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2017051974 Zollinger, Barbara (University of Zurich, Department of Geography, Zurich, Switzerland); Alewell, Christine; Kneisel, Christof; Brandova, Dagmar; Petrillo, Marta; Plotze, Michael; Christl, Marcus and Egli, Markus. Soil formation and weathering in a permafrost environment of the Swiss Alps; a multi-parameter and non-steady-state approach: Earth Surface Processes and Landforms, 42(5), p. 814-835, illus. incl. 5 tables, 82 ref., April 2017.
Spatially discontinuous permafrost conditions frequently occur in the European Alps. How soils under such conditions have evolved and how they may react to climate warming is largely unknown. This study focuses on the comparison of nearby soils that are characterised by the presence or absence of permafrost (active-layer thickness: 2-3 m) in the alpine (tundra) and subalpine (forest) range of the Eastern Swiss Alps using a multi-method (geochemical and mineralogical) approach. Moreover, a new non-steady-state concept was applied to determine rates of chemical weathering, soil erosion, soil formation, soil denudation, and soil production. Long-term chemical weathering rates, soil formation and erosion rates were assessed by using immobile elements, fine-earth stocks and meteoric 10Be. In addition, the weathering index (K + Ca)/Ti, the amount of Fe- and Al-oxyhydroxides and clay minerals characteristics were considered. All methods indicated that the differences between permafrost-affected and non-permafrost-affected soils were small. Furthermore, the soils did not uniformly differ in their weathering behaviour. A tendency towards less intense weathering in soils that were affected by permafrost was noted: at most sites, weathering rates, the proportion of oxyhydroxides and the weathering stage of clay minerals were lower in permafrost soils. In part, erosion rates were higher at the permafrost sites and accounted for 79-97% of the denudation rates. In general, soil formation rates (8.8-86.7 t/km2/yr) were in the expected range for Alpine soils. Independent of permafrost conditions, it seems that the local microenvironment (particularly vegetation and subsequently soil organic matter) has strongly influenced denudation rates. As the climate has varied since the beginning of soil evolution, the conditions for soil formation and weathering were not stable over time. Soil evolution in high Alpine settings is complex owing to, among others, spatio-temporal variations of permafrost conditions and thus climate. This makes predictions of future behaviour very difficult. Copyright Copyright 2016 John Wiley & Sons, Ltd.
DOI: 10.1002/esp.4040
2017053179 Dong Xicheng (Chinese Academy of Sciences, Cryosphere Research Station on the Qinghai-Tibetan Plateau, Lanzhou, China); Xie Changwei; Zhao Lin; Yao Jimin; Hu Guojie and Qiao Yongping. Characteristics of surface energy budget components in the permafrost region of Mahan Mountain, Lanzhou, China: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(2), p. 320-326, (Chinese) (English sum.), illus. incl. 3 tables, 24 ref., April 2013.
Sensible and latent fluxes in the Mahan Mountains' permafrost region from July 1st, 2010, to June 30th, 2011, were calculated using the meteorological gradient approach. At the same time, the characteristics of the surface energy balance were analyzed alongside the net radiation. This study finds that the net radiation in this region has significant annual variations, slightly more than in Xidatan and less that Tanggula on the Tibetan Plateau. The net radiation in the permafrost region of the Mahan Mountains mainly converts into sensible heat in winter and spring and converts into latent heat in summer and autumn, similar to the annual variation characteristics of sensible and latent heat flux in the permafrost regions of the Tibetan Plateau. The average annual latent heat flux is slightly higher than the sensible heat flux due to the protective effects of a marsh landscape and adequate moisture conditions in the Mahan Mountains. In addition, the existence of underground ice effectively protects the permafrost in the region.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=32 ...
2017053162 Chang Xiaoli (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Jin Huijun; He Ruixia; Jing Hongyuan; Li Guoyu; Wang Yongping; Luo Dongliang; Yu Shaopeng and Sun Haibin. Review of permafrost monitoring in the northern Da Hinggan Ling, northeastern China: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(1), p. 93-100, (Chinese) (English sum.), illus. incl. 2 tables, 28 ref., February 2013.
Permafrost is well-developed in the northern Da Hinggan Ling of Northeast China; however, its development and distribution are significantly affected by local factors such as vegetation, snow cover, and more. Consequently, such permafrost is recognized as the Xing'an-Baikal type. In recent years, permafrost monitoring systems have been gradually established in the northern Da Hinggan Ling, including a ground temperature monitoring system, automated meteorological stations, snow property observation systems, active layer temperature and moisture observation systems, and a thaw settlement monitoring system. These systems' data series have been collected for analysis, and meaningful results have been obtained from their examination.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=31 ...
2017053157 Mu Cuicui (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Zhang Tingjun; Cao Bin; Wan Xudong; Peng Xiaoqing and Cheng Guodong. Study on the organic carbon storage in the active layer of permafrost on Eboling Mountain in the upper reaches of the Heihe River, eastern Qilian Mountains: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(1), p. 1-9, (Chinese) (English sum.), illus., 40 ref., February 2013.
In order to understand carbon pools in permafrost under changing climate conditions, organic carbon storage in the active layer and its geomorphological features at different elevations were investigated at Eboling Mountain along the upper reaches of the Heihe River through both field exploration and laboratory experiments. The results indicate that there were significant periglacial phenomena and active seasonal freeze-thaw processes at Eboling Mountain. The organic carbon content in the active layer was high. The average depth of the active layer in the study region was 1.1 m. The organic matter content of the soils in the active layer was about 72.1% on average within the study region. Consequently, carbon storage was estimated to be about 1.57 Mt C in a study region about 2.5 km2 in area. The organic content varied with depth in the active layer. The organic content decreases with depth in the active layer, but reaches a high value in the vicinity of the permafrost table. While the elevation and soil moisture content control the organic carbon content of the soil, the microtopography and lithological soil types have a great effect on the organic content of soil in the active layer.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=31 ...
2017053159 Wang Qingfeng (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Zhang Tingjun; Wu Jichun; Peng Xiaoqing; Zhong Xinyue; Mu Cuicui; Wang Kang; Wu Qingbai and Cheng Guodong. Investigation of permafrost distribution in the upper reaches of the Heihe River in the Qilian Mountains: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(1), p. 19-29, (Chinese) (English sum.), illus. incl. 3 tables, sketch map, 46 ref., February 2013.
Permafrost and seasonally frozen ground have a dramatic effect on surface hydrological processes, ecosystems, carbon cycles, and infrastructure in cold regions. The upper reaches of the Heihe River, which are located in the eastern part of the Qilian Mountains, are in a cold, semi-arid climate. Studies of permafrost distribution in the Heihe River basin are important for systematically understanding the regional eco-hydrological process, climate and environmental changes, and water resource assessment. Field investigations of permafrost distribution were conducted in the river's upper reaches over the summer of 2011. Seven boreholes, ranging from 20 to 100 m in depth, were drilled in early August 2011. Based on the borehole drilling information and temperature profiles measured at least two months after drilling, the authors found that the lower boundary of the permafrost is between 3650 and 3700 m a.s.l. Depending on the altitude, the active layer's depth varies from 1.6 m at 4132 m a.s.l. to about 4.0 m near the lower boundary of the permafrost, just above 3650 m a.s.l. The mean annual ground temperature at a depth of zero annual amplitude increases from -1.7°C at 4132 m a.s.l to near 0.0°C at the premafrost's lower boundary. The permafrost's depth decreases from more than 100 m at 4132 m a.s.l. to 0.0 m at 3650 m a.s.l. At the same time, other local factors, such as slope, aspect, soil type, soil water (ice) content, vegetation, and river channels, may also have a significant effect on permafrost conditions.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=31 ...
2017053158 Yu Qihao (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); You Yanhui; Yan Hai and Liu Xifeng. Distribution and characteristics of permafrost on Nalati Mountain, western Tien Shan, China: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(1), p. 10-18, (Chinese) (English sum.), illus. incl. 1 table, sketch map, 30 ref., February 2013.
Nalati Mountain is located in the western Tien Shan in Xinjiang, China. Changes in permafrost in this region affect the natural environment and engineering activities. Owing to many factors, such as transportation difficulties and the scarcity of previous human activities, there has been little research regarding the permafrost and the environment in this area. The permafrost distribution characteristics at Nalati Mountain and their main effects were systematically studied and combined with a permafrost investigation of a transmission line which was built from Yining to Kuche. We found that permafrost in this region is typical mountain permafrost, and thus the development area, types, ground ice characteristics, and thermal regime all depend on altitude, topography, and swamp conditions. Any changes in altitude, topography, and swamp conditions will result in a change in permafrost distribution, type, and ground ice. In addition, there are many periglacial phenomena that have developed, such as solifluction terraces and lobes, stone rings, and block streams. Depending on the slope aspect, vegetation, water, and other factors, the active layer depth varies from 0.7 m to 4.5 m, and the permafrost thickness on the southern slopes increases from about 20-22 m at the lower limit (3000 m) of continuous permafrost to 70-100 m at an altitude of 3300 m. Based on temperature data, the authors found that the regional annual mean air temperature has rapidly increased since 1985 at a rate of about 0.088 °C/a. Therefore, some permafrost degradation features can be seen, such as rising ground temperature degrading marsh wetlands and vegetation, and frozen ground detachment.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=31 ...
