|
2019082949 Natali, Susan M. (Woods Hole Research Center, Falmouth, MA); Watts, Jennifer D.; Rogers, Brendan M.; Potter, Stefano; Ludwig, Sarah M.; Selbmann, Anne-Katrin; Sullivan, Patrick F.; Abbott, Benjamin W.; Arndt, Kyle A.; Birch, Leah; Björkman, Mats P.; Bloom, A. Anthony; Celis, Gerardo; Christensen, Torben R.; Christiansen, Casper T.; Commane, Roisin; Cooper, Elisabeth J.; Crill, Patrick; Czimczik, Claudia; Davydov, Sergey; Du, Jinyang; Egan, Jocelyn E.; Elberling, Bo; Euskirchen, Eugenie S.; Friborg, Thomas; Genet, Hélène; Göckede, Mathias; Goodrich, Jordan P.; Grogan, Paul; Helbig, Manuel; Jafarov, Elchin E.; Jastrow, Julie D.; Kalhori, Aram A. M.; Kim, Yongwon; Kimball, John S.; Kutzbach, Lars; Lara, Mark J.; Larsen, Klaus S.; Lee, Bang-Yong; Liu Zhihua; Loranty, Michael M.; Lund, Magnus; Lupascu, Massimo; Madani, Nima; Malhotra, Avni; Matamala, Roser; McFarland, Jack; McGuire, A. David; Michelsen, Anders; Minions, Christina; Oechel, Walter C.; Olefeldt, David; Parmentier, Frans-Jan W.; Pirk, Norbert; Poulter, Ben; Quinton, William; Rezanezhad, Fereidoun; Risk, David; Sachs, Torsten; Schaefer, Kevin; Schmidt, Niels M.; Schuur, Edward A. G.; Semenchuk, Philipp R.; Shaver, Gaius; Sonnentag, Oliver; Starr, Gregory; Treat, Claire C.; Waldrop, Mark P.; Wang, Yihui; Welker, Jeffrey; Wille, Christian; Xu, Xiaofeng; Zhang, Zhen; Zhuang, Qianlai and Zona, Donatella. Large loss of CO2 in winter observed across the northern permafrost region: Nature Climate Change, Oct. 21, illus. incl. sketch maps, 49 ref., October 21, 2019.
Recent warming in the Arctic, which has been amplified during the winter1-3, greatly enhances microbial decomposition of soil organic matter and subsequent release of carbon dioxide (CO2)4. However, the amount of CO2 released in winter is not known and has not been well represented by ecosystem models or empirically based estimates 5,6. Here we synthesize regional in situ observations of CO2 flux from Arctic and boreal soils to assess current and future winter carbon losses from the northern permafrost domain. We estimate a contemporary loss of 1,662 TgC per year from the permafrost region during the winter season (October-April). This loss is greater than the average growing season carbon uptake for this region estimated from process models (-1,032 TgC per year). Extending model predictions to warmer conditions up to 2100 indicates that winter CO2 emissions will increase 17% under a moderate mitigation scenario-Representative Concentration Pathway 4.5-and 41% under business-as-usual emissions scenario-Representative Concentration Pathway 8.5. Our results provide a baseline for winter CO2 emissions from northern terrestrial regions and indicate that enhanced soil CO2 loss due to winter warming may offset growing season carbon uptake under future climatic conditions.
DOI: 10.1038/s41558-019-0592-8
2019082938 Troianovski, Anton, reporter; Mooney, Chris, reporter and Chavez, Michael Robinson, photographer. 2°C; beyond the limit; radical warming in Siberia leaves millions on unstable ground: The Washington Post, Oct. 3, 2019, illus., October 3, 2019.
URL: https://www.washingtonpost.com/graphics/2019/national/climate-environment/climat ...
2019082759 Han Fenglei (Chongqing Jiaotong University, School of Civil Engineering, Chongqing, China); Yu Wenbing; Zhang Xuefu; Yu Fan; Yi Xin and Hu, Da. Parameter sensitivity analyses of influence on thermal regime of embankment in permafrost regions along the Qinghai-Tibet engineering corridor: Cold Regions Science and Technology, 166, Article 102817, illus. incl. 5 tables, October 2019. Based on Publisher-supplied data.
Several engineering projects have been built in the Qinghai-Tibet Plateau Engineering Corridor (QTPEC). The proposed Qinghai-Tibet Expressway will be located between the existing projects. The interaction of the thermal influence among the engineering projects will affect the stability of the permafrost and infrastructure. This study uses mathematical model and field observations, in conjunction with four factors along the QTPEC, to analyze the law of heat influence and the key impact factors of the permafrost embankment introducing the grey relational analysis. Results indicate that the extent of the embankment heat influence is negatively correlated with the embankment height and the mean annual air temperature (MAAT), while it is positively correlated with the pavement width and water content. After 50 years, the maximum and minimum distance of the heat influence from the foot of the embankment slope will be 32.45 m and 7.22 m, respectively. The most significant factor impacting the thermal regime is the MAAT. The pavement width is the second most significant, the water content is the third most significant, and the embankment height is least significant. The results are expected to serve as a guide for the design of the Qinghai-Tibet Expressway.
DOI: 10.1016/j.coldregions.2019.102817
2019082760 Li Anyuan (Shaoxing University, College of Civil Engineering, Shaoxing, China); Niu Fujun; Xia Caichu; Bao Chunyan and Zheng, Hao. Water migration and deformation during freeze-thaw of crushed rock layer in Chinese high-speed railway subgrade; large scale experiments: Cold Regions Science and Technology, 166, Article 102841, illus. incl. 3 tables, October 2019. Based on Publisher-supplied data.
The water migration and deformation of soil induced by freeze-thaw cycle is a significant issue which influences the stability of subgrade in Chinese high-speed railway. Soil column studies under controlled laboratory settings can help understand the thermal-hydrodynamics of the crushed rock layer. In this study, four large-scale subgrade models with different initial soil moisture contents, fine contents were subjected to freeze-thaw action by bringing the soil surfaces exposed to air temperature fluctuating between -15 and 15°C. The results show that soil moisture migration occurs in both frozen and unfrozen soils during the freeze-thaw cycle. The freezing-induced soil water distribution is affected by fines content and loading conditions. Crushed rock with 50% fines content produced visual deformation, and the maximum amount of frost heave was 12.1 mm under external loading, comparable with the results from the previous field investigation. The unfrozen water content of fills decreases gradually with the depression of soil temperature. Some liquid water remained unfrozen at the end of the freezing period with residual unfrozen water content between 0.07 m3 m-3 and 0.10 m3 m-3, and continuing to exist even at -8.7°C. The frozen soil contains more volumetric water content at the same minus soil temperature, resulting in a hysteresis loop-like behavior in the soil characteristics curve. The results of this study will help in understanding, and finally forecasting, the deformation of subgrade in Chinese high-speed railway.
DOI: 10.1016/j.coldregions.2019.102841
2019082757 Tang Liyun (Xi'an University of Science and Technology, School of Architecture & Civil Engineering, Xi'an, China); Wang Ke; Deng, Lijun; Yang Gengshe; Chen Jianbing and Jin Long. Axial loading behaviour of laboratory concrete piles subjected to permafrost degradation: Cold Regions Science and Technology, 166, Article 102820, illus. incl. 3 tables, October 2019. Based on Publisher-supplied data.
Global warming causes a large area of permafrost degradation, which leads to increasingly engineering problems related to pile foundations in Tibetan Plateau, particularly in warm permafrost. The present research investigated the effects of permafrost degradation on the axial behaviour of concrete piles in warm permafrost. Quick axial compression tests were conducted on concrete piles installed in frozen soils in the cold room laboratory. Results showed that the behaviours of pile gradually degenerated with the increase of active layer thickness (za) and ground temperature. The development of shaft resistance as the pile settled was compared at various cases. Adfreeze strength on the pile shaft was reduced with increased ground temperature. The adfreeze strength for concrete piles was obtained in silt and clay at temperature of -1.10°C to -2.35°C. Adfreeze strength was not reached near the pile tip. Piles in frozen soils could still gain the tip resistance at a displacement as much as 10% pile diameter and did not reach the plunging failure at such a displacement.
