July 2015 Permafrost Alert
The U.S. Permafrost Association, together with the American Geosciences Institute (AGI), is pleased to provide the following Permafrost Monthly Alerts (PMA). The AGI GeoRef service regularly scans the contents of over 3500 journals in 40 languages from the global geosciences literature, comprised of approximately 345 different sources. In addition to journals, special publications such as papers in proceedings and hard-to-find publications are provided. Each PMA represents a listing of the permafrost-related materials added to GeoRef during the previous month. Where available, a direct link to the publication is included, which provides access to the full document if you or your institution have a current online subscription.
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15076441 Chang Xiaoli (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Jin Huijun; Zhang Yanlin; He Ruixia; Luo Dongliang; Wang Yongping; Lu Lanzhi and Zhang Qiuliang. Thermal impacts of boreal forest vegetation on active layer and permafrost soils in northern Da Xing'anling (Hinggan) Mountains, northeast China: in Changing cryosphere under a warming climate (Zhang Tingjun, prefacer; et al.), Arctic, Antarctic, and Alpine Research, 47(2), p. 267-279, illus. incl. 2 tables, sketch map, 46 ref., May 2015.
A comprehensive observing system was established at the Da Xing'anling (Hinggan) Mountains Station (Gen'he) of China Forest Ecological Research Network (CFERN) in Northeast China in 2009 and gradually improved since in order to evaluate the influences of boreal forest vegetation with complex structures and various components on the thermal regimes of active layer and shallow permafrost soils. At three selected typical forest sites with similar micro-reliefs, soils, and drainage conditions, the soil temperatures on the ground surface and at various depths ranging from 0.05 to 5.0 m were measured with thermistor cables permanently installed in boreholes. The temperature data were compared and contrasted for various vegetative features. In a control experiment, trees and shrubs were removed to better understand the hydrothermal effects of vegetation removal. Results show that: (1) The vegetative layer provides an evident effect of thermal insulation on the ground. The ground temperature at the same depth was lower at a stand with denser vegetation when other conditions are held the same. (2) The ground warms up when the vegetation degrades, and the ground temperature rises from the vegetation degradation could reach much deeper in winter than in summer. (3) In cases of extensive vegetation degradation, the resultant ground warming persists for a long time, resulting in a deepening active layer.
15076437 Mu Cuicui (Lanzhou University, Laboratory of Western China's Enviornmental Systems, Lanzhou, China); Zhang Tingjun; Wu Qingbai; Cao Bin; Zhang Xiankai; Peng Xiaoqing; Wan Xudong; Zheng Lei; Wang Qingfeng and Cheng Guodong. Carbon and nitrogen properties of permafrost over the Eboling Mountain in the upper reach of Heihe River basin, northwestern China: in Changing cryosphere under a warming climate (Zhang Tingjun, prefacer; et al.), Arctic, Antarctic, and Alpine Research, 47(2), p. 203-211, illus. incl. sketch maps, 58 ref., May 2015.
The sensitivity of soil carbon and nitrogen to warming is a major uncertainty in projections of climate. However, previous studies about soil organic carbon (SOC) stocks and potential emission predominantly concentrated on the shallow soil layer in high latitude ecosystems. In this study, we analyzed the SOC, total nitrogen (TN) and soil inorganic carbon (SIC) stocks, C/N ratios, and stable carbon isotope (d13C) in the active layer and permafrost layer on the Eboling Mountain in the upper reach of Heihe River basin, northwestern China. Our results showed that the average stocks of SOC, TN, and SIC in permafrost layer above soil parent materials (71.7 kg m-2, 8.0 kg m-2, 34.7 kg m-2) were much higher than those in the active layer (44.3 kg m-2, 5.3 kg m-2, 12.2 kg m-2). The d13C pattern in the soil profiles indicated that historical drainage conditions and pedogenesis were important factors in determining soil organic matter (SOM) stocks in this permafrost region. The d13C and C/N ratios of the transient layer and some layers of permafrost implied that the degradation of SOM was different. These results highlight that carbon and nitrogen in permafrost regions with Alpine Kobresia meadow could make significant contribution to China's terrestrial carbon cycle.
15079744 Kaverin, D. A. (Russian Academy of Sciences, Komi Science Center, Institute of Geology, Syktyvkar, Russian Federation); Pastukhov, A. V. and Mazhitova, G. G. Temperaturnyy rezhim tundrovykh pochv i podstilayushchikh mnogoletnemerzlykh porod (yevropeyskiy Severo-Vostok Rossii) [Thermal regime of tundra soils and underlying permafrost (European northeastern Russia)]: Kriosfera Zemli = Earth Cryosphere, 18(3), p. 23-32 (English sum.), illus. incl. 5 tables, 20 ref., September 2014.
The temperature regime has been studied in seven permafrost soils formed in mineral and peat soil-forming deposits in various landscapes of the southern tundra in northeastern European Russia. Seasonal and long-term temperature dynamics have been revealed in both the active layer and underlying permafrost. The soil temperature regime has been classified according to the Russian and American systems. The differentiation of permafrost soils has been shown according to the main temperature parameters.
15074802 Antcibor, I. (Hamburg University, Institute of Soil Science, Hamburg, Germany); Eschenbach, A.; Zubrzycki, S.; Kutzbach, L.; Bolshiyanov, D. and Pfeiffer, E. M. Trace metal distribution in pristine permafrost-affected soils of the Lena River delta and its hinterland, northern Siberia, Russia: Biogeosciences, 11(1), p. 1-15, illus. incl. 5 tables, sketch map, 80 ref., 2014.
Soils are an important compartment of ecosystems and have the ability to buffer and immobilize substances of natural and anthropogenic origin to prevent their movement to other environment compartments. Predicted climatic changes together with other anthropogenic influences on Arctic terrestrial environments may affect biogeochemical processes enhancing leaching and migration of trace elements in permafrost-affected soils. This is especially important since Arctic ecosystems are considered to be highly sensitive to climatic changes as well as to chemical contamination. This study characterises background levels of trace metals in permafrost-affected soils of the Lena River delta and its hinterland in northern Siberia (73.5-69.5° N), representing a remote region far from evident anthropogenic trace metal sources. Investigations on the element content of iron (Fe), arsenic (As), manganese (Mn), zinc (Zn), nickel (Ni), copper (Cu), lead (Pb), cadmium (Cd), cobalt (Co), and mercury (Hg) in different soil types developed in different geological parent materials have been carried out. The highest median concentrations of Fe and Mn were observed in soils belonging to ice-rich permafrost sediments formed during the Pleistocene (ice-complex) while the highest median values of Ni, Pb and Zn were found in soils of both the ice-complex and the Holocene estuarine terrace of the Lena River delta region, as well as in the southernmost study unit of the hinterland area. Detailed observations of trace metal distribution on the micro scale showed that organic matter content, soil texture and iron-oxide contents influenced by cryogenic processes, temperature, and hydrological regimes are the most important factors determining the metal abundance in permafrost-affected soils. The observed range of trace element background concentrations was similar to trace metal levels reported for other pristine northern areas.
15080051 Matveyev, A. V. (Krasnoyarsk Drilling Company, Krasnoyarsk, Russian Federation) and Neskoromnykh, V. V. Bureniye inzhenerno-geologicheskikh skvazhin bol'shogo diametra v mnogoletnemerzlkh porodakh [Drilling of large-diameter engineering geological boreholes in permafrost]: Razvedka i Okhrana Nedr, 2013(9), p. 14-18, illus., 3 ref., September 2013.
Features of technology and the main results of a driving of engineering and geological wells of big diameter (150-400 mm) in permafrost rocks around Norilsk ore body with use of pneumoshock ramming cars and gas fluid mixes are stated. Results of researches of greasing properties of gas fkuid mixes are given in article in vitro and recommendations about technology of drilling are made by pneumodrummers.
