Ice and Snow (E-Journal) / Лёд и Снег
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Реконструкция среднеянварской температуры воздуха в раннем голоцене на восточном побережье Чукотки
Get PDFThe investigation is concerned with the Early Holocene syngenetic massive wedge ice exposed in the outcrop of a polygonal peatland in the upper part of the third marine terrace near Lorino settlement on the eastern coast of Chukotka. Based on the obtained radiocarbon dates of peat, it was found that the formation of a peatland in the area began about 14–13 cal ka BP, at the end of the Younger Dryas, while the termination of the active stage of peat accumulation was dated to about 10–9 cal ka BP. The beginning of peat accumulation at the end of the Younger Dryas, earlier the officially accepted limit of the lower boundary of the Holocene (11.7 cal ka BP), and the termination of its formation by the middle of the Greenlandian Holocene period is not a rare phenomenon in Russian permafrost zone, although it is traditionally assumed that the most active formation of peatlands has been going on during the thermal maximum in the middle of the Holocene. The age inversions noted in the peat vertical profiles are the most likely indicative of the processes of re-deposition of ancient organic material due to erosion by water of the third marine terrace sediments and the separation of the allochthonous peat. During the period from 2015 to 2021, six fragments of peatland exposures with the ice wedges were studied. Analysis of the obtained data on the content of stable oxygen isotopes in the ice show that δ18О values vary within the range from –15.5 to –18‰. These values are in good agreement with the data for Early Holocene ice wedges earlier obtained in other areas of the eastern coast of Chukotka (Anadyr town, Uelen settlement), where authors report the δ18O values from –16 to –19.4‰. This suggests that the ice wedge growth as well as the peat accumulation were the most active in Early Holocene. The highest δ18О values (from –13.1 to –16.8‰) were obtained for the modern ice veinlets. The ratio δ2 H–δ18O in the ice wedges, in general, is indicative of a good preservation of isotope signature of winter precipitation. It has been found that approximate mean January air temperature in the Early Greenlandian period varied from –23 to –27°С, which is, on average, 3°С below than the present-day ones.Формирование полигонального торфяника на поверхности третьей морской террасы в районе села Лорино на восточном побережье Чукотки началось в конце позднего дриаса и завершилось в начале голоцена. Среднеянварская температура воздуха в первой половине гренландского периода голоцена, реконструированная на основе данных изотопного состава повторно-жильных льдов, возраст которых не моложе 10–9 тыс. кал. лет назад, в среднем на 3°С ниже современной и варьировала от –23 до –27°С
Микроэлементы в пыли снежного покрова на примере городов Тюмень и Тобольск
Get PDFInhomogeneities of trace elements content in dust of snow cover were studied in two industrial Siberian cities Tobolsk and Tyumen. The clustering method was used, for which standardized values of the content of trace elements in the snow dust of both cities were used. Eight clusters have been identified, which were divided into two classes by location: Tyumen and Tobolsk. The classes were divided into groups: non-specific and specific ones, of which the two subgroups were distinguished: technogenic and natural. The average values of trace elements in nominal terms were calculated for each cluster. Clusters C1, C2, C4, C7, C8 are characterized by a high content of heavy metals V, Cr, Ni, Cu, Co, Zn, Cd, W, Pb. Background clusters C5 and C6 have a low content of trace elements. Specific technogenic C4 contains more copper than other clusters, and C2 contains more lead. Sources of the formation of technogenic clusters are emissions into the atmosphere of enterprises of the fuel and energy complex, foundry and machine-building industries, and transport. The heterogeneity of the content of microelements