Ice and Snow (E-Journal) / Лёд и Снег
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Строение и формирование ледогрунтовых жил второй озёрно-аллювиальной террасы на севере Гыдана в позднем неоплейстоцене–голоцене
Get PDFThe syngenetic ice and ice-ground composite veins in khasyrey (alas) and interalas plateaus were studied on the second lake-alluvial terrace located in the North of the Gydan Peninsula near the village of Gyda. On the basis of the radiocarbon dating, the time of formation of deposits containing veins from was established – from 16 640 to 854 BP. The peat deposits are mainly represented by the following species: Carex sp., Eriophorum sp., Betula nana, Equisetum sp., Calamagrostis sp., Vaccinium vitis-idaea, Drepanocladus sp., Empetrum sp., Vaccinium uliginosum, Rubus arcticus, Petasites sp. It is established that the polygonal-veined ice of khasyrey and interalas plateaus, except for vertical-striped «clean» ice, contain areas with vertical wavy streaks of ice-ground. Ice of elementary veins and segregation ice were revealed in the composition of veins according to structural and textural features in polarized light. Elementary ice veins compose «clean» ice sections of veins and segregation ice which are their ice-ground sections. Elementary veins are indicative of the predominance of the process of frost cracking during the formation of polygonal-vein ices. The presence of inclusions of ice-ground in the structure of veins points is evidence of a manifestation of local thermokarst processes under the growth of polygonal-vein ice. Ice-ground veins were formed by repeated thawing of the initial ice veins. The formation of ice-ground veins during syngenetic freezing of sediments of the second lake-alluvial terrace is related to uneven manifestation of thermokarst in different facies situations and and climate changes at the Early Pleistocene and Holocene.Изучены сингенетические ледяные и ледогрунтовые жилы, а также сезонно- и мёрзлые отложения на севере Гыданского полуострова. Включение сегрегационного льда в состав полигонально-жильного проходило в период сингенетического промерзания осадков второй террасы на севере Гыдана в динамичной озёрно-аллювиальной обстановке и связано с неравномерным проявлением термокарста во второй половине сартанского периода и в голоцене
Оценка техногенного загрязнения городской среды Читы по состоянию снежного покрова
Get PDFThe pollution of the snow cover in the city of Chita (Transbaikalia) with heavy metals (Zn, Cd, Pb, and Cu) is analyzed, and a level of its pollution is compared with similar characteristics in the cities of neighboring regions. The method of inversion voltammetery made possible to find that the content of water-soluble forms of toxic trace elements in the snow is several times greater than in other settlements outside Chita. However, the median values of these values (indicators) are close. Similar results (indicators) were also noted in the ecological and geochemical coefficients, according to which the city of Chita may be attributed to areas with the average level of pollution (ZC = 35.66). Trends in the accumulation of mobile forms of heavy metals in the snow cover of other cities were similar features as it follows from low values of the Saet coefficient (ZC < 32). The charge coefficient calculated for the liquid fraction of the snow cover was found to be high. Therefore, for safe use, melt water should be diluted with clean water 75.24 times for fishery purposes and 9.4 times for economic and drinking use. Rather low content of heavy metals was found in the dust fraction of the snow cover, but in the industrial zone and the zone of residential many-storeyed buildings concentrations of all trace elements exceeded the maximum permissible values (TLV - threshold limit value). At the same time, similar data for other settlements had still greater values, and the exceedings were tens and hundreds times greater the TLV values (the maximum permissible concentrations). The total pollution index (ZC = 72.5) with consideration for the toxicity of chemical elements (ZCT = 98.8) shows that the geochemical conditions in Chita is at the average level. For most other cities, values of the Saet coefficient were smaller 32 that corresponds to low and medium pollution levels. According to the level of dust load Chita is characterized by a high level of pollution (Pn ≥ 10 tons/km2), and it means that more than 8000 tons of dust fall to the snow cover. It has been found that by the total load index (Zp = 493.5) the dust fraction characterizes urbanized territory of Chita as highly polluted, and in this case cadmium (Cu = 255.47) is the main polluter. Comparison of our results with those of other researchers allows making the conclusion that during the period of the Soviet Union disintegration by the beginning of the XXI century pollution of a snow cover notably reduced.Анализируется загрязнённость снега города Читы цинком, кадмием, свинцом и медью в сравнении с соседними городами. В Чите содержание водорастворимых форм тяжёлых металлов в снегу в несколько раз больше, чем в других городах. Суммарный показатель загрязнённости (Zc = 72,5) с учётом токсичности (ZCT = 98,8) - средний, но пылевая нагрузка (Zp = 493,5) очень высока
Современные тенденции изменения снеголавинного режима Центрального Кавказа (на примере Приэльбрусья)
Get PDFThe climate change during cold seasons of 1995–2017 in the Central Caucasus is estimated, and its influence on the avalanche regime is shown. Data on the avalanche releases in the Central Caucasus for the period 1968– 2017 together with observations of high-altitude meteorological stations were used for the analysis. The paper presents estimates of snowiness of the winters and their frequency of occurrence in the area under investigation. The winter snowiness was noted to decrease since the beginning of the 2000s. The last decade of the period was not snowy, especially its series of six winters having very small amounts of snow. It is shown that in the second half of the XX century the heaviest snowfalls took place mostly in Januaries, and they were followed by releases of avalanches with the volumes exceeding 1 million cubic metres. In the early 2000‑ies, intensive January snowfalls were observed later, i.e. during the winter-spring period. In the warmer months March and April, the destructive potential of avalanches was noticeably smaller. In the present time, the warming and decrease of winter snowiness resulted in significant diminution of the avalanche hazard in the region. At the same time, on the background of general warming the certain increase in inter-seasonal variability of air temperature was noted. These changes may be compared to the warming of 1910–1945 when during its warmest phase the Europe suffered with one of the harshest winters in 1941/42. The swing of the «temperature pendulum» indicates that a harsh winter with heavy snowfalls and avalanches with catastrophic consequences may occur on the background of winters with mild and moderate avalanche danger. This is one of probable scenarios in the development of avalanche activity in the Greater Caucasus in the context of the current climate change.На рубеже XX–XXI вