 27(1), p. 76-95, illus. incl. 1 table, sketch map, 35 ref., March 2016.

Ice-wedge polygon mires feature a micro-relief of dry ridges, shallow wet depressions, deeper wet troughs and transitional sites, resulting in a local mosaic of vegetation. The correct recognition of these landscape elements in paleoecological studies of peat sections requires insight about the suitability of proxies and their potential for paleoecological reconstruction in order to reconstruct vegetation and wetness patterns as well as dynamics. This paper analyses a 105.5 cm long peat section with a base dating to about 4000 cal yr BP from an ice-wedge polygon mire near Kytalyk (NE Siberia). Pollen, macrofossils, testate amoebae, geochemistry and sediment properties were analysed in order to compare the suitability of these proxies to reconstruct past surface wetness. The proxies show similar wetness trends. Pollen and geochemistry data did not always permit wetness reconstruction, the former because many pollen types do not allow the identification of taxa at a low taxonomic resolution, the latter because later taphonomic processes modify chemical variables in deeper peat layers. Macrofossils provided the most detailed wetness reconstruction, because they could be identified to genera or species, for which the moisture requirements are accurately known from their present-day distribution in ice-wedge polygons. All proxies, except geochemistry, show an obvious change from wet to dry conditions at around 20 cm depth. However, as the proxies sometimes show contradictory results, a multi-proxy approach is preferable over a single proxy interpretation as it allows the reconstruction of environmental development in a broader paleoecological context. Copyright Copyright 2016 John Wiley & Sons, Ltd.

DOI: 10.1002/ppp.1869

2016044117 Morozova, Daria (GeoForschungsZentrum Potsdam, Section Geomicrobiology, Potsdam, Germany); Moeller, Ralf; Rettberg, Petra and Wagner, Dirk. Enhanced radiation resistance of Methanosarcina soligelidi SMA-21, a new methanogenic archaeon isolated from a Siberian permafrost-affected soil in direct comparison to Methanosarcina barkeri: Astrobiology, 15(11), p. 951-960, illus. incl. 2 tables, 59 ref., November 2015.

DOI: 10.1089/ast.2015.1319

2016039627 Oswell, J. M. (Naviq Consulting, Calgary, AB, Canada) and Nixon, J. F. Thermal design considerations for raised structures on permafrost: Journal of Cold Regions Engineering, 29(1), unpaginated, illus. incl. 4 tables, 18 ref., March 2015.

URL: http://dx.doi.org/10.1061/(ASCE)CR.1943-5495.0000075

2016039623 Regehr, Jonathan D. (University of Manitoba, Department of Civil Engineering, Winnipeg, MB, Canada); Milligan, Craig A.; Montufar, Jeannette and Alfaro, Marolo. Review of effetiveness and costs of strategies to improve roadbed stability in permafrost regions: Journal of Cold Regions Engineering, 27(3), p. 109-131, illus. incl. 8 tables, 60 ref., September 2013.

URL: http://dx.doi.org/10.1061/(ASCE)CR.1943-5495.0000054

2016039621 Filler, Dennis M. (University of Alaska Fairbanks, Department of Civil and Environmental Engineering) and Peterson, Rorik. Cryogenic freezeback of uncontrolled artesian wells in permafrost: Journal of Cold Regions Engineering, 27(2), p. 55-66, illus., 4 ref., June 2013.

URL: http://dx.doi.org/10.1061/(ASCE)CR.1943-5495.0000043

2016045220 Petrenko, Vasilii V. (University of Rochester, Department of Earth and Environmental Sciences, Rochester, NY); Severinghaus, Jeffrey P.; Schaefer, Hinrich; Smith, Andrew M.; Kuhl, Tanner; Baggenstos, Daniel; Hua, Quan; Brook, Edward J.; Rose, Paul; Kulin, Robb; Bauska, Thomas; Harth, Christina; Buizert, Christo; Orsi, Anais; Emanuele, Guy; Lee, James E.; Brailsford, Gordon; Keeling, Ralph and Weiss, Ray F. Measurements of ¹⁴C in ancient ice from Taylor Glacier, Antarctica constrain in situ cosmogenic ¹⁴CH₄ and ¹⁴CO production rates: Geochimica et Cosmochimica Acta, 177, p. 62-77, illus. incl. 6 tables, sketch map, 83 ref., March 15, 2016. Includes appendices.

Carbon-14 (¹⁴C) is incorporated into glacial ice by trapping of atmospheric gases as well as direct near-surface in situ cosmogenic production. ¹⁴C of trapped methane (¹⁴CH₄) is a powerful tracer for past CH₄ emissions from "old" carbon sources such as permafrost and marine CH₄ clathrates. ¹⁴C in trapped carbon dioxide (¹⁴CO₂) can be used for absolute dating of ice cores. In situ produced cosmogenic ¹⁴C in carbon monoxide (¹⁴CO) can potentially be used to reconstruct the past cosmic ray flux and past solar activity. Unfortunately, the trapped atmospheric and in situ cosmogenic components of ¹⁴C in glacial ice are difficult to disentangle and a thorough understanding of the in situ cosmogenic component is needed in order to extract useful information from ice core ¹⁴C. We analyzed very large (»1000 kg) ice samples in the 2.26-19.53 m depth range from the ablation zone of Taylor Glacier, Antarctica, to study in situ cosmogenic production of ¹⁴CH₄ and ¹⁴CO. All sampled ice is >50 ka in age, allowing for the assumption that most of the measured ¹⁴C originates from recent in situ cosmogenic production as ancient ice is brought to the surface via ablation. Our results place the first constraints on cosmogenic ¹⁴CH₄ production rates and improve on prior estimates of ¹⁴CO production rates in ice. We find a constant ¹⁴CH₄/¹⁴CO production ratio (0.0076 ± 0.0003) for samples deeper than 3 m, which allows the use of ¹⁴CO for correcting the ¹⁴CH₄ signals for the in situ cosmogenic component. Our results also provide the first unambiguous confirmation of ¹⁴C production by fast muons in a natural setting (ice or rock) and suggest that the ¹⁴C production rates in ice commonly used in the literature may be too high. Abstract Copyright (2016) Elsevier, B.V.

DOI: 10.1016/j.gca.2016.01.004

2016044459 Bailey, Brenda L. (University of Waterloo, Department of Earth and Environmental Sciences, Waterloo, ON, Canada); Blowes, David W.; Smith, Leslie and Sego, David C. The Diavik waste rock project; geochemical and microbiological characterization of low sulfide content large scale waste rock test piles: Applied Geochemistry, 65, p. 54-72, illus. incl. 4 tables, 31 ref., February 2016. Includes appendices.

Two experimental waste-rock piles (test piles), each 15 m in height ´ 60 m ´ 50 m, were constructed at the Diavik diamond mine in Northern Canada to study the behavior of low-sulfide content waste rock, with a similarly low acid-neutralization potential, in a continuous permafrost region. One test pile with an average of 0.035 wt.% S (<50 mm fraction; referred to as Type I) and a second test pile with an average of 0.053 wt.% S (<50 mm fraction; referred to as Type III) were constructed in 2006. The average carbon content in the <50 mm fraction of waste rock in the Type I test pile was 0.031 wt.% as C and in the Type III test pile was 0.030 wt.% as C. The NP:AP ratio, based on the arithmetic mean of particle-size weighted NP and AP values, for the Type I test pile was 12.2, suggesting this test pile was non-acid generating and for the Type III test pile was 2.2, suggesting an uncertain acid-generating potential. The Type I test pile maintained near-neutral pH for the 4-year duration of the study. Sulfate and dissolved metal concentrations were low, with the exception of Ni, Zn, Cd, and Co in the fourth year following construction. The pore water in the Type III test pile contained higher concentrations of SO₄^2- and dissolved metals, with a decrease in pH to <4.7 and an annual depletion of alkalinity. Maximum concentrations of dissolved metals (20 mg L^-1 Ni, 2.3 mg L^-1 Cu, 3.7 mg L^-1 Zn, 35 mg L^-1 Cd, and 3.8 mg L^-1 Co) corresponded to decreases in flow rate, which were observed at the end of each field season when the contribution of the total outflow from the central portion of the test pile was greatest. Bacteria were present each year in spite of annual freeze/thaw cycles. The microbial community within the Type I test pile included a population of neutrophilic S-oxidizing bacteria. Each year, changes in the water quality of the Type III test-pile effluent were accompanied by changes in the microbial populations. Populations of acidophilic S-oxidizing bacteria and Fe-oxidizing bacteria became more abundant as the pH decreased and internal test pile temperatures increased. Irrespective of the cold-climate conditions and low S content of the waste rock, the geochemical and microbiological results of this study are consistent with other acid mine drainage studies; indicating that a series of mineral dissolution-precipitation reactions controls pH and metal mobility, and transport is controlled by matrix-dominated flow and internal temperatures. Abstract Copyright (2016) Elsevier, B.V.

DOI: 10.1016/j.apgeochem.2015.10.010

2016040790 Peng Xiaoqing (Lanzhou University, Ministry of Education, Gansu, China); Zhang Tingjun; Cao Bin; Wang Qingfeng; Wang Kang; Shao Wanwan and Guo Hong. Changes in freezing-thawing index and soil freeze depth over the Heihe River basin, western China: Arctic, Antarctic, and Alpine Research, 48(1), p. 161-176, illus. incl. 9 tables, sketch map, 45 ref., February 2016.

Freezing/thawing index is an important indicator of climate change, and can be used to estimate depths of the active layer and seasonally frozen ground (SFG). Using the mean monthly grid air temperature from 2000 to 2009 as well as daily air and ground surface temperatures from 12 meteorological stations across the Heihe River Basin, this study investigated spatial and temporal variability of the freezing/thawing index and seasonal soil freeze depth. The mean annual air temperature increased at a rate of 0.35 °C decade-1 from 1960 to 2013, or approximately 1.9 °C for the 54-year period. We found that the freezing index (FI) showed a decreasing trend over the study area, while the thawing index (TI) had an increasing trend. Changes in both FI and TI are consistent with an increasing mean annual air temperature. The TI and freezing n-factor (nf) decrease with elevation increase, while FI and thawing n-factor (nt) increase with elevation. Soil potential seasonal freezing depth was primarily between 1.5 and 2.5 m in permafrost regions. However, the soil maximum freezing depth is below 2.5 m in SFG region.

DOI: 10.1657/AAAR00C-13-127

2016042398 Broder, Lisa (Stockholm University, Department of Environmental Science and Analytical Chemistry, Stockholm, Sweden); Tesi, Tommaso; Andersson, August; Eglinton, Timothy I.; Semiletov, Igor P.; Dudarev, Oleg V.; Roos, Per and Gustafsson, Orjan. Historical records of organic matter supply and degradation status in the East Siberian Sea: Organic Geochemistry, 91, p. 16-30, illus. incl. 1 table, sketch map, 101 ref., January 2016. Includes appendices.

Destabilization and degradation of permafrost carbon in the Arctic regions could constitute a positive feedback to climate change. A better understanding of its fate upon discharge to the Arctic shelf is therefore needed. In this study, bulk carbon isotopes as well as terrigenous and marine biomarkers were used to construct two centennial records in the East Siberian Sea. Differences in topsoil and Pleistocene Ice Complex Deposit permafrost concentrations, modeled using d¹³C and D¹⁴C, were larger between inner and outer shelf than the changes over time. Similarly, lignin-derived phenol and cutin acid concentrations differed by a factor of ten between the two stations, but did not change significantly over time, consistent with the dual-carbon isotope model. High molecular weight (HMW) n-alkane and n-alkanoic acid concentrations displayed a smaller difference between the two stations (factor of 3-6). By contrast, the fraction for marine OC drastically decreased during burial with a half-life of 19-27 years. Vegetation and degradation proxies suggested supply of highly degraded gymnosperm wood tissues. Lipid Carbon Preference Index (CPI) values indicated more extensively degraded HMW n-alkanes on the outer shelf with no change over time, whereas n-alkanoic acids appeared to be less degraded toward the core top with no large differences between the stations. Taken together, our results show larger across-shelf changes than down-core trends. Further investigation is required to establish whether the observed spatial differences are due to different sources for the two depositional settings or, alternatively, a consequence of hydrodynamic sorting combined with selective degradation during cross-shelf transport. Abstract Copyright (2016) Elsevier, B.V.

DOI: 10.1016/j.orggeochem.2015.10.008

2016047373 Foley, Neil (University of California, Earth and Planetary Sciences, Santa Cruz, CA); Tulaczyk, Slawek; Auken, Esben; Schamper, Cyril; Dugan, Hilary; Mikucki, Jill; Virginia, Ross and Doran, Peter. Helicopter-borne transient electromagnetics in high-latitude environments; an application in the McMurdo dry valleys, Antarctica: Geophysics, 81(1), p. WA87-WA99, illus. incl. 2 tables, 85 ref., January 2016.

The McMurdo Dry Valleys are a polar desert in coastal Antarctica, where glaciers, permafrost, ice-covered lakes, and ephemeral summer streams coexist. Liquid water is found at the surface only in lakes and in the temporary streams that feed them. Past geophysical exploration has yielded ambiguous results regarding the presence of subsurface water. In 2011, we used a helicopter-borne, time-domain electromagnetic (TDEM) sensor to map resistivity in the subsurface across the Dry Valleys. The airborne electromagnetic (AEM) method excels at finding subsurface liquid water in polar deserts, where water remains liquid under cold conditions if it is sufficiently saline, and therefore electrically conductive. Over the course of 26 h of helicopter time, we covered large portions of the Dry Valleys and vastly increased our geophysical understanding of the subsurface, particularly with respect to water. Our data show extensive subsurface low-resistivity layers approximately 150-250 m below the surface and beneath higher resistivity layers. We interpret the low-resistivity layers as geologic materials containing freeze-concentrated or "cryoconcentrated" hyper saline brines lying beneath glaciers and frozen permafrost. These brines appeared to be contiguous with surface lakes, subglacial regions, and the Ross Sea, which could indicate a regional-hydrogeologic system, wherein solutes might be transported between surface reservoirs by ionic diffusion and subsurface flow. The presence of such brines underneath glaciers might have implications for glacier movement. Systems such as this, where brines exist beneath glacial ice and frozen permafrost, may exist elsewhere in coastal Antarctica; AEM resistivity is an ideal tool to find and survey them. Our application of TDEM demonstrates that in polar subsurface environments containing conductive brines, such a diffusive electromagnetic method is superior to radar surveying in terms of depth of penetration and ability to differentiate hydrogeologic conditions.

DOI: 10.1190/geo2015-0186.1

2016047347 Merz, Kaspar (Eidgenössische Technische Hochschule Zürich, Institute of Geophysics, Zurich, Switzerland); Maurer, Hansruedi; Rabenstein, Lasse; Buchli, Thomas; Springman, Sarah M. and Zweifel, Matthias. Multidisciplinary geophysical investigations over an alpine rock glacier: Geophysics, 81(1), p. WA1-WA11, illus., 40 ref., January 2016.

We have performed a multidisciplinary geophysical survey combined with geotechnical investigations over a degrading alpine rock glacier. A dense grid of helicopter-borne ground-penetrating radar data allowed the 3D shape of the bedrock topography and the gross transition from ice-rich to ice-poor parts of the rock glacier to be delineated. The bedrock topography served as a 2D structural constraint for tomographic inversions of seismic and geoelectric data acquired on coincident profiles parallel and perpendicular to the rock glacier flow direction. These profile data were complemented by a small 3D geoelectric tomography experiment. Only a combined interpretation of all the results allowed reliable and unambiguous interpretation of the tomograms. We could distinguish between the active layer, bedrock, ice-bearing rock glacier material, and degraded permafrost within the rock glacier. The latter could be further distinguished in areas where the ice must have melted only recently, and regions that had degraded some time ago. Additionally, high-resolution cross-hole radar tomography, performed in an area of opening crevices, allowed small-scale structures to be resolved, which were indicative of the dominant deformation mechanisms style of the rock glacier. The success of our study was primarily based on the availability of 3D data sets that allowed important structures to be traced over larger areas and the integrated interpretation of several data types. We have identified the internal structure of the rock glacier to be surprisingly heterogeneous with several small-scale features that were judged to be critical for assessing its stability. This underpinned the need for comprehensive 3D structural investigations to augment geotechnical measurements linearly with inclinometers or at points in boreholes.

DOI: 10.1190/geo2015-0157.1

2016047355 Schennen, Stephan (Universität Potsdam, Institut für Erd- und Umweltwissenschaften, Potsdam, Germany); Tronicke, Jens; Wetterich, Sebastian; Allroggen, Niklas; Schwamborn, Georg and Schirrmeister, Lutz. 3D ground-penetrating radar imaging of ice complex deposits in northern east Siberia: Geophysics, 81(1), p. WA195-WA202, illus. incl. 1 table, 42 ref., January 2016.