in the snow dust under background conditions is demonstrated. The microelements are divided into natural background (cluster C5) and the background with anthropogenic pollution with higher content of Ag and Sn (cluster C6). In urban conditions, a solid phase of snow with a low and minimal content of trace elements in dust (cluster C3) is formed. Increased content of Ni and a reduced content of Pb and Sc is noted in the C3 cluster relative to C5 щту. Using the Mann-Whitne test, it was revealed that the content of trace elements in snow dust within the cities Tyumen and Tobolsk are different for the following elements: Li, V, Cr, Cu, Zn, Ga, As, Rb, Sr, Y, Zr, Nb, Mo, Ag, Cd, Sb, Cs, Ba, Pb. Mean values in are higher than similar ones in Tyumen. The content of Zn, As, Rb, Sc elements in urban clusters differs by more than two times relative to the background ones. In the case of elements Sn, Cs, W, the content of them in the snow dust of Tyumen is higher than that of Tobolsk. The method of clustering makes possible to identify natural background values (C5) and to calculate more precise values of the coefficient Kc as well as to determine the index of the integral pollution. In Tobolsk, the index is indicative of high and dangerous level of pollution, especially in the zone of technogenic impact. The average level is typical for the city of Tyumen.Выявлены различия содержания микроэлементов снеговой пыли в городах Тюмень и Тобольск с применением иерархического кластерного анализа. Для кластеризации использованы стандартизованные взвешенные значения. Выделено восемь кластеров, разделённых на группы и подгруппы. Обоснована неоднородность состава микроэлементов. Показано, что в Тобольске содержание элементов выше, чем в Тюмени и соответственно экологическая опасность территорий Тобольска выше, чем Тюмени
Качество характеристик снежного покрова, полученных на основе реанализа ERA 5-Land для территории Пермского края
Get PDFAgreement between values of the mean monthly snow depth provided by the ERA 5-Land reanalysis and similar characteristics of snow cover calculated on the basis of the extended hydrometeorological monitoring performed in the Perm Region for 1990–2020 is analyzed. It was found that ERA 5-Land in 73% of cases reproduces the presence/absence of snow during the onset period, and in 53% – during the period of snow loss. The conclusions made in the authors' previous studies based on more limited material were generally confirmed. It is shown that the reanalysis values of the snow depth are overestimated in relation to instrumental measurements for most of the hydrometeorological stations of the Perm Region. In space, the magnitude of the reanalysis error increases from the southwest to the northeast of the region, with the exception of its central part, where the influence of the Kama water reservoir is perceptible. But the interannual variability of the average snow depth in the Perm Region was reproduced by the ERA 5-Land reanalysis adequately. For 30 years, the magnitude of the reanalysis error decreased as it was compared with 61% observation points. The analysis of seasonal variability showed that in ERA 5-Land time of the maximum snow depth was shifted to earlier onset. The complete coincidence of the seasonal course was recorded only in 5% of hydrometeorological monitoring sites. The value of the average monthly discrepancies between the data of the reanalysis and the information of the posts as a whole exceeds the similar characteristic for the stations, which is especially evident during the period of active snowmelt.Рассмотрены вопросы соответствия информации о среднемесячной высоте снега, содержащейся в реанализе ERA 5-Land, данным наблюдательной сети Пермского края. Показано, что ERA 5-Land завышает фактические значения этого параметра. В сезонном выражении максимумы снегонакопления в реанализе сдвинуты в сторону более раннего наступления, в межгодовом – ERA 5-Land в целом соответствует фактической изменчивости высоты снега
Лёд и снег озера Стемме (о. Западный Шпицберген) зимой 2019/20 г.