15071606 Slater, Andrew G. (University of Colorado, Boulder, Cooperative Institute for Research in Environmetnal Sciences, Boulder, CO) and Lawrence, David M. Diagnosing present and future permafrost from climate models: Journal of Climate, 26(15), p. 5608-5623, August 2013. Based on Publisher-supplied data.
Permafrost is a characteristic aspect of the terrestrial Arctic and the fate of near-surface permafrost over the next century is likely to exert strong controls on Arctic hydrology and biogeochemistry. Using output from the fifth phase of the Coupled Model Intercomparison Project (CMIP5), the authors assess its ability to simulate present-day and future permafrost. Permafrost extent diagnosed directly from each climate model's soil temperature is a function of the modeled surface climate as well as the ability of the land surface model to represent permafrost physics. For each CMIP5 model these two effects are separated by using indirect estimators of permafrost driven by climatic indices and compared to permafrost extent directly diagnosed via soil temperatures. Several robust conclusions can be drawn from this analysis. Significant air temperature and snow depth biases exist in some model's climates, which degrade both directly and indirectly diagnosed permafrost conditions. The range of directly calculated present-day (1986-2005) permafrost area is extremely large (~4-25 ´ 106 km2). Several land models contain structural weaknesses that limit their skill in simulating cold region subsurface processes. The sensitivity of future permafrost extent to temperature change over the present-day observed permafrost region averages (1.67 ± 0.7) ´ 106 km2 °C-1 but is a function of the spatial and temporal distribution of climate change. Because of sizable differences in future climates for the representative concentration pathway (RCP) emission scenarios, a wide variety of future permafrost states is predicted by 2100. Conservatively, the models suggest that for RCP4.5, permafrost will retreat from the present-day discontinuous zone. Under RCP8.5, sustainable permafrost will be most probable only in the Canadian Archipelago, Russian Arctic coast, and east Siberian uplands.
15071604 Burke, Eleanor J. (Met Office Hadley Centre, Exeter, United Kingdom); Jones, Chris D. and Koven, Charles D. Estimating the permafrost-carbon climate response in the CMIP5 climate models using a simplified approach: Journal of Climate, 26(14), p. 4897-4909, July 2013. Based on Publisher-supplied data.
Under climate change, thawing permafrost may cause a release of carbon, which has a positive feedback on the climate. The permafrost-carbon climate response (gPF) is the additional permafrost-carbon made vulnerable to decomposition per degree of global temperature increase. A simple framework was adopted to estimate gPF using the database for phase 5 of the Coupled Model Intercomparison Project (CMIP5). The projected changes in the annual maximum active layer thicknesses (ALTmax) over the twenty-first century were quantified using CMIP5 soil temperatures. These changes were combined with the observed distribution of soil organic carbon and its potential decomposability to give gPF. This estimate of gPF is dependent on the biases in the simulated present-day permafrost. This dependency was reduced by combining a reference estimate of the present-day ALTmax with an estimate of the sensitivity of ALTmax to temperature from the CMIP5 models. In this case, gPF was from -6 to -66 PgC K-1(5th-95th percentile) with a radiative forcing of 0.03-0.29 W m-2 K-1. This range is mainly caused by uncertainties in the amount of soil carbon deeper in the soil profile and whether it thaws over the time scales under consideration. These results suggest that including permafrost-carbon within climate models will lead to an increase in the positive global carbon climate feedback. Under future climate change the northern high-latitude permafrost region is expected to be a small sink of carbon. Adding the permafrost-carbon response is likely to change this region to a source of carbon.
15076440 Ran Youhua (Baoji University of Arts and Science, Department of Geography and Environmental Engineering, Baoji, China); Li Xin; Jin Rui and Guo Jianwen. Remote sensing of the mean annual surface temperature and surface frost number for mapping permafrost in China: in Changing cryosphere under a warming climate (Zhang Tingjun, prefacer; et al.), Arctic, Antarctic, and Alpine Research, 47(2), p. 255-265, illus. incl. 3 tables, 35 ref., May 2015.
In this paper the climate characteristics of the first date of ?0 °C temperature are analyzed; furthermore, the farming responses to climate warming are discussed using a climate diagnosis analysis and the least squares methods, which are based on the daily minimum temperature data in East China from 1961 to 2009. It was found that over the past 50 years there has been a trend of the first date of ?0 °C temperature being delayed at a rate of 1.6 days per 10 years; however, between 1961 and 1990 the first date of ?0 °C temperature arrived early at a rate of 1.8 days per 10 years, and then was delayed at a rate of 3.3 days per 10 years. Furthermore, the average first date of ≤&eq;0 °C temperature is 30 October in northern regions, and the frequency of the first date of ≤&eq;0 °C temperature is greater in October and November than in other months; however, the boundary of the first date of ≤&eq;0 °C temperature shifts from south to north during September to December, and this has been especially evident since the 1990s. It was also found that in some southern stations, ≤&eq;0 °C temperature never occurs. The first date of ≤&eq;0 °C temperature occurs earlier in the north than in the south, and the interannual variation of the first date of ≤&eq;0 °C temperature is large in low latitudes and small in high latitudes. Additionally, the sustained period of ≤&eq;0 °C temperature, from beginning to end, decreased at a rate of 5 days per 10 years, which leads to a reduction in the length of the frost periods and causes a structural adjustment to the type of crops that can be planted. Therefore, the study reveals the significant effects that the first date of ≤&eq;0 °C temperature can have on the length of frost periods and farming and provides useful findings with regard to the prevention of frost damage and agricultural management.
15079743 Badu, Yu. B. (Moscow State University, Moscow, Russian Federation). Vliyaniye gazonosnykh struktur na moshchnost' kriogennoy tolshchi Yamala [Influence of natural gas-bearing structures on permafrost thickness in the Yamal Peninsula]: Kriosfera Zemli = Earth Cryosphere, 18(3), p. 11-22 (English sum.), illus. incl. sect., sketch maps, 27 ref., September 2014.
Cryogenic strata of the north of West Siberia is regarded as a single cryogenic formation of the middle and late Neopleistocene and Holocene that occurred on the background of the rhythms of transgression-regression of the polar basin during cyclic changes of the harsh climate. On the basis of the current data new ideas about the development of cryogenic strata in subaerial and submarine environments are formulated. The influence of gas accumulation layer in the thickness of cryogenic strata is demonstrated in the section and in the area of the gas-bearing structures.
15077711 Kritsuk, L. N. (Russian Research Institute of Hydrogeology and Engineering Geology (VSEGINGEO), Moscow, Russian Federation); Dubrovin, V. A. and Yastreba, N. V. Metodika distantsionnogo monitoringa lineynykh sooruzheniy v kriolitozone [Methods of remote sensing applied for pipeline monitoring in the permafrost zone]: Razvedka i Okhrana Nedr, 2013(3), p. 29-34 (English sum.), illus., 10 ref., March 2013.
The paper describes the technique and results of monitoring of geocryological conditions along the gas pipeline "Bovanenkovo - Baidaratskaya Bay" on Yamal Peninsula. Repeated decoding of different-time Earth's sounding results (AFI and CI) gave the possibility to reveal the dynamics of geocryological conditions along the gas pipeline in the testing areas and, first of all, manifestations of current natural and technogenic processes, as well as to distinguish the areas of their potential manifestation, the development of which should be carried out with special care.