Ice complex deposits are characteristic, ice-rich formations in northern East Siberia and represent an important part in the arctic carbon pool. Recently, these late Quaternary deposits are the objective of numerous investigations typically relying on outcrop and borehole data. Many of these studies can benefit from a 3D structural model of the subsurface for upscaling their observations or for constraining estimations of inventories, such as the local carbon stock. We have addressed this problem of structural imaging by 3D ground-penetrating radar (GPR), which, in permafrost studies, has been primarily used for 2D profiling. We have used a 3D kinematic GPR surveying strategy at a field site located in the New Siberian Archipelago on top of an ice complex. After applying a 3D GPR processing sequence, we were able to trace two horizons at depths below 20 m. Taking available borehole and outcrop data into account, we have interpreted these two features as interfaces of major lithologic units and derived a 3D cryostratigraphic model of the subsurface. Our data example demonstrated that a 3D surveying and processing strategy was crucial at our field site and showed the potential of 3D GPR to image geologic structures in complex ice-rich permafrost landscapes.

DOI: 10.1190/geo2015-0129.1

2016047358 Voytek, Emily B. (Colorado School of Mines, Hydrologic Science and Engineering Program, Golden, CO); Rushlow, Caitlin R.; Godsey, Sarah E. and Singha, Kamini. Identifying hydrologic flowpaths on arctic hillslopes using electrical resistivity and self potential: Geophysics, 81(1), p. WA225-WA232, illus., 53 ref., January 2016.

Shallow subsurface flow is a dominant process controlling hillslope runoff generation, soil development, and solute reaction and transport. Despite their importance, the location and geometry of these flow paths are difficult to determine. In arctic environments, shallow subsurface flow paths are limited to a thin zone of seasonal thaw above permafrost, which is traditionally assumed to mimic the surface topography. We have used a combined approach of electrical resistivity tomography (ERT) and self-potential (SP) measurements to map shallow subsurface flow paths in and around water tracks, drainage features common to arctic hillslopes. ERT measurements delineate thawed zones in the subsurface that control flow paths, whereas SP is sensitive to groundwater flow. We have found that areas of low electrical resistivity in the water tracks were deeper than manual thaw depth estimates and varied from the surface topography. This finding suggests that traditional techniques might underestimate active-layer thaw and the extent of the flow path network on arctic hillslopes. SP measurements identify complex 3D flow paths in the thawed zone. Our results lay the groundwork for investigations into the seasonal dynamics, hydrologic connectivity, and climate sensitivity of spatially distributed flow path networks on arctic hillslopes.

DOI: 10.1190/geo2015-0172.1

2016037848 Yang Yuzhong (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Wu Qingbai and Jin Huijun. Evolutions of water stable isotopes and the contributions of cryosphere to the alpine river on the Tibetan Plateau: Environmental Earth Sciences, 75(1), Article 49, illus. incl. 7 tables, sketch map, 62 ref., January 2016.

The significant changes of cryosphere on the Tibetan Plateau (TP) are an important cause of concern for the huge population in Asia which depends on the glacier-permafrost feed rivers. Up to now, little is known about the response of runoff to the cryospheric changes under a warming climate. Taking an example of a typical alpine river (hereafter named KLR River) in Kunlun Mountains Pass on the TP to investigate the hydrological processes and quantify the potential recharge sources using stable isotopes and electrical conductivities. The results showed significantly temporal variations in isotopes of precipitation and river water. Deviations in the precipitation isotopes indicated that precipitation in Kunlun Mountains Pass during summer months mainly originated from local recycled moisture and slightly influenced by monsoon. The KLR river was separated into three hydrological components which include precipitation, meltwater of glacier and meltwater of subsurface ground ice. On average, the meltwater of glacier accounted for 56.64 % of total flow, whereas the meltwater of subsurface ground ice contributed 37.44 % and only 5.92 % was supplied by precipitation. Evidently, the contributions of glacier and thawing permafrost are up to as high as 94 %. The cryosphere played a crucial role on the hydrological cycle on the TP which would be important to understand the water resource distribution in permafrost regions on the TP under the global warming. Copyright 2015 Springer-Verlag Berlin Heidelberg

DOI: 10.1007/s12665-015-4894-5

2016044113 Bartlein, P. J. (University of Oregon, Department of Geography, Eugene, OR); Edwards, M. E.; Hostetler, S. W.; Shafer, S. L.; Anderson, P. M.; Brubaker, L. B. and Lozhkin, A. V. Early-Holocene warming in Beringia and its mediation by sea-level and vegetation changes: Climate of the Past, 11(9), p. 1197-1222, illus. incl. 2 tables, sketch maps, 103 ref., 2015.

Arctic land-cover changes induced by recent global climate change (e.g., expansion of woody vegetation into tundra and effects of permafrost degradation) are expected to generate further feedbacks to the climate system. Past changes can be used to assess our understanding of feedback mechanisms through a combination of process modeling and paleo-observations. The subcontinental region of Beringia (northeastern Siberia, Alaska, and northwestern Canada) was largely ice-free at the peak of deglacial warming and experienced both major vegetation change and loss of permafrost when many arctic regions were still ice covered. The evolution of Beringian climate at this time was largely driven by global features, such as the amplified seasonal cycle of Northern Hemisphere insolation and changes in global ice volume and atmospheric composition, but changes in regional land-surface controls, such as the widespread development of thaw lakes, the replacement of tundra by deciduous forest or woodland, and the flooding of the Bering-Chukchi land bridge, were probably also important. We examined the sensitivity of Beringia's early Holocene climate to these regional-scale controls using a regional climate model (RegCM). Lateral and oceanic boundary conditions were provided by global climate simulations conducted using the GENESIS V2.01 atmospheric general circulation model (AGCM) with a mixed-layer ocean. We carried out two present-day simulations of regional climate - one with modern and one with 11 ka geography - plus another simulation for 6 ka. In addition, we performed five ~ 11 ka climate simulations, each driven by the same global AGCM boundary conditions: (i) 11 ka Control, which represents conditions just prior to the major transitions (exposed land bridge, no thaw lakes or wetlands, widespread tundra vegetation), (ii) sea-level rise, which employed present-day continental outlines, (iii) vegetation change, with deciduous needleleaf and deciduous broadleaf boreal vegetation types distributed as suggested by the paleoecological record, (iv) thaw lakes, which used the present-day distribution of lakes and wetlands, and (v) post-11 ka All, incorporating all boundary conditions changed in experiments (ii)-(iv). We find that regional-scale controls strongly mediate the climate responses to changes in the large-scale controls, amplifying them in some cases, damping them in others, and, overall, generating considerable spatial heterogeneity in the simulated climate changes. The change from tundra to deciduous woodland produces additional widespread warming in spring and early summer over that induced by the 11 ka insolation regime alone, and lakes and wetlands produce modest and localized cooling in summer and warming in winter. The greatest effect is the flooding of the land bridge and shelves, which produces generally cooler conditions in summer but warmer conditions in winter and is most clearly manifest on the flooded shelves and in eastern Beringia. By 6 ka continued amplification of the seasonal cycle of insolation and loss of the Laurentide ice sheet produce temperatures similar to or higher than those at 11 ka, plus a longer growing season.

URL: http://www.clim-past.net/11/1197/2015/cp-11-1197-2015.pdf

2016040791 Vandenberghe, Jef (VU University, Department of Earth Sciences, Amsterdam, Netherlands); Woronko, Barbara; Nieuwendam, Alexandre and Bateman, Mark, editors. Paleoenvironment special issue: Permafrost and Periglacial Processes, 27(1), 143 p., illus., March 2016. Individual papers are cited separately.

2016040799 Woronko, Barbara (University of Warsaw, Faculty of Geology, Warsaw, Poland) and Pisarska-Jamrozy, Malgorzata. Micro-scale frost weathering of sand-sized quartz grains: in Paleoenvironment special issue (Vandenberghe, Jef, editor; et al.), Permafrost and Periglacial Processes, 27(1), p. 109-122, illus. incl. 3 tables, 44 ref., March 2016.

The surface textures of almost 1300 quartz grains in the 0.8-1.0 mm and 0.5-0.8 mm size fractions were studied in order to analyze the effects of frost weathering. Some grains had undergone periglacial processes in present-day active layers in Canada, Spitsbergen and Mongolia, whereas other grains were sampled from a former active layer in Poland. Microstructures were studied under a scanning electron microscope and the results statistically analysed in order to distinguish characteristic microstructures resulting from frost weathering. The quartz grains with these microstructures had been deposited by fluvial, aeolian and glacial processes and their characteristic microstructures are classified as primary microstructures. Microstructures that developed on primary ones as a result of frost weathering are called secondary microstructures. The most characteristic secondary frost weathering microstructures on the quartz grains are (1) small breakage blocks (<10 mm), (2) big breakage blocks (>10 mm) and (3) single small conchoidal fractures (<10 mm). These secondary microstructures developed commonly on the following primary microstructures: (1) sharp edges of big conchoidal fractures (>10 mm), (2) microsteps, (3) edge roundings and (4) crescentic gouges. These findings facilitate the reconstruction of cryogenic conditions, support the recognition of ancient active layers and indicate grains that are particularly susceptible to frost weathering. Copyright Copyright 2015 John Wiley & Sons, Ltd.

