scholarly journals Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta

2011 ◽  
Vol 5 (3) ◽  
pp. 1495-1545 ◽  
Author(s):  
A. Morgenstern ◽  
G. Grosse ◽  
F. Günther ◽  
I. Fedorova ◽  
L. Schirrmeister
Keyword(s):  
Developmental Stages ◽  
Permafrost Degradation ◽  
Lena River ◽  
Thermokarst Lakes ◽  
Carbon Release ◽  
Future Potential ◽  
Lake Drainage ◽  
Landscape Units ◽  
Lena River Delta ◽  
Ice Complex

Abstract. Distinctive periglacial landscapes have formed in late-Pleistocene ice-rich permafrost deposits (Ice Complex) of Northern Yakutia, Siberia. Thermokarst lakes and thermokarst basins alternate with ice-rich Yedoma uplands. We investigate different thermokarst stages in Ice Complex deposits of the Lena River Delta using remote sensing and geoinformation techniques. The morphometry and spatial distribution of thermokarst lakes on Yedoma uplands, thermokarst lakes in basins, and thermokarst basins are analyzed, and possible dependence upon relief position and cryolithological context is considered. Of these thermokarst stages, developing thermokarst lakes on Yedoma uplands alter ice-rich permafrost the most, but occupy only 2.2 % of the study area compared to 20.0 % occupied by thermokarst basins. The future potential for developing large areas of thermokarst on Yedoma uplands is limited due to shrinking distances to degradational features and delta channels that foster lake drainage. Further thermokarst development in existing basins is restricted to underlying deposits that have already undergone thaw, compaction, and old carbon mobilization, and to deposits formed after initial lake drainage. Therefore, a distinction between developmental stages of thermokarst and landscape units is necessary to assess the potential for future permafrost degradation and carbon release due to thermokarst in Siberian Yedoma landscapes.

scholarly journals Spatial analyses of thermokarst lakes and basins in Yedoma landscapes of the Lena Delta

2011 ◽  
Vol 5 (4) ◽  
pp. 849-867 ◽  
Author(s):  
A. Morgenstern ◽  
G. Grosse ◽  
F. Günther ◽  
I. Fedorova ◽  
L. Schirrmeister
Keyword(s):  
Spatial Analyses ◽  
Lena River ◽  
Thermokarst Lakes ◽  
Thermokarst Lake ◽  
Warming Climate ◽  
Future Potential ◽  
Lake Drainage ◽  
Carbon Balances ◽  
Lena River Delta ◽  
Ice Complex

Abstract. Distinctive periglacial landscapes have formed in late-Pleistocene ice-rich permafrost deposits (Ice Complex) of northern Yakutia, Siberia. Thermokarst lakes and thermokarst basins alternate with ice-rich Yedoma uplands. We investigate different thermokarst stages in Ice Complex deposits of the Lena River Delta using remote sensing and geoinformation techniques. The morphometry and spatial distribution of thermokarst lakes on Yedoma uplands, thermokarst lakes in basins, and thermokarst basins are analyzed, and possible dependence upon relief position and cryolithological context is considered. Of these thermokarst stages, developing thermokarst lakes on Yedoma uplands alter ice-rich permafrost the most, but occupy only 2.2% of the study area compared to 20.0% occupied by thermokarst basins. The future potential for developing large areas of thermokarst on Yedoma uplands is limited due to shrinking distances to degradational features and delta channels that foster lake drainage. Further thermokarst development in existing basins is restricted to underlying deposits that have already undergone thaw, compaction, and old carbon mobilization, and to deposits formed after initial lake drainage. Future thermokarst lake expansion is similarly limited in most of Siberia's Yedoma regions covering about 106 km2, which has to be considered for water, energy, and carbon balances under warming climate scenarios.

scholarly journals Observation-based modelling of permafrost carbon fluxes with accounting for deep carbon deposits and thermokarst activity