15076436 Gusmeroli, Alessio (University of Alaska, Fairbanks, International Arctic Research Center, Fairbanks, AK); Lin Liu; Schaefer, Kevin; Zhang Tingjun; Schaefer, Timothy and Grosse, Guido. Active layer stratigraphy and organic layer thickness at a thermokarst site in Arctic Alaska identified using ground penetrating radar: in Changing cryosphere under a warming climate (Zhang Tingjun, prefacer; et al.), Arctic, Antarctic, and Alpine Research, 47(2), p. 195-202, illus. incl. sketch map, 26 ref., May 2015.
In permafrost terrains, the frozen-unfrozen boundary, located at the base of the active layer, is a prominent ground-penetrating radar (GPR) target and is typically used to retrieve active layer thickness. Less attention has been given to the capability of the GPR in detecting structures within the active layer. In this paper, using 500 MHz GPR data from a thermokarst site in the Arctic Coastal Plain, we demonstrate that GPR can retrieve, when present, the internal stratigraphy of the thawed layer. We recognized two types of thermokarst-related microtopographic units: dry-and-uniform peaty hummocks with a thin (~30 cm) active layer and inter-hummock depressions with a thicker (~60 cm) active layer characterized by two different layers-a surface peat layer on top of silt confirmed by test pits. Radar wave velocity analysis, done with a common-midpoint survey, suggests a contrast in volumetric water content (87% and 45% for the upper and lower layers, respectively). The subsurface radar wave velocity suggests that the porous peat layer contains more water (87% by volume) than the underlying silt layer (45% by volume), resulting in a strong dielectric contrast and a strong radar reflection. This study demonstrates the usefulness of GPR to measure the thickness and properties of the surface organic layer in permafrost regions.
15076438 Jin Rui (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Zhang Tingjun; Li Xin; Yang Xingguo and Ran Youhua. Mapping surface soil freeze-thaw cycles in China based on SMMR and SSM/I brightness temperatures from 1978 to 2008: in Changing cryosphere under a warming climate (Zhang Tingjun, prefacer; et al.), Arctic, Antarctic, and Alpine Research, 47(2), p. 213-229, illus. incl. 3 tables, sketch maps, 36 ref., May 2015.
This paper aims to provide a long time-series data set documenting the surface soil freeze-thaw cycles in China over a period of more than 30 years. The remote sensing data are from the daily brightness temperatures recorded by the Scanning Multichannel Microwave Radiometer (SMMR, 1978-1987) and Special Sensor Microwave Imager (SSM/I, 1987-2008), which have a 25 km spatial resolution. The classification method used to identify the surface soil freeze-thaw states is a dual-indices algorithm based on the 37 GHz vertical polarization brightness temperature and spectral gradient between the 37 GHz and 18/19 GHz brightness temperatures. This algorithm has been recalibrated for SMMR and SSM/I using the in situ daily minimal ground surface temperatures observed at 77 meteorological stations covering the dominant land surface types of China. The daily classifications of surface soil freeze-thaw states were validated by observations from an additional 273 meteorological stations. The classification accuracy of the frozen and thawed soils as well as the total accuracy exceed 80%. Based on this data set, we analyzed the seasonal and interannual variations across the areal extent and timing of surface soil freezing, trend of the onset date of surface soil freezing and thawing, and duration of surface soil thawing in China. The results showed that the maximum frozen extent during 1978-1987 was 6.93 ´ 106 km2 or 72.8% of the area, and it generally occurred in late December and January. The minimum frozen extent was 0.26 ´ 106 km2 or 3.0% of the area, and it occurred in late July and August. The first day of soil freezing occurred between September and November, whereas the first day of soil thawing occurred between March and May. The trend analysis demonstrated that from 1978 to 2008, the onset date of surface freezing was postponed by 19.6 ± 14.6 days, whereas the onset of surface thawing was advanced by -19.0 ± 9.4 days, and the thawing period was prolonged by 34.3 ± 16.5 days. These trends revealed a pattern of earlier thawing, later freezing, and longer growing seasons because of climate warming, especially in the seasonally frozen ground and permafrost regions with high ground temperatures.
15078635 Newman, B. D. (Los Alamos National Laboratory, Earth and Environmental Sciences Division, Los Alamos, NM); Throckmorton, H. M.; Graham, D. E.; Gu, B.; Hubbard, S. S.; Liang, L.; Wu, Y.; Heikoop, J. M.; Herndon, E. M.; Phelps, T. J.; Wilson, C. J. and Wullschleger, S. D. Microtopographic and depth controls on active layer chemistry in Arctic polygonal ground: Geophysical Research Letters, 42(6), p. 1808-1817, illus. incl. 1 table, sketch map, 30 ref., March 28, 2015.
Polygonal ground is a signature characteristic of Arctic lowlands, and carbon release from permafrost thaw can alter feedbacks to Arctic ecosystems and climate. This study describes the first comprehensive spatial examination of active layer biogeochemistry that extends across high- and low-centered, ice wedge polygons, their features, and with depth. Water chemistry measurements of 54 analytes were made on surface and active layer pore waters collected near Barrow, Alaska, USA. Significant differences were observed between high- and low-centered polygons suggesting that polygon types may be useful for landscape-scale geochemical classification. However, differences were found for polygon features (centers and troughs) for analytes that were not significant for polygon type, suggesting that finer-scale features affect biogeochemistry differently from polygon types. Depth variations were also significant, demonstrating important multidimensional aspects of polygonal ground biogeochemistry. These results have major implications for understanding how polygonal ground ecosystems function, and how they may respond to future change. Abstract Copyright (2015), . American Geophysical Union. All Rights Reserved.
15072852 Tornqvist, Rebecka (Stockholm University, Department of Physical Geography and Quaternary Geology, Stockholm, Sweden); Jarsjo, Jerker; Pietron, Jan; Bring, Arvid; Rogberg, Peter; Asokan, Shilpa M. and Destouni, Georgia. Evolution of the hydro-climate system in the Lake Baikal basin: Journal of Hydrology, 519(Part B), p. 1953-1962, illus. incl. 3 tables, sketch map, 55 ref., November 27, 2014. Includes appendices.
Climatic changes can profoundly alter hydrological conditions in river basins. Lake Baikal is the deepest and largest freshwater reservoir on Earth, and has a unique ecosystem with numerous endemic animal and plant species. We here identify long-term historical (1938-2009) and projected future hydro-climatic trends in the Selenga River Basin, which is the largest sub-basin (>60% inflow) of Lake Baikal. Our analysis is based on long-term river monitoring and historical hydro-climatic observation data, as well as ensemble mean and 22 individual model results of the Coupled Model Intercomparison Project, Phase 5 (CMIP5). Study of the latter considers a historical period (from 1961) and projections for 2010-2039 and 2070-2099. Observations show almost twice as fast warming as the global average during the period 1938-2009. Decreased intra-annual variability of river discharge over this period indicates basin-scale permafrost degradation. CMIP5 ensemble projections show further future warming, implying continued permafrost thaw. Modelling of runoff change, however, is highly uncertain, with many models (64%) and their ensemble mean failing to reproduce historical behaviour, and with indicated future increase being small relative to the large differences among individual model results. Abstract Copyright (2014) Elsevier, B.V.
15072181 Kurylyk, Barret L. (University of New Brunswick, Canadian Rivers Institute, Fredericton, NB, Canada) and Watanabe, Kunio. The mathematical representation of freezing and thawing processes in variably-saturated, non-deformable soils: Advances in Water Resources, 60, p. 160-177, illus. incl. 1 table, 180 ref., October 2013.