DOI: 10.1002/ppp.1855

2016042846 Jones, Vivienne J. (University College London, Department of Geography, London, United Kingdom) and Solomina, Olga. The geography of Kamchatka: in Holocene environmental change in Kamchatka (Brooks, S. J., editor; et al.), Global and Planetary Change, 134, p. 3-9, illus. incl. sketch map, 80 ref., November 2015.

This paper briefly reviews the physical and human geography of the Kamchatka region and summarises previous research on Holocene climate dynamics. We provide context for the rest of the Special Issue of the Journal Global and Planetary Change entitled 'Holocene climate change in Kamchatka', the primary focus of which is the use of lake sediment records for palaeoclimatic inferences. In this paper an additional perspective from ongoing tree ring, ice core and borehole temperature reconstructions illustrates that the Kamchatka region is rich in paleoclimatic proxies. The period of the last 200 years is sufficiently covered by the proxy information, including reconstructions with annual resolution. In this period the tree-rings, ice cores, boreholes, and glacier fluctuations recorded a 1 °C warming and a general glacier retreat, i.e. the transition from the Little Ice Age climate to the modern one. Although the proxies have different resolution, accuracy and seasonality in general they demonstrate a coherent picture of environmental changes in the last two centuries. The tree ring and ice core records are up to four-six hundred years long and they provide information on annual to decadal variability of summer temperature, accumulation processes, volcanic eruptions and lahar activity.

DOI: 10.1016/j.gloplacha.2015.06.003

2016039612 Luo Jing (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Niu Fujun; Lin Zhanju; Liu Minghao and Yin Guoan. Thermokarst lake changes between 1969 and 2010 in the Beilu River basin, Qinghai-Tibet Plateau, China: Science Bulletin, 60(5), p. 556-564, illus. incl. 1 table, geol. sketch map, 38 ref., March 2015.

This work presents changes of thermokarst lakes from Beilu River Basin on the Qinghai-Tibet Plateau over the past four decades (1969-2010) using aerial and satellite image interpretation. The results indicated that thermokarst lake activity had generally increased rapidly between 1969 and 2010. The number of thermokarst lakes had increased by approximately 534, and their coverage expanded by about 410 ha. The two main changes observed were an increase in the number of small lakes and the expansion of larger lakes. These changes are likely the result of persistent climate warming and a gradually increasing imbalance between precipitation and evapotranspiration (P-ET). However, some non-climatic factors, such as the lake-bottom substrate and local engineering activities, have also influenced the lake changes. If air temperature and P-ET continue to rise, the number of thermokarst lakes and the area they cover may continue to increase in the future. Copyright 2015 Science China Press and Springer-Verlag Berlin Heidelberg

DOI: 10.1007/s11434-015-0730-2

2016042496 Heckmann, Tobias (Katholische Universität Eichstätt-Ingolstadt, Physical Geography, Eichstatt, Germany); McColl, Samuel and Morche, David. Retreating ice; research in pro-glacial areas matters: Earth Surface Processes and Landforms, 41(2), p. 271-276, illus., 41 ref., February 2016.

Glacier forefields are landscapes in transition from glacial to non-glacial conditions; this implies intense geomorphic, hydrological and ecological dynamics with important on- and off-site effects. This special issue collects 13 papers covering recent research in both (sub-)polar and alpine pro-glacial environments that focus on (i) pro-glacial sediment sources, (ii) pro-glacial rivers, (iii) pro-glacial lakes, (iv) ground water and ice, and (v) the development of soil and vegetation in its interplay with morphodynamics. Advances in mapping, surveying and geophysical techniques form the basis for research perspectives related to the historical evolution of pro-glacial areas, the understanding of complex interactions of multiple processes, and the effects of continued glacier recession. Copyright Copyright 2015 John Wiley & Sons, Ltd.

DOI: 10.1002/esp.3858

2016047356 Axtell, Charlotte (Swansea University, Glaciology Group, Swansea, United Kingdom); Murray, Tavi; Kulessa, Bernd; Clark, Roger A. and Gusmeroli, Alessio. Improved accuracy of cross-borehole radar velocity models for ice property analysis: Geophysics, 81(1), p. WA203-WA212, illus., 61 ref., January 2016.

Cross-borehole radar (XBHR) is widely used for the quantification of pore-scale liquid water in geologic materials, inferred from bulk velocity variations caused by differences in electromagnetic properties between the water and the surrounding material. The XBHR can accurately and repeatedly measure variation at depth, with sampled material remaining under natural stresses, while maintaining good lateral sampling. However, even small errors in measured radar velocities result in large errors in water content estimates, emphasizing the need to quantify and minimize errors. We have rigorously assessed the sources of uncertainty in XBHR surveys undertaken in a glaciological setting. We have summarized and quantified the three main areas of uncertainty in data collection: (1) instrument time drift, (2) first-break picking, and (3) borehole geometry. Our analysis of field data indicated that contemporary acquisition procedures can produce velocity errors of ±3.0% (±0.0050 m/ns), equivalent to ±0.84 vol% water content. We have developed several revisions to produce improved data acquisition. Through enhancement of existing techniques, the velocity uncertainties were improved to ±1.5%. We also found the measurement of borehole diameter during hot-water drilling, which could hypothetically further reduce the velocity uncertainty to ±0.8%, equivalent to ±0.2 vol% water content. The need for such precise measurement is clear because an increase in englacial water content, from 0% to 0.8%, has been proven to triple the strain rate and soften the ice. Liquid water between ice crystals has also been linked to faster velocities in ice streams and surging events.

DOI: 10.1190/geo2015-0131.1

2016046211 Liu, Lu (University of Washington, Department of Earth and Space Sciences, Seattle, WA); Sletten, Ronald S.; Hagedorn, Birgit; Hallet, Bernard; McKay, Christopher P. and Stone, John O. An enhanced model of the contemporary and long-term (200 ka) sublimation of the massive subsurface ice in Beacon Valley, Antarctica: Journal of Geophysical Research: Earth Surface, 120(8), p. 1596-1610, August 2015.

A massive ice body buried under several decimeters of dry regolith in Beacon Valley, Antarctica, is believed to be more than 1 Ma old and perhaps over 8.1 Ma; however, vapor diffusion models suggest that subsurface ice in this region is not stable under current climate conditions. To better understand the controls on sublimation rates and stability of this massive ice, we have modeled vapor diffusion using 12 years of climate and soil temperature data from 1999 to 2011, including field measurements of episodic snow cover and snowmelt events that have not been represented in previous models of ground ice sublimation. The model is then extended to reconstruct the sublimation history over the last 200 ka using paleotemperatures estimated from ice core data from nearby Taylor Dome and a relationship between atmospheric temperature and humidity derived from our meteorological records. The model quantifies the impact of episodic snow events; they account for a nearly 30% reduction in the massive ice loss. The sublimation rate of ground ice averages 0.11 mm a^-1 between 1999 and 2011 in Beacon Valley. Parameterized with past environmental conditions and assuming the same regolith thickness, the modeled sublimation rate of ground ice in Beacon Valley averages 0.09 mm a^-1 for the last 200 ka, comparable to the long-term average rate estimated independently from various studies based on cosmogenic isotopes. This study provides a realistic estimate of the long-term sublimation history and supports the inference that the buried ice in Beacon Valley is older than 1 Ma. Abstract Copyright (2015), American Geophysical Union. All Rights Reserved.

DOI: 10.1002/2014JF003415

2016039626 Hromadka, T. V., II (U. S. Military Academy, Department of Mathematical Sciences, West Point, NY); McInvale, H. D.; Gatzke, B.; Phillips, M. and Espinosa, B. Cumulative departure model of the cryosphere during the Pleistocene: Journal of Cold Regions Engineering, 28(3), unpaginated, illus. incl. 1 table, 45 ref., September 2014.

URL: http://dx.doi.org/10.1061/(ASCE)CR.1943-5495.0000071

2016039445 Ning Jianguo (Beijing Institute of Technology, State Key Laboratory of Explosion Science and Technology, Beijing, China); He Yuexiang and Zhu Zhiwu. Dynamic constitutive modeling of frozen soil under impact loading: Chinese Science Bulletin, 59(26), p. 3255-3259, 8 ref., September 2014. Based on Publisher-supplied data.