2015 ◽  
Vol 12 (11) ◽  
pp. 3469-3488 ◽  
Author(s):  
T. Schneider von Deimling ◽  
G. Grosse ◽  
J. Strauss ◽  
L. Schirrmeister ◽  
A. Morgenstern ◽  
...  
Keyword(s):  
Organic Matter ◽  
21St Century ◽  
Radiative Forcing ◽  
Permafrost Degradation ◽  
Emission Rates ◽  
Thermokarst Lakes ◽  
Air Temperatures ◽  
Carbon Release ◽  
Pool Model ◽  
Carbon Dioxide Co2

Abstract. High-latitude soils store vast amounts of perennially frozen and therefore inert organic matter. With rising global temperatures and consequent permafrost degradation, a part of this carbon stock will become available for microbial decay and eventual release to the atmosphere. We have developed a simplified, two-dimensional multi-pool model to estimate the strength and timing of future carbon dioxide (CO2) and methane (CH4) fluxes from newly thawed permafrost carbon (i.e. carbon thawed when temperatures rise above pre-industrial levels). We have especially simulated carbon release from deep deposits in Yedoma regions by describing abrupt thaw under newly formed thermokarst lakes. The computational efficiency of our model allowed us to run large, multi-centennial ensembles under various scenarios of future warming to express uncertainty inherent to simulations of the permafrost carbon feedback. Under moderate warming of the representative concentration pathway (RCP) 2.6 scenario, cumulated CO2 fluxes from newly thawed permafrost carbon amount to 20 to 58 petagrams of carbon (Pg-C) (68% range) by the year 2100 and reach 40 to 98 Pg-C in 2300. The much larger permafrost degradation under strong warming (RCP8.5) results in cumulated CO2 release of 42 to 141 Pg-C and 157 to 313 Pg-C (68% ranges) in the years 2100 and 2300, respectively. Our estimates only consider fluxes from newly thawed permafrost, not from soils already part of the seasonally thawed active layer under pre-industrial climate. Our simulated CH4 fluxes contribute a few percent to total permafrost carbon release yet they can cause up to 40% of total permafrost-affected radiative forcing in the 21st century (upper 68% range). We infer largest CH4 emission rates of about 50 Tg-CH4 per year around the middle of the 21st century when simulated thermokarst lake extent is at its maximum and when abrupt thaw under thermokarst lakes is taken into account. CH4 release from newly thawed carbon in wetland-affected deposits is only discernible in the 22nd and 23rd century because of the absence of abrupt thaw processes. We further show that release from organic matter stored in deep deposits of Yedoma regions crucially affects our simulated circumpolar CH4 fluxes. The additional warming through the release from newly thawed permafrost carbon proved only slightly dependent on the pathway of anthropogenic emission and amounts to about 0.03–0.14 °C (68% ranges) by end of the century. The warming increased further in the 22nd and 23rd century and was most pronounced under the RCP6.0 scenario, adding 0.16 to 0.39 °C (68% range) to simulated global mean surface air temperatures in the year 2300.

scholarly journals Physical processes of thermokarst lakes in the continuous permafrost zone of northern Siberia – observations and modeling (Lena River Delta, Siberia)

2015 ◽  
Vol 12 (8) ◽  
pp. 6637-6688 ◽  
Author(s):  
J. Boike ◽  
C. Georgi ◽  
G. Kirilin ◽  
S. Muster ◽  
K. Abramova ◽  
...  
Keyword(s):  
Heat Flux ◽  
Numerical Modeling ◽  
Water Column ◽  
River Water ◽  
Lena River ◽  
Thermokarst Lakes ◽  
Continuous Permafrost ◽  
Lake Bottom ◽  
Break Up ◽  
Lena River Delta