DOI: 10.1016/j.coldregions.2019.102820
2019082923 Wang, Ru (University of Leeds, School of Earth & Environment, Leeds, United Kingdom); Colombera, Luca and Mountney, Nigel P. Geological controls on the geometry of incised-valley fills; insights from a global dataset of late-Quaternary examples: Sedimentology, 66(6), p. 2134-2168, illus. incl. sects., 3 tables, sketch map, 507 ref., October 2019.
Incised valleys that develop due to relative sea-level change are common features of continental shelves and coastal plains. Assessment of the factors that control the geometry of incised-valley fills has hitherto largely relied on conceptual, experimental or numerical models, else has been grounded on case studies of individual depositional systems. Here, a database-driven statistical analysis of 151 late-Quaternary incised-valley fills has been performed, the aim being to investigate the geological controls on their geometry. Results of this analysis have been interpreted with consideration of the role of different processes in determining the geometry of incised-valley fills through their effect on the degree and rate of river incision, and on river size and mobility. The studied incised-valley fills developed along active margins are thicker and wider, on average, than those along passive margins, suggesting that tectonic setting exerts a control on the geometry of incised-valley fills, probably through effects on relative sea-level change and river behaviour, and in relation to distinct characteristics of basin physiography, water discharge and modes of sediment delivery. Valley-fill geometry is positively correlated with the associated drainage-basin size, confirming the dominant role of water discharge. Climate is also inferred to exert a potential control on valley-fill dimensions, possibly through modulations of temperature, peak precipitation, vegetation and permafrost, which would in turn affect water discharge, rates of sediment supply and valley-margin stability. Shelves with slope breaks that are currently deeper than 120 m contain incised-valley fills that are thicker and wider, on average, than those hosted on shelves with breaks shallower than 120 m. No correlation exists between valley-fill thickness and present-day coastal-prism convexity, which is measured as the difference in gradient between lower coastal plains and inner shelves. These findings challenge some concepts embedded in sequence stratigraphic thinking, and have significant implications for analysis and improved understanding of 'source to sink' sediment route-ways, and for attempting predictions of the occurrence and characteristics of hydrocarbon reservoirs. Abstract Copyright (2019), International Association of Sedimentologists.
DOI: 10.1111/sed.12596
2019082942 Cao Bin (Lanzhou University, Laboratory of Western China's Environmental Systems, Lanzhou, China); Zhang Tingjun; Wu Qingbai; Sheng Yu; Zhao Lin and Zou Defu. Permafrost zonation index map and statistics over the Qinghai-Tibet Plateau based on field evidence: Permafrost and Periglacial Processes, 30(3), p. 178-194, illus. incl. 5 tables, sketch map, 54 ref., September 2019. Includes 2 appendices.
Permafrost is prevalent over the Qinghai-Tibet Plateau (QTP), but mapping its distribution is challenging due to the limited availability of ground-truth data sets and strong spatial heterogeneity in the region. Based on a recently developed inventory of permafrost presence or absence from 1475 in situ observations, we developed and trained a statistical model and used it to compile a high-resolution (30 arc-seconds) permafrost zonation index (PZI) map. The PZI model captures the high spatial variability of permafrost distribution over the QTP because it considers multiple controlling variables, including near-surface air temperature downscaled from re-analysis, snow cover days and vegetation cover derived from remote sensing. Our results showed the new PZI map achieved the best performance compared to available existing PZI and traditional categorical maps. Based on more than 1000 in situ measurements, the Cohen's kappa coefficient and overall classification accuracy were 0.62 and 82.5%, respectively. Excluding glaciers and lakes, the area of permafrost regions over the QTP is approximately 1.54 (1.35-1.66)´106 km2, or 60.7 (54.5-65.2)% of the exposed land, while area underlain by permafrost is about 1.17 (0.95-1.35)´106 km2, or 46 (37.3-53.0)%. Abstract Copyright (2019), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2006
2019082943 Chang Juan (Lanzhou University, College of Earth and Environment Science, Laboratory of Western China's Environmental Systems, Lanzhou, China); Wang Genxu and Guo Linmao. Simulation of soil thermal dynamics using an artificial neural network model for a permafrost alpine meadow on the Qinghai-Tibetan Plateau: Permafrost and Periglacial Processes, 30(3), p. 195-207, illus. incl. 6 tables, sketch map, 48 ref., September 2019.
The thermal regime of the active layer temperature (ALT) is a key variable with which to monitor permafrost changes and to improve the precision of simulations and predictions of land surface processes. The dynamics of the active layer thermal regime can differ substantially under various land surface types and climatic conditions. The proper simulation of these different processes is essential for accurately predicting the changes in water cycles and ecosystems under a warming climate scenario. In this paper, an artificial neural network (ANN) forecasting model system was developed using only two accessible parameters, air and ground surface temperatures, to predict and simulate the ALT thermal regime. The model results show that the ANN model has better real-time prediction capability than other physics-based models and performs well at simulating and forecasting variations in soil temperature with a step size of 12 days in permafrost regions on the Qinghai-Tibetan Plateau. The influence of an increase in air temperature on the ALT thermal regime was more intense during the thawing process than during the freezing process, and this influence decreased with an increase in soil depth. Abstract Copyright (2019), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2003
2019082940 Dvornikov, Yury A. (Russian Academy of Sciences, Siberian Branch, Earth Cryosphere Institute, Tyumen, Russian Federation); Leibman, Marina O.; Khomutov, Artem V.; Kizyakov, Alexander I.; Semenov, Petr; Bussmann, Ingeborg; Babkin, Evgeny M.; Heim, Birgit; Portnov, Alexey; Babkina, Elena A.; Streletskaya, Irina D.; Chetverova, Antonina A.; Kozachek, Anna and Meyer, Hanno. Gas-emission craters of the Yamal and Gydan Peninsulas; a proposed mechanism for lake genesis and development of permafrost landscapes: Permafrost and Periglacial Processes, 30(3), p. 146-162, illus. incl. 3 tables, sketch map, 71 ref., September 2019.
This paper describes two gas-emission craters (GECs) in permafrost regions of the Yamal and Gydan peninsulas. We show that in three consecutive years after GEC formation (2014-2017), both morphometry and hydrochemistry of the inner crater lakes can become indistinguishable from other lakes. Craters GEC-1 and AntGEC, with initial depths of 50-70 and 15-19 m respectively, have transformed into lakes 3-5 m deep. Crater-like depressions were mapped in the bottom of 13 out of 22 Yamal lakes. However, we found no evidence that these depressions could have been formed as a result of gas emission. Dissolved methane (dCH4) concentration measured in the water collected from these depressions was at a background level (45 ppm on average). Yet, the concentration of dCH4 from the near-bottom layer of lake GEC-1 was significantly higher (824-968 ppm) during initial stages. We established that hydrochemical parameters (dissolved organic carbon, major ions, isotopes) measured in GEC lakes approached values measured in other lakes over time. Therefore, these parameters could not be used to search for Western Siberian lakes that potentially resulted from gas emission. Temperature profiles measured in GEC lakes show that the water column temperatures in GEC-1 are lower than in Yamal lakes and in AntGEC - close to values of Gydan lakes. Given the initial GEC depth >50 m, we suggest that at least in GEC-1 possible re-freezing of sediments from below might take place. However, with the present data we cannot establish the modern thickness of the closed talik under newly formed GEC lakes. Abstract Copyright (2019), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2014
2019082941 Li Xiaoying (Chinese Academy of Sciences, Northeast China Observatory of Frozen-Soils Engineering and Environment, Lanzhou, China); Jin Huijun; He Ruixia; Huang Yadong; Wang Hongwei; Luo Dongliang; Jin Xiaoying; Lu Lanzhi; Wang Lizhong; Li Wei'hai; Wei Changlei; Chang Xiaoli; Yang Sizhong and Yu Shaopeng. Effects of forest fires on the permafrost environment in the northern Da Xing'anling (Hinggan) Mountains, northeast China: Permafrost and Periglacial Processes, 30(3), p. 163-177, illus. incl. 4 tables, sketch map, 92 ref., September 2019.