In this study, an isotropic hardening constitutive model is presented to study the behavior of frozen soil under impact loading. In plasticity, a modified Drucker-Prager yield function is adopted. Based on the experimental investigations at different strain rates and different temperatures by means of split Hopkinson pressure bar, the Drucker-Prager criterion has been modified with consideration in the effect of strain rate, and the model parameters have been determined. Compared the constitutive model with the experimental results, the predicted tendencies of the model corresponded well to the test curves. Copyright 2014 Science China Press and Springer-Verlag Berlin Heidelberg

DOI: 10.1007/s11434-014-0488-y

2016039625 Kong, Qingzhao (University of Houston, Department of Mechanical Engineering, Houston, TX); Wang Ruolin; Song, Gangbing; Yang, Zhaohui Joey and Still, Benjamin. Monitoring the soil freeze-thaw process using piezoceramic-based smart aggregate: Journal of Cold Regions Engineering, 28(2), unpaginated, illus. incl. 5 tables, 22 ref., June 2014.

URL: http://dx.doi.org/10.1061

2016039624 Crowther, G. Scott (Crowther Associates, Anchorage, AK). Retracted; frozen soil strength criteria for lateral pile analysis: Journal of Cold Regions Engineering, 27(3), p. 155-167, illus. incl. 3 tables, 15 ref., September 2013.

URL: http://dx.doi.org/10.1061/(ASCE)CR.1943-5495.0000058

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2016046246 Tai Bowen (Beijing Jiaotong University, School of Civil Engineering, Beijing, China); Fang Jianhong; Liu Lei; Xu Anhua; Liu Jiankun and Tian Yahu. Temperature monitoring of the XPS board insulated subgrade along the newly constructed Gonghe-Yushu Highway in permafrost regions: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 520-527, illus., 15 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

On the basis of on-site measured data of the newly constructed Gonghe-Yushu Highway in a permafrost region, this paper analyzed thermal conditions of the subgrade with XPS insulated board according to different selected monitoring sections in various locations. We also summarized the geothermal distribution and change rules of subgrade with XPS insulation board under the asphalt pavement in summarized a high temperature frozen soil region. It is suggested that the shoulder of subgrade with XPS insulation board be widen to a reasonable width so as to keep the subgrade stable.

DOI: 10.3724/SP.J.1226.2015.00520

2016046251 Xiong Zhiwen (Northwest Research Institute Company, Gansu, China); Yang Yongpeng; Zhu Zhaorong; Zhao Xiangqing and Cai Haicheng. Effect of climate change and railway embankment on the degradation of underlain permafrost: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 554-559, illus. incl. 3 tables, 16 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

Because of the global warming and the increasing human activity, the air temperature and the precipitation along the Qinghai-Tibet Railway increased gradually in recent years, which endanger the permafrost table, the embankment of the railway. The statistics of the air temperature, the precipitation and the geothermal temperature in recent 50 years in this dissertation come from the four weather station along the railway, that are Wudaoliang Station, Fenghuo Mountains Station, Tuotuo River Station and Ando Station. This dissertation analyzes the change of climate along the railway and then develops a research on the effect of the changing geothermal temperature on permafrost table and its countermeasures. The experiment result shows that the air temperature of the permafrost region rise steadily in about 50 years, especially in this century, the tendency of rising temperature is more obvious. The precipitation fluctuates but it is also rising rapidly, for the largest precipitation reached 492.6 mm. For 30 years now, the Qinghai-Tibet Plateau has been in the megathermal period, which also affects the permafrost region along the railway. The condition of permafrost is degrading greatly.

DOI: 10.3724/SP.J.1226.2015.00554

2016046252 Yang Yongpeng (Northwest Research Institute Company, Gansu, China); Qu Yaohui; Cai Hancheng; Cheng Jia and Tang Caimei. A system for automated monitoring of embankment deformation along the Qinghai-Tibet Railway in permafrost regions: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 560-567, illus. incl. 2 tables, 12 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

At present, the monitoring of embankment deformation in permafrost regions along the Qinghai-Tibet Railway is mainly done manually. However, the harsh climate on the plateau affects the results greatly by lowering the observation frequency, so the manual monitoring can barely meet the observational demand. This research develops a system of automated monitoring of embankment deformation, and aims to address the problems caused by the plateau climate and the permafrost conditions in the region. The equipment consists of a monitoring module, a data collection module, a transmission module, and a data processing module. The field experiments during this program indicate that (1) the combined automated monitoring device overcame the problems associated with the complicated and tough plateau environment by means of wireless transmission and automatic analysis of the embankment settlement data; (2) the calibration of the combined settlement gauge at -20°C was highly accurate, with an error rate always <0.5%; (3) the gauge calibration at high-temperature conditions was also highly accurate, with an error rate <0.5% even though the surface of the instrument reached more than 50°C; and (4) compared with the data manually taken, the data automatically acquired during field monitoring experiments demonstrated that the combined settlement gauge and the automated monitoring system could meet the requirements of the monitoring mission in permafrost regions along the Qinghai-Tibet Railway.

DOI: 10.3724/SP.J.1226.2015.00560

2016044771 James, S. R. (University of Florida, Department of Geological Sciences, Gainesville, FL); Knox, H. A. and Abbott, R. E. Monitoring seasonal changes in permafrost using seismic interferometry [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract S34B-06, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

The effects of climate change in polar regions and their incorporation in global climate models has recently become an area of great interest. Permafrost holds entrapped greenhouse gases, e.g. CO2 and CH4, which are released to the atmosphere upon thawing, creating a positive feedback mechanism. Knowledge of seasonal changes in active layer thickness as well as long term degradation of permafrost is critical to the management of high latitude infrastructures, hazard mitigation, and increasing the accuracy of climate predictions. Methods for effectively imaging the spatial extent, depth, thickness, and discontinuous nature of permafrost over large areas are needed. Furthermore, continuous monitoring of permafrost over annual time scales would provide valuable insight into permafrost degradation. Seismic interferometry using ambient seismic noise has proven effective for recording velocity changes within the subsurface for a variety of applications, but has yet to be applied to permafrost studies. To this end, we deployed 7 Nanometrics Trillium posthole broadband seismometers within Poker Flat Research Range, located 30 miles north of Fairbanks, Alaska in a zone of discontinuous permafrost. Approximately 2 years worth of nearly continuous ambient noise data was collected. Using the python package MSNoise, relative changes in velocity were calculated. Results show high amounts of variability throughout the study period. General trends of negative relative velocity shifts can be seen between August and October followed by a positive relative velocity shift between November and February. Differences in relative velocity changes with both frequency and spatial location are also observed, suggesting this technique is sensitive to permafrost variation with depth and extent. Overall, short and long term changes in shallow subsurface velocity can be recovered using this method proposing seismic interferometry is a promising new technique for permafrost monitoring. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

2016037365 Douglas, Thomas A. (U. S. Army Cold Regions Research and Engineering Laboratory, Fort Wainwright, AK). Dramatic seasonality of biogeochemical signatures in watersheds underlain by permafrost [abstr.]: in Goldschmidt abstracts 2015, V.M. Goldschmidt Conference - Program and Abstracts, 25, p. 770, 2015. Meeting: Goldschmidt 2015, Aug. 16-21, 2015, Prague, Czech Republic.

URL: http://goldschmidt.info/2015/uploads/abstracts/finalPDFs/770.pdf

2016042015 Murphy, M. J. (University of Oxford, Department of Earth Sciences, Oxford, United Kingdom); Pogge von Strandmann, P. A. E.; Porcelli, D.; Hirst, C.; Andersson, P.; Kutscher, L. and Maximov, T. Lithium isotopes in waters draining a large permafrost-dominated watershed; the Lena River [abstr.]: in Goldschmidt abstracts 2015, V.M. Goldschmidt Conference - Program and Abstracts, 25, p. 2224, 2015. Meeting: Goldschmidt 2015, Aug. 16-21, 2015, Prague, Czech Republic.

URL: http://goldschmidt.info/2015/uploads/abstracts/finalPDFs/2224.pdf

2016046241 Burukin, Alexey Y. (Open Joint Stock Company, Moscow, Russian Federation); Lutskiy, Svyatoslav Ya. and Khripkov, Konstantin. In-depth improvement of soil at the base of roads on taliks: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 475-481, illus., 22 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

The article presents a new technological solution to improve the safety of embankment bases on taliks during construction periods. The use of geotextile-sleeved sand columns and geogrids on low-temperature permafrost is investigated. The correlations between mechanical and temperature processes under this in-depth base improvement method are calculated.