Recently, there has been a revival in the development of models simulating coupled heat and water transport in cold regions. These models represent significant advances in our ability to simulate the sensitivity of permafrost environments to future climate change. However, there are considerable differences in model formulations arising from the diverse backgrounds of researchers and practitioners in this field. The variability in existing model formulations warrants a review and synthesis of the underlying theory to demonstrate the implicit assumptions and limitations of a particular approach. This contribution examines various forms of the Clapeyron equation, the relationship between the soil moisture curve and soil freezing curve, and processes for developing soil freezing curves and hydraulic conductivity models for partially frozen soils. Where applicable, results from recent laboratory tests are presented to demonstrate the validity of existing theoretical formulations. Identified variations in model formulations form the basis for briefly comparing and contrasting existing models. Several unresolved questions are addressed to highlight the need for further research in this rapidly expanding field. Abstract Copyright (2013) Elsevier, B.V.
15079763 Lebedeva, Ye. V. (Rossiyskaya Akademiya Nauk, Institut Geografii, Moscow, Russian Federation); Shvarev, S. V. and Gotvanskiy, V. I. Prirodno-obuslovlennaya napryazhennost' geomorfologicheskikh protsessov Dal'nego Vostoka Rossii [Natural intensity of geomorphological processes in the Russian Far East]: Geomorfologiya, 2014(4), p. 48-59 (English sum.), illus. incl. table, sketch map, 27 ref., December 2014.
A map of due-to-natural "tensity" of geomorphologic processes on the scale 1:8,000,000 in the territory of the Russian Far East was compiled. The "tensity" is the readiness of a geomorphologic system to come out of the equilibrium state and risk of the catastrophic processes rise under the action of external and/or internal forces. Zones with different tensity of geomorphologic processes were distinguished; the tensity value ranges from 3 to 16 balls in the region and depends on the degree of ecologic hazard of contemporary geomorphic processes, depth of dissection, seismicity, precipitation, and presence of thick loose permafrost. The earlier stated supposition about increasing the nature-defined tensity of geomorphologic processes in the Northwest Pacific Ocean coast area from west to east was confirmed. Thus, processes tensity of the Western Okhotsk Sea coast was estimated at 7-10 points, in the Sakhalin it was 10-12, in Eastern Kamchatka it was 13-15, and in some Kuril Islands it was 16 points. An analysis of the areas with different tensity showed near-normal distribution of this parameter with the maximum at 6-8 points: corresponding areas occupy about half of the territory (47 %). Potentially catastrophic areas (over 15 points) occupy near 0.3% of studied territory, but in certain regions such as the Kurils, their rate rise up to 49%. Sites with very high intensity (10-15 points) occupy 15.2% of the territory, sites with high intensity (5-9 points) occupy 76.2 %, and sites with low intensity (less than 5 points) cover just near 8.3% of the territory.
15070946 Rontani, Jean-François (Aix-Marseille University, Mediterranean Institute of Oceanography, Marseille, France); Charrière, Bruno; Sempéré, Richard; Doxaran, David; Vaultier, Frédéric; Vonk, Jorien E. and Volkman, John K. Degradation of sterols and terrigenous organic matter in waters of the Mackenzie Shelf, Canadian Arctic: Organic Geochemistry, 75, p. 61-73, illus. incl. 1 table, sketch map, 94 ref., October 2014.
Sterols and their biotic and abiotic degradation products were quantified in suspended particulate matter (SPM) from surface waters in the Mackenzie River mouth to the Beaufort Sea shelf (Canadian Arctic). 24-Ethylcholesterol (sitosterol) and 24-methylcholesterol (campesterol) appeared to be extensively degraded by bacterial and especially autoxidative degradation in the samples. Degradation was most extensive in some samples from the outer boundaries of the plume, which exhibited much higher sitosterol/campesterol ratio values than previously observed in studies of the Beaufort Sea. The lack of reactivity of specific planktonic sterols such as cholesterol, 24-methylcholesta-5,22E-dien-3b-ol (epi-brassicasterol) and 24-methylenecholesterol and the good correlation between the abundances of sitosterol, campesterol and dehydroabietic acid (DHAA, a biomarker of Pinaceae resin) oxidation products allowed us to attribute the main origin of these two sterols to terrigenous vascular plants. A good correlation was observed between the extent of autoxidation and salinity, suggesting that the free radical oxidation is enhanced via contact with seawater. Laboratory incubation of Mackenzie River SPM in Milli-Q water and seawater confirmed this proposal. To explain the specific induction of autoxidation on vascular plant-derived material, a mechanism involving homolytic cleavage of photochemically produced hydroperoxides resulting from the senescence of higher plants on land is proposed. Cleavage could be catalyzed by redox-active metal ions released from SPM in the mixing zone of riverine water and marine water. The greatest extent of degradation observed at outer boundaries of the plume is attributed to preferential settling of lithic material relative to less dense higher plant debris increasing the proportion of highly degraded vascular plant material in the SPM. The results are important for this ecologically vulnerable region, where destabilization of permafrost by global warming is expected to increase the input of terrigenous C to coastal seas. Autoxidation, which until now has received little attention, plays a key role in the degradation of vascular plant-derived lipids in surface waters and should be taken into consideration during future studies of terrigenous organic matter degradation. Abstract Copyright (2014) Elsevier, B.V.
15076439 Wang Qingfeng (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Zhang Tingjun; Peng Xiaoqing; Cao Bin and Wu Qingbai. Changes of soil thermal regimes in the Heihe River basin over western China: in Changing cryosphere under a warming climate (Zhang Tingjun, prefacer; et al.), Arctic, Antarctic, and Alpine Research, 47(2), p. 231-241, illus. incl. 2 tables, sketch map, 48 ref., May 2015.
Investigation of the changes in soil thermal regimes is essential to the understanding of ecohydrological processes, resource development, and climate change. We use soil temperatures from 12 meteorological stations of the China Meteorological Administration in the Heihe River Basin to estimate soil seasonal freeze depth, the onset and end dates of soil freeze, and the duration of soil freeze. Based on the characteristics of the soil temperature in the seasonal freezing layer, the freeze/thaw processes of this layer were divided into four stages: the winter freezing stage, spring thawing stage, summer warming stage, and autumn cooling stage. Spring, summer, autumn, and winter ground surface temperatures in the basin exhibit significant increasing trends in 1972-2006, of 0.65 °C decade-1, 0.73 °C decade-1, 0.48 °C decade-1, and 0.44 °C decade-1, respectively. Mean annual soil temperature at 0.0-0.20 m depths reveals an increasing trend of 0.58-0.63 °C decade-1 in 1972-2006. The onset date of soil freeze, the end date of soil freeze, and the duration of soil freeze in 1972-2006 exhibit a statistically significant trend of +2 days decade-1, -4 days decade-1, and -6 days decade-1, respectively. The maximum thickness of the seasonally frozen ground for 1960-2007 reveals a statistically significant trend of -4.0 cm decade-1 and a net change of -19.2 cm for the 48-year period. These are all related to the increase in spring, summer, autumn, and winter air temperature and the mean annual air temperature in the basin, a possible result of global warming.
15076435 Zhang Tingjun (Lanzhou University, College of Earth and Environmental Sciences, Lanzhou, China) and Wang Ninglian, prefacers. Changing cryosphere under a warming climate: Arctic, Antarctic, and Alpine Research, 47(2), p. 191-405, illus., May 2015. Individual papers within scope are cited separately.
15079745 Slagoda, Ye. A. (Russian Academy of Sciences, Siberian Division, Institute of the Cryosphere, Tyumen, Russian Federation); Kurchatova, A. N.; Opokina, O. L.; Tomberg, I. V.; Khodzher, T. V.; Firsova, A. D.; Rodionova, Ye. V.; Popov, K. A. and Nikulina, Ye. L. Kriolitologicheskoye stroyeniye pervoy terrasy ostrova Belyy v Karskom more; geokriologicheskaya istoriya i izmeneniya prirodnykh usloviy; Chast' 3 [Cryolithological structure of first terrace in Belyy Island, Kara Sea; geocryological evolution and change of environments; Part 3]: Kriosfera Zemli = Earth Cryosphere, 18(3), p. 33-45 (English sum.), illus. incl. sketch maps, 62 ref., September 2014.