Forest fires have significantly impacted the permafrost environment, and many research programs looking at this have been undertaken at higher latitudes. However, their impacts have not yet been systematically studied and evaluated in the northern part of northeast China at mid-latitudes. This study simultaneously measured ecological and geocryological changes at various sites in the boreal forest at different stages after forest fires (chronosequence approach) in the northern Da Xing'anling (Hinggan) Mountains, Northeast China. We obtained results through field investigations, monitoring and observations, remote sensing interpretations, and laboratory tests. The results show that forest fires have resulted in a decreased Normalized Difference Vegetation Index (NDVI) and soil moisture contents in the active layer, increased active layer thickness (ALT) and ground temperatures, and the release of a large amount of C and N from the soils in the active layer and at shallow depths of permafrost. NDVI and species biodiversity have gradually increased in the years since forest fires. However, the vegetation has not fully recovered to the climax community structures and functions of the boreal forest ecosystems. For example, ground temperatures, ALT, and soil C and N contents have been slowly recovering in the 30 years after the forest fires, but they have not yet been restored to pre-fire levels. This study provides important scientific bases for assessment of the impacts of forest fires on the boreal forest ecosystems in permafrost regions, environmental restoration and management, and changes in the carbon stock of soils at shallow (<3 m) depths in the Da Xingan'ling Mountains in northeast China. Abstract Copyright (2019), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2001
2019082944 Liu Jiankun (Sun Yat-sen University, School of Civil Engineering, Guangzhou, China); Tai Bowen and Fang Jianhong. Ground temperature and deformation analysis for an expressway embankment in warm permafrost regions of the Tibet Plateau: Permafrost and Periglacial Processes, 30(3), p. 208-221, illus. incl. 2 tables, sketch map, 44 ref., September 2019.
The physical and mechanical processes relating to infrastructure are strongly intertwined in subgrades of road or railway in warm permafrost regions, where the evolution of these processes may influence the functionality of infrastructure. Thus, this study analyzed the embankment thermal regime and thaw settlement behavior based on monitored data for three sections of the newly constructed Gonghe-Yushu expressway (GYE) in a warm permafrost area of Tibet. The efficiencies of crushed rock, ventilated, and insulated embankments in maintaining permafrost temperature were evaluated in relation to the permafrost table (PT) and the annual warming rate of the permafrost. The deformation characteristics of three embankments for different soil layers are summarized, along with analysis of heat balance. The results show that: (a) the permafrost thaw rate has a positive linear correlation with mean annual ground temperature; (b) the permafrost displays a warming trend regardless of whether PT increases or decreases; (c) the total deformation of a given embankment shows a tendency toward settlement; and (d) subgrade peak thaw settlement occurs later than its maximum seasonal thaw depth. Abstract Copyright (2019), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2007
2019082939 Mithan, Huw Thomas (Cardiff University, School of Earth and Ocean Sciences, Cardiff, United Kingdom); Hales, Tristram Charles and Cleall, Peter John. Supervised classification of landforms in Arctic mountains: Permafrost and Periglacial Processes, 30(3), p. 131-145, illus. incl. 1 table, sketch map, 80 ref., September 2019.
Erosional and sediment fluxes from Arctic mountains are lower than for temperate mountain ranges due to the influence of permafrost on geomorphic processes. As permafrost extent declines in Arctic mountains, the spatial distribution of geomorphic processes and rates will change. Improved access to high-quality remotely sensed topographic data in the Arctic provides an opportunity to develop our understanding of the spatial distribution of Arctic geomorphological processes and landforms. Utilizing newly available Arctic digital topography data, we have developed a method for geomorphic mapping using a pixel-based linear discriminant analysis method that could be applied across Arctic mountains. We trained our classifier using landforms within the Adventdalen catchment in Svalbard and applied it to two adjacent catchments and one in Alaska. Slope gradient, elevation-relief ratio and landscape roughness distinguish landforms to a first order with >80% accuracy. Our simple classification system has a similar overall accuracy when compared across our field sites. The simplicity and robustness of our classification suggest that it is possible to use it to understand the distribution of Arctic mountain landforms using extant digital topography data and without specialized classifications. Our preliminary assessments of the distribution of geomorphic processes within these catchments demonstrate the importance of post-glacial hillslope processes in governing sediment movement in Arctic mountains. Abstract Copyright (2019), John Wiley & Sons, Ltd.
DOI: 10.1002/ppp.2015
2019079311 Colucci, Renato R. (CNR, Instituto di Scienze Marine, Trieste, Italy); Forte, Emanuele; Zebre, Manja; Maset, Eleonora; Zanettini, Carlotta and Guglielmin, Mauro. Is that a relict rock glacier?: Geomorphology, 330, p. 177-189, illus. incl. 3 tables, geol. sketch maps, 94 ref., April 1, 2019.
The distribution of rock glaciers is often used to investigate the occurrence of permafrost in mountain areas and to understand their climate and paleoclimate evolution. This requires the creation of regional and global inventories capable of discriminating active and relict landforms in order to forecast the presence or absence of ice in the ground. In this paper, geomorphological, geophysical and microclimatic surveys are performed on a rock glacier of the Carnic Alps (Eastern European Alps). In the classification currently used for implementing regional inventories of permafrost evidence in the Alps, this rock glacier would be defined as relict. However the geophysical, climatological and geomorphological results indicate that internal ice is widespread in large portions of the rock glacier. These are generally interpreted as ice in pore spaces and local ice lenses, probably without layers of massive ice. Moreover the occurrence of ice during the maximum thawing season at depths <15 m, assumed here as the depth of zero annual amplitude, suggests that the ice occurring within the rock glacier is related to current cryotic conditions due to density driven air flow (i.e. the chimney effect). This research demonstrates that the current altitudinal limit of alpine permafrost can be locally several hundreds of meters lower than forecasted by empirical modeling based only on the rock glacier distribution and classification. Therefore, rock glacier classifications based only on remote sensing and geomorphological evidence as the main sources for extracting regional climate and paleoclimate signals should be treated with caution.
DOI: 10.1016/j.geomorph.2019.02.002
2019082685 Marchand, Nicolas (Université de Sherbrooke, Centre d'Applications et de Recherches en Télédétection, Sherbrooke, QC, Canada); Royer, Alain; Krinner, Gerhard; Roy, Alexandre; Langlois, Alexandre and Vargel, Céline. Snow-covered soil temperature retrieval in Canadian Arctic permafrost areas, using a land surface scheme informed with satellite remote sensing data: Remote Sensing, 10(11), 18 p., illus. incl. 4 tables, sketch map, 68 ref., November 2018.
High-latitude areas are very sensitive to global warming, which has significant impacts on soil temperatures and associated processes governing permafrost evolution. This study aims to improve first-layer soil temperature retrievals during winter. This key surface state variable is strongly affected by snow's geophysical properties and their associated uncertainties (e.g., thermal conductivity) in land surface climate models. We used infrared MODIS land-surface temperatures (LST) and Advanced Microwave Scanning Radiometer for EOS (AMSR-E) brightness temperatures (Tb) at 10.7 and 18.7 GHz to constrain the Canadian Land Surface Scheme (CLASS), driven by meteorological reanalysis data and coupled with a simple radiative transfer model. The Tb polarization ratio (horizontal/vertical) at 10.7 GHz was selected to improve snowpack density, which is linked to the thermal conductivity representation in the model. Referencing meteorological station soil temperature measurements, we validated the approach at four different sites in the North American tundra over a period of up to 8 years. Results show that the proposed method improves simulations of the soil temperature under snow (Tg) by 64% when using remote sensing (RS) data to constrain the model, compared to model outputs without satellite data information. The root mean square error (RMSE) between measured and simulated Tg under the snow ranges from 1.8 to 3.5 K when using RS data. Improved temporal monitoring of the soil thermal state, along with changes in snow properties, will improve our understanding of the various processes governing soil biological, hydrological, and permafrost evolution.
DOI: 10.3390/rs10111703
2019080373 Wu Zhijian (Nanjing Tech University, College of Transportation Science & Engineering, Nanjing, China); Chen Tuo; Zhao Tao and Wang Lili. Dynamic response analysis of railway embankments under train loads in permafrost regions of the Qinghai-Tibet Plateau: Soil Dynamics and Earthquake Engineering (1984), 112, p. 1-7, illus. incl. 2 tables, 25 ref., September 2018.
Using real-time strong-motion observation tests of a crushed-rock embankment and a plain-fill embankment in a permafrost region of the Beiluhe River section along Qinghai-Tibet Railway (QTR), we collected the real-time acceleration data when trains were passing. We used field test data and dynamic finite element analysis software (two-dimensional, nonlinear) to analyze the characteristics of dynamic transmission, displacement response, and the stress-strain relationship of both types of embankments bearing the load of a train. By comparing the dynamic response characteristics of the plain-fill embankment, we analyzed the dynamic transmission mechanism of the crushed-rock embankment of QTR. The results showed that vibration acceleration transmission was decreased through the crushed-rock layer, which could improve the stability of the embankment. Also, the vibration settlement caused by train loading was decreased obviously in the crushed-rock layer, in which the maximum settlement displacement was only 0.81 mm, while that of the plain-fill embankment reached 1.87 mm. Thus, the crushed-rock layer changed the state of stress-strain within the embankment, which helped increase the maximum principal stress of the embankment and decrease the amplitude and range of the maximum shear strain.
DOI: 10.1016/j.soildyn.2018.04.047
2019079086 Jaskolski, Marek W. (University of Wroclaw, Institute of Geography and Regional Development, Wroclaw, Poland); Pawlowski, Lukasz and Strzelecki, Mateusz C. High Arctic coasts at risk-the case study of coastal zone development and degradation associated with climate changes and multidirectional human impacts in Longyearbyen (Adventfjorden, Svalbard): Land Degradation & Development, 29(8), p. 2514-2524, illus. incl. 2 tables, sketch map, 57 ref., August 2018.
Longyearbyen is the major administrative, touristic, and scientific centre in Svalbard and so-called 'European Gateway' to the Arctic. The number of inhabitants and tourists as well as community infrastructure has significantly expanded over the recent decade, and present-day community faces development thresholds associated with climate warming and disturbance of cold region landscape. Coastal zone is a key interface where severe environmental changes impact directly on Longyearbyen infrastructure. We applied the combination of environmental assessment methods and geographic information system analyses together with field mapping to investigate the scale of degradation of coastal zone in Longyearbyen and examine the impact of coastal hazards on major elements of community infrastructure. Rate of observed coastal changes, the diversity of natural and man-made hazards mapped along the coast, and observed damages in infrastructure suggest a need for coastal change monitoring and coastal protection in Longyearbyen. The part of the Longyearbyen coast that should be monitored and protected are sections spreading between new port and surroundings of Longyearelva delta significantly modified by coastal erosion and landsliding. In order to improve coastal zone protection and safety of town development, we present arguments supporting the incorporation of Longyearbyen into recently established Circum-Arctic Coastal Communities Knowledge Network. Abstract Copyright (2018), John Wiley & Sons, Ltd.
DOI: 10.1002/ldr.2974
2019080323 Ramage, Justine L. (Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Department of Periglacial Research, Potsdam, Germany); Irrgang, Anna M.; Morgenstern, Anne and Lantuit, Hugues. Increasing coastal slump activity impacts the release of sediment and organic carbon into the Arctic Ocean: Biogeosciences, 15(5), p. 1483-1495, illus. incl. 3 tables, 69 ref., March 2018.
Retrogressive thaw slumps (RTSs) are among the most active thermokarst landforms in the Arctic and deliver a large amount of material to the Arctic Ocean. However, their contribution to the organic carbon (OC) budget is unknown. We provide the first estimate of the contribution of RTSs to the nearshore OC budget of the Yukon Coast, Canada, and describe the evolution of coastal RTSs between 1952 and 2011 in this area. We (1) describe the evolution of RTSs between 1952 and 2011; (2) calculate the volume of eroded material and stocks of OC mobilized through slumping, including soil organic carbon (SOC) and dissolved organic carbon (DOC); and (3) estimate the OC fluxes mobilized through slumping between 1972 and 2011. We identified RTSs using high-resolution satellite imagery from 2011 and geocoded aerial photographs from 1952 and 1972. To estimate the volume of eroded material, we applied spline interpolation on an airborne lidar dataset acquired in July 2013. We inferred the stocks of mobilized SOC and DOC from existing related literature. Our results show a 73% increase in the number of RTSs and 14% areal expansion between 1952 and 2011. In the study area, RTSs displaced at least 16.6´106 m3 of material, 53% of which was ice, and mobilized 145.9´106 kg of OC. Between 1972 and 2011, 49 RTSs displaced 8.6´103 m3 yr-1 of material, adding 0.6% to the OC flux released by coastal retreat along the Yukon Coast. Our results show that the contribution of RTSs to the nearshore OC budget is non-negligible and should be included when estimating the quantity of OC released from the Arctic coast to the ocean.
DOI: 10.5194/bg-15-1483-2018
2019078886 Vasil'chuk, Yurij K. (Lomonosov Moscow State University, Geography and Geology Departments, Moscow, Russian Federation); Vasil'chuk, Alla C. and Stanilovskaya, Julia V. Early Holocene climate signals from stable isotope composition of ice wedges in the Chara Basin, northern Transbaikalia, Russia: Geoscience Frontiers, 9(2), p. 471-483, illus. incl. 3 tables, sketch map, 46 ref., March 2018.
DOI: 10.1016/j.gsf.2017.04.008
2019080317 Brüchert, Volker (Stockholm University, Department of Geological Sciences, Stockholm, Sweden); Bröder, Lisa; Sawicka, Joanna E.; Tesi, Tommaso; Joye, Samantha B.; Sun, Xiaole; Semiletov, Igor P. and Samarkin, Vladimir A. Carbon mineralization in Laptev and East Siberian Sea shelf and slope sediment: Biogeosciences, 15(2), p. 471-490, illus. incl. 5 tables, sketch maps, 64 ref., February 2018.
The Siberian Arctic Sea shelf and slope is a key region for the degradation of terrestrial organic material transported from the organic-carbon-rich permafrost regions of Siberia. We report on sediment carbon mineralization rates based on O2 microelectrode profiling; intact sediment core incubations; 35S-sulfate tracer experiments; pore-water dissolved inorganic carbon (DIC); d13CDIC; and iron, manganese, and ammonium concentrations from 20 shelf and slope stations. This data set provides a spatial overview of sediment carbon mineralization rates and pathways over large parts of the outer Laptev and East Siberian Arctic shelf and slope and allows us to assess degradation rates and efficiency of carbon burial in these sediments. Rates of oxygen uptake and iron and manganese reduction were comparable to temperate shelf and slope environments, but bacterial sulfate reduction rates were comparatively low. In the topmost 50 cm of sediment, aerobic carbon mineralization dominated degradation and comprised on average 84% of the depth-integrated carbon mineralization. Oxygen uptake rates and anaerobic carbon mineralization rates were higher in the eastern East Siberian Sea shelf compared to the Laptev Sea shelf. DIC/NH4+ ratios in pore waters and the stable carbon isotope composition of remineralized DIC indicated that the degraded organic matter on the Siberian shelf and slope was a mixture of marine and terrestrial organic matter. Based on dual end-member calculations, the terrestrial organic carbon contribution varied between 32 and 36%, with a higher contribution in the Laptev Sea than in the East Siberian Sea. Extrapolation of the measured degradation rates using isotope end-member apportionment over the outer shelf of the Laptev and East Siberian seas suggests that about 16 Tg C yr-1 is respired in the outer shelf seafloor sediment. Of the organic matter buried below the oxygen penetration depth, between 0.6 and 1.3 Tg C yr-1 is degraded by anaerobic processes, with a terrestrial organic carbon contribution ranging between 0.3 and 0.5 Tg yr-1.
DOI: 10.5194/bg-15-471-2018
2019080361 Woronko, B. (University of Warsaw, Faculty of Geology, Warsaw, Poland); Rychel, Joanna; Karasiewicz, T. M.; Kupryjanowicz, Miroslawa; Adamczyk, A.; Filoc, Magdalena; Marks, Leszek; Krzywicki, Tomasz and Pochocka-Szwarc, Katarzyna. Post-Saalian transformation of dry valleys in Eastern Europe; an example from NE Poland: in Vegetation and climate of the Eemian interglacial and early Weichselian (Vistulian) in Poland; from the local to regional scale (Kupryjanowicz, Miroslawa, editor; et al.), Quaternary International, 467(Part A), p. 161-177, illus. incl. geol. sketch map, 1 table, sects., 133 ref., February 20, 2018.