Get PDFThe results of observations and modeling of the formation of the snow-ice cover of Lake Stemme (West Svalbard Island) in winter 2019/20 are presented. The main information was obtained by two radar (GPR) survey, performed on the floating ice of the Lake on March 12 and April 22 of 2020. Authors believe that probably these observations were the first ones on the Lake. The use of the radar made it possible to obtain data on the dynamics of the thickness of the layers of snow and ice cover, the so-called “snow ice” which is formed when the boundary between snow and ice was submerged under water. During the time between records, the thickness of the last “snow ice” increased two to three times, i.e., from units to the first tens of cm, and it spread to the entire deep-water part of the Lake area. In addition, analysis of high-precision positioning of the radar records revealed a significant deflection in the ice surface in the central part of the Lake under the influence of snow load and the decreasing level of the reservoir. The calculations of the thermodynamics of the floating ice cover have shown that its thickening occurs as a result of the processes of congelation and isostatic ice formation, replacing each other at its lower and upper boundaries, respectively. At the same time, the formation of “snow ice” violates the characteristic feature of decreasing of ice thickness with growth of the snow thickness, which significantly influences on the thermal and mass balance of the Lake snow-ice cover. Results of calculations of the ice cover deformation did show that it takes place not only due to the elastic, but also to the viscous properties of ice, and it is concentrated in a narrow coastal zone. The maximum radial stress is reached at a distance of several meters from the shore, where a circular crack parallel to the shoreline is formed. Such a crack is formed at all ice thicknesses at about the same distance from the shore.Представлены и проанализированы результаты комплексных наблюдений снежно-ледяного покрова оз. Стемме (о. Западный Шпицберген) зимой 2019/20 г. Полевые данные дополнены результатами моделирования, описывающими особенности его нарастания и деформации
Влияние льдообразования в трещинах на поле температур в холодном слое ледника
Get PDFThe work focuses on modeling the warming of a glacier due to heat release during the refreezing of meltwater in glacier crevasses (cryo-hydrologic warming). The simulation is performed for a polythermal Arctic glacier with a regular network of crevasses filled with water at 0 °C, for the1-year period of freezing of water in crevasses in the cold layer of a glacier, below the active layer. The upper (active layer base) and lower (initial cold-temperate transition surface) boundaries of the cold layer are considered horizontal planes; the crevasses are assumed to be identical narrow straight parallel water-filled channels. These assumptions allow considering the corresponding mathematical problem in a 2D setting. The time-dependent temperature distribution in the modeled domain is calculated explicitly as the solution to a 2D initial boundary value problem for the heat equation with spatially distributed heat sources that model the network of crevasses. The initial temperature distribution and the spatial parameters of the model are set based on the field data from the polythermal glacier Austre Grønfjordbreen (Svalbard). For a fixed geometry of the crevasses (the distance between neighboring crevasses is 10 m, the depth is 10 m, the width is of order 0.1 m) we performed an analytical-solution-based simulation of the temperature field at the end of a year-long period of heating varying the active layer base temperature (-3, -2 °C) and the initial thickness of the cold layer (20, 40, 60 m). The results suggest that the temperature field is more influenced by the cold layer thickness than the upper boundary temperature. The maximum temperature increment is 1–2 °C depending on the simulated case. The cold-temperate transition surface shifts up under the crevasse area by a maximum of 3.4 m (only in the case of 20-m cold layer). The temperature field remains unperturbed at a distance of 20 m or more in any direction from the crevasse zone. Our results may be useful for quantitative comparison of cryo-hydrologic warming with other factors of the temperature state of glaciers.Для условий ледника Восточный Грёнфьорд (Западный Шпицберген) выполнено моделирование изменений температурного поля в холодном слое в конце годового периода отепления за счёт замерзания воды в трещинах. Показано, что температура в леднике повысится на 1–2 °C, граница холодного и тёплого льда сместится вверх максимум на 3,4 м, возмущения температурного поля распространятся не далее 20 м от области трещиноватости
Термический режим снежного покрова зимой в высокогорной части Эльбруса по натурным данным и результатам моделирования
No full textBased on the analysis of the results of two measurement episodes in February 2021/22 and calculations using the LSM SPONSOR model, we obtained estimates of the variability of the snow surface thermal balance components and the thermal regime of the snowpack in the ablation zone of the Garabashi glacier on the southern slope of Mount Elbrus at 3850 m above sea level. A quantitative assessment of the sensitivity of the heat balance components to variations in key physical parameters has been performed. It is shown that the optimal value of the emissivity coefficient of snow cover in mountainous areas is 0.98: the absolute error in calculating the radiation temperature of the snow surface at this value does not exceed 1°С, in addition, the model adequately reproduces the thermal regime of deep layers of snow cover. It is also shown that a change in snow density by ±100 kg/m3 can lead to deviations in the temperature of the snow mass by several degrees. This indicates an urgent need to solve the methodological problem of measurements with thermocouples, in which the integrity of the snow mass is inevitably violated. A good agreement between the results of calculations of turbulent sensible heat fluxes in the SPONSOR model with direct measurements (correlation coefficient > 0.9) is demonstrated. Based on the measurement data, the fact of a fairly high frequency of high values of turbulent fluxes under conditions of intense radiative heating in combination with high wind speeds was revealed, which apparently turns out to be typical for high-mountain regions in winter (unlike the plains). For cases of strongly stable stratification in the surface layer, the model systematically overestimates the absolute values of heat fluxes. This may be due to the well-known problem of implementing the calculation scheme based on the Monin-Obukhov theory under conditions of temperature inversions. The inaccuracy in determining the snow surface roughness parameter, which in high mountain conditions is characterized by significant temporal variability, can contribute to the error.На основе данных наблюдений на леднике Гарабаши на юго-восточном склоне Эльбруса в феврале 2021/22 г. проведена верификация LSM SPONSOR для условий периода аккумуляции. Показано, что при значении коэффициента серости 0.98 ошибка моделирования радиационной температуры снежной поверхности не превышает 1°С. Кроме того, модель адекватно воспроизводит термический режим глубоких слоев снежного покрова. Показано, что методическая проблема измерений термического режима в нарушенном снежном покрове может приводить к существенным ошибкам измерения температуры снега. Сравнение результатов моделирования с прямыми измерениями потоков явного тепла по методу eddy covariance показало их хорошее соответствие (коэффициент корреляции более 0.9), хотя для случаев температурной инверсии в приземном слое отмечается систематическое завышение моделью абсолютных значений потоков. На основе данных измерений выявлен факт достаточно высокой повторяемости высоких значений турбулентных потоков в условиях интенсивного радиационного прогрева в сочетании с высокими скоростями ветра, что по всей видимости оказывается типичным для высокогорных районов в зимнее время
Малые ледники плато Путорана на фоне климатических перемен
Get PDFThe characteristic feature of the Putorana Plateau is that the glaciological objects here are mostly represented by small glaciers and perennial snow patches. Their regime and morphology have so much common features that separation of these two categories of nival glacial formations from one another is extremely difficult problem. The distinctions between results of earlier studies carried out in the 1970s (the USSR Glacier Inventory estimated local resources at 22 glaciers with a total area of 2.5 km2) and at the beginning of the current century (in 2005, V.A. Sarana identified 61 glaciers with a total area of 7 km2) are too large to make any reliable conclusions about the current trends of the Putoran glaciation. In such conditions, the materials of rare field monitoring work performed on individual nival-glacial bodies become very valuable. Three expedition seasons of 2002–2004 included thorough geodetic and mass-balance measurements on 3 reference objects on the northern ledge of Lama Mts. – Prives (No. 30) Glacier, Marlborough (No. 31) Glacier and Strudoms snow patch. Similar field monitoring was repeated in summer’2019. The change in their configuration according to digital photography data, including the results of the analysis of satellite images, make possible to reveal that interannual fluctuations in the area of each glacier occur due to different vector displacements of its different sections along their entire perimeters. In 2019, the somewhat unexpected good budget state of all 3 monitored objects was detected. It manifested itself in growth of their areas and increased fraction of firn basin as well as in larger water equivalent of the firn residue as this followed from results of snow surveys. This fact contradicts the previous conclusion about the steady trend of deglaciation on the Putorana Plateau. The favourable condition for small glaciers occurred here in 2019 was mainly caused by reduced ablation owing to the weakened insolation that resulted from tremendous forest fires in Siberia, remarkable by their abnormal intensity in this year.По итогам экспедиционных исследований снежников и ледников Ламских гор на плато Путорана в 2002–2004 и 2019 гг. для суждений об их современном состоянии получены новые сведения о режиме и эволюции малых форм оледенения на фоне климатических тенденций последних лет. В условиях неблагоприятных климатических перемен малые ледники плато Путорана демонстрируют большую устойчивость по сравнению с крупными ледниками и малыми формами оледенения, существующими в тёплой фирновой зоне льдообразования
Баланс массы ледника Козельский на Камчатке за 1977–2022 гг.