Abstract. The thermal regimes of five lakes located within the continuous permafrost zone of northern Siberia (Lena River Delta) have been investigated using hourly water temperature and water level records covering a three year period (2009–2012), together with bathymetric survey data. The lakes included thermokarst lakes located on Holocene river terraces that may be connected to Lena River water during spring flooding, and a thermokarst lake located on deposits of the Pleistocene Ice Complex. The data were used for numerical modeling with FLake software, and also to determine the physical indices of the lakes. The lakes vary in area, depths and volumes. The winter thermal regime is characterized by an ice cover up to 2 m thick that survives for more than 7 months of the year, from October until about mid-June. Lake-bottom temperatures increase at the start of the ice-covered period due to upward-directed heat flux from the underlying thawed sediment. The effects of solar radiation return prior to ice break-up, effectively warming the water beneath the ice cover and inducing convective mixing. Ice break-up starts the beginning of June and takes until the middle or end of June for completion. Mixing occurs within the entire water column from the start of ice break-up and continues during the ice-free periods, as confirmed by the Wedderburn numbers. Some of the lakes located closest to the Lena River are subjected to varying levels of spring flooding with river water, on an annual basis. Numerical modeling using FLake software indicates that the vertical heat flux across the bottom sediment tends towards an annual mean of zero, with maximum downward fluxes of about 5 W m−2 in summer and with heat released back into the water column at a~rate of less than 1 W m−2 during the ice-covered period. The lakes are shown to be efficient heat absorbers and effectively distribute the heat through mixing. Monthly bottom water temperatures during the ice-free period range up to 15 °C and are therefore higher than the associated monthly air or ground temperatures in the surrounding frozen permafrost landscape. The investigated lakes remain unfrozen at depth, with mean annual lake-bottom temperatures of between 2.7 and 4 °C. The data are available in the Supplement for this paper and through the PANGAEA website (http://www.pangaea.de/).

scholarly journals Crustaceans in the Meiobenthos and Plankton of the Thermokarst Lakes and Polygonal Ponds in the Lena River Delta (Northern Yakutia, Russia): Species Composition and Factors Regulating Assemblage Structures

Water ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 1936
Author(s):  
Elena S. Chertoprud ◽  
Anna A. Novichkova
Keyword(s):  
River Delta ◽  
Water Bodies ◽  
Low Flow ◽  
Ecological Groups ◽  
Lena River ◽  
Thermokarst Lakes ◽  
Small Water ◽  
Tundra Ponds ◽  
Main Components ◽  
Lena River Delta

Information about invertebrates in the low-flow water bodies of northeastern Siberia is far from complete. In particular, little is known about crustaceans—one of the main components of meiobenthic and zooplanktonic communities. An open question is which environmental factors significantly affect the crustaceans in different taxonomic and ecological groups? Based on the data collected on the zooplankton and meiobenthos in the tundra ponds in the southern part of the Lena River Delta, analysis of the crustacean taxocene structure was performed. In total, 59 crustacean species and taxa were found. Five of these are new for the region. The species richness was higher in the large thermokarst lakes than in the small water bodies, and the abundance was higher in small polygonal ponds than in the other water bodies. Variations in the Cladocera assemblages were mainly affected by the annual differences in the water temperature; non-harpacticoid copepods were generally determined by hydrochemical factors; and for Harpacticoida, the macrophyte composition was significant. Three types of the crustacean assemblages characteristic of different stages of tundra lake development were distinguished. The hypothesis that the formation of crustacean taxocenes in the Lena River Delta is mainly determined by two types of ecological filters, temperature and local features of the water body, was confirmed.

scholarly journals Observation-based modelling of permafrost carbon fluxes with accounting for deep carbon deposits and thermokarst activity

2014 ◽  
Vol 11 (12) ◽  
pp. 16599-16643 ◽  
Author(s):  
T. Schneider von Deimling ◽  
G. Grosse ◽  
J. Strauss ◽  
L. Schirrmeister ◽  
A. Morgenstern ◽  
...  
Keyword(s):  
Organic Matter ◽  
21St Century ◽  
Radiative Forcing ◽  
Permafrost Degradation ◽  
Emission Rates ◽  
Thermokarst Lakes ◽  
Methane Fluxes ◽  
Carbon Release ◽  
Carbon Dioxide Co2 ◽  
Carbon Store