The studies were conducted in a dry valley in NE Poland. They were aimed at determining the origin of this structure and tracing the processes that have shaped the dry valley in a time span of about 130 ka. The research included detailed geological mapping, including piercing of a number of boreholes and electrical resistivity tomography (ERT) surveys. The obtained material was pollen analysed, OSL dated, and the grain size distribution and the morphoscopy of sand quartz grains were investigated; additionally the organic matter (OM) content was determined. Based on the obtained results it was concluded that the structure currently occupied by sediments of the dry valley was formed during the Warta Stadial of the Odranian Glaciation (Saalian; MIS 6) as a glacial tunnel valley. Small, probably isolated depressions functioned in the dry valley bottom after the ice sheet retreat. The sediments record a full succession of climate oscillations from the Eemian Interglacial (MIS 5e) (pollen zones E1 to E7) through the Early Vistulian (MIS 5a-5d) to MIS 4. In the Early Vistulian, the depressions functioned as lakes, or got shallower and were replaced by peat-bogs, depending on the climate conditions. During MIS 4, the bottom of the dry valley was subjected to erosion as a result of concentrated water flow. This caused draining of the existing depressions and their incorporation within the flow. Probably during MIS 3, solifluction was activated on the slopes of the dry valley. During LGM, permafrost aggradation occurred in the study area, recorded by two generations of epigenetic sand wedges and development of aeolian processes. In contrast to analogous processes within the European Sand Belt, the latter processes acted for a short time and only locally. The final record are Holocene soils. It seems that the analysed valley is a good example of palaeoenvironmental conditions in Eastern Europe.
DOI: 10.1016/j.quaint.2016.09.054
2019080337 Yanina, T. (Lomonosov Moscow State University, Moscow, Russian Federation); Sorokin, V.; Bezrodnykh, Yu. P. and Romanyuk, B. F. Late Pleistocene climatic events reflected in the Caspian Sea geological history (based on drilling data): in IGCP 610 second special volume of Quaternary International (Yanko-Hombach, Valentina V., editor; et al.), Quaternary International, 465(Part A), p. 130-141, illus. incl. sketch map, strat. col., 1 table, sects., 80 ref., January 20, 2018. IGCP Project No. 610.
The analysis of seismic-acoustic profiles and drilling data from the Northern Caspian showed the climatic events are quite distinguishable in the Upper Pleistocene sedimentary sequence. The climatic events of the first half of Late Pleistocene (MIS 5) resulted in the onset of two warm-water transgressive basins - Late Khazarian and Hyrcanian ones. Though cooler than at the late Khazarian transgression, the climate during the Hyrcanian time was attributable to interglacial one. As the glacial stage MIS 4 approached its maximum under conditions of a dry and cold climate the Hyrcanian sea basin regressed. The Atelian regression of the Caspian Sea corresponded to MIS 4 stage and to the initial phases of the MIS 3 interstadial warming. The development of the global interstadial warming led to a considerable increase in the surface runoff from the catchment and resulted in the rising of the Atelian lake level and the onset of the first phase of the Khvalynian transgression. The sea level rising was interrupted at the time of maximum cooling and aridization at MIS 2 and resumed when the ice sheet was decaying. The conspicuous climatic events known as warm phases of Bolling and Allerod promoted the ice sheet melting along with thawing of permafrost, the latter having been widespread in the Volga drainage basin. All the above contributed to the Khvalynian transgression. The 'chocolate' clays were accumulated in the Volga estuary, as well as in depressions of the Pre-Khvalynian topography. Phases of a noticeable cooling known as the Oldest, Older and Younger Dryas marked by a decrease in the runoff volume from the Caspian drainage basin are correlated with regressive stages in the Khvalynian basin history. The Khvalynian came to its end at the time of the first sharp warming that resulted in the rise of the Caspian level and is generally taken as marking the Pleistocene/Holocene boundary. The Mangyshlakian regression is dated to the Holocene and was essentially a response of the Caspian Sea to the increase in the climate continentality during the Boreal period.
DOI: 10.1016/j.quaint.2017.08.003
2019077750 Antonova, Sofia (Alfred Wegener Institute Helmholtz Center for Polar and Marine Research, Periglacial Research Section, Potsdam, Germany); Sudhaus, Henriette; Strozzi, Tazio; Zwieback, Simon; Kaab, Andreas; Heim, Birgit; Langer, Moritz; Bornemann, Niko and Boike, Julia. Thaw subsidence of a yedoma landscape in northern Siberia, measured in situ and estimated from TerraSAR-X interferometry: Remote Sensing, 10(4), Article 494, illus. incl. 2 tables, sketch maps, 44 ref., 2018.
In permafrost areas, seasonal freeze-thaw cycles result in upward and downward movements of the ground. For some permafrost areas, long-term downward movements were reported during the last decade. We measured seasonal and multi-year ground movements in a yedoma region of the Lena River Delta, Siberia, in 2013-2017, using reference rods installed deep in the permafrost. The seasonal subsidence was 1.7 ± 1.5 cm in the cold summer of 2013 and 4.8 ± 2 cm in the warm summer of 2014. Furthermore, we measured a pronounced multi-year net subsidence of 9.3 ± 5.7 cm from spring 2013 to the end of summer 2017. Importantly, we observed a high spatial variability of subsidence of up to 6 cm across a sub-meter horizontal scale. In summer 2013, we accompanied our field measurements with Differential Synthetic Aperture Radar Interferometry (DInSAR) on repeat-pass TerraSAR-X (TSX) data from the summer of 2013 to detect summer thaw subsidence over the same study area. Interferometry was strongly affected by a fast phase coherence loss, atmospheric artifacts, and possibly the choice of reference point. A cumulative ground movement map, built from a continuous interferogram stack, did not reveal a subsidence on the upland but showed a distinct subsidence of up to 2 cm in most of the thermokarst basins. There, the spatial pattern of DInSAR-measured subsidence corresponded well with relative surface wetness identified with the near infra-red band of a high-resolution optical image. Our study suggests that (i) although X-band SAR has serious limitations for ground movement monitoring in permafrost landscapes, it can provide valuable information for specific environments like thermokarst basins, and (ii) due to the high sub-pixel spatial variability of ground movements, a validation scheme needs to be developed and implemented for future DInSAR studies in permafrost environments.
DOI: 10.3390/rs10040494
2019077749 Bodin, Xavier (Université Savoie Mont-Blanc, Laboratoire Environnements, Chambery, France); Thibert, Emmanuel; Sanchez, Olivier; Rabatel, Antoine and Jaillet, Stéphane. Multi-annual kinematics of an active rock glacier quantified from very high-resolution DEMs; an application-case in the French Alps: Remote Sensing, 10(4), Article 547, illus. incl. 3 tables, 32 ref., 2018.
Rock glaciers result from the long-term creeping of ice-rich permafrost along mountain slopes. Under warming conditions, deformation is expected to increase, and potential destabilization of those landforms may lead to hazardous phenomena. Monitoring the kinematics of rock glaciers at fine spatial resolution is required to better understand at which rate, where and how they deform. We present here the results of several years of in situ surveys carried out between 2005 and 2015 on the Laurichard rock glacier, an active rock glacier located in the French Alps. Repeated terrestrial laser-scanning (TLS) together with aerial laser-scanning (ALS) and structure-from-motion-multi-view-stereophotogrammetry (SFM-MVS) were used to accurately quantify surface displacement of the Laurichard rock glacier at interannual and pluri-annual scales. Six very high-resolution digital elevation models (DEMs, pixel size <50 cm) of the rock glacier surface were generated, and their respective quality was assessed. The relative horizontal position accuracy (XY) of the individual DEMs is in general less than 2 cm with a co-registration error on stable areas ranging from 20-50 cm. The vertical accuracy is around 20 cm. The direction and amplitude of surface displacements computed between DEMs are very consistent with independent geodetic field measurements (e.g., DGPS). Using these datasets, local patterns of the Laurichard rock glacier kinematics were quantified, pointing out specific internal (rheological) and external (bed topography) controls. The evolution of the surface velocity shows few changes on the rock glacier's snout for the first years of the observed period, followed by a major acceleration between 2012 and 2015 affecting the upper part of the tongue and the snout.