DOI: 10.3724/SP.J.1226.2015.00475

2016044786 Ajo Franklin, J. B. (Lawrence Berkeley National Laboratory, Berkeley, CA); Lindsey, N.; Martin, E. R.; Wagner, Anna M.; Robertson, M.; Bjella, Kevin; Gelvin, Arthur B.; Ulrich, C.; Wu, Y.; Freifeld, B. M.; Daley, T. M. and Dou, Shan. Ambient noise surface wave tomography for geotechnical monitoring using "large n" distributed acoustic sensing [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract S41A-2707, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

Surface wave tomography using ambient noise sources has found broad application at the regional scale but has not been adopted fully for geotechnical applications despite the abundance of noise sources in this context. The recent development of Distributed Acoustic Sensing (DAS) provides a clear path for inexpensively recording high spatial resolution (< 1m sampling) surface wave data in the context of infrastructure monitoring over significant spatial domains (10s of km). Infrastructure monitoring is particularly crucial in the context of high-latitude installations where a changing global climate can trigger reductions in soil strength due to permafrost thaw. DAS surface wave monitoring systems, particularly those installed in/near transport corridors and coupled to ambient noise inversion algorithms, could be a critical "early warning" system to detect zones of decreased shear strength before failure. We present preliminary ambient noise tomography results from a 1.3 km continuously recording subsurface DAS array used to record traffic noise next to an active road in Fairbanks, AK. The array, deployed at the Farmer's Loop Permafrost Test Station, was designed as a narrow 2D array and installed via trenching at »30 cm. We develop a pre-processing and QC approach to analyze the large resulting volume of data, equivalent to a 1300 geophone array sampled at 1 khz. We utilize automated dispersion analysis and a quasi-2D MC inversion to generate a shear wave velocity profile underneath the road in a region of discontinuous permafrost. The results are validated against a high-resolution ERT survey as well as direct-push data on ice content. We also compare vintages of ambient noise DAS data to evaluate the short-term repeatability of the technique in the face of changing noise environments. The resulting dataset demonstrates the utility of using DAS for real-time shear-modulus monitoring in support of critical infrastructure.

2016044824 Martin, E. R. (Stanford University, Stanford, CA); Lindsey, N.; Biondi, B. C.; Chang, J. P.; Ajo Franklin, J. B.; Dou, S.; Daley, T. M.; Freifeld, B. M.; Robertson, M.; Ulrich, C.; Wagner, Anna M. and Bjella, Kevin. Fast algorithm for continuous monitoring with ambient noise [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract S41B-2745, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

A common approach to analyzing ambient seismic noise involves O(n²) pairwise cross-correlations of n sensors. Following cross-correlations the resulting coherent waveforms are then synthesized into a velocity estimate, often in the form of a dispersion image. As we move towards larger surveys and arrays for continuous subsurface monitoring, this computation can become prohibitively expensive. We show that theoretically equivalent results can be achieved by a simple algorithm which skips the cross-correlations, and scales as O(n). Additionally, this algorithm is embarrassingly parallel, and is significantly cheaper than the commonly used algorithms. We demonstrate the algorithm on two field data sets: (1) a continuously recording linear trenched distributed acoustic sensing (DAS) array designed as a pilot test to develop a permafrost thaw monitoring system, and (2) the Long Beach Array, an irregularly spaced 3D array. These results show superior performance in both speed and numerical accuracy. An open-source implementation of this algorithm is available.

2016044864 Shao, Haibing (Helmholtz Centre for Environmental Research, Leipzig, Germany). Modeling coupled thermal-mechanical processes of frozen soil induced by borehole heat exchanger [abstr.]: in AGU 2015 fall meeting, American Geophysical Union Fall Meeting, 2015, Abstract T13E-04, December 2015. Meeting: American Geophysical Union 2015 fall meeting, Dec. 14-18, 2015, San Francisco, CA.

To utilize the shallow geothermal energy, heat pumps are often coupled with Borehole Heat Exchangers (BHE) to provide heating and cooling for buildings. In cold regions, soil freezing around the BHE is a potential problem which will dramatically influence the underground soil temperature distribution, subsequently the inlet and outlet refrigerant temperature of the BHE, and finally the efficiency of the heat pump. In this study, a numerical model has been developed to simulate the coupled temperature evolution both inside the BHE, and the propagating freezing front in the surrounding soil. The coupled model was validated against analytical solutions and experimental data. The influence of the freezing process on the overall system permafrost performance is investigated by comparing one long BHE configuration without freezing and another short one with latent heat from the frozen groundwater. It is found that when freezing happens, the coefficient of performance (COP) of the heat pump will decrease by around 0.5, leading to more electricity consumption. Furthermore, analysis of the simulation result reveals that the exploitation of latent heat through groundwater freezing is only economically attractive if electricity price is low and interest rate high, and it is not the case is most European countries.

2016037709 Stelling, Jonathan M. (Lehigh University, Department of Earth and Environmental Sciences, Bethlehem, PA); Yu, Zicheng; Beilman, David W. and Loisel, Julie. Late Holocene ecological and climate change from peat records in the western Antarctic Peninsula [abstr.]: in Geological Society of America, 2015 annual meeting & exposition, Abstracts with Programs - Geological Society of America, 47(7), p. 501, 2015. Meeting: Geological Society of America, 2015 annual meeting & exposition, Nov. 1-4, 2015, Baltimore, MD.

The Western Antarctic Peninsula (WAP) has experienced rapid warming over the past 50 years. The marine record from nearby Palmer Deep shows large magnitude changes in climate during the last 3,000 years. However, the response of terrestrial ecosystems to these changes is poorly understood. Peat deposits accumulating in permafrost-influenced moss banks in the Maritime Antarctic preserve a terrestrial record of past ecology and climate. Here we present a paleoecological record of ecosystem change derived from an 80 cm core collected from a peat bank on Litchfield Island (-64.77, -64.09) near Palmer Station. Chronology is established using Bayesian statistical age modeling of six AMS ¹⁴C dates with a basal age of 2,580 cal years BP. Age modeling shows that vertical accumulation of the peat bank ranges from 0.15 to 1 mm yr^-1 with a mean of 0.3 mm yr^-1. Macrofossil analysis results show that species dominance shifts between Polytrichum strictum, Chorisodontium aciphyllum and Pohlia sp in ca. 600 year cycles. Bulk density and LOI results show that carbon accumulation rates range from 8 to 92 gC m^-2 yr^-1 with a mean of 22 gC m^-2 yr^-1. There are marked periods of increased carbon accumulation over the past 350 years as well as a pronounced peak around 1,400 cal years BP. Oscillations of species dominance are interpreted as changes in local temperature or moisture availability due to climate change, as opposed to ecological succession. This new record shows the banks are highly dynamic ecosystems sensitive to climate and environmental changes. Increases in carbon accumulation rates in the past 350 years are likely due to increased production in response to more hospitable conditions in the WAP.

2016046259 Cai Degou (Chinese Academy of Rails Science, Railway Engineerinig Research Institute, Beijing, China); Yao Jianping; Yan Hongye; Zhang Qianli; Cheng Aijun and Liu Hie. Investigation of frost heave prevention using permeable subgrade structure: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 611-618, illus. incl. 3 tables, 15 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

This paper set up a series of comprehensive targets based on the concept of 'anti-freeze filler', which include reasonable water retention rate, frost heave characteristics, and compaction characteristics of filling material. Then, a type of permeable graded gravel is proposed, suitable for high-speed railway subgrade. A series of in-door water retention, permeability, and frost heave tests were performed under different graded conditions. Water retention, permeability, and frost heave characteristic of different graded filling materials can be determined, in order to define the gradation range of permeable graded gravel. Relying on the frost-heave monitoring record of high speed railway in Northeast China, a series of experimental studies were performed, which included on-site filler production, compaction test, and the anti-frost effect test, in order to improve the production and compaction techniques of permeable graded gravel. From the research of this paper, the use of permeable graded gravel subgrade as the anti-frost structure for the high-speed railway subgrade in cold areas is feasible.