Abstract. High-latitude soils store vast amounts of perennially frozen and therefore inert organic matter. With rising global temperatures and consequent permafrost degradation, a part of this carbon store will become available for microbial decay and eventual release to the atmosphere. We have developed a simplified, two-dimensional multi-pool model to estimate the strength and timing of future carbon dioxide (CO2) and methane (CH4) fluxes from newly thawed permafrost carbon (i.e. carbon thawed when temperatures rise above pre-industrial levels). We have especially simulated carbon release from deep deposits in Yedoma regions by describing abrupt thaw under thermokarst lakes. The computational efficiency of our model allowed us to run large, multi-centennial ensembles under various scenarios of future warming to express uncertainty inherent to simulations of the permafrost-carbon feedback. Under moderate warming of the representative concentration pathway (RCP) 2.6 scenario, cumulated CO2 fluxes from newly thawed permafrost carbon amount to 20 to 58 petagrammes of carbon (Pg-C) (68% range) by the year 2100 and reach 40 to 98 Pg-C in 2300. The much larger permafrost degradation under strong warming (RCP8.5) results in cumulated CO2 release of 42–141 and 157–313 Pg-C (68% ranges) in the years 2100 and 2300, respectively. Our estimates do only consider fluxes from newly thawed permafrost but not from soils already part of the seasonally thawed active layer under preindustrial climate. Our simulated methane fluxes contribute a few percent to total permafrost carbon release yet they can cause up to 40% of total permafrost-affected radiative forcing in the 21st century (upper 68% range). We infer largest methane emission rates of about 50 Tg-CH4 year–1 around the mid of the 21st century when simulated thermokarst lake extent is at its maximum and when abrupt thaw under thermokarst lakes is accounted for. CH4 release from newly thawed carbon in wetland-affected deposits is only discernible in the 22nd and 23rd century because of the absence of abrupt thaw processes. We further show that release from organic matter stored in deep deposits of Yedoma regions does crucially affect our simulated circumpolar methane fluxes. The additional warming through the release from newly thawed permafrost carbon proved only slightly dependent on the pathway of anthropogenic emission and amounts about 0.03–0.14 °C (68% ranges) by end of the century. The warming increased further in the 22nd and 23rd century and was most pronounced under the RCP6.0 scenario with adding 0.16–0.39 °C (68% range) to simulated global mean surface air temperatures in the year 2300.

scholarly journals Thermal processes of thermokarst lakes in the continuous permafrost zone of northern Siberia – observations and modeling (Lena River Delta, Siberia)

2015 ◽  
Vol 12 (20) ◽  
pp. 5941-5965 ◽  
Author(s):  
J. Boike ◽  
C. Georgi ◽  
G. Kirilin ◽  
S. Muster ◽  
K. Abramova ◽  
...  
Keyword(s):  
Heat Flux ◽  
Water Column ◽  
Permafrost Zone ◽  
Thermal Processes ◽  
Lena River ◽  
Thermokarst Lakes ◽  
Continuous Permafrost ◽  
Lake Bottom ◽  
Break Up ◽  
Lena River Delta

Abstract. Thermokarst lakes are typical features of the northern permafrost ecosystems, and play an important role in the thermal exchange between atmosphere and subsurface. The objective of this study is to describe the main thermal processes of the lakes and to quantify the heat exchange with the underlying sediments. The thermal regimes of five lakes located within the continuous permafrost zone of northern Siberia (Lena River Delta) were investigated using hourly water temperature and water level records covering a 3-year period (2009–2012), together with bathymetric survey data. The lakes included thermokarst lakes located on Holocene river terraces that may be connected to Lena River water during spring flooding, and a thermokarst lake located on deposits of the Pleistocene Ice Complex. Lakes were covered by ice up to 2 m thick that persisted for more than 7 months of the year, from October until about mid-June. Lake-bottom temperatures increased at the start of the ice-covered period due to upward-directed heat flux from the underlying thawed sediment. Prior to ice break-up, solar radiation effectively warmed the water beneath the ice cover and induced convective mixing. Ice break-up started at the beginning of June and lasted until the middle or end of June. Mixing occurred within the entire water column from the start of ice break-up and continued during the ice-free periods, as confirmed by the Wedderburn numbers, a quantitative measure of the balance between wind mixing and stratification that is important for describing the biogeochemical cycles of lakes. The lake thermal regime was modeled numerically using the FLake model. The model demonstrated good agreement with observations with regard to the mean lake temperature, with a good reproduction of the summer stratification during the ice-free period, but poor agreement during the ice-covered period. Modeled sensitivity to lake depth demonstrated that lakes in this climatic zone with mean depths > 5 m develop continuous stratification in summer for at least 1 month. The modeled vertical heat flux across the bottom sediment tends towards an annual mean of zero, with maximum downward fluxes of about 5 W m−2 in summer and with heat released back into the water column at a rate of less than 1 W m−2 during the ice-covered period. The lakes are shown to be efficient heat absorbers and effectively distribute the heat through mixing. Monthly bottom water temperatures during the ice-free period range up to 15 °C and are therefore higher than the associated monthly air or ground temperatures in the surrounding frozen permafrost landscape. The investigated lakes remain unfrozen at depth, with mean annual lake-bottom temperatures of between 2.7 and 4 °C.