The diversity of microphytes and their coastal habitats have been determined in frozen sediments of the first terrace at Bely Island in the Kara Sea. Analyses of the distribution of the types of litho- and cryofacies in the structure of terrace fixing processes of freezing and thawing of strata have been made. Sequences of the geocryological events caused by climatic changes and sea level fluctuations in the Neopleistocene-Holocene have been reconstructed in detail.
15073761 Szymanski, Wojciech (Jagiellonian University, Institute of Geography and Spatial Management, Cracow, Poland); Skiba, Michal; Wojtun, Bronislaw and Drewnik, Marek. Soil properties, micromorphology, and mineralogy of Cryosols from sorted and unsorted patterned grounds in the Hornsund area, SW Spitsbergen: Geoderma, 253-254, p. 1-11, illus. incl. 4 tables, sketch map, 58 ref., September 2015.
Patterned grounds are probably the most interesting features produced by natural processes acting on the Earth's surface. Such features occur mainly in polar areas and in high mountains indicating that the origin of patterned grounds is related to frost action and cryoturbation. In spite of the many studies concerning the mechanism of the formation and the various forms of patterned grounds, very little attention has been paid to the qualitative and quantitative analyses of their mineral composition, and especially the mineralogy of the clay fraction. The analysis of the mineralogy of clay fraction is very important due to the finest particles (especially clay minerals) may play a crucial role in cryoturbation and cryosegregation as the particles are mainly responsible for accumulation of water and rheological properties of the ground. Thus, the main aim of the present study was to verify the hypothesis that the presence of swelling clay minerals in parent material favors the development of sorted patterned grounds. To verify the hypothesis, the physical, chemical, micromorphological, and qualitative and quantitative mineralogical properties of Cryosols from sorted and unsorted patterned grounds in the Hornsund area (SW Spitsbergen) were determined. The obtained results show that Turbic Cryosols from sorted patterned grounds featuring clear frost cracking, frost segregation, and cryoturbation are characterized by a lack of clearly developed soil horizons, loamy texture and low content of soil organic matter. Haplic Cryosols show better developed soil horizonation and contain lower amounts of the silt and clay fractions, higher content of the sand fraction and soil organic matter in comparison with Turbic Cryosols exhibiting strong cryoturbation. Micromorphological analysis of Turbic Cryosols indicates frost action manifested by a vesicular microstructure; round, oval, and deformed (mammillated) vesicles as dominant voids; vertically-oriented rock fragments; and silt and silt-clay cappings occurring on rock fragments. In addition, the occurrence of Fe-Mn nodules showing a sharp boundary indicates mixing of soil material. Micromorphology of the studied Turbic Cryosols indicates that cryoturbation prevails over cryosegregation. The soil material of the studied Cryosols is composed mainly of quartz, K-feldspar, plagioclase, dioctahedral mica (muscovite and/or illite), biotite, augite, hornblende, garnet, chlorite, swelling clays (smectite, vermiculite), goethite, and in some cases also calcite and traces of kaolinite. Majority of the minerals are most likely primary minerals inherited from parent material due to weak chemical weathering in the severe Arctic climate conditions and relatively young soils. However, weak chemical weathering of biotite and formation of vermiculite and mixed layered clay minerals also take place. Quantitative mineralogical analysis shows that besides texture and moisture, the mineral composition of soil material may also play some role in the susceptibility to cryoturbation and the formation of sorted and unsorted patterned grounds. However, the small differences in mineral content between the studied Turbic Cryosols and Haplic Cryosols indicate that the mineral composition of parent material is not a crucial characteristic responsible for the formation of sorted patterned grounds. Abstract Copyright (2015) Elsevier, B.V.
15072809 Cheng, Q. (China Agricultural University, College of Information and Electrical Engineering, Beijing, China); Sun, Y.; Jones, S. B.; Vasilyev, V. I.; Popov, V. V.; Wang, G. and Zheng, L. In situ measured and simulated seasonal freeze-thaw cycle; a 2-year comparative study between layered and homogeneous field soil profiles: Journal of Hydrology, 519(Part B), p. 1466-1473, illus. incl. 3 tables, sketch map, 27 ref., November 27, 2014.
Annual freeze-thaw cycles of soil significantly impact agricultural and ecosystem services in cold regions. For advancing our understanding of freeze-thaw process, both improved measurements and simulations of coupled-heat-water-transfer (CHWT) phenomenon are needed under different field conditions. This paper focused on a comparative study between a CHWT-model simulation versus in situ measurements of liquid soil water content (LSWC) and soil temperature (ST) at two agricultural field sites. The first site consisted of a layered soil profile with sandy silt loam (0-60 cm) and clay loam (60-130 cm) layers, and the other site was a uniform sand profile (0-110 cm). Measurements were made over two winters between 2011 and 2013, i.e. the first winter is 2011-2012 (year 1) and the second winter is 2012-2013 (year 2), in the northeast of China employing an access-tube dielectric sensor combined with a temperature measurement array. During the freezing period of the year 1 winter, the soil freezing characteristic curves (SFCCs) were determined in situ in relation to the site-specific data of LSWC and ST and subsequently used for the model calibration. For the thawing process of year 1 and the freeze-thaw process of year 2, the resulting ST simulation time series were well-correlated with field measurements. In terms of the resulting LSWC, the numerical simulations also correlated well (R2 > 0.895, RMSE < 0.0381 cm3 cm-3) with the in situ observations of freezing and quasi-steady-state conditions at depths of 50- and 100-cm. The reasons for relatively reduced agreement between simulated and measured LSWC during the thawing stage (i.e., R2 > 0.702, RMSE < 0.0468 cm3 cm-3) are discussed. The resulting time series simulations confirm the model's capability for describing freeze- and thaw-front migration in layered and homogeneous freezing soils. Abstract Copyright (2014) Elsevier, B.V.
15072797 Yi Jun (Northwest Agriculture and Forestry University, Yangling, China); Zhao Ying; Shao Ming'an; Zhang Jianguo; Cui Lele and Si Bingcheng. Soil freezing and thawing processes affected by the different landscapes in the middle reaches of Heihe River basin, Gansu, China: Journal of Hydrology, 519(Part B), p. 1328-1338, illus. incl. 1 table, sketch map, 48 ref., November 27, 2014.
An understanding of soil freezing and thawing processes in seasonally frozen soil is important for many agricultural and environmental issues, especially under different landscapes in terms of land use and climate change. In this study, sandy soil behavior under soil freezing and thawing cycles were investigated under three typical landscapes (i.e., farmland, forest, and desert) in the middle reaches of the Heihe River Basin, Northwest China, from December 2011 to May 2012. Both Neutron Moisture Meter and Time Domain Reflectometry techniques were used to investigate the total soil water content (TSWC) and liquid soil water content (LSWC), respectively, and further based on to calculate soil ice content (SIC) and ice ratio (IR). The partition TSWC into LSWC and SIC at different depths is shown to be corresponded well with soil temperature, frost depth and groundwater dynamics, provided a vigorous basis for augmenting the limited data on soil water redistribution in seasonally frozen soils under natural conditions of different landscapes. The greatest freezing cycles were observed for the farmland, characterized with the deepest frost depths (106 cm), the highest IR (>0.9), and the largest upward heat fluxes (120 W m-2), followed by the forest, and then the desert. These differences were primarily attributed to landscape-dependent initial soil water content, soil surface cover and groundwater levels, with marginal effect being attributed to soil physical properties. Profiled water redistribution upon soil freezing and thawing was obviously observed in the moist forest, but neither in the wettest farmland or in the driest desert. The soil frozen processes had a beneficial effect on soil water conservation with reduced evaporation and seepage, and high water content maintained, which could be useful for plant germination in the following spring. Abstract Copyright (2014) Elsevier, B.V.
