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Earths Cryosphere

2021 year, number 3

1.
NATURAL ENVIRONMENT DYNAMICS AND MORPHOLITHOGENESIS IN SHALLOWS OF THE EAST SIBERIAN ARCTIC SHELF

A.V. Gavrilov, E.I. Pizhankova
Lomonosov Moscow State University, Faculty of Geology, Leninskie Gory 1, Moscow, 119991, Russia
Keywords: morpholithogenesis, sedimentation, morphostructures, modern climate warming, remote sensing data, marine shallows

Abstract >>
The shallows of the Laptev and East Siberian seas formed on the site of islands composed of the sediments of the Late Pleistocene Ice Complex which eroded in the 17th-20th centuries and are linked to positive morphostructures. The present article considers factors of modern sedimentation in marine shallows with the formation of islands (Yaya, Nanosny, Zatoplyaemyy, Leykina, etc.). Among these factors are a decrease in sea ice extent, an increase in the duration of the ice-free period, and the activation of destructive cryogenic processes triggered by the current climate warming. A decrease in ice coverage led to the dominance of hydrodynamic processes in sedimentation, unlike the primary role of sea ice in this process in the 17th-19th centuries. Sediment deficit in these centuries is substituted by its excess owing to the activation of cryogenic processes at the turn of the 20th and 21st centuries. As a result, the erosional shoreface profile is transforming into an accumulative one. Sedimentation is occurring parallel to a rising sea level related to a warming climate. A rise in the surface of islands and sandbanks is recorded on satellite images where there are modern positive vertical movements. The formation of islands and sandbanks is accompanied by their syngenetic freezing.
																								



2.
GEOCRYOLOGICAL FACTORS OF DYNAMICS OF THE THERMOKARST LAKE AREA IN CENTRAL YAKUTIA

N.V. Nesterova1,2, O.M. Makarieva1,2, A.N. Fedorov3, A.N. Shikhov4
1St. Petersburg State University, Institute of Earth Sciences, Universitetskaya nab. 7-9, St. Petersburg, 199034, Russia
2North-Eastern Permafrost Station, Portovaya str. 16, Magadan, 685000, Russia
3Melnikov Permafrost Institute, SB RAS, Merzlotnaya str. 36, Yakutsk, 677010, Russia
4Perm State University, Bukireva str. 15, Perm, 614068, Russia
Keywords: thermokarst lakes, permafrost, Landsat images, Central Yakutia, temperature and water content of seasonally thawed layer, precipitation, snow cover, Spasskaya Pad’

Abstract >>
The analysis of the Landsat satellite images revealed a significant increase in the area of thermokarst lakes in Central Yakutia over the period 2000-2019. The lake area increased twice in the basins of the Suola and Taatta River basins and by 25 % in the Tanda River basin. It has been established that, despite the presence of a general linear trend, the increase in the area of lakes occurs abruptly. Qualitative relationship between the changes in the state of the upper layer of permafrost and the dramatical increase in the area of thermokarst lakes has been revealed. The main factor leading to disruption of a stable state of thermokarst forms are short-term (1-3 years) periods of sudden changes in temperature of seasonally thawed layer from below-average to anomalously high values. These periods can be caused by a rare combination of hydrometeorological conditions, such as anomalously high values of snow water equivalent, increased annual precipitation, and an increased water content of soils of the seasonally thawed layer.
																								



3.
ZONE OF STABILITY OF METHANE HYDRATES IN THE AREA OF THE SREDNEVILYUISK GAS-CONDENSATE FIELD (VILYUI SYNECLISE)

A.D. Duchkov1, V.P. Semenov2, L.S. Sokolova1, A.I. Sivtsev3
1Trofimuk Institute of Petroleum Geology and Geophysics, SB RAS, Akademika Koptyuga prs. 3, Novosibirsk, 630090, Russia
2Melnikov Permafrost Institute, SB RAS, Permafrost str. 36, Yakutsk, 677010, Russia
3TAAS-Yuryakh Neftegazodobycha LLC, Ammosova str. 18, Yakutsk, 677018, Russia
Keywords: Vilyui syneclise, Srednevilyuisk gas-condensate field, permafrost, methane natural gas hydrate stability zone, boundaries of the zone, Late Neopleistocene-Holocene

Abstract >>
The results of determining the lower boundary of the methane hydrate stability zone based on geothermal measurements in 22 wells of the Srednevilyuysk gas-condensate field have been presented. A graphical method has been applied, which consisteds in comparing the thermograms with a phase diagram characterizing the equilibrium conditions of formation for the methane gas hydrates contained in the upper deposits of the field. At present, the upper gas deposits of the field (depths of 1035 and 1057 m) are located only 60-70 m below the stability zone. An approximate assessment of changes in the location of the lower boundary of the stability zone of methane hydrates in the Late Neopleistocene-Holocene has been made. It has been revealed that during the cold periods (~ 130 and 15 thousand years ago), the stability zone could fall below the upper gas deposits of the Srednevilyuysk field by 20-50 m.
																								