DOI: 10.3390/rs10040547
2019082307 Chen Jie (Chinese University of Hong Kong, Institute of Space and Earth Information Science, Hong Kong, China); Günther, Frank; Grosse, Guido; Liu Lin and Lin Hui. Sentinel-1 InSAR measurements of elevation changes over yedoma uplands on Sobo-Sise Island, Lena Delta: Remote Sensing, 10(7), Article 1152, illus. incl. 1 table, sketch maps, 43 ref., 2018.
Yedoma-extremely ice-rich permafrost with massive ice wedges formed during the Late Pleistocene-is vulnerable to thawing and degradation under climate warming. Thawing of ice-rich Yedoma results in lowering of surface elevations. Quantitative knowledge about surface elevation changes helps us to understand the freeze-thaw processes of the active layer and the potential degradation of Yedoma deposits. In this study, we use C-band Sentinel-1 InSAR measurements to map the elevation changes over ice-rich Yedoma uplands on Sobo-Sise Island, Lena Delta with frequent revisit observations (as short as six or 12 days). We observe significant seasonal thaw subsidence during summer months and heterogeneous inter-annual elevation changes from 2016-17. We also observe interesting patterns of stronger seasonal thaw subsidence on elevated flat Yedoma uplands by comparing to the surrounding Yedoma slopes. Inter-annual analyses from 2016-17 suggest that our observed positive surface elevation changes are likely caused by the delayed progression of the thaw season in 2017, associated with mean annual air temperature fluctuations.
DOI: 10.3390/rs10071152
2019082286 Fraser, Robert (Natural Resources Canada, Canada Centre for Mapping and Earth Observation, Ottawa, ON, Canada); Kokelj, Steven; Lantz, Trevor; McFarlane-Winchester, Morgan; Olthof, Ian and Lacelle, Denis. Climate sensitivity of high Arctic permafrost terrain demonstrated by widespread ice-wedge thermokarst on Banks Island: Remote Sensing, 10(6), Article 954, illus. incl. sketch maps, 66 ref., 2018.
Ice-wedge networks underlie polygonal terrain and comprise the most widespread form of massive ground ice in continuous permafrost. Here, we show that climate-driven thaw of hilltop ice-wedge networks is rapidly transforming uplands across Banks Island in the Canadian Arctic Archipelago. Change detection using high-resolution WorldView images and historical air photos, coupled with 32-year Landsat reflectance trends, indicate broad-scale increases in ponding from ice-wedge thaw on hilltops, which has significantly affected at least 1500 km2 of Banks Island and over 3.5% of the total upland area. Trajectories of change associated with this upland ice-wedge thermokarst include increased micro-relief, development of high-centred polygons, and, in areas of poor drainage, ponding and potential initiation of thaw lakes. Millennia of cooling climate have favoured ice-wedge growth, and an absence of ecosystem disturbance combined with surface denudation by solifluction has produced high Arctic uplands and slopes underlain by ice-wedge networks truncated at the permafrost table. The thin veneer of thermally-conductive mineral soils strongly links Arctic upland active-layer responses to summer warming. For these reasons, widespread and intense ice-wedge thermokarst on Arctic hilltops and slopes contrast more muted responses to warming reported in low and subarctic environments. Increasing field evidence of thermokarst highlights the inherent climate sensitivity of the Arctic permafrost terrain and the need for integrated approaches to monitor change and investigate the cascade of environmental consequences.
DOI: 10.3390/rs10060954
2019078920 Neradovskiy, L. G. (Rossiyskaya Akademiya Nauk, Sibirskoye Otdeleniye, Institut Merzlotovedeniya, Yakutsk, Russian Federation). Kolichestvennaya otsenka ob'yemnoy l'distosti merzlykh gruntov metodom dipol'nogo elektromagnitnogo profilirovaniya [Quantitative estimates of ice volume in frozen ground based on dipole electromagnetic profiles]: Led i Sneg = Ice and Snow, 58(1), p. 94-104 (English sum.), illus. incl. 2 tables, 18 ref., 2018.
Volumetric estimation of the ice content in frozen soils is known as one of the main problems in the engineering geocryology and the permafrost geophysics. A new way to use the known method of dipole electromagnetic profiling for the quantitative estimation of the volumetric ice content in frozen soils is discussed. Investigations of foundation of the railroad in Yakutia (i.e. in the permafrost zone) were used as an example for this new approach. Unlike the conventional way, in which the permafrost is investigated by its resistivity and constructing of geo-electrical cross-sections, the new approach is aimed at the study of the dynamics of the process of attenuation in the layer of annual heat cycle in the field of high-frequency vertical magnetic dipole. This task is simplified if not all the characteristics of the polarization ellipse are measured but the only one which is the vertical component of the dipole field and can be the most easily measured. Collected data of the measurements were used to analyze the computational errors of the average values of the volumetric ice content from the amplitude attenuation of the vertical component of the dipole field. Note that the volumetric ice content is very important for construction. It is shown that usually the relative error of computation of this characteristic of a frozen soil does not exceed 20% if the works are performed by the above procedure using the key-site methodology. This level of accuracy meets requirements of the design-and-survey works for quick, inexpensive, and environmentally friendly zoning of built-up remote and sparsely populated territories of the Russian permafrost zone according to a category of a degree of the ice content in frozen foundations of engineering constructions.
DOI: 10.15356/2076-6734-2018-1-94-104
2019077732 Niu Fujun (Northwest Institute of Eco-Environment and Resources, Laboratory of Frozen Soils Engineering, Lanzhou, China); Yin Guoan; Luo Jing; Lin Zhanju and Liu Minghao. Permafrost distribution along the Qinghai-Tibet engineering corridor, China using high-resolution statistical mapping and modeling integrated with remote sensing and GIS: Remote Sensing, 10(2), Article 215, illus. incl. 7 tables, sketch maps, 70 ref., 2018.
Permafrost distribution in the Qinghai-Tibet Engineering Corridor (QTEC) is of growing interest due to the increase in infrastructure development in this remote area. Empirical models of mountain permafrost distribution have been established based on field sampled data, as a tool for regional-scale assessments of its distribution. This kind of model approach has never been applied for a large portion of this engineering corridor. In the present study, this methodology is applied to map permafrost distribution throughout the QTEC. After spatial modelling of the mean annual air temperature distribution from MODIS-LST and DEM, using high-resolution satellite image to interpret land surface type, a permafrost probability index was obtained. The evaluation results indicate that the model has an acceptable performance. Conditions highly favorable to permafrost presence (>&eq;70%) are predicted for 60.3% of the study area, declaring a discontinuous permafrost distribution in the QTEC. This map is useful for the infrastructure development along the QTEC. In the future, local ground-truth observations will be required to confirm permafrost presence in favorable areas and to monitor permafrost evolution under the influence of climate change.
DOI: 10.3390/rs10020215
2019079329 Saito, Hitoshi (Kanto Gakuin University, College of Economics, Kanagawa, Japan); Iijima, Yoshihiro; Basharin, Nikolay; Fedorov, Alexander and Kunitsky, Viktor. Thermokarst development detected from high-definition topographic data in central Yakutia: Remote Sensing, 10(10), Article 1579, illus. incl. 2 tables, sketch maps, 40 ref., 2018.
Eastern Siberia is characterized by widespread permafrost thawing and subsequent thermokarst development. Estimation of the impacts of the predicted rise in precipitation and air temperatures under climate change requires quantitative knowledge about the spatial distribution of thermokarst development. In the last few years, unmanned aerial systems (UAS) and structure-from-motion multi-view stereo (SfM-MVS) photogrammetry attracted a tremendous amount of interest for acquiring high-definition topographic data. This study detected characteristics of thermokarst landforms using UAS and SfM-MVS photogrammetry at a disused airfield (3.0 ha) and for arable land that was previously used for farming (6.3 ha) in the Churapcha area, located on the right bank of the Lena River in central Yakutia. Orthorectified photographs and digital terrain models with spatial resolutions of 4.0 cm and 8.0 cm, respectively, were obtained for this study. At the disused airfield site and the abandoned arable land, 174 and 867 high-centered polygons that developed after the 1990s were detected, respectively. The data showed that the average diameter and average area of the polygons at the disused airfield site were 11.6 m and 111.2 m2, respectively, while those of the polygons in the abandoned arable land were 7.4 m and 46.8 m2, respectively. The abandoned arable land was characterized by smaller polygons and a higher polygon density. The differences in polygon size for the abandoned arable land and the disused airfield site indicate a difference in the ice wedge distributions and thermokarst developments. The subsidence rate was estimated as 2.1 cm/year for the disused airfield site and 3.9 cm/year for the abandoned arable land.