2017056528 Ding Jinzhi (Chinese Academy of Sciences, Institute of Botany, Beijing, China); Chen Leiyi; Ji Chengjun; Hugelius, Gustaf; Li Yingnian; Liu Li; Qin Shuqi; Zhang Beibei; Yang Guibiao; Li Fei; Fang Kai; Chen Yongliang; Peng Yunfeng; Zhao Xia; He Honglin; Smith, Pete; Fang Jingyun and Yang Yuanhe. Decadal soil carbon accumulation across Tibetan permafrost regions: Nature Geoscience, 10(6), p. 420-424, illus. incl. 1 table, 41 ref., June 2017.
DOI: 10.1038/NGEO2945
2017052173 Roy-Leveillee, Pascale (Laurentian University of Sudbury, School of Northern and Community Studies, Sudbury, ON, Canada) and Burn, Christopher R. Near-shore talik development beneath shallow water in expanding thermokarst lakes, Old Crow Flats, Yukon: Journal of Geophysical Research: Earth Surface, 122(5), p. 1070-1089, illus. incl. 8 tables, sketch maps, 60 ref., May 2017.
It is generally assumed that permafrost is preserved beneath shallow lakes and ponds in the Western North American Arctic where water depth is less than about two thirds of the late-winter lake ice thickness. Here we present field observations of talik development beneath water as shallow as 0.2 m despite a lake ice thickness of 1.5 m, in Old Crow Flats (OCF), YT. Conditions leading to the initiation and development of taliks beneath shallow water were investigated with field measurements of shore erosion rates, bathymetry, ice thickness, snow accumulation, and lake bottom temperature near the shores of two expanding lakes in OCF. The sensitivity of talik development to variations in lake bottom thermal regime was then investigated numerically. Where ice reached the lake bottom, talik development was controlled by the ratio of freezing degree days to thawing degree days at the lake bottom (FDDlb/TDDlb). In some cases, spatial variations in on-ice snow depth had a minimal effect on annual mean lake bottom temperature (Tlb) but caused sufficient variations in FDDlb/TDDlb to influence talik development. Where Tlb was close to but greater than 0°C simulations indicated that the thermal offset allowed permafrost aggradation to occur under certain conditions, resulting in irregular near-shore talik geometries. The results highlight the sensitivity of permafrost to small changes in lake bottom thermal conditions where the water column freezes through in early winter and indicate the occurrence of permafrost degradation beneath very shallow water in the near-shore zone of Arctic ponds and lakes. Abstract Copyright (2017), . American Geophysical Union. All Rights Reserved.
DOI: 10.1002/2016JF004022
2017052167 Thibodeau, Benoit (Academy of Science, Humanities and Literature, Mainz, Germany); Bauch, Dorothea and Voss, Maren. Nitrogen dynamic in Eurasian coastal Arctic ecosystem; insight from nitrogen isotope: Global Biogeochemical Cycles, 31(5), p. 836-849, illus. incl. 4 tables, sketch map, 73 ref., May 2017.
Primary productivity is limited by the availability of nitrogen (N) in most of the coastal Arctic, as a large portion of N is released by the spring freshet and completely consumed during the following summer. Thus, understanding the fate of riverine nitrogen is critical to identify the link between dissolved nitrogen dynamic and coastal primary productivity to foresee upcoming changes in the Arctic seas, such as increase riverine discharge and permafrost thaw. Here we provide a field-based study of nitrogen dynamic over the Laptev Sea shelf based on isotope geochemistry. We demonstrate that while most of the nitrate found under the surface freshwater layer is of remineralized origin, some of the nitrate originates from atmospheric input and was probably transported at depth by the mixing of brine-enriched denser water during sea ice formation. Moreover, our results suggest that riverine dissolved organic nitrogen (DON) represents up to 6 times the total riverine release of nitrate and that about 62 to 76% of the DON is removed within the shelf waters. This is a crucial information regarding the near-future impact of climate change on primary productivity in the Eurasian coastal Arctic. Abstract Copyright (2017), . American Geophysical Union. All Rights Reserved.
DOI: 10.1002/2016GB005593
2017051225 Kokfelt, U. (Geological Survey of Denmark and Greenland, Copenhagen, Denmark); Muscheler, R.; Mellstrom, A.; Struyf, E.; Rundgren, M.; Wastegard, S. and Hammarlund, D. Diatom blooms and associated vegetation shifts in a subarctic peatland; responses to distant volcanic eruptions?: JQS. Journal of Quaternary Science, 31(7), p. 723-730, illus. incl. 2 tables, sketch map, 43 ref., October 2016.
We test the hypothesis that rich occurrences of diatoms observed at transitions between major peat units representing different vegetation communities in a peat sequence from subarctic northern Sweden reflect responses to acid deposition from the Samalas AD 1257 and Laki AD 1783/1784 eruptions. We observe sudden changes in the mire ecosystem and thereby in the trophic status and biogeochemical cycling of the peatland. Both the eruptions are known to have been associated with significant acid deposition events and climatic anomalies, as recorded in polar ice cores. To test the hypothesis, new chronological analyses and age modelling were applied to existing biogeochemical and biological records from the peat sequence. This approach yielded modeled age ranges of AD 1239-1284 (1s)/AD 1210-1303 (2s) (median: AD 1260) and AD 1674-1795 (1s)/AD 1665-1875 (2s) (median AD 1743), respectively, for the stratigraphic transitions. Hence, the modeled age ranges bracket the ages of the eruptions in question and the hypothesis could therefore not be rejected. Impacts of acid deposition from the eruptions are assumed to have caused instant acidification, vegetation damage, increased nutrient cycling and blooms of opportunistic epiphytic diatoms. In addition, cooling may have contributed to vegetation changes through permafrost inception, frost heave and thereby altered hydrological conditions. Abstract Copyright (2010), John Wiley & Sons, Ltd.
DOI: 10.1002/jqs.2898
2017053176 Liu Yang (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Zhao Lin and Li Ren. Simulation of soil water-thermal features within the active layer in the Tanggula Range, Tibetan Plateau, using the SHAW model: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(2), p. 280-290, (Chinese) (English sum.), illus. incl. 5 tables, 34 ref., April 2013.
Using data observed from the meteorology gradient tower and in the active layer of the Tanggula Observation Site on the Tibetan Plateau in 2007 combined with the SHAW model, the soil's hydrological and thermal features within the active layer were simulated. Three different surface albedo programs were tested during the simulation process. Comparing the observed data with the three simulated values, the authors determined that the SHAW model can successfully simulate surface energy fluxes and soil temperature features within the active layer of permafrost regions, while a simulation of the soil's unfrozen water content is not as accurate, but the simulated change trends seem to correlate well. In the simulation, there will be obvious improvements in surface energy flux, soil temperature, and moisture within the active layer when the monthly average surface albedo for each month is taken as the model's input. After revising the model's input parameters by using the computational results from a parameterization scheme of the surface albedo, the simulation results for the soil temperature and moisture within the active layer were significantly improved. However, there is no obvious of improvement in simulating surface energy fluxes. Overall, the SHAW model has advantages in simulating the soil freezing-thawing process in permafrost regions of the Tibetan Plateau. It is an ideal surface model to study the hydrological and thermal processes within the active layer of permafrost regions at high elevations.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=32 ...
2017053189 Yin Zhenliang (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Xiao Honglang; Zou Songbing; Lu Zhixiang and Wang Weihua. Progress in research on hydrological simulation of the main stream of the Heihe River, Qilian Mountains: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(2), p. 438-446, (Chinese) (English sum.), illus. incl. 1 table, sketch map, 70 ref., April 2013.
This hydrological watershed simulation mathematically demonstrates hydrological processes based on previous hydrological knowledge. In cases of minimal observation data, hydrological modeling is an effective method for studying hydrological processes. As a typical inland river basin, the Heihe River Basin is a popular location to study hydrology and water resources in cold arid regions. Hydrological modeling of mountainous runoff from the main stream of the Heihe River allowed the researchers to apply empirical, conceptual, and distributed hydrological models to the study area. At the beginning of the study, empirical models were constructed by using observations to predict variation trends in mountainous runoff. Then, conceptual models were employed to generally simulate the area's hydrological processes. However, due to the larger glaciers, snow cover, permafrost, and unique geological structures and terrain conditions, the main stream of the Heihe River has special hydrological processes characterized by high altitude and low temperatures, which have not been covered in previous hydrological models and are typically ignored. Although several of these previous studies yield relatively accurate simulated results for mountainous runoff using various models, many are still limited in describing hydrological processes characterized by high altitude and low temperature in detail. By considering these unique hydrological processes caused by glaciers, snow cover, and permafrost, the ability to represent these processes is a crucial issue for hydrologically modeling inland river basins in high cold areas. In future, more in-situ observations should be carried out in order to acquire more observation data and the hydrological processes of permafrost and snow cover should be investigated further in order to develop a genuine hydrological model suited for high-altitude cold areas.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=32 ...
2017053185 Zhou Jian (Chinese Academy of Sciences, Lanzhou, China); Zhang Wei; Pomeroy, John W.; Cheng Guodong; Wang Genxu; Chen Chong and Li Hongyi. Simulating hydrological processes in cold regions of northwestern China with a modular modeling method: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(2), p. 389-400, (Chinese) (English sum.), illus. incl. 5 tables, sketch map, 35 ref., April 2013.
Permafrost, seasonally-frozen soil, and snow cover are widely distributed throughout Northwest China. Spring snowmelt and thawing of frozen soil are normally the most important hydrological events in the region. However, modeling the hydrological processes of cold regions is extremely difficult due to a lack of data on the watershed scale. The Cold Regions Hydrological Model (CRHM) platform, a flexible object-oriented modeling system, was devised to solve this problem by connecting modules into the model through problem-solving objectives, application scale, and data constraints. In this study, two watersheds were chosen to validate the CRHM. The first is the Binggou watershed, an experimental area for researching snow accumulation and ablation processes, as well as the effects of snow ablation on runoff. The second is the Zuomaokong watershed, which is an experimental area for examining the effects of soil freezing and thawing on runoff. For the Binggou watershed, a cold region hydrological model was created within CRHM to simulate the contributions of sublimation to the alpine snow mass balance and snowmelt runoff process. Comparisons of simulated snow depth with observations from October 30, 2007 to May 6, 2008 show that snow accumulation/ablation processes can be simulated much better with a physically-based snowmelt model that includes layering, hourly time intervals, an energy-balance snowpack ablation module (Snobal CRHM), and a blowing snow module (pbsm Snobal) as compared to a temperature-index snowmelt model. Further comparisons of the simulated results using switched on/off different process modules reveals that sublimation loss could reach about 69 cm in the alpine regions of the Binggou Basin, accounting for 48% of the total snowfall (145.5 cm), and half of the sublimation loss is attributed to snow drifting (about 35 cm). It can be concluded that snow sublimation loss is vital for accurately calculating snow ablation, and snow drifting sublimation loss is significant in the alpine regions of the Binggou Basin. The model is able to accurately reproduce the measured streamflow without calibration, with RMSE of 0.52 m3/s and NSE of 0.64. For the Zuomaokong permafrost watershed, a cold region hydrological model is created in CRHM to simulate the effect of the soil freeze-thaw process on runoff. A comparison of the simulated results to the observations shows that a model including the module for handling frozen soil infiltration can capture the main runoff processes, especially those in the frozen soil thawing period in spring. The RMSE and NSE values between the simulated and observed runoffs are 0.31 m3/s and 0.67, respectively. Overall, the validated results from the two watersheds show that CRHM is capable of simulating various elements of the hydrological cycle in cold regions of Northwest China without calibration. This is encouraging for the model's ability to predict the hydrological processes of ungauged basins.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=32 ...
2017053167 Xu Min (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Ye Baisheng and Zhao Qiudong. Estimation of the real evaporation in the source regions of the Huang He using GRACE satellite data: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(1), p. 138-147, (Chinese) (English sum.), illus. incl. 2 tables, sketch map, 32 ref., February 2013.
Water storage data from 2003 to 2008 in the Yellow River's source regions were retrieved from GRACE satellite data. Furthermore, the monthly real evaporation in the source regions was estimated using runoff and precipitation data. The authors found that these data are more consistent and correlate well not only to observations with an evaporation pan (20 cm), but also with the simulated results of the SiB2 model. The annual average evaporation in the Tangnag Basin is nearly 506.4 mm, of which 130.9 mm occurs in spring (March, April, and May), 275.2 mm in summer (June, July, and August), 74.3 mm in autumn (September, October, and November), and 26.1 mm in winter (December, January, and February). From 2003 to 2008, precipitation has increased slightly, and real evaporation has obviously decreased. Precipitation increased at a rate of 0.019 mm per month; water storage changed at a rate of 0.51 mm per month; and evaporation decreased at a rate of 0.52 mm per month. During the study period, water storage in the source regions of the Yellow River increased about 496.6´104 m3, which is equivalent to 82.6´104 m3·a-1. Precipitation did not change as significantly. However, declining evaporation and permafrost degradation has led to a significant increase in storage capacity and surface runoff.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=32 ...
2017051496 Ahlborn, Marieke (Friedrich Schiller University Jena, Institute of Geography, Jena, Germany); Haberzettl, Torsten; Wang Junbo; Henkel, Karoline; Kasper, Thomas; Daut, Gerhard; Zhu Liping and Mäusbacher, Roland. Synchronous pattern of moisture availability on the southern Tibetan Plateau since 17.5 cal. ka BP; the Tangra Yumco Lake sediment record: Boreas, 46(2), p. 229-241, illus. incl. sketch map, 72 ref., April 2017.
A possible asynchronicity of the spatial and temporal moisture availability on the Tibetan Plateau has been a controversial subject of discussion in recent years. Here we present the first attempt to systematically investigate possible spatial and temporal variations in moisture availability by examining two lakes, Tangra Yumco and Nam Co, on an east-west transect on the southern Tibetan Plateau using identical proxies for palaeoenvironmental reconstruction. In this study, an independent record from Tangra Yumco was analyzed applying a multi-proxy approach to reconstruct variations in moisture availability since the Lateglacial. Results were subsequently compared with previously published records from Nam Co and additional records from Tso Moriri (northwestern Himalaya) and Naleng Co (southeastern Tibetan Plateau). Our results show that Tangra Yumco was at least partially ice covered prior to 17.1 cal. ka BP. A temperature rise after 17.1 cal. ka BP probably resulted in thawing of the permafrost. At 16.0 cal. ka BP moisture availability increased, representing an initial monsoonal intensification. Warmer conditions between 13.0 and 12.4 cal. ka BP and cooler conditions between 12.4 cal. ka BP and the onset of the Holocene reflect the Bolling-Allerod and Younger Dryas. At the onset of the Holocene moisture availability rapidly increased, with moisture highest prior to 8.5 cal. ka BP when temperatures were also highest. After 8.5 cal. ka BP the moisture availability gradually decreased and showed only minor amplitude variations. These findings are consistent with the records from large lakes like Nam Co, Tso Moriri, and Naleng Co, revealing a synchronous pattern of moisture availability on the southern Tibetan Plateau. Abstract Copyright (2010), John Wiley & Sons, Ltd.
DOI: 10.1111/bor.12204
2017051416 Stahli, Manfred (Swiss Federal Institute for Forest, Snow and Landscape Research, Switzerland). Hydrological significance of soil frost for Prealpine areas: Journal of Hydrology, 546, p. 90-102, illus. incl. 7 tables, sketch map, 52 ref., March 2017.
Soil frost can have a substantial impact on water flows at the soil surface and-potentially-alter the dynamics of catchment runoff. While these findings are mainly based on studies from alpine and Northern-latitude areas (including permafrost areas), little is known about the significance of soil frost for hydrology in pre-alpine areas, i.e. the region at the transition from central European lowlands to high-alpine areas. Here I synthesize soil temperature data and soil frost observations from ten sites in Switzerland to assess the occurrence of soil frost and to determine its impact on catchment runoff. In addition, a well-established numerical model was used to reconstruct the presence of soil frost in two first-order catchments for single runoff events and winters. The data clearly demonstrates that shallow soil frost has formed regularly in this altitudinal range over the past decade. The presence of a frozen soil surface was found to be highly variable among the sites under study and did not significantly correlate with altitude or forest density. For the first-order catchments, it was not possible to relate important flood peaks or increased runoff coefficients to winter situations with substantial soil frost. Thus, the present analysis suggests that although soil frost is widespread and regularly occurring at this altitudinal range, it has no significant impact on winter runoff in pre-alpine watersheds.
DOI: 10.1016/j.jhydrol.2016.12.032
2017055137 Uhlemann, Sebastian and Kuras, Oliver. Numerical simulations of capacitive resistivity imaging (CRI) measurements: Near Surface Geophysics, 12(4), p. 523-537, 16 ref., August 2014.
Electrical resistivity tomography (ERT) is a well-developed geophysical technique that is used to study a variety of geoscientific problems. In recent years it has been applied to the study of permafrost processes at both field and laboratory scale. However, highly resistive surface conditions limit its applicability due to high and variable contact resistances. The use of capacitively coupled sensors is expected to overcome this problem by providing a steady contact impedance regime. Although the theory of capacitive resistivity imaging (CRI) is well understood, a point-pole approximation of the sensors is typically used to show the similarity between CRI and ERT. Due to their nature, capacitive sensors cannot be designed as point-poles as they require a finite extent. This paper assesses the effects the finite size of sensors has on the applicability of CRI theory and aims to provide an improved understanding of the measured data. We employ finite-element numerical modelling to simulate CRI measurements over a homogeneous halfspace and on a finite rock sample. The results of a parameter study over a homogeneous halfspace are compared to an analytical solution. Observed discrepancies between the two solutions clearly indicate that large sensor sizes and small sensor separations violate the point-pole assumption of the analytical solution. In terms of data interpretation, this dictates that sensor separations smaller than twice the sensor size have to be avoided in order to remain below a generic error threshold of 5%. We show that sensor elevation, halfspace resistivity, halfspace permittivity, and measurement frequency have only minor effects on the discrepancy between simulation and analytical solution. The simulation of sequential CRI measurements on a finite rock sample suggests that, in line with expectations, the measured signals lie mainly in the 4th quadrant of the complex plane. However, we can also observe data with negative geometric factors, which are related to uncommon array. A comparison between simulated and measured data showed very good agreement; it validated the simulations and explained the measured data acquired using a prototype multisensor CRI system. We show that a comparison of simulated and measured imaginary parts of the transfer impedance can be used to assess CRI measurement errors. Our work demonstrates that finite-element numerical modelling of CRI measurements is a valuable tool with which to define limitations on array design and to assess data quality.
DOI: 10.3997/1873-0604.2014008
2017053177 Chen Xiaolei (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Yang Meixue; Wan Guoning; Wang Xuejia; Luo Xiaoqing and Liang Xiaowen. Simulation studies using CLM3.0 and SHAW at the NMQ Station on the central Tibetan Plateau: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(2), p. 291-300, (Chinese) (English sum.), illus. incl. 4 tables, 34 ref., April 2013.
Observation data collected at the NMQ Station was used as the atmospheric forcing data for the general land surface process model (Community Land Model, CLM3.0) and the Simultaneous Heat and Water model (SHAW). Single-point simulation studies were carried out for the seasonally frozen soil regions of the central Tibetan Plateau. Comparing the observed and simulated values for the two land surface process models, it was found that simulation values of upward short-wave and upward long-wave radiation in the SHAW model are similar to those of CLM3.0. However, neither model considers the effects of upward short-wave radiation from new snow or of upward long-wave radiation due to latent heat release during the daily freeze-thaw cycle. In addition, daily variations in ground temperature are well simulated by SHAW and CLM3.0, but they perform better for the upper layers than for the lower layers. Compared to the SHAW model, the simulation values from CLM3.0 are closer to the measured values. When simulating soil water content, when the depth is less than or equal to 60 cm, SHAW and CLM3.0 both have advantages and disadvantages, but at depths of more than 60 cm, the SHAW model works better than CLM3.0, especially for soil freeze-thaw processes.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=32 ...
2017053175 Sun Caiqi (Beijing University, College of Urban and Environmental Sciences, Beijing, China); Li Chuanchuan; Chen Yixin; Zhang Mei; Nie Zhenyu and Liu Gengnian. Long-term monitoring of frost heaving in the periglacial environment of the Tien Shan: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(2), p. 272-279, (Chinese) (English sum.), illus. incl. 4 tables, sketch map, 34 ref., April 2013.
Freezing and thawing are important geomorphic processes in periglacial environments. This activity is a direct reflection of climate change, and thus an important part of the cryospheric process. Based on long-term monitoring in the source region of the Urumqi River from 1991 to 2011, a detailed discussion of the characteristics of sorted circles and frost heaving mechanisms in the Tien Shan is offered in this article. In the source region, the frost heaving effect is strongest within the surface layer to 20 cm deep, while a stake 3 cm in diameter is least affected by frost heaving. Inside a sorted circle, frost heaving is weaker along the radius, and decreases from the center to the edge. Frost heaving in a sorted circle area is stronger than in areas without sorted circles. Altitude has a significant effect on frost heaving. At an altitude range of 3500-4000 m, frost heaving increases with altitude and reaches a maximum at 3900 m, which is the glaciers' equilibrium altitude line. Correlation analysis demonstrates that the development of frost heaving and sorted circles is closely connected to the moisture and thermal regime during the warm half of the year, from May to October. Frost heaving is positively correlated to precipitation in the warm season, and transfer days when the ground temperature varies around 0°C are also an important factor. Sorted circle monitoring reveals that this periglacial landform is sensitive to regional climate change, and has had an active response to rising air temperature in the past two decades.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=32 ...
2017055619 Chou Yaling (Lanzhou University of Technology, Key Laboratory of Disaster Prevention and Mitigation in Civil Engineering of Gansu Province, Lanzhou, China); He Binbin; Jiang Xiangang and Yu Sheng. Frozen loess mechanical behavior based on structural characteristics: The Electronic Journal of Geotechnical Engineering, 19(BUNDLE V), p. 6605-6618, illus. incl. 3 tables, 21 ref., 2014. WWW.
The structural characteristics is a basic attribute of soil, which has a strong influence on engineering properties of soil. The effect of structural characteristics on the mechanical properties of frozen loess has been investigated. Based on triaxial compression tests of remolded frozen loess and artificial structured frozen loess with different content of cement, this paper studied how the confining pressure, initial water content, temperature and the cement amount had influenced the frozen loess' strength behavior. The experimental results showed that in the same experiments, there were some differences of the stress-strain relationship between the unsaturated and saturated frozen loess. The temperature and confining pressure were the main important factors that influenced the shearing strengths of frozen soil. The lower the temperature is, the higher the failure strength is. The shearing strengths of unsaturated frozen loess are increasing with confining pressure, but that of saturated frozen loess has little relationship with confining pressure. The initial water content is another main factor affecting the frozen loess strength. As the increase of water content, the frozen loess strength is also increasing, but there is a peak point. After it the frozen loess strength would decrease gradually with the water content increasing, and the strength of saturated frozen loess reached the lowest. With regard to the unsaturated frozen loess, the yield strength and failure strength are both increasing with the content of cement. For the saturated frozen loess, the yield strength is increasing with the content of cement, too. However, the failure strength has little relationship with the cement content. The mentioned factors have obvious influence on the structural characteristics of frozen loess, but the cement content and water content are the dominating factors. The mechanical properties and structural characteristics of frozen loess depend on not only the single factor, such as confining pressure, initial water content, temperature and the cement amount etc., but also on possible interaction of the various factors. At last, the comprehensively structural coefficient M which correlates closely with parameters of shear strength was presented. By regression analysis, the exponential function relationship between M and c, as well as M and tan , were obtained, respectively. Moreover, the exponential functions were validated feasible.
URL: http://www.ejge.com/2014/Ppr2014.598me.pdf
2017053188 Li Hongyi (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China) and Wang Jian. Key research topics and advances in modeling snow hydrological processes: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(2), p. 430-437, (Chinese) (English sum.), 60 ref., April 2013.
Recent snow hydrology research is reviewed in this paper. After briefly describing the basic methods of snowmelt simulation, the key points of these methods are discussed. The discussion focuses on the details of the simulation algorithms and how snow variables, such as the snow cover area, are used in different models. Considering the snow distribution features of the Tibetan Plateau, three main research topics are suggested: the simulation of heterogeneous snow on a sub-grid scale; the parameterization of a blowing snow simulation; and a snowmelt simulation for seasonally frozen soil. The latest research on these three topics is reviewed in detail individually. The importance of developing suitable algorithms for snow cover depletion in a sub-grid snowmelt simulation is emphasized. The spatial parameterization of the blowing snow simulation is discussed. Problems in the snowmelt simulation for seasonally frozen soil are analyzed.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=32 ...
2017053182 Su Kai (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Zhang Jianming; Liu Shiwei; Zhang Hu and Ruan Guofeng. Compressibility of warm, ice-rich frozen soil: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(2), p. 369-375, (Chinese) (English sum.), illus. incl. 6 tables, 15 ref., April 2013.