DOI: 10.3724/SP.J.1226.2015.00611

2016046242 Edil, Tuncer B. (University of Wisconsin, Department of Civil and Environmental Engineering, Madison, WI) and Cetin, Bora. Freeze-thaw performance of chemically stabilized natural and recycled highway materials: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 482-491, illus. incl. 4 tables, 24 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

This article provides an overview of several previous studies that investigated the stiffness and strength performance of chemically stabilized roadway materials under winter conditions (freeze-thaw cycling). The objective of this research was to understand the behavior of different materials stabilized with different type of binders when they were subjected to freeze-thaw cycling. Nine different materials including natural soils (organic soil, clay, silt, sand, and road surface gravel), reclaimed pavement material, and recycled asphalt pavement stabilized with nine different binders (five different fly ashes, lime, cement, lime kiln dust, cement kiln dust) were discussed. This article investigated how the volume, resilient modulus and unconfined compressive strength of soils/materials stabilized with different binders change in response to freeze-thaw cycling. Overall, the review results indicate that the stiffness and strength of all stabilized materials decrease somewhat with freeze-thaw cycling. However, the reduced strength and stiffness of stabilized materials after freeze-thaw cycling was still higher than that of unstabilized-unfrozen original soils and materials. In addition, materials stabilized with cement kiln dust provided the best performance against freeze-thaw cycling

DOI: 10.3724/SP.J.1226.2015.00482

2016046248 Stoyanovich, Gennady M. (Far Eastern State Transport, Department of Railway Track and Railway Engineering, Khabarovsk, Russian Federation) and Pupatenko, Viktor V. Propagation of vibrations in thawing deep seasonally frozen soils in railway subgrade: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 534-540, illus., 17 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

In this study, in-situ testing results are given, and the analytical relationship of the vibrations' amplitudes inside an embankment by the thawing of the subgrade surface of seasonably deep frozen soils is provided. The peculiarities of the vibration waves' propagation during the springtime thawing of soils compared to those during the summertime period and the correlation of the vibrations with the under-rail basement modulus of elasticity are defined.

DOI: 10.3724/SP.J.1226.2015.00534

2016046250 Yue Zurun (Shijiazhuang Tiedao University, Graduate School, Hebei, China); Tai Bowen and Sun Tiecheng. Analysis of temperature field characteristics based on subgrade site measurements of Harbin-Qiqihar high-speed railway in a deep seasonal frozen soil region: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 547-553, illus. incl. 3 tables, 16 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

Recent years have seen a large number of high-speed railways built and will be built in seasonal frozen soil regions of China. Although high-speed railways are characterized by being fast, comfortable and safe, higher standards for deformation of the railways' frozen subgrade are required. Meanwhile, changes in subgrade soil temperatures are the main factors affecting the deformation of frozen subgrade. Therefore, this paper selected typical test subgrade sections of the Harbin-Qiqihar Line, a special line for passenger transport built in the deep seasonal frozen soil regions of China, to monitor field temperatures. Also, the temperature changing laws of railways' subgrade in this region was analyzed by using testing data, the aim of which is to provide a technical support for future design and construction of buildings and structures in a deep seasonal frozen soil region.

DOI: 10.3724/SP.J.1226.2015.00547

2016046258 Zhao Yingying (Harbin Institute of Technology, School of Civil Engineering, Heilongjiang, China); Ling Xianzhang; Wang Ziyu; Shao Xinyan; Tian Lihui and Geng Lin. Test on dynamic characteristics of subgrade of heavy-haul railway in cold regions: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 605-610, illus. incl. 2 tables, 20 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

Dynamic characteristics of heavy-haul railway subgrade under vibratory loading in cold regions are investigated via low-temperature dynamic triaxial tests with multi-stage cyclic loading process. The relationship between dynamic shear stress and dynamic shear strain of frozen soil of subgrade under train loading and the influence of freezing temperatures on dynamic constitutive relation, dynamic shear modulus and damping ratio are observed in this study. Test results show that the dynamic constitutive relations of the frozen soils with different freezing temperatures comply with the hyperbolic model, in which model parameters a and b decrease with increasing freezing temperature. The dynamic shear modulus of the frozen soils decreases with increasing dynamic shear strains initially, followed by a relatively smooth attenuation tendency, whereas increases with decreasing freezing temperatures. The damping ratios decrease with decreasing freezing temperatures. Two linear functions are defined to express the linear relationships between dynamic shear modulus (damping ratio) and freezing temperature, respectively, in which corresponding linear coefficients are obtained through multiple regression analysis of test data.

DOI: 10.3724/SP.J.1226.2015.00605

2016037340 Dimova, Natasha T. (University of Alabama, Department of Geological Sciences, Tuscaloosa, AL); Paytan, Adina; Kessler, John D.; Sparrow, Katy J.; Garcia-Tigreros, Fenix; Lecher, Alanna; Murray, Joseph and Tulaczyk, Slawomir M. Magnitude and mechanisms of submarine groundwater discharge (SGD) in the Arctic during warming climate; case study from Alaska [abstr.]: in Goldschmidt abstracts 2015, V.M. Goldschmidt Conference - Program and Abstracts, 25, p. 745, 2015. Meeting: Goldschmidt 2015, Aug. 16-21, 2015, Prague, Czech Republic.

URL: http://goldschmidt.info/2015/uploads/abstracts/finalPDFs/745.pdf

2016037356 Dong, Shuofei (Centre de Recherches Pétrographiques et Géochimiques, Nancy, France); Cloquet, Christophe and Pienitz, Reinhard. Zinc and Pb isotope signatures suggest change in lake sediment source in response to global warming [abstr.]: in Goldschmidt abstracts 2015, V.M. Goldschmidt Conference - Program and Abstracts, 25, p. 761, 2015. Meeting: Goldschmidt 2015, Aug. 16-21, 2015, Prague, Czech Republic.

URL: http://goldschmidt.info/2015/uploads/abstracts/finalPDFs/761.pdf

2016039992 Kutscher, Liselott (Stockholm University, Department of Geological Sciences, Stockholm, Sweden); Andersson, Per S.; Mörth, Carl-Magnus; Porcelli, Don; Hirst, Catherine and Maximov, Trofim. Export and sources of organic carbon in the Lena River catchment, Siberia [abstr.]: in Goldschmidt abstracts 2015, V.M. Goldschmidt Conference - Program and Abstracts, 25, p. 1728, 2015. Meeting: Goldschmidt 2015, Aug. 16-21, 2015, Prague, Czech Republic.

URL: http://goldschmidt.info/2015/uploads/abstracts/finalPDFs/1728.pdf

2016045971 Santos Assuncao, S. (Universidad Politécnica de Cataluña, Spain); Rodés, J. Pedret and Pérez Gracia, V. Ground-penetrating radar railways inspection [abstr.]: in 75th EAGE conference & exhibition incorporating SPE EUROPEC 2013, Conference and Technical Exhibition - European Association of Geoscientists and Engineers, 75, Abstract Tu P09 02, illus., 6 ref., 2013. Meeting: 75th EAGE conference & exhibition incorporating SPE EUROPEC 2013, June 10-13, 2013, London, United Kingdom.

Ground penetrating radar has been fully applied in civil engineering problems. This paper presents a case study applied to a railway line evaluation. The aim of the job was to study the stability of part of a railway line, using ground penetrating radar images. Radar data was processed in order to optimize the images, and different possible causes of the anomalies are evaluated. Radar data was acquired along the railway line, and noise due to metallic bars was diminished using migration processing. 3D radar imaging was obtained by interpolating the different radar profiles, and anomalies were analyzed in the three axes, defining their possible shape and position. As a result, two possible damaged zones were defined: the first one corresponds to a missing reflector, and could be caused by the merge of two or more layers; the second one was a deformed reflector, possible attributed to a sunken layer or a more wet material.

DOI: 10.3997/2214-4609.20130635

2016046262 Akagawa, Satoshi (Cryosphere Engineering Laboratory, Tokyo, Japan) and Hori, Michiaki. Frost heaving in ballast railway tracks: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 632-636, illus. incl. 3 tables, 6 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

Frost heaving is a well-known phenomenon in cold regions, which may occur in wet clayey grounds during winter. Railway track upheaval occurring in cold regions during the winter is generally understood as frost heaving in the subgrade layer. However, it has been confirmed that upheaval due to frost heaving sometimes occurs in the ballast layer. This understanding has been observed in active railways in northern Japan. The samples collected from ballast and subgrade layers have been examined for frost heave susceptibilities and confirmed that ballast layers which contain fines may heave.