DOI: 10.3390/rs10101579
2019077734 Shi Yaya (Chinese Academy of Science, Northwest Institute of Eco-Environment and Resources, Laboratory of Frozen Soil Engineering, Lanzhou, China); Niu Fujun; Yang Chengsong; Che Tao; Lin Zhanju and Luo Jing. Permafrost presence/absence mapping of the Qinghai-Tibet Plateau based on multi-source remote sensing data: Remote Sensing, 10(2), Article 309, illus. incl. 6 tables, sketch maps, 71 ref., 2018.
The Qinghai-Tibet Plateau (QTP) is known as the Third Polar of the earth and the Water Tower of Asia, with more than 70% of the area on the QTP is covered by permafrost possibly. An accurate permafrost distribution map based on valid and available methods is indispensable for the local environment evaluation and engineering constructions planning. Most of the previous permafrost maps have employed traditional mapping method based on field surveys and borehole investigation data. However their accuracy is limited because it is extremely difficulties in obtaining mass data in the high-altitude and cold regions as the QTP; moreover, the mapping method, which would effectively integrate many factors, is still facing great challenges. With the rapid development of remote sensing technology in permafrost mapping, spatial data derived from the satellite sensors can recognize the permafrost environment features and quantitatively estimate permafrost distribution. Until now there is no map indicated permafrost presence/absence on the QTP that has been generated only by remote sensing data as yet. Therefore, this paper used permafrost-influencing factors and examined distribution features of each factor in permafrost regions and seasonally frozen ground regions. Then, using the Decision Tree method with the environmental factors, the 1 km resolution permafrost map over the QTP was obtained. The result shows higher accuracy compared to the previous published map of permafrost on the QTP and the map of the glaciers, frozen ground and deserts in China, which also demonstrates that making comprehensive use of remote sensing technology in permafrost mapping research is fast, macro and feasible. Furthermore, this result provides a simple and valid method for further permafrost research.
DOI: 10.3390/rs10020309
2019078919 Streletskaya, Irina D. (Moskovskiy Gosudarstvennyy Universitet, Moscow, Russian Federation); Vasil'yev, A. A.; Oblogov, G. Ye.; Semenov, P. B.; Vanshteyn, B. G. and Rivkina, Ye. M. Metan v podzemnykh l'dakh i merzlykh otlozheniyakh na poberezh'ye i shel'fe Karskogo morya [Methane in ground ice and frozen sediments on the Kara Sea coast and continental shelf]: Led i Sneg = Ice and Snow, 58(1), p. 65-77 (English sum.), illus. incl. 2 tables, sketch map, 43 ref., 2018.
Degradation of permafrost on the continental shelf and shores of the Arctic seas may be a main cause of the methane emission to the atmosphere from marine sediments. To quantify this effect it is necessary to have reliable data on the methane content in the underground ice and frozen Quaternary deposits. Samples of frozen (permafrost) sediments and ground ice, taken in three reference coastal sections made in the Mid- and Late Pleistocene coastal exposures and on the Kara sea shelf, were collected and studied. The samples were analyzed to determine composition, salinity, organic carbon content, and other characteristics of the underground ices. About 270 samples allowed determination of the gas composition and the methane concentration. The gas is present in the pores of the rocks and air bubbles in the ice. Gas was present in pores of sediments and in bubbles within the ice. It has been established that the composition of non-hydrocarbon gases in the underground ice does not correspond to the composition of the atmosphere in the time of formation of them. The methane content in the underground ice and frozen sediments is characterized by very high variability. The highest concentrations of methane are inherent in layers of the massive ground ice and reach up to 23000 ppm; the maximum concentration of methane in the massive vein ices does not exceed 900 ppm. High concentrations of methane in layers of the massive ice confirm their non-glacier formation. The highest, up to 6400 ppm, methane concentrations in permafrost sediments are characteristic for the Late Pleistocene marine clays, while in the Mid Pleistocene marine clays it does not exceed 1700 ppm. The isotopic composition of methane in frozen sediments and ground ice in both, the Cara Sea coast and shelf, is indicative of similar bacterial genesis of the gas. The total organic carbon content plays the limiting role in the methane production and its accumulation in the frozen sediments and ground ice.
DOI: 10.15356/2076-6734-2018-1-65-77
2019082289 Swanson, David K. (National Park Service, Arctic Inventory and Monitoring Network, Fairbanks, AK) and Nolan, Matt. Growth of retrogressive thaw slumps in the Noatak Valley, Alaska, 2010-2016, measured by airborne photogrammetry: Remote Sensing, 10(7), Article 983, illus. incl. 3 tables, sketch maps, 58 ref., 2018.
We monitored the growth of 22 retrogressive thaw slumps (RTS), dramatic erosion features associated with thaw of permafrost, in the Noatak Valley of northern Alaska using high-resolution structure-from-motion digital photogrammetry. We created time-series of 3-6 Digital Elevation Models (DEMs) and orthophoto mosaics during the time period from 2010-2016 at each slump, using high-resolution digital single-lens reflex (SLR) photographs taken from airplanes or helicopters. DEMs created using airborne GPS camera locations were adequate to detect elevations changes as small as 10 to 15 cm. Measurements made on these DEMs and orthophotographs showed slump growth rates of up to 38 m yr-1, with the fastest rates on slumps with scarps of moderate height (1 to 4 m) exposing Pleistocene glacial ice. Most of the slumps grew at constant or declining rates during the study, apparently as a result of the slumps encountering more gentle topography as they expanded upslope. Sedimentation was predominantly on the slump floor within 40 m of the active scarp, and the zone of accumulation migrated upslope with the scarp, away from adjacent water bodies. This study demonstrates that low-cost cameras coupled with airborne GPS and no ground control are suitable for monitoring geomorphic change on the order of decimeters and are a powerful tool for monitoring in remote settings.
DOI: 10.3390/rs10070983
2019077751 Van der Sluijs, Jurjen (Northwest Territories Centre for Geomatics, Government of Northwest Territories, Yellowknife, NT, Canada); Kokelj, Steven; Fraser, Robert; Tunnicliffe, Jon and Lacelle, Denis. Permafrost terrain dynamics and infrastructure impacts revealed by UAV photogrammetry and thermal imaging: Remote Sensing, 10(11), Article 1734, illus. incl. 3 tables, sketch maps, 98 ref., 2018.
Unmanned Aerial Vehicle (UAV) systems, sensors, and photogrammetric processing techniques have enabled timely and highly detailed three-dimensional surface reconstructions at a scale that bridges the gap between conventional remote-sensing and field-scale observations. In this work 29 rotary and fixed-wing UAV surveys were conducted during multiple field campaigns, totaling 47 flights and over 14.3 km2, to document permafrost thaw subsidence impacts on or close to road infrastructure in the Northwest Territories, Canada. This paper provides four case studies: (1) terrain models and orthomosaic time series revealed the morphology and daily to annual dynamics of thaw-driven mass wasting phenomenon (retrogressive thaw slumps; RTS). Scar zone cut volume estimates ranged between 3.2 ´ 103 and 5.9 ´ 106 m3. The annual net erosion of RTS surveyed ranged between 0.35 ´ 103 and 0.39 ´ 106 m3. The largest RTS produced a long debris tongue with an estimated volume of 1.9 ´ 106 m3. Downslope transport of scar zone and embankment fill materials was visualized using flow vectors, while thermal imaging revealed areas of exposed ground ice and mobile lobes of saturated, thawed materials. (2) Stratigraphic models were developed for RTS headwalls, delineating ground-ice bodies and stratigraphic unconformities. (3) In poorly drained areas along road embankments, UAV surveys detected seasonal terrain uplift and settlement of up to 0.5 m (>1700 m2 in extent) as a result of injection ice development. (4) Time series of terrain models highlighted the thaw-driven evolution of a borrow pit (6.4 ´ 105 m3 cut volume) constructed in permafrost terrain, whereby fluvial and thaw-driven sediment transfer (1.1 and 3.9 ´ 103 m3 a-1 respectively) was observed and annual slope profile reconfiguration was monitored to gain management insights concerning site stabilization. Elevation model vertical accuracies were also assessed as part of the case studies and ranged between 0.02 and 0.13 m Root Mean Square Error. Photogrammetric models processed with Post-processed Kinematic image solutions achieved similar accuracies without ground control points over much larger and complex areas than previously reported. The high resolution of UAV surveys, and the capacity to derive quantitative time series provides novel insights into permafrost processes that are otherwise challenging to study. The timely emergence of these tools bridges field-based research and applied studies with broad-scale remote-sensing approaches during a period when climate change is transforming permafrost environments.