The compressibility of warm, ice-rich frozen soil (a type of plastic frozen soil) is remarkable under loads. In order to study the compressive properties of warm, ice-rich frozen soil, compression tests under constant temperature and stepped loads were conducted at temperatures of -0.3, -0.5, -0.7, -1.0, and -1.5 °C and with water contents of 40%, 80%, and 120%. From this, the volume compressibility coefficients were obtained. The test results indicate the following. (1) The soil's compressibility is considerable; for example, the volume compressibility coefficient of a clay sample at -0.3°C with a water content of 40% could reach 0.328 MPa, classifying the sample as a high compressibility soil. (2) something exists in the soil during the compression process, and mostly occurs in the initial loading stage. (3) The soil's temperature and water content, which control the volumetric unfrozen water content, are the most important factors affecting compressibility. (4) Under the aforementioned testing conditions, soil compressibility increases as temperature increases and water content decreases. When the temperature is high, the effect of the water content on the soil compressibility is significant, but is far less obvious when the temperature is relatively low.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=32 ...
2017053183 Wang Quan (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Ma Wei; Zhang Ze; Zhao Shuping; Li Guoyu and Mao Yuncheng. Research on the secondary collapse properties of loess under the freeze-thaw cycle: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(2), p. 376-382, (Chinese) (English sum.), illus. incl. 3 tables, 18 ref., April 2013.
In subgrade construction in loess areas, some methods like pre-collapsing are always used to stabilize the subgrade. However, in seasonally frozen soil areas, some degraded loess subgrades develop, such as vast areas of uneven settlement or collapse, after a few years. In order to study and analyze the effects of the freeze-thaw cycle on secondary loess collapse, laboratory experiments were carried out. First, a large-volume loess sample was collapsed, underwent a freeze-thaw cycle, and then was collapsed again. These experiments determined that the intact and remolded loess's secondary collapse coefficients gradually approach the same value as the freeze-thaw cycle proceeds. Both the intact and remolded loess have secondary collapse coefficients greater than 0.015, which is standard in identifying a loess area's ability to collapse. Thus, both the intact and remolded loess can experience secondary collapse following a freeze-thaw cycle.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=32 ...
2017053170 Chen Shijie (Chinese Academy of Sciences, Cold and Arid Regions Environmental and Engineering Research Institute, Lanzhou, China); Zhao Shuping; Ma Wei; Du Yuxia and Xing Lili. Studying frozen soil with CT technology; current studies and prospects: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(1), p. 193-200, (Chinese) (English sum.), illus. incl. 1 table, 32 ref., February 2013.
In this paper, the characteristics of CT technology are introduced, and the history and current situation for the use of CT technology in frozen soil studies are reviewed, including the auxiliary equipment specially designed for frozen soil testing, using CT numbers to analyze changes in frozen soil's internal structure as well as define and explore damage evolution, and using CT images to observe soil's mesostructure. In addition, representative achievements in studies of frozen soil related to CT technology are summarized. Finally, problems, possible solutions, and challenges in frozen soil studies using CT technology are pointed out. This paper emphasizes how to obtain high-quality CT images and how to process digital CT images of frozen soil. The correlation between the CT number and each component of the frozen soil specimens is also discussed. This examination finds that CT technology is one of the most ideal and effective technologies for studying frozen soil's mesostructure in a non-destructive manner. CT technology will play a greater role in studies of frozen soils through the use of auxiliary equipment and digital image processing.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=32 ...
2017053168 Wang Huini (Changan University, College of Geology, Engineering and Geomatics, Xi'an, China); Liu Haisong; Dong Sheng; Ni Wankui and Lin Zhanju. Processing of high-spatial-resolution remote sensing data in dynamic monitoring of thermokarst lakes on the Tibetan Plateau: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(1), p. 164-170, (Chinese) (English sum.), illus. incl. 1 table, sketch maps, 13 ref., February 2013.
Remote sensing technology has become an important tool for dynamically monitoring the processes of thermokarst lakes on the Tibetan Plateau, from which macroscopic spatial data can be rapidly obtained. In this study, data processing methods, including data correction, data fusion, and information extraction, are proposed and discussed based on the characteristics of high-resolution spatial remote sensing data from QuickBird and SPOT-5, combined with the characteristics of the thermokarst lakes on the Tibetan Plateau. Furthermore, a highly suitable procedure was applied to investigate changes in the thermokarst lakes within a limited area about 63 km2 in size located north of the Beiluhe River Basin from 2006 to 2009. The area stretches from Honglianghe to Xiushuihe, along the Qinghai-Tibet Highway. The results show that the content and total area of the thermokarst lakes has slightly increased.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=32 ...
2017053169 Yin Xiaowen (Qingdao Technological University, Civil Engineering Department, Linyi, China); Fu Qiang and Ma Kunlin. Study on a nonlinear mathematical model for triaxial creep of frozen soil: Bingchuan Dongtu = Journal of Glaciology and Geocryology, 35(1), p. 171-176, (Chinese) (English sum.), illus. incl. 2 tables, 15 ref., February 2013.
Triaxial creep tests on laboratory-prepared frozen clay specimens were carried out using a MTS-810 hydraulic servo material testing machine, from which creep curves of the frozen clay under a complex stress state are obtained. The results show that creep deformation in frozen soil has strong temperature sensitivity: the higher the temperature, the greater the sensitivity. Similarly, at a constant temperature, the greater the stress load on the soil, the greater the soil's creep deformation. Using relevant theories, a nonlinear mathematical model for the triaxial creep of frozen clay under a complex stress state is derived. Then, the model's equation parameters are obtained using MATLAB's fitting function. There is a close correlation between the model parameters and temperature. Thus, a mathematical expression between the two was established. The fitted accuracy between the simulated curves and the experimental curves is high. This mathematical model can accurately describe the creep law for frozen soil, and provides an effective theory for predicting deformation in practical frozen soil engineering.
URL: http://bcdt.westgis.ac.cn/EN/article/downloadArticleFile.do?attachType=PDF&id=32 ...
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2017051143 Chlachula, Jiri (Adam Mickiewicz University, Institute of Geoecology and Geoinformation, Poznan, Poland) and Czerniawska, Jolanta. Present permafrost degradation in NE Siberia; environmental implications [abstr.]: in 35th international geological congress; abstracts, International Geological Congress, Abstracts = Congrès Géologique International, Résumés, 35, Abstract 3077, 2016. Meeting: 35th international geological congress, Aug. 27-Sept. 4, 2016, Cape Town, South Africa.
Permafrost degradation is causing major environmental and engineering problems in the (sub-) Arctic areas. Prominent changes in the natural and occupation environment of Yakutia (the Sakha Republic, NE Siberia) have been increasingly observed during the last two decades due to permafrost thaw and associated geomorphic actions, such as surface collapsing, slope slumping, thermokarst lake (alas) expansion and increased ground salinization, among others. All these processes pose major risks to the local communities as well as the regional infrastructure. Of particular concern are the stability of largely unpaved gravel roads and maintenance of the transportation route system, as well as overall industrial development. Monitoring of the actual cryogenic hazards and modeling of their potential impact lo local communities in the formerly permafrost-stable central and northern areas are of key relevance. Effects of mass collapses of deconsolidated grounds are observed in an increased measure especially in the lowland locations along riverine channels. The main rivers (Lena, Viluy, Aldan) experience enhanced seasonal water level fluctuations due to intensified early summer (May-June) warming, causing landscape openings at the expense of tundra-forest, bringing a higher regional thermal capacity. The increased solar radiation triggers thermokarst lake expansion and top ground water saturation leading to vegetation cover changes and formation of marshlands. A regular monitoring of these processes is essential for sustainability of local Yakut and geographically largely dispersed communities, infrastructure maintenance, as well as the overall central economic planning. Present absolute atmospheric and regional hydrology measurements confirm empiric field observations on raising MAT in the Verkhoyansk Region, causing accelerated permafrost degradation on both the river floodplains and the mountain plateaus. This fact has a fundamental bearing for a better visibility of unburied occurrences of fossil fauna records released from the ancient permafrost grounds, precipitating and facilitating more active paleontology and geoarchaeology exploration with employment of the integrated Quaternary geology - palaeoecology research approaches. Diagnostic stone and bone tools as well as anthropogenically modified and used parts of skeletal remains of Late Pleistocene fossil fauna associated with exposed de-freezing alluvial and colluvial formations provide evidence of rather early (>40,000-yr) human adaptations to the (mid- and late) Last Glacial Arctic and sub-Arctic environments [1-2]. Our recent investigations in the Yana River basin (66-68°N) produced new multi-proxy data on the palaeogeography development and geo-contexts of Palaeolithic cultural finds associated with the initial prehistoric occupation of this geographically marginal territory. Mapped alluvial formations inter-bedded by moss/fossil wood horizons illustrate past environmental shifts within meandering stream settings with marked fluvial dynamics of laterally shifting palaeo-channels. Sequenced series of silty-clay strata interspersed by fossil organic/peat/layers from active permafrost settings point to detailed high-resolution (palaeo) climate variations in NE Siberia during the Late Pleistocene - Holocene time span as well as the marked rate of present erosional processes.