DOI: 10.3724/SP.J.1226.2015.00632

2016046260 Baykal, Gokhan (Bogazici University, Department of Civil Engineering, Istanbul, Turkey). Use of fly ash with no water consumption for cold regions transportation infrastructure: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 619-625, illus. incl. 4 tables, 22 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

The construction period in cold regions is very short due to problems related to excavation and use of frozen soils in embankment construction, which leads to excessive deformations upon thawing. Also, handling of compaction water is critical due to freezing temperatures. Coal burning thermal power plants are very common in cold regions to supply electricity. The inorganic part of the pulverized coal after burning produces fly ash, which is available in large volumes. Due to excavation difficulties and the poor engineering behavior of frozen soils in cold regions, the utilization of fly ash when it is readily available must be promoted. Any construction technique which utilizes alternative materials like fly ash and minimizes water consumption has a potential to extend the short construction season and even allow service and maintenance during extreme weather conditions. This paper presents two potential techniques to solve the moisture affinity of silt-sized materials like fly ash. One technique involves in-plant production of fly ash pellets using cold-bonding pelletization to manufacture aggregates of up to 40,000-mm diameter from 15- to 60-mm-diameter fly ash grains. Large disc pelletizers have annual production capacities of up to one million ton at a reasonable cost. The product has adequate strength for embankment construction even when no water is used and no compaction is applied. The second technique is an in situ mixing technique which uses snow instead of compaction water for fly ash. The snow is the main element in this technique to compact the embankment. Water is needed for the hydration reactions to form cementitious minerals in fly ash. The slower the hydration reaction, the greater the crystal growth of cementitious minerals. In the proposed technique, in situ snow is mixed with fly ash and is compacted on-site. The temperature increase due to the hydration reaction of fly ash upon contact with snow crystals provides water for continued long-term hydration, which results in high strength, a high void ratio, light weight, and high thermal insulation capability. The presented techniques have the potential to extend the short construction season in cold regions and will provide fill material, decreasing the need for excavation. Both techniques are well documented under laboratory conditions, the research results have been published, and the techniques are ready for field trials to assess implementability.

DOI: 10.3724/SP.J.1226.2015.00619

2016046257 Luo Qiang (Southwest Jiaotong University, School of Civil Engineering, Sichuan, China); Lu Wenqiang; Ye Qingzhi and Zhang Ruiguo. Structural analysis and design of frost resistance function for subgrade of high-speed railway ballasted track in cold regions: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 594-604, illus. incl. 5 tables, 22 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

According to the technical characteristics of short fixed wheelbase of a high-speed carriage, a subgrade-track integrated space mechanical response analysis model is proposed for trains under the action of biaxial load after the comparison of the stress distribution characteristics of the ballast track subgrade bed structures for high-speed railway under the action of uniaxial load and biaxial load. The loading threshold value (high-cycle long-term dynamic strength) under the circumstance where the cumulative deformation of subgrade structure gradually develops and finally reaches the convergent state, and its relationship with the foundation coefficient K₃₀ were deduced, based on the characteristics of cumulative deformation evolution obtained from the unit structure filling model test under the action of cyclic loading. In view of structure stability and frost resistance requirements of the railway subgrade in cold regions, technical conditions to maintain good service performance of subgrade structure of high-speed railway ballasted track are discussed and analyzed. Study results show that the additive effect manifests itself obviously for railway train bogies under the action of biaxial load than uniaxial load, which has a significant dynamic effect on the subgrade bed bottom and a slight effect on the surface layer. Thus, the adoption of a biaxial load model in the design of a high-speed railway subgrade accurately reflects the vehicle load. Pursuant to the structure design principle, the design method of the subgrade structure of high-speed railway ballasted track is proposed to meet the technical requirements such as structural strength, bearing stiffness and high-cyclic and long-term stability. Technical indicators are obtained for the variation of thickness of the surface layer of reinforced subgrade bed in the double-layer subgrade mode along with the change of K₃₀ at the subgrade bed bottom. The double-layer structure mode of "closure on the upper layer and drainage on the lower layer" was proposed in order to meet the waterproofing and drainage requirements of the upper layer of the subgrade bed in cold regions. A dense-framework graded gravel filler with weak water permeability at a coefficient of 10^-4 cm/s is used on the upper layer and the void-framework graded gravel filler at the water permeability coefficient of 10^-2 cm/s is adopted on the lower layer.

DOI: 10.3724/SP.J.1226.2015.00594

2016046256 Ma Hongyan (Harbin Institute of Technology, School of Transportation Science and Engineering, Heilongjiang, China); Zhang Feng; Feng Decheng and Lin Bo. Determination of allowable subgrade frost heave with the pavement roughness index in numerical analysis: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 587-593, illus. incl. 2 tables, 19 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

Frost heave is an upward swelling of soil during cryogenic conditions in cold regions. It is caused by the accumulation of ice crystals in subgrade soil, which grow upwards when freezing temperatures penetrate into the subgrade. This study establishes the allowable soil subgrade frost heave based on the roughness standard of asphalt pavement in China, and aims to balance the pavement design and frost heave resistance of subgrades in cold regions. We formulated a mechanical model of pavement supported by the boundary conditions of differential frost heave, based on the elastic layered system theory. The differential soil subgrade frost heave was modeled as a sinusoidal function, and the allowable frost heave and the roughness index were modeled as the displacement boundaries for the top and bottom of the pavement structure. Then the allowable frost heave was back-calculated according to the roughness standard. Numerical results show that the allowable frost heave depends on the pavement structure, material properties, the highway grade, and other factors. In order to ensure that the actual soil subgrade frost heave is lower than the allowable frost heave, pavement structures and materials need to be selected and designed carefully. The numerical method proposed here can be applied to establish the frost heave resistance of subgrade when the pavement structure and materials are determined.

DOI: 10.3724/SP.J.1226.2015.00587

2016046249 Stoyanovich, Gennady M. (Far Eastern State Transport University, Department of Railway Track and Railway Engineering, Khabarovsk, Russian Federation); Pupatenko, Viktor V. and Sukhobok, Yury A. Detection of ground ice using ground penetrating radar method: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 541-546, illus. incl. sketch map, 16 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

The paper presents the results of a ground penetrating radar (GPR) application for the detection of ground ice. We combined a reflection traveltime curves analysis with a frequency spectrogram analysis. We found special anomalies at specific traces in the traveltime curves and ground boundaries analysis, and obtained a ground model for subsurface structure which allows the ground ice layer to be identified and delineated.

DOI: 10.3724/SP.J.1226.2015.00541

2016046245 Wang Qingzhi (Beijing Jiaotong University, School of Civil Engineering, Beijing, China); Tai Bowen; Liu Zhenya and Liu Jiankun. Study on the sunny-shady slope effect on the subgrade of a high-speed railway in a seasonal frozen region: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 513-519, illus. incl. 2 tables, 15 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

The temperature distributions of different parts of a subgrade were analyzed based on the results of three years of monitoring data from the Harbin-Qiqihaer Passenger Dedicated Line, a high-speed railway, including the slope toes, shoulders, and natural ground. The temperature variation with time and the maximum frozen depths showed that an obvious sunny-shady effect exists in the railway subgrade, which spans a seasonal frozen region. Development of frost heave is affected by the asymmetric temperature distribution. The temperature field and the maximum frozen depths 50 years after the subgrade was built were simulated with a mathematical model of the unsteady phase transition of the geothermal field.

DOI: 10.3724/SP.J.1226.2015.00513

2016046247 Yang Guotao (Beijing Jiaoton University, School of Civil Engineering, Beijing, China); Ke Zaitian; Cai Degou; Yan Hongye; Yao Jianping and Chen Feng. Investigation of monitoring system for high-speed railway subgrade frost heave: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 528-533, illus., 15 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

This paper presents methods for monitoring frost heave, device requirements, testing principals, and data analysis requirements, such as manual leveling observation, automatic monitoring (frost heave, frost depth, and moisture), track dynamic detection, and track status detection. We focused on the requirements of subgrade frost heave monitoring for high speed railways, and the relationship of different monitoring methods during different phases of the railway. The comprehensive monitoring system of high speed railway subgrade frost heave provided the technical support for dynamic design during construction and safe operation of the rail system.

DOI: 10.3724/SP.J.1226.2015.00528

2016046253 Zhou Xin (Jilin University, College of Construction Engineering, Jilin, China); Wang Qing; Zhang Xuefei; Yu Tianwen and Zhang Xudong. Basic properties of saline soil in Da'an, western Jilin, China: in The 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015); Special issue B (Liu Jiankun, editor; et al.), Sciences in Cold and Arid Regions, 7(5), p. 568-572, illus. incl. 3 tables, 19 ref., October 2015. Meeting: 2nd international symposium on Transportation soil engineering in cold regions (TRANSOILCOLD2015), Sept. 24-26, 2015, Novosibirsk, Russian Federation.

This paper studied the basic properties of saline soil at different depths of a sampling site in Da'an, China, through field reconnaissance and laboratory analysis. A series of experiments which comprised the analyses of grain size distribution, mineral composition, soil physical properties, soluble salt content, pH, organic content and cation exchange capacity were conducted. Through these experiments, the distribution rule of each property and their causes are discussed. These results could provide a fundamental base for the study of moisture migration.

DOI: 10.3724/SP.J.1226.2015.00568

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