Get PDFThe change in the volume of the Kozelsky Glacier in Kamchatka for the period 1977–2022 (1977–2015 and 2015–2022) was estimated using historical data and modern DEM. During this period, the area of the glacier did not change much. At the same time, its length increased by about 0.7 km, while the width decreased over its almost whole extent. The volume of the glacier decreased by 34.15 ± 6.74 million m3, and its surface became lower by 17.30 m, on the average. The cumulative mass balance amounted 14.70 ± 3.94 m w.e., and the mean annual value –0.33 m w.e. yr–1. In the last 45 years, the ice loss and redistribution to lower hypsometric levels took place on the Kozelsky Glacier. In 1977–2015, the average area change in the altitude of the glacier surface was equal to –17.84 m, the volume decreased by 35.21 ± 7.20 million m3, the cumulative mass balance amounted –15.16 ± 4.17 m w.e., and the mean annual balance –0.40 m w.e. yr–1. In the period 2015–2022, an elevation of the glacier surface was recorded by 0.59 ± 1.55 m on the average, the volume increased by 1.01 ± 2.65 million m3, the cumulative mass balance amounted to 0.50 ± 1.35 m w.e., and the mean annual balance – to 0.07 m w.e. yr–1. During the last decade, a slowdown in the movement of the glacier front down the valley was recorded. In 2012–2022, the glacier front advanced with a velocity of about 5.2 m/year, while it was 17.9 m/year in 1977–2007, and 20.0 m/year in 2007–2012. The current climatic conditions are not favorable for development of glaciers. In 1977–2022, a trend of the summer air temperature rise was observed with a relatively stable amount of precipitation falling during the cold period. The almost continuous (except 1978–1981) advance of the glacier in 1977–2022 can be explained by the influence of the volcanic factor. A thick surface moraine covers more than 2/3 of the glacier area and, thus, prevents the surface ablation. Increased seismic activity associated with active volcanism promotes the ice movement.Дана оценка изменения объёма ледника Козельский на Камчатке за 1977–2022 гг. Площадь ледник за это время практически не изменилась, фронт продвинулся вперёд почти на 0.7 км, объём сократился на 34.15 ± 6.74 млн м3, поверхность в среднем понизилась на 17.3 м, кумулятивный баланс массы составил –14.70 ± 3.94 м в.э., а удельный среднегодовой –0.33 м в.э./год. Продвижение линии фронта в последние 10 лет замедлилось и составляло около 5 м/год
Оценка снегозапасов в засушливой зоне по данным глобальных численных моделей ICON и GFS/NCEP (на примере бассейна реки Селенга)
Get PDFThe possibility to use the global numerical (NWP) models ICON and GFS/NCEP for We consider the applicability of ICON and GFS/NCEP global numerical atmospheric model data for calculating the snow water equivalent (SWE) in the Selenga River basin located the semiarid zone. SWE was calculated for the cold periods of 2020–2022 based on the empirical methodology previously developed for the Kama River basin and adapted to the semiarid conditions. The main components of the SWE balance that are taken into account in the calculation are atmospheric precipitation (liquid or solid phase), snowmelt, sublimation from the snow surface and precipitation interception by vegetation with subsequent sublimation. The validation of the results was performed for the Russian part of the basin using the data of snow surveys carried out in the second half of the winter of 2021/22. In general, reasonable estimates of the SWE spatial distribution were obtained. While in 2021, both overestimation and underestimation by 1–15 mm (20–50%) of the calculated SWE was observed at different sites compared to the measurements, in 2022, its systematic underestimation was observed, especially significant in calculations using the ICON model data. In the steppe zone, SWE is significantly underestimated, which may be due to overestimation of the intensity of sublimation from the snow surface. The comparison of these results with the ERA5-Land reanalysis data and MODIS satellite images showed that the ERA5-Land reanalysis significantly overestimates the SWE and the snow cover area. The simulation results based on the GFS/NCEP and ICON models underestimated the snow cover area in 2022 and reproduced well in 2021, which correlates with the results of the SWE calculation.Рассматривается применимость данных глобальных численных моделей прогноза погоды ICON и GFS/NCEP для оценки снегонакопления в бассейне р. Селенги, на примере 2020–2022 гг. Валидация результатов выполнена по данным снегомерных съёмок. Получены реалистичные оценки пространственного распределения снегозапасов. Результаты сопоставлены с данными реанализа ERA5–Land и спутниковыми снимками MODIS