scholarly journals Projecting circum-Arctic excess-ground-ice melt with a sub-grid representation in the Community Land Model

2020 ◽  
Vol 14 (12) ◽  
pp. 4611-4626
Author(s):  
Lei Cai ◽  
Hanna Lee ◽  
Kjetil Schanke Aas ◽  
Sebastian Westermann
Keyword(s):  
Surface Subsidence ◽  
Permafrost Degradation ◽  
Ice Melting ◽  
Ground Ice ◽  
Lena River ◽  
Land Unit ◽  
Ice Melt ◽  
Community Land Model ◽  
Warming Climate ◽  
Lena River Delta

Abstract. To address the long-standing underrepresentation of the influences of highly variable ground ice content on the trajectory of permafrost conditions simulated in Earth system models under a warming climate, we implement a sub-grid representation of excess ground ice within permafrost soils using the latest version of the Community Land Model (CLM5). Based on the original CLM5 tiling hierarchy, we duplicate the natural vegetated land unit by building extra tiles for up to three cryostratigraphies with different amounts of excess ice for each grid cell. For the same total amount of excess ice, introducing sub-grid variability in excess-ice contents leads to different excess-ice melting rates at the grid level. In addition, there are impacts on permafrost thermal properties and local hydrology with sub-grid representation. We evaluate this new development with single-point simulations at the Lena River delta, Siberia, where three sub-regions with distinctively different excess-ice conditions are observed. A triple-land-unit case accounting for this spatial variability conforms well to previous model studies for the Lena River delta and displays markedly different dynamics of future excess-ice thaw compared to a single-land-unit case initialized with average excess-ice contents. For global simulations, we prescribed a tiling scheme combined with our sub-grid representation to the global permafrost region using presently available circum-Arctic ground ice data. The sub-grid-scale excess ice produces significant melting of excess ice under a warming climate and enhances the representation of sub-grid variability of surface subsidence on a global scale. Our model development makes it possible to portray more details on the permafrost degradation trajectory depending on the sub-grid soil thermal regime and excess-ice melting, which also shows a strong indication that accounting for excess ice is a prerequisite of a reasonable projection of permafrost thaw. The modeled permafrost degradation with sub-grid excess ice follows the pathway that continuous permafrost transforms into discontinuous permafrost before it disappears, including surface subsidence and talik formation, which are highly permafrost-relevant landscape changes excluded from most land models. Our development of sub-grid representation of excess ice demonstrates a way forward to improve the realism of excess-ice melt in global land models, but further developments require substantially improved global observational datasets on both the horizontal and vertical distributions of excess ground ice.

scholarly journals Projecting circum-Arctic excess ground ice melt with a sub-grid representation in the Community Land Model

2020 ◽  
Author(s):  
Lei Cai ◽  
Hanna Lee ◽  
Kjetil Schanke Aas ◽  
Sebastian Westermann
Keyword(s):  
Surface Subsidence ◽  
Permafrost Degradation ◽  
Ice Melting ◽  
Ground Ice ◽  
Lena River ◽  
Ice Melt ◽  
Community Land Model ◽  
Warming Climate ◽  
Ice Conditions ◽  
Lena River Delta