15075208 Lodygin, E. D. (Russian Academy of Sciences, Ural Branch, Institute of Biology, Syktyvkar, Russian Federation); Beznosikov, V. A. and Vasilevich, R. S. Molecular composition of humic substances in Tundra soils (13C-NMR spectroscopic study): Eurasian Soil Science, 47(5), p. 400-406, 33 ref., May 2014. Based on Publisher-supplied data.
Functional groups and molecular fragments of humic substances (HSs) from cryohydromorphic peat gley tundra and surface-gley tundra soils have been identified by 13C-NMR spectroscopy. The analysis of HS preparations has shown that the molecules of humic acids (HAs) are enriched with aromatic fragments compared to fulvic acids (FAs). Aliphatic chains, carbohydrate- and amino acid-type structures prevail in the carbon skeleton of the FAs. An integrated parameter of the HS hydrophobicity has been proposed. The parameter represents the total portion of unoxidized carbon atoms and allows indirectly assessing the amphiphilic properties of HSs. Copyright 2014 Pleiades Publishing, Ltd.
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15076365 Levy, Joseph (University of Texas, Austin, Jackson School of Geosciences, Austin, TX). A hydrological continuum in permafrost environments; the morphological signatures of melt-driven hydrology on Earth and Mars: in Planetary geomorphology (Burr, Devon M., editor; et al.), Geomorphology, 240, p. 70-82, illus. incl. 2 tables, sketch maps, 94 ref., July 1, 2015. Meeting: 45th annual Binghamton geomorphology symposium, Sep. 12-14, 2014, Knoxville, TN.
This paper examines relationships between the morphology of cold desert hydrological features and the water sources, and it relates the formation of diagnostic deposits and erosion patterns to environmentally controlled patterns of discharge. In particular, three sets of landforms found in the McMurdo Dry Valleys of Antarctica are compared to similar features on Mars: Antarctic streams/rivers to Amazonian valleys, terrestrial gullies to Martian gullies, and water tracks to recurring slope lineae. Similarities in landform morphology are highlighted for each set. Hydrological characteristics are aggregated or calculated, and they are shown to scale comparably across the landforms for the terrestrial and Martian groups. Accordingly, a hydrological continuum is proposed, linking the magnitude and the persistence of water sources in cold desert environments to flow response and the formation of diagnostic landforms. This concept provides a framework for examining the relationships between climate, hydrology, and geomorphology in the cold desert environments of these two worlds. Abstract Copyright (2015) Elsevier, B.V.
15080994 Hilton, Robert G. (Durham University, Durham, United Kingdom); Galy, Valier; Dellinger, Mathieu; Gaillardet, Jerome; Bryant, Charlotte; O'Regan, Matt and Grocke, Darren. Widespread export of permafrost-derived organic carbon by the Mackenzie River; a carbon dioxide sink rather than source? [abstr.]: in Goldschmidt abstracts 2014, V.M. Goldschmidt Conference - Program and Abstracts, 24, p. 989, 4 ref., 2014. Meeting: Goldschmid 2014, June 8-13, 2014, Sacramento, CA.
15076367 Matsubara, Yo (Smithsonian Institution, National Air and Space Museum, Washington, DC); Howard, Alan D.; Burr, Devon M.; Williams, Rebecca M. E.; Dietrich, William E. and Moore, Jeffery M. River meandering on Earth and Mars; a comparative study of Aeolis Dorsa meanders, Mars and possible terrestrial analogs of the Usuktuk River, AK, and the Quinn River, NV: in Planetary geomorphology (Burr, Devon M., editor; et al.), Geomorphology, 240, p. 102-120, illus. incl. sketch maps, 151 ref., July 1, 2015. Meeting: 45th annual Binghamton geomorphology symposium, Sep. 12-14, 2014, Knoxville, TN.
The paleo-meanders in the Aeolis Dorsa (AD) region show that meandering channels can develop in the absence of vegetation. Three possible mechanisms other than vegetation could contribute to the bank cohesion required to promote meandering: permafrost, abundant mud, and chemical cementation. Banks at the meandering Quinn River show little vegetation cover. Almost all sediment samples collected from the Quinn River deposits contain at least 41% mud (silt/clay), which is much higher than for most meandering streams. Ion chromatography (IC) analysis and scanning electron microscope (SEM) images showed presence of salts in river waters and sediments which may induce fine sediment to flocculate and be deposited. We find that bank cohesion promoting meandering can be provided by silt/clay, the deposition of which may be induced by dissolved salts. The sinuous Usuktuk River in the continuous permafrost region near Barrow, Alaska exhibited no exposed permafrost on stream banks. Instead vegetation seemed to be the dominant control of bank erosion. We have not found evidence for ice control of bank cohesion in this or other terrestrial rivers of similar size and in meandering pattern to the Martian AD meanders. We conclude that bank cohesion in the AD meanders was probably provided by deposition of fine suspended sediment that was flocculated by dissolved salts. Abstract Copyright (2015) Elsevier, B.V.
15074661 Yang Yuzhong (Chinese Academy of Sciences, Soil Engineering, Cold and Arid Regions Environmental and Engineering Research Institute, State Key Laboratory of Frozen Soil Engineering, Lanzhou, China); Wu Qingbai and Yun Hanbo. Stable isotope variations in the ground ice of Beiluhe Basin on the Qinghai-Tibet Plateau: in Proxies for Quaternary monsoon reconstruction on the Tibetan Plateau (Mishke, Steffen, editor; et al.), Quaternary International, 313-314, p. 85-91, illus. incl. 1 table, sketch map, 34 ref., November 5, 2013. Meeting: Tibetan Plateau; formation, climate, ecosystems, April 3-4, 2012, Berlin, Germany.
Ground ice is extensive in the permafrost regions of the Qinghai-Tibet Plateau. It is useful for regulating water resources in Plateau regions, and affects the ecological water environment in permafrost areas. This research investigated the isotope characteristics of ground ice on the Qinghai-Tibet Plateau. In this work, 73 samples of ground ice from 4 boreholes were collected to analyze and compare stable isotopes with precipitation and river water. The results show that isotope composition of ground ice varied in narrow ranges, ranging from -13.16 ppm to -9.08 ppm for d18O and from -103.61 ppm to -69.92 ppm for dD. The isotope composition of subsurface ground ice is slightly more positive than that of deep-layers due to the fractionation of freezing. Based on the recharge relationships among ground ice, precipitation, and river water, subsurface ground ice is partly recharged by precipitation and river water. However, the isotope variations of deep-layer ground ice may be the result of isotope fractionation under different climate conditions. Abstract Copyright (2013) Elsevier, B.V.
15080592 Busby, R. W. (Incorporated Research Institutions for Seismology (IRIS), Washington, DC); Woodward, R. and Hafner, K. EarthScope's transportable array in Alaska [abstr.]: in AGU 2013 fall meeting, American Geophysical Union Fall Meeting, 2013, Abstract S21A-2385, December 2013. Meeting: American Geophysical Union 2013 fall meeting, Dec. 9-13, 2013, San Francisco, CA.