URL: http://www.americangeosciences.org/sites/default/files/igc/3077.pdf
2017053231 Cable, William (University of Alaska at Fairbanks, Geophysical Institute, Fairbanks, AK) and Romanovsky, Vladimir. Evaluating ecotypes as a means of scaling-up permafrost thermal measurements in western Alaska [abstr.]: in European Geosciences Union general assembly 2015, Geophysical Research Abstracts, 17, Abstract EGU2015-967, 2015. Meeting: European Geosciences Union general assembly 2015, April 12-17, 2015, Vienna, Austria.
In many regions, permafrost temperatures are increasing due to climate change and in some cases permafrost is thawing and degrading. In areas where degradation has already occurred the effects can be dramatic, resulting in changing ecosystems, carbon release, and damage to infrastructure. Yet in many areas we lack baseline data, such as subsurface temperatures, needed to assess future changes and potential risk areas. Besides climate, the physical properties of the vegetation cover and subsurface material have a major influence on the thermal state of permafrost. These properties are often directly related to the type of ecosystem overlaying permafrost. Thus, classifying the landscape into general ecotypes might be an effective way to scale up permafrost thermal data. To evaluate using ecotypes as a way of scaling-up permafrost thermal data within a region we selected an area in Western Alaska, the Selawik National Wildlife Refuge, which is on the boundary between continuous and discontinuous permafrost. This region was selected because previously an ecological land classification had been conducted and a very high-resolution ecotype map was generated. Using this information we selected 18 spatially distributed sites covering the most abundant ecotypes, where we are collecting low vertical resolution soil temperature data to a depth of 1.5 meters at most sites. At three additional core sites, we are collecting air temperature, snow depth, and high vertical resolution soil temperature to a depth of 3 meters. The sites were installed in the summers of 2011 and 2012; consequently, we have at least two years of data from all sites. Mean monthly and mean annual air temperature and snow depth for all three core sites are similar within the 2012-2014 period. Additionally, the average air temperature and snow depth from our three cores sites compares well with that of a nearby meteorological station for which long-term data is available. During the study period snow depth was anomalously low during both winters, while mean monthly and annual air temperature was similar to the long-term average the first year and considerably warmer (warm winter) the second year. Our results indicate that it is possible to extract information about subsurface temperature, active layer thickness, and other permafrost characteristics based on these ecotype classifications. Additionally, we find that within some ecotypes the absence of a moss layer is indicative of the absence of near surface permafrost. As a proof of concept, we used this information to translate the ecotype landcover map into a map of mean annual ground temperature ranges at 1 m depth. While this map is preliminary and would benefit from additional data and modeling exercises (both ongoing), we believe it provides useful information for decision making with respect to land use and understanding how the landscape might change under future climate scenarios. [Copyright Author(s) 2015. CC Attribution 3.0 License: URL: http://meetingorganizer.copernicus.org/EGU2015/EGU2015-967.pdf
2017055013 Draebing, Daniel (, Bonn, Germany); Krautblatter, Michael and Hoffmann, Thomas. Identification of thermo- and ice-mechanical stresses and their occurrence conditions in a steep permafrost rockwall [abstr.]: in European Geosciences Union general assembly 2015, Geophysical Research Abstracts, 17, Abstract EGU2015-828, 2 ref., 2015. Meeting: European Geosciences Union general assembly 2015, April 12-17, 2015, Vienna, Austria.
Thermo- and ice-mechanical stresses can initiate and expand fractures in high alpine rockwalls, cause instabilities and, thus, natural hazards. In permafrost rockwalls, research focus traditionally on ice-mechanical stresses by frost weathering processes while thermo-mechanical stresses are paid little attention. We use Seismic Refraction Tomography (SRT) to quantify permafrost distribution as well as crackmeters and piezometer to monitor fracture expansions in a permafrost-affected rockwall between August 2012 and August 2014. The calculation of thermal expansion coefficients enables the differentiation of expansion into (i) thermal expansion and contraction, (ii) ice segregation as well as (iii) volumetric expansion and ice erosion during phase transitions. In the Steintaelli at 3100 m a.s.l., mean annual rock surface temperature (MARST) ranges from -0.52 C to -4.47 C in 2012/13 and from -0.74 C to -4.42 C in 2013/14 indicating possible permafrost conditions on the crestline and probable permafrost conditions in the north face. Active-layer thawing and permafrost distribution is quantified by SRT (Krautblatter & Draebing, 2014). Permafrost is present in the north face and the crestline below 5 m depth and preserved by an up to 3 m high snow cornice in 2013 (Draebing et al., 2014) and 2014 while the south-face is permafrost-free. Water availability and fracture permeability are significantly altered by permafrost. Snow covers the rock surface between 119 and 312 days in 2012/13 and 0 to 365 days in 2013/14 with longer snow cover duration on the less-insolated north face and crestline. Snow cover controls the occurrence of thermo-and ice-mechanical stresses During snow-free conditions high-frequent rock surface temperature (RST) changes result in thermal expansion and contraction of the rockwall and, thus, in thermo-mechanical-induced fracture opening and closing up to 0.7 cm. RSTs within the frost cracking window of -3 to -6 C are preserved by isolating snow cover and enable ice segregation. Fracture water pressure show negative values due to cryosuction with coincident fracture opening up to 0.9 cm. Due to enhanced water availability, ice segregation is emphasized in fractures close to permafrost-free areas of the crestline. Volumetric expansion and ice erosion occur in the freeze-thaw window of -0.7 C. Due to unsufficient water saturation of fractures volumetric expansion occurs rarely, however, refreezing during snow melt periods results in fracture dilation up to 0.2 cm. Advected heat transported by snow meltwater erodes ice and decreases ice pressure with coincident fracture closing. Here, we identified for the first time conditions enabling thermo- and ice-mechanical stresses in a permafrost rockwall and show how snow and permafrost control and influence these stresses. Draebing, D., M. Krautblatter, and R. Dikau (2014), Interaction of thermal and mechanical processes in steep permafrost rock walls: a conceptual approach, Geomorphology 226, 226-235. Krautblatter, M., and D. Draebing (2014), Pseudo 3D-P-wave refraction seismic monitoring of permafrost in steep unstable bedrock, Journal of Geophysical Research: Earth Surface, 2012JF002638. [Copyright Author(s) 2015. CC Attribution 3.0 License: URL: http://meetingorganizer.copernicus.org/EGU2015/EGU2015-828.pdf
2017053236 Oliva, Marc (University of Lisbon, Institute of Geography, Lisbon, Portugal) and Ruiz-Fernández, Jesús. The impacts of permafrost degradation in paraglacial environments in Elephant Point (Livingston Island, Antarctica) [abstr.]: in European Geosciences Union general assembly 2015, Geophysical Research Abstracts, 17, Abstract EGU2015-978, 2015. Meeting: European Geosciences Union general assembly 2015, April 12-17, 2015, Vienna, Austria.