Abstract. To address the longstanding underrepresentation of the influences of highly variable ground ice content on the trajectory of permafrost conditions simulated in Earth System Models under a warming climate, we implement a sub-grid representation of excess ground ice within permafrost soils using the latest version of the Community Land Model (CLM5). Based on the original CLM5 tiling hierarchy, we duplicate the natural vegetated landunit by building extra tiles for up to three different excess ice conditions for each grid cell. For the same total amount of excess ice, introducing sub-grid variability in excess ice contents leads to different excess ice melting rates at the grid level. In addition, there are impacts on permafrost thermal properties and local hydrology with sub-grid representation. We evaluate this new development at a single-point at the Lena river delta, Siberia, where three sub-regions with distinctively different excess ice conditions are observed. A triple-landunit case accounting for this spatial variability conforms well to previous model studies for the Lena river delta and displays a markedly different dynamics of future excess ice thaw compared to a single-landunit case initialized with average excess ice contents. We prescribed a tiling scheme combined with our sub-grid representation to the global permafrost region using the dataset “Circum-Arctic Map of Permafrost and Ground-Ice Conditions” (Brown et al., 2002). The sub-grid scale excess ice produces significant melting of excess ice under a warming climate and enhances the representation of sub-grid variability of surface subsidence on a global scale. Our model development makes it possible to portray more details on the permafrost degradation trajectory depending on the sub-grid soil thermal regime and excess ice melting. The modeled permafrost degradation with sub-grid excess ice follows the pathway that continuous permafrost transforms into discontinuous permafrost before it disappears, including surface subsidence and talik formation, which are highly permafrost-relevant landscape changes excluded from most land models. Our development of sub-grid representation of excess ice demonstrates a way forward to enhance improve the realism of excess ice melt in global land models, but further developments rely on additional global observational datasets on both the horizontal and vertical distributions of excess ground ice.

scholarly journals Trace metal distribution in pristine permafrost-affected soils of the Lena River delta and its hinterland, northern Siberia, Russia

2014 ◽  
Vol 11 (1) ◽  
pp. 1-15 ◽  
Author(s):  
I. Antcibor ◽  
A. Eschenbach ◽  
S. Zubrzycki ◽  
L. Kutzbach ◽  
D. Bolshiyanov ◽  
...  
Keyword(s):  
Trace Metal ◽  
Climatic Changes ◽  
River Delta ◽  
Metal Distribution ◽  
Lena River ◽  
Northern Siberia ◽  
Metal Levels ◽  
Trace Metal Distribution ◽  
Lena River Delta ◽  
Ice Complex

Abstract. Soils are an important compartment of ecosystems and have the ability to buffer and immobilize substances of natural and anthropogenic origin to prevent their movement to other environment compartments. Predicted climatic changes together with other anthropogenic influences on Arctic terrestrial environments may affect biogeochemical processes enhancing leaching and migration of trace elements in permafrost-affected soils. This is especially important since Arctic ecosystems are considered to be highly sensitive to climatic changes as well as to chemical contamination. This study characterises background levels of trace metals in permafrost-affected soils of the Lena River delta and its hinterland in northern Siberia (73.5–69.5° N), representing a remote region far from evident anthropogenic trace metal sources. Investigations on the element content of iron (Fe), arsenic (As), manganese (Mn), zinc (Zn), nickel (Ni), copper (Cu), lead (Pb), cadmium (Cd), cobalt (Co), and mercury (Hg) in different soil types developed in different geological parent materials have been carried out. The highest median concentrations of Fe and Mn were observed in soils belonging to ice-rich permafrost sediments formed during the Pleistocene (ice-complex) while the highest median values of Ni, Pb and Zn were found in soils of both the ice-complex and the Holocene estuarine terrace of the Lena River delta region, as well as in the southernmost study unit of the hinterland area. Detailed observations of trace metal distribution on the micro scale showed that organic matter content, soil texture and iron-oxide contents influenced by cryogenic processes, temperature, and hydrological regimes are the most important factors determining the metal abundance in permafrost-affected soils. The observed range of trace element background concentrations was similar to trace metal levels reported for other pristine northern areas.

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