Since 2003, EarthScope has been installing a network of seismometers, known as the Transportable Array-across the continental United States and southern Canada. The station deployments will be completed in the Conterminous US in the fall of 2013. Beginning in October, 2013, and continuing for 5 years, EarthScope's Transportable Array plans to create a grid of seismic sensors in approximately 300 locations In Alaska and Western Canada. The proposed station grid is 85 km, and target locations will supplement or enhance existing seismic stations operating in Alaska. When possible, they will also be co-located with existing GPS stations constructed by the Plate Boundary Observatory. We review the siting plans for stations, the progress towards reconnaissance and permitting, and detail the engineering concept of the stations. In order to be able to determine the required site conditions and descriptions of installation methods to the permitting agencies, the National Science Foundation (NSF) has been supporting exploratory work on seismic station design, sensor emplacement and communication concepts appropriate for the challenging high-latitude environment that is proposed for deployment. IRIS has installed several experimental stations to evaluate different sensor emplacement schemes both in Alaska and the lower-48 U.S. The goal of these tests is to maintain or enhance a station's noise performance while minimizing its footprint and the equipment, materials, and overall expense required for its construction. Motivating this approach are recent developments in posthole broadband seismometer design and the unique conditions for operating in Alaska, where most areas are only accessible by small plane or helicopter, and permafrost underlies much of the region. IRIS has experimented with different portable drills and drilling techniques to create shallow holes (1-5M) in permafrost and rock outcrops. Seasonal changes can affect the performance of seismometers in different ways depending on the emplacement technique. Results of these tests are described in a companion presentation.
15080543 Davi, N. K. (Lamont-Doherty Earth Observatory, Palisades, NY); D'Arrigo, R.; Cook, E. R.; Baatarbileg, N.; Jacoby, G. C.; Anchukaitis, K. J. and Pederson, N. A millennial scale tree-ring based summer temperature reconstruction for northern Mongolia (931-2005 C.E.) [abstr.]: in AGU 2013 fall meeting, American Geophysical Union Fall Meeting, 2013, Abstract PP51A-1941, December 2013. Meeting: American Geophysical Union 2013 fall meeting, Dec. 9-13, 2013, San Francisco, CA.
Warming over Mongolia and adjacent Central Asia has been unusually rapid over the past few decades, with surface temperature anomalies higher than for much of the globe. With few meteorological records available in this remote region prior to the 1950s, longer, paleoclimatic time series must be used to understand annual-centennial climate variability, potential forcing mechanisms (e.g. volcanism, increasing greenhouse gases) and the significance of such major features of the past millennium as the Medieval Climate Anomaly and Little Ice Age. In this study we use an unusually extensive collection of living and subfossil wood samples from temperature-sensitive larch trees to produce the first millennial-length, well-calibrated and verified reconstruction of summer temperatures for Mongolia and vicinity. The reconstruction shows a very cold mid-900s, rapid and sustained warming during the MCA, cooling during the LIA epoch LIA (1350-1850), and warming during the 20th century. There is very rapid tree growth found in 2004-2005, which may result from very warm temperatures and melting permafrost. The recent warming exceeds that of the MCA. Extreme cooling in several years is attributed to several major volcanic eruptions over the past millennium.
15080454 Frolking, Steve E. (University of New Hampshire, Durham, NH); Talbot, J.; Kurnianto, Sofyan and Treat, Claire C. Using a simple, process-based model to address (and raise) questions about relationships between climate, land-use, and decadal to millennial peatland carbon cycling [abstr.]: in AGU 2013 fall meeting, American Geophysical Union Fall Meeting, 2013, Abstract PP12B-01, December 2013. Meeting: American Geophysical Union 2013 fall meeting, Dec. 9-13, 2013, San Francisco, CA.
The Holocene Peat Model simulates peatland coupled carbon and water cycling to estimate long-term peat carbon accumulation driven by climate variability. Recent model developments include incorporation of permafrost/active layer dynamics, radiocarbon labeling, and an empirical representation of tropical peatland hydrology. The model operates at an annual time step and generates a peat profile that includes characterization of depth vs. age, degree of humification, and vegetation composition. This profile can be compared to data from contemporary peat cores. The simulation results also include the peatland development trajectory that generated the contemporary profile - annual net C-balance, water table, plant community composition and productivity. In this way, the model provides a process-based hypothesis for how climate history (or future climate and/or land use) affects the peat profile in ways that potentially can be observed in the field. Here we present an overview of the model, and some recent applications, including climate-warming impacts on high-latitude permafrost peatland systems, and land-use conversion impacts on tropical peat swamp forests.
15072405 Head, J. W. (Brown University, Geological Sciences, Providence, RI) and Marchant, D. R. Geologic and environmental context for Gale Crater, Mars; insights from the Antarctic dry valleys [abstr.]: in AGU 2013 fall meeting, American Geophysical Union Fall Meeting, 2013, Abstract P23B-1780, December 2013. Meeting: American Geophysical Union 2013 fall meeting, Dec. 9-13, 2013, San Francisco, CA.
The broad geologic context of Gale crater provides important perspectives for the discoveries of the Mars Science Laboratory Curiosity rover. Regional studies show abundant evidence for running water: valley networks and open- and closed-basin lakes, interpreted by many to indicate the presence of a "warm and wet" pluvial early Mars climate. Alternatively, recent climate models suggest a "cold and icy" early Mars dominated by snowfall. Could such a "cold and icy" environment be consistent with the geologic evidence and provide important insight into Curiosity findings? Extensive characterization of the Antarctic McMurdo Dry Valleys (MDV) has shown that streams and lakes can form in hypothermal, hyperarid environments analogous to Mars, where the mean annual temperature is well below freezing. Streams, lakes and ponds in temperate areas are largely of pluvial origin; in contrast, the hyperarid, hypothermal conditions in the MDV mean that there is no rainfall, water sources are limited primarily to meltwater from cold-based glacier surfaces, and drainage by streams into lakes is seasonal and highly variable, being related to changing and sluggish response to surface ice hypsometry, itself a function of changing climate. The hydrologic cycle/system is horizontally stratified. The shallow substrate is characterized by permafrost with an ice table at 15-40 cm depth beneath a regionally dry active layer. Recharge zones are limited to perennial and annual snow patches, some of which are trapped in alcoves and gully channels that undergo top-down melting. Initially, meltwater percolates vertically downward, wetting the dry active layer below, and then migrates laterally to create a wetted zone along the margins of channels (the hyporheic zone). Significant volumes of meltwater infiltrate from the surface, flow downslope along the top of the ice table, wicking up and feeding the advancing hyporheic zone. Flow in the hyporheic zone along ephermal streams occurs at three scales: 1) locally in the stream bed flux may be insufficient to overcome the infiltration capacity of the channel sediment, and meltwater percolates into the substrate only to re-emerge a few meters down-channel in springs; 2) at the base of slopes and near valley bottoms, wet-topped polygons form in topographic lows, creating a "swampy" spongy area; 3) water may continue to travel along the ice table in the valley floor until it can intersect the surface, forming a local pond. Streams form and flow during peak summer insolation, feeding lakes; lake surface level fluctuations are caused by imbalances between meltwater input and sublimation from the lake surface ice and this sensitive balance tends to magnify even minor climate signals. This framework of seasonal melting and fluvial/lacustrine processes in an otherwise hyperarid, hypothermal Mars-like Antarctic cold-based non-pluvial environment provides a baseline of environmental conditions suggesting that a "cold and icy" early Mars could produce the observed fluvial and lacustrine features during transient warming periods. These parallels provide a framework in which to interpret Curiosity results.
15072565 Mellon, M. T. (Southwest Research Institute, Department of Space Studies, Boulder, CO). Modeling regolith temperatures and volatile ice processes [abstr.]: in AGU 2013 fall meeting, American Geophysical Union Fall Meeting, 2013, Abstract P52A-03, December 2013. Meeting: American Geophysical Union 2013 fall meeting, Dec. 9-13, 2013, San Francisco, CA.