Elephant Point constitutes an ice-free environment of only 1.16 km2 in the south-western corner of Livingston Island (South Shetland Islands, Antarctica). In January 2014 we conducted a detailed geomorphological mapping in situ, examining the distribution of processes and landforms in Elephant Point. Four main geomorphological environments were identified: proglacial area, moraine system, bedrock plateaus and marine terraces. The ice cap covering most part of the western half of this island has significantly retreated during the last decades in parallel to the accelerated warming trend recorded in the Antarctic Peninsula. Between 1956 and 2010 this rapid retreat has exposed 17.3% of the present-day land surface in Elephant Point. Two of these geomorphological units are located in this new ice-free area: a polygenic moraine stretching from the western to the eastern edges of the peninsula and a relatively flat proglacial environment. The glacier sat next to the northern slope of the moraine in 1956, but the retreat of the Rotch dome glacier during the last decades left these environments free of glacier ice. Following the deglaciation, the postglacial dynamics in these areas showed the characteristic response of paraglacial systems. Very different geomorphological processes occur today in the northern and southern slopes of the moraine, which is related to the different stage of paraglacial adjustment in both sides. The southern slope shows a low to moderate activity of slope processes operating on coarser sediments that have built pronival ramparts, debris flows and alluvial fans. By contrast, mass wasting processes are very active in the northern slope, which is composed of fine-grained unconsolidated sediments. Here, ice-rich permafrost has been observed in slumps degrading the moraine. The sediments of the moraine are being mobilized down-slope in large amounts by landslides and slumps. Up to 9.6% of the surface of the moraine is affected by retrogressive-thaw slumps. Other features indicative of the degradation of the ground ice were found in Elephant Point, such as the kettle lakes distributed in the hummocky terrain between the moraine ridges and in the proglacial environment. It is expected that paraglacial processes and permafrost degradation will continue in this maritime permafrost environment in the near future, though their intensity and extension will depend on the future climate conditions prevailing in the northern Antarctic Peninsula. Acknowledgements: This research was financially supported by the HOLOANTAR project (Holocene environmental change in the Maritime Antarctic. Interactions Between permafrost and the lacustrine environment, reference PTDC/CTE-GIX/119582/2010) funded by the Portuguese Science Foundation as well as by the PROPOLAR (Portuguese Polar Program). [Copyright Author(s) 2015. CC Attribution 3.0 License: URL: http://meetingorganizer.copernicus.org/EGU2015/EGU2015-978.pdf
2017053227 Popescu, Razvan (University of Bucharest, Faculty of Geography, Bucharest, Romania); Vespremeanu-Stroe, Alfred; Alexandru, Onaca and Cruceru, Nicolae. Lithology, porosity and morphology influence on temperate low- and mid-altitudes cold screes susceptible to host permafrost [abstr.]: in European Geosciences Union general assembly 2015, Geophysical Research Abstracts, 17, Abstract EGU2015-959, 2015. Meeting: European Geosciences Union general assembly 2015, April 12-17, 2015, Vienna, Austria.
The ventilated cold screes from the temperate regions develop high negative thermal anomalies (ground versus air annual temperature) in their lower parts due to cold air aspiration in wintertime, which support the formation of cold reservoirs and sometimes of the perennial frozen ground. Ground and air temperature monitoring, geophysical soundings, debris texture and porosity measurements and dendrogeomorphological analyses were applied at Detunata sites in Apuseni Mts (Western Romanian Carpathians) to investigate a low-altitude cold scree (ca. 1080 m) accommodated in basalt debris. The large negative anomalies (6-6.8 C), the high resistivity values (up to 65 km) recorded in late spring and mid-autumn and the dwarf forest occurrence (whose growth rates are ca. 3 times smaller than the common forest) support the permafrost presence. The new results were integrated into an inter-site evaluation based on the internationally reported cold screes which reveals the priority of lithology in controlling their thermal behavior and implicitly the cold reservoir formation or even permafrost into low- and mid-altitude cold screes. As long as the mean slope of debris exceeds a critical threshold (25°), the exceptional high porosity is the driving factor for an extensive and intensified chimney circulation responsible for the overcooling of the winter aspiration zone normally placed on the slope bottoms and on the negative features (depressions, furrows) in case of rock glacier-talus slope morphology. Lithology assessment highlights that most of the cold screes (ca. 2/3) are composed by only two rock types: basalts and limestones. The poor thermal-conductive basalts which built the most porous screes show the highest negative offsets (6-9°C), which recommend them as the optimum rock type for the low-altitude permafrost sites (<1200 m) and stands for more than 3/4 of the cold screes. Limestone is a preferred accommodation for the mid-altitude permafrost sites (1200-1800 m) in the cases of steep debris with blocky lower sectors that also develop large thermal anomalies, up to 4-5°C. Scree orientation proves unimportant for the low-altitude permafrost due to the extraordinary large thermal anomalies (>6°C) that fade the exposure impact (most of the reported cases are western and southern exposed debris), but for the mid-altitude permafrost sites the slope exposure really count, as ca. 80% of them develop on the shadowed northern aspects. [Copyright Author(s) 2015. CC Attribution 3.0 License: URL: http://meetingorganizer.copernicus.org/EGU2015/EGU2015-959.pdf
2017053773 Matveeva, T. V. (VNIIOkeangeologia, St. Petersburg, Russian Federation) and Semenova, A. A. Methane hydrates of the Russian Arctic seas; forecasts of distribution and resource assessment [abstr.]: in 35th international geological congress; abstracts, International Geological Congress, Abstracts = Congrès Géologique International, Résumés, 35, Abstract 2484, 2 p., 3 ref., 2016. Meeting: 35th international geological congress, Aug. 27-Sept. 4, 2016, Cape Town, South Africa.
This paper summarizes results of the VNIIOkeangeologia assessment of the undiscovered in-place gas hydrate (GH) resources for the Arctic seas within the limits of the 200 nautical mile Russian Federation Exclusive Economic Zone (RF EEZ). The thickness and distribution of the gas hydrate stability zone (GHSZ) both for the cryogenic and filtrogenic GH within the study area was determined by use of various data obtained from Russian scientific reports and scientific publications. The base of the relic permafrost within Russian Arctic seas (0°C isotherm) occurs at the depths more than 260 m irrespectively from the water depth [1]. The calculated volume of the GHSZ related to the relic permafrost is 2.5·1014 m3. Routine method described in [2] was used in order to define pressure-temperature conditions for the filtrogenic GH. The calculations were based on distribution of measured bottom water temperatures, salinity and heat flow assuming the pure methane as a hydrate-forming gas. These data together with the available seismic and sediment gas chemistry datasets allowed revealing hydrate-prone areas for the filtrogenic GH. Some of these areas are characterized by the presence of high methane concentrations in the shallow sediment and evidences of hydrocarbon gases migration suggesting favorable conditions for methane generation. These data were incorporated for the resource assessment by using specific analogy factor varying from 1 (proved GH) to 0.5 (an absence of any GH indications). For the Russian Arctic seas (within the limits of RF EEZ) total area of GHSZ distribution is estimated as much as 1 843 845 square km. The GHSZ with thickness of 200-400 m (filtrogenic and cryogenic GH) is estimated to reach of 792 072 square km, whereas that of 0-200 m (filtrogenic GH) occupies an area of 37 471 square km. The undiscovered in-place GH resources were calculated using analogy approach taking into account the analogy factor. While hydrate resources are well characterized at the European Arctic at the Nyegga site offshore mid-Norway [3] that have significant hydrate gas resources and the Arctic frontier basins offshore Russia are underexplored with little information about the GH, therefore, the analog method provides a way to understand the frontier basin by comparing the basin with the proven hydrate resources. The minimum, average and maximum values of total in-place GH resources for the Barents, Kara, Laptev, East Siberian and Chukchi seas are estimated as 0.83, 9.31, and 12.51 trillion cubic meters of gas (TCM), respectively. It should be noted, that gas hydrate resources are assessed as in-place volumes and reported as the amount of natural gas that occur in the form of gas hydrate in the subsurface of the studied area, without regard to technical recoverability and individual accumulation size.
URL: http://www.americangeosciences.org/sites/default/files/igc/2484.pdf
2017053241 Ewertowski, Marek (Durham University, Department of Geography, Durham, United Kingdom); Pleskot, Krzysztof and Tomczyk, Aleksandra. Alteration of glacigenic landforms by gravitational mass movements, Ragnarbreen and Ebbabreen, Svalbard [abstr.]: in European Geosciences Union general assembly 2015, Geophysical Research Abstracts, 17, Abstract EGU2015-991, 2015. Meeting: European Geosciences Union general assembly 2015, April 12-17, 2015, Vienna, Austria.