DOI: 10.3390/rs10111734
2019079337 Villarroel, Cristian (National University of San Juan, National Council of Scientific and Technical Research, San Juan, Argentina); Tamburini Beliveau, Guillermo; Forte, Ana; Monserrat, Oriol and Morvillo, Monica. DInSAR for a regional inventory of active rock glaciers in the dry Andes Mountains of Argentina and Chile with Sentinel-1 data: Remote Sensing, 10(10), Article 1588, illus. incl. 3 tables, sketch maps, 80 ref., 2018.
The Dry Andes region of Argentina and Chile is characterized by a highly developed periglacial environment. In these arid or semi-arid regions, rock glaciers represent one of the main pieces of evidence of mountain creeping permafrost and water reserves in a solid state. However, their distribution, degree of activity, and response to global warming are not yet well understood. In this context, this work aims to show the potential of the Sentinel-1-based interferometric technique (DInSAR) to map active rock glaciers at a regional level. In particular, the paper presents an active rock glacier inventory for the study area, which covers approximately 40,000 km2, ranging from latitude 30°21'S to 33°21'S. A total of 2116 active rock glaciers have been detected, and their elevations show a high correlation with the west-east direction. This result was obtained by using only 16 interferometric pairs. Compared to other remote sensing classification techniques, the interferometric technique offers a means to measure surface displacement (active rock glacier). This results in a reliable classification of the degree of activity compared to other methods, based on geomorphological, geomorphometric, and/or ecological criteria. This work presents evidence of this aspect by comparing the obtained results with existing optical data-based inventories. We conclude that the combination of both types of sensors (radar and optical) is an appropriate procedure for active rock glacier inventories, as both mapping methodologies are complementary.
DOI: 10.3390/rs10101588
2019079336 Wang Chao (Chinese Academy of Sciences, Institute of Remote Sensing and Digital Earth, Key Laboratory of Digital Earth Science, Beijing, China); Zhang Zhengjia; Paloscia, Simonetta; Zhang Hong; Wu Fan and Wu Qingbai. Permafrost soil moisture monitoring using multi-temporal TerraSAR-X data in Beiluhe of northern Tibet, China: Remote Sensing, 10(10), Article 1577, illus. incl. 1 table, sketch map, 40 ref., 2018.
Global change has significant impact on permafrost region in the Tibet Plateau. Soil moisture (SM) of permafrost is one of the most important factors influencing the energy flux, ecosystem, and hydrologic process. The objectives of this paper are to retrieve the permafrost SM using time-series SAR images, without the need of auxiliary survey data, and reveal its variation patterns. After analyzing the characteristics of time-series radar backscattering coefficients of different landcover types, a two-component SM retrieval model is proposed. For the alpine meadow area, a linear retrieving model is proposed using the TerraSAR-X time-series images based on the assumption that the lowest backscattering coefficient is measured when the soil moisture is at its wilting point and the highest backscattering coefficient represents the water-saturated soil state. For the alpine desert area, the surface roughness contribution is eliminated using the dual SAR images acquired in the winter season with different incidence angles when retrieving soil moisture from the radar signal. Before the model implementation, landcover types are classified based on their backscattering features. 22 TerraSAR-X images are used to derive the soil moisture in Beiluhe, Northern Tibet with different incidence angles. The results obtained from the proposed method have been validated using in-situ soil moisture measurements, thus obtaining RMSE and Bias of 0.062 cm3/cm3 and 4.7%, respectively. The retrieved time-series SM maps of the study area point out the spatial and temporal SM variation patterns of various landcover types.
DOI: 10.3390/rs10101577
2019077724 Whitley, Matthew A. (University of Alaska Fairbanks, Department of Geosciences, Fairbanks, AK); Frost, Gerald V.; Jorgenson, M. Torre; Macander, Matthew J.; Maio, Chris V. and Winder, Samantha G. Assessment of lidar and spectral techniques for high-resolution mapping of sporadic permafrost on the Yukon-Kuskokwim delta, Alaska: Remote Sensing, 10(2), Article 258, illus. incl. 5 tables, sketch maps, 47 ref., 2018.
Western Alaska's Yukon-Kuskokwim Delta (YKD) spans nearly 67,200 km2 and is among the largest and most productive coastal wetland ecosystems in the pan-Arctic. Permafrost currently forms extensive elevated plateaus on abandoned floodplain deposits of the outer delta, but is vulnerable to disturbance from rising air temperatures, inland storm surges, and salt-kill of vegetation. As pan-Arctic air and ground temperatures rise, accurate baseline maps of permafrost extent are critical for a variety of applications including long-term monitoring, understanding the scale and pace of permafrost degradation processes, and estimating resultant greenhouse gas dynamics. This study assesses novel, high-resolution techniques to map permafrost distribution using LiDAR and IKONOS imagery, in tandem with field-based parameterization and validation. With LiDAR, use of a simple elevation threshold provided a permafrost map with 94.9% overall accuracy; this approach was possible due to the extremely flat coastal plain of the YKD. The addition of high spatial-resolution IKONOS satellite data yielded similar results, but did not increase model performance. The methods and the results of this study enhance high-resolution permafrost mapping efforts in tundra regions in general and deltaic landscapes in particular, and provide a baseline for remote monitoring of permafrost distribution on the YKD.
DOI: 10.3390/rs10020258
2019077719 Zhang Zhengjia (China University of Geosciences, Faculty of Information Engineering, Wuhan, China); Wang Chao; Zhang Hong; Tang Yixian and Liu Xiuguo. Analysis of permafrost region coherence variation in the Qinghai-Tibet Plateau with a high-resolution TerraSAR-X image: Remote Sensing, 10(2), Article 298, illus. incl. 11 tables, sketch maps, 38 ref., 2018.
The Qinghai-Tibet Plateau (QTP) is heavily affected by climate change and has been undergoing serious permafrost degradation due to global warming. Synthetic aperture radar interferometry (InSAR) has been a significant tool for mapping surface features or measuring physical parameters, such as soil moisture, active layer thickness, that can be used for permafrost modelling. This study analyzed variations of coherence in the QTP area for the first time with high-resolution SAR images acquired from June 2014 to August 2016. The coherence variation of typical ground targets was obtained and analyzed. Because of the effects of active-layer (AL) freezing and thawing, coherence maps generated in the Beiluhe permafrost area exhibits seasonal variation. Furthermore, a temporal decorrelation model determined by a linear temporal-decorrelation component plus a seasonal periodic-decorrelation component and a constant component have been proposed. Most of the typical ground targets fit this temporal model. The results clearly indicate that railways and highways can hold high coherence properties over the long term in X-band images. By contrast, mountain slopes and barren areas cannot hold high coherence after one cycle of freezing and thawing. The possible factors (vegetation, soil moisture, soil freezing and thawing, and human activity) affecting InSAR coherence are discussed. This study shows that high-resolution time series of TerraSAR-X coherence can be useful for understanding QTP environments and for other applications.
DOI: 10.3390/rs10020298
|
The USPA is pleased to announce the availability of an updated searchable database on permafrost-related publications. The American Geosciences Institute (AGI), with support from the National Science Foundation (NSF), has migrated the previous Cold Regions Bibliography to a new platform. Included are the USPA supported PMAs dating back to 2011. The Bibliography is searchable at 