Surface and subsurface temperatures are an important tool for exploring the distribution and dynamics of volatile ices on and within planetary regoliths. I will review thermal-analysis approaches and recent applications in the studies of volatile ice processes. Numerical models of regolith temperatures allow us to examine the response of ices to periodic and secular changes in heat sources such as insolation. Used in conjunction with spatially and temporally distributed remotely-sensed temperatures, numerical models can: 1) constrain the stability and dynamics of volatile ices; 2) define the partitioning between phases of ice, gas, liquid, and adsorbate; and 3) in some instances be used to probe the distribution of ice hidden from view beneath the surface. The vapor pressure of volatile ices (such as water, carbon dioxide, and methane) depends exponentially on temperature. Small changes in temperature can result in transitions between stable phases. Cyclic temperatures and the propagation of thermal waves into the subsurface can produce a strong hysteresis in the population and partitioning of various phases (such as between ice, vapor, and adsorbate) and result in bulk transport. Condensation of ice will also have a pronounced effect on the thermal properties of otherwise loose particulate regolith. Cementing grains at their contacts through ice deposition will increase the thermal conductivity, and may enhance the stability of additional ice. Likewise sintering of grains within a predominantly icy regolith will increase the thermal conductivity. Subsurface layers that result from ice redistribution can be discriminated by remote sensing when combined with numerical modeling. Applications of these techniques include modeling of seasonal carbon dioxide frosts on Mars, predicting and interpreting the subsurface ice distribution on Mars and in Antarctica, and estimating the current depth of ice-rich permafrost on Mars. Additionally, understanding cold trapping ices in regions of the regolith of airless bodies, such as Mercury and the Moon, are aided by numerical modeling of regolith temperatures. Thermally driven sublimation of volatiles (water ice on Mars and more exotic species on icy moons in the outer solar system) can result in terrain degradation and collapse.
15075341 Millar, Constance I. (U. S. Department of Agricultre Forest Service, Pacific Southwest Research Station, Albany, CA); Westfall, Robert D. and Delany, Diane L. Thermal and hydrologic attributes of rock glaciers and periglacial talus landforms; Sierra Nevada, California, USA: in PACLIM; proceedings of the 25th Pacific climate workshop, 2011 (Starratt, Scott), Quaternary International, 310, p. 169-180, illus. incl. 5 tables, sketch map, 27 ref., October 15, 2013. Meeting: 25th Pacific climate workshops, March 6-9, 2011, Pacific Grove, CA.
To explore thermal regimes and hydrologic capacity of rock glaciers and related periglacial talus landforms, mini-thermochrons were deployed in and around potentially ice-embedded features of the Sierra Nevada. Results from pilot studies at 13 rock glaciers and 7 taluses indicate that outlet springs from these landforms generally do not desiccate but persist year-round as ice (frozen) in winter and flowing water in the warm season. Temperatures of water (liquid and ice) in rock-glacier outlet springs had an annual mean of -0.2°C and mean of 0.6°C during the warm season with very low diurnal fluctuation. These and other attributes suggest the existence of internal ice and/or permafrost supplying the springs. Air temperatures of rock-glacier matrices (1 m below the surface) versus surface air corroborate the periglacial nature of internal environments: annual air temperatures of matrices were below freezing (mean, -0.8°C). Compared to surface air, especially during the warm season, matrix air temperatures were significantly colder and fluctuated less. Talus landforms followed a similar pattern, although water- and matrix air temperatures were warmer, and contrasts with surface air were not as strong as for rock glaciers. For rock glaciers and talus slopes, matrix air temperatures showed resistance (buffering) to changes in external air temperatures. Unique geomorphic conditions of rock glaciers and periglacial taluses in the Sierra Nevada appear to maintain cool-buffered thermal regimes at least partly decoupled from external air. Springs support persistent wetlands and lakes at their snouts, retaining water in otherwise semi-arid high cirques, and contribute as hydrologic reserves and critical habitat for alpine biota. Daily and seasonal lags and buffering effects suggest that ice within these landforms might resist surface warming on the longer term, which could make these landforms increasingly important as regional climates change. Abstract Copyright (2013) Elsevier, B.V.
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15078763 Barbato, Robyn A. (U. S. Army Cold Regions Research and Engineering Labortory, Hanover, NH); Foley, Karen L.; Reynolds, Charles M.; Anderson, John E.; Edwards, Jarrod D. and Douglas, Thomas A. Field biogeochemical measurements in support of remote sensing signatures and characterization of permafrost terrain; integrated technologies for delineating permafrost and ground-state conditions: ERDC/CRREL Technical Report, Rep. No. ERDC/CRREL TR-15-1, 24 p., illus. incl. 3 tables, 42 ref., March 2015.
This report highlights the acquisition of plant canopy spectral reflectance, leaf-level gas and fluorescence, and associated soil conditions at discrete locations along two transects located within the U.S. Army Engineer Research and Development Center, Cold Regions Research and Engineering Laboratory (ERDC-CRREL), near Fairbanks, AK. Ecotones in interior Alaska have unique vegetative cover and heterogeneous terrains that are underlain by sporadic discontinuous permafrost. Permafrost thaw is expected to cause ecological consequences; and because vegetation and local soil microflora are tightly coupled, changes to this system offer a source of significant impacts on surface hydrology and soil strength. The objective of this study was to investigate potential relationships between vegetative vigor and soil biochemistry in permafrost-affected areas for use in the development of standoff sensors for mapping the subsurface composition of permafrost terrains and to help in predicting how and where thawing permafrost will alter vegetation and soil ecology. Our results showed that redox chemistry is an important driver of ecosystem dynamics, and we identified relationships between fluorescence and reducing conditions at these transects. While it is well known that redoxymorphic conditions help drive plant composition in wetlands, it is less apparent how permafrost thaw influences this dynamic.
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15078762 Pradhan, Nawa Raj (U. S. Army Coastal and Hydraulics Laboratory, Vicksburg, MS); Downer, Charles W.; Byrd, Aaron; Marchenko, Sergei; Liljedahl, Anna and Douglas, Thomas A. Development of a coupled framework for simulating interactive effects of frozen soil hydrological dynamics in permafrost regions: ERDC/CRREL Technical Report, Rep. No. ERDC TR-13-15, 21 p., illus. incl. 1 table, 22 ref., November 2013.
Climate warming is expected to degrade permafrost in many regions of the world, including Alaska. Degradation of permafrost has the potential to dramatically affect soil thermal, hydrological, and vegetation regimes. Projections of long-term effects of climate warming on high latitude ecosystems require a coupled representation of soil thermal state and hydrological dynamics. Such a framework was developed to explicitly simulate the soil moisture effects of soil thermal conductivity and heat capacity and its effects on hydrological response. The model is the result of coupling the Gridded Surface Subsurface Hydrologic Analysis (GSSHA) model with the Geophysical Institute Permafrost Laboratory (GIPL) model. The GIPL model simulates soil temperature dynamics, the depth of seasonal freezing and thawing, and the permafrost location by numerically solving a one-dimensional nonlinear heat equation with phase change. The GSSHA model is a spatially explicit hydrological model that simulates two dimensional groundwater flow and one-dimensional vadose zone flow. These two models were combined by incorporating the GIPL model into the GSSHA model. The GIPL model is used to compute a soil temperature profile in every two-dimensional GSSH A grid. GSSHA uses this information to adjust hydraulic conductivities for both the vertical unsaturated soil flow and lateral saturated groundwater flow. Test case results indicate that freezing temperatures reduces soil storage capacity thereby producing higher peak discharges and lower base flow.
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