The extensive recession of Svalbard's glaciers exposed areas containing large amount of dead-ice covered by relatively thin--usually less than a couple of meters--veneer of debris. This landscape can be very dynamic, mainly due to the mass movement processes and dead-ice melting. Continuous redistribution of sediments causes several phases of debris transfer and relief inversion. Hence, the primary glacial deposits released from ice are subsequently transferred by mass movement processes, until they finally reach more stable position. Investigations of dynamics of the mass movement and the way in which they alter the property of glacigenic sediments are therefore crucial for proper understanding of sedimentary records of previous glaciations. The main objectives of this study were to: (1) quantify short-term dynamic of mass wasting processes; (2) investigate the transformation of the sediment's characteristic by mass wasting processes; (3) assess the contribution of different process to the overall dynamic of proglacial landscape. We focused on the mass-wasting processes in the forelands of two glaciers, Ebbabreen and Ragnarbreen, located near the Petuniabukta at the northern end of the Billefjorden, Spitsbergen. Repetitive topographic scanning was combined with sedimentological analysis of: grain size, clast shape in macro and micro scale and thin sections. Debris falls, slides, rolls and flows were the most important processes leading to reworking of glacigenic sediments and altering their properties. Contribution of different processes to the overall dynamic of the landforms was related mainly to the local conditions. Four different morphological types of sites were identified: (1) near vertical ice-cliffs covered with debris, transformed mainly due to dead-ice backwasting and debris falls and slides, (2) steep debris slopes with exposed ice-cores dominated by debris slides, (3) gentle sediment-mantled slopes transformed due to debris flows, and (4) non-active debris-mantled areas transformed only by dead-ice downwasting. The amount of volume loss due to the active mass movement processes and dead-ice melting (including both backwasting and downwasting) was up to more than 1.8 m a-1. In comparison, the amount of volume loss due to the dead-ice downwasting only was significantly lower at a maximum of 0.3 m a-1. The spatial and temporal distribution of volume changes, however, was quite diverse and for the most part related to local geomorphic conditions (e.g. slope gradient, occurrence of streams, and meltwater channels). We proposed a simplified model of spatio-temporal switching between stable and active conditions within the forelands of the studied glaciers. Transformations of landforms were attributed to the period of deglaciation and debris cover development. Stage 1 -- shortly after deglaciation when the debris cover is thin (thinner than the permafrost active layer's thickness) mass movement processes become fairly common. They are facilitated by the dead-ice melting and steepness of the slopes. This stage can be observed in many lateral moraines, which are characterised by steep slopes, abundance of active mass movement processes, and by consequence a high degree of transformation. Stage 2 -- ongoing mass-wasting processes lead to the transfer of sediments from steep slopes to more stable positions. As the thickness of the sediments increases, the debris cover starts to protect the dead-ice from melting and also contribute to the decrease in slope gradient. Thus, the resulting landscape is relatively stable and in equilibrium with current climatic and topographic conditions. This stage characterises most parts of the frontal (end) moraine complex of the studied glaciers; thus, their transformation rates are either very low or close to zero. Stage 3 -- some parts of this stable landscape can be subsequently transformed again into an unstable state, mainly due to the effect of external factors such as streams or meltwater channels. This can lead to the development of mass movement processes and further slope instability, which could facilitate subsequent generation of debris flows. Stages described above can occur in a sort of spatio-temporal cycle, and, depending on local and external factors, the changes between stabilization of landforms and activation of mass flows can be repeated several times for any given area until the dead-ice is completely melted. [Copyright Author(s) 2015. CC Attribution 3.0 License: URL: http://meetingorganizer.copernicus.org/EGU2015/EGU2015-991.pdf
2017053244 Nosevich, Ekaterina (Saint Petersburg State University, Department of Physical Geography, Saint Petersburg, Russian Federation); Anisimov, Michail and Sapelko, Tatyana. Vegetation and climate history of Franz Jozef Land Archipelago in the late Holocene according pollen data [abstr.]: in European Geosciences Union general assembly 2015, Geophysical Research Abstracts, 17, Abstract EGU2015-999, 2015. Meeting: European Geosciences Union general assembly 2015, April 12-17, 2015, Vienna, Austria.
The archipelago Franz-Josef Land is situated in the Arctic Ocean (80°40'N, 54°50'E). It is one of the important areas for arctic research due to organization of Russian Arctic National Park there. Therefore, an interest to the environmental history of this territory grows up and any new data might have a high value. However, geographical remoteness of the archipelago is the reason why there are not much work has been done up to date. A focus of our researches is vegetation and climate reconstruction during the Late Holocene history according pollen data. In frame of studying of the Franz Josef Land during complex expedition of Russian Arctic National Park on the islands geomorphological and botanical researches was occurred. Nowadays the typical island of archipelago presents the ice cap and glacier-free marine terraces of 35 m high at maximum, where solifluction and permafrost are developed. The archipelago has a maritime Arctic climate. Vegetation of archipelago Franz-Josef Land presents the northern type of Polar Desert. It includes 57 species of vascular plants (Poaceae, Juncaceae, Caryophyllaceae, Brassicaceae, Saxifragaceae etc). We studied the peat core from the southern part of Majbel Island, in the archipelago Franz Josef Land. More than a half of the island is covered by glacier. The core was sampled at the inner margin of ice-free high marine terrace, near the southern slope of bedrock hill. We received preliminary pollen data and radiocarbon data 3010±80 C14 y.a. at the bottom. The pollen concentration is low, but we manage to make some reconstructions of vegetation and climate. For correct interpretation of our results, we used surface samples from different islands of archipelago (Jackson, Hooker, Greely, Alexandra land, Yeva-Liv, Appolonov, Georg land, Kane, Bell). Subrecent spectra include species presented in flora of region, but also those which are not founded at this region in this time. [Copyright Author(s) 2015. CC Attribution 3.0 License: URL: http://meetingorganizer.copernicus.org/EGU2015/EGU2015-999.pdf
2017054950 Siekacz, Liliana (Adam Mickiewicz University, Cryosphere Research Department, Poznan, Poland). Salix polaris growth responses to active layer detachment and solifluction processes in High Arctic [abstr.]: in European Geosciences Union general assembly 2015, Geophysical Research Abstracts, 17, Abstract EGU2015-686, 04 ref., 2015. Meeting: European Geosciences Union general assembly 2015, April 12-17, 2015, Vienna, Austria.
The work is dedicated to demonstrate the potential of Salix polaris grow properties in the dendrogemorphologic image, analyzing periglacially induced slope processes in the high Arctic.. Observed anatomical and morphological plants responses to solifluction and active layer detachment processes are presented qualitatively and quantitatively as a summary of presented features frequency. The results are discussed against the background of the other research results in this field. The investigations was performed in Ebba valley, in the vicinity of Petunia Bay, northernmost part of Billefjorden in central Spitsbergen (Svalbard). Environmental conditions are characterized by annual precipitation sum lower than 200 mm (Hagen et al.,1993) and average summer temperature of about 5°C, with maximum daily temperatures rarely exceeding 10°C (Rachlewicz, 2009). Collected shrub material was prepared according to the methods presented by Schweingruber and Poschlod (2005). Thin (approx. 15-20 m) sections of the whole cross-section were prepared with a sledge microtome, stained with Safranine and Astra blue and finally permanently fixed on microslides with Canada balsam and dried. Snapshots were taken partially for each cross-section with digital camera (ColorView III, Olympus) connected to a microscope (Olympus BX41) and merged into one, high resolution image. After all, ring widths were measured in 3-4 radii in every single cross-section using ImageJ software. Analyzed plants revealed extremely harsh environmental conditions of their growth. Buchwal et al. (2013) provided quantitative data concerning missing rings and partially missing rings in shrubs growing on Ebba valley floor. Mean ring width at the level of 79 m represents one of the smallest values of yearly growth ever noted. The share of missing rings and partially missing rings was 11,2% and 13,6% respectively. Plants growing on Ebba valley slope indicate almost twice smaller values of ring width (41 m), and higher participation of missing and partially missing rings. Share of missing rings in shrubs growing within an active layer detachment on the valley slope reached 16,22% and 15,36%. Even higher variation is observed in partially missing rings which account for 31,07% within detachment and 23,39% on surrounding slope. Those values are more than twice higher comparing to the valley floor. There is also noticeable difference between detachment and surrounding slope indicating that wedging rings are an effect of mechanical stress that is higher within the detachment. Comparing growth patterns in aboveground and belowground plant parts different growth allocation is noticed. Years of detachment event growth rings were present only in aboveground parts. It is supposed that mechanical stress delays the onset of the growing season similarly to low temperatures (Buchwal et al., 2013), resulting in not enough time to fully allocate resources for growth in the belowground parts. Growth pattern is extremely irregular, indicating that the slope is in constant movement, which disrupts growth conditions. Analyzed shrubs showed two possible event years: 2006 and 2008, with the highest participation of missing and partially missing rings. Air and ground temperature data were also analyzed and confirmed that active layer detachment happened in 2006. References: Buchwal A., Rachlewicz G., Fonti P., Cherubini P., Gartner H., (2013) Temperature modulates intra-plant growth of Salix Polaris from a high Arctic site (Svalbard). Polar Biol 36:1305-1318. Hagen J. O., Liestol O., Roland E., Jorgensen T., (1993) Glacier atlas of Svalbard and Jan Mayen. Norsk Polarinstitutt Meddelelser 129: 160. Rachlewicz G, (2009) Contemporary sediment fluxes and relief changes in high Arctic glacierized valley systems (Billefjorden, Central Spitsbergen). Wyd. Nauk. UAM Poznan, seria Geografia 87:204. Schweingruber F. H., Poschlod P., (2005) Growth rings in herbs and shrubs: life span, age determination and stem anatomy. For Snow Landsc Res 79:195-415 [Copyright Author(s) 2015. CC Attribution 3.0 License: URL: http://meetingorganizer.copernicus.org/EGU2015/EGU2015-686.pdf
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