4.
CONJUNCTION OF CHANGES IN AIR TEMPERATURE, SNOW COVER THICKNESS AND SOIL TEMPERATURE OF EAST EUROPEAN PLAIN

L.M. Kitaev
Institute of Geography, RAS, Staromonetny per. 29, Moscow, 119017, Russia
Keywords: snow thickness, surface air temperature, soil temperature, spatial distribution, multiyear progress

Abstract >>
The main goal of the research is to assess the nature of the spatio-temporal changes in the temperature regime of the soil of the East European Plain (Russian part) under the conditions of changes in snow cover and soil temperature in recent decades - at the local and regional levels. The phases of changes in soil temperature, snow thickness, and surface air temperature, typical for the study area, have been identified. Significant long-term tendencies in the progress of in soil temperature are characteristic of low-snow autumn and spring periods, as well as a significant correlation between soil temperature and air temperature during those periods in the absence of statistical relationships during the snow season. A sharp decrease in the seasonal and inter-annual variability of soil temperature in the period with stable snow cover has been revealed - by 3-5 times relative to the variability of the surface air temperature, and by 1.3-2.5 times relative to the variability of soil temperature in the pre-winter and spring periods with a progress of changes. Thus, the appearance of stable snow cover in the winter season determines the progress of soil temperature within a narrow corridor of near-zero values, low or insignificant coefficients of the linear trend, low seasonal and inter-annual variability, the absence of statistical relationships with the course of changes in snow thickness and surface air temperature - both at the local, and at the regional levels of the East European Plain.
																								



5.
CALCULATION OF THE HEAT BALANCE COMPONENTS OF THE ALDEGONDA GLACIER (WESTERN SPITSBERGEN) DURING THE ABLATION PERIOD ACCORDING TO THE OBSERVATIONS OF 2019

U.V. Prokhorova1, A.V. Terekhov1, B.V. Ivanov1,2, S.R. Verkulich1
1Arctic and Antarctic Research Institute, Bering str. 38, St. Petersburg, 199397, Russia
2Saint Petersburg State University, Universitetskaya emb. 7/9, St. Petersburg, 199011, Russia
Keywords: Svalbard, mountain glacier, glacier ablation, heat balance, physical modelling

Abstract >>
Surface heat balance components have been calculated for the mountain valley Aldegonda Glacier (West Spitsbergen Island) based on a physical model with distributed parameters. The meteorological and actinometric observations on the glacier during the ablation period of 2019, a digital elevation model, as well as the remote sensing data needed for assessment of the reflective characteristics of the surface have been used as the input data. As a result of modeling, a spatial distribution of the values of the heat flux spent on melting with a resolution of one day has been obtained. According to the calculations, the average radiation balance for the period has been 89 W/m2, which is approximately an order of magnitude higher than the heat inflow from turbulent flows (11 W/m2). The obtained results have been verified using data on the glaciological mass balance monitoring based on ablation stakes. Predicted thickness of melted ice layer is in good agreement with the measurements on ablation stakes. The model systematically overestimates the magnitude of ice melt, but the glacier-average value remains within the confidence interval of the observed value.
																								



6.
MARINA OSKAROVNA LEIBMAN (on the 70th anniversary)

A.I. Kizyakov1, I.D. Streletskaya1, A.V. Khomutov2
1Lomonosov Moscow State University, Leninskie Gory 1, Moscow, 119991, Russia
2Earth Cryosphere Institute, Tyumen Scientific Centre SB RAS, Malygina str. 86, Tyumen, 625026, Russia
Keywords: ryogenic processes, permafrost, ground ice

Abstract >>
On the 22 of June, 2021 famous scientist, doctor of science in geology and mineralogy, Marina Oskarovna Leibman has celebrated her 70th anniversary. Marina Oskarovna combines a fundamental scientific approach with active field research, managing to cover a wide range of tasks for the study of permafrost and cryogenic processes. She has become an attentive scientific consultant and scientific advisor for many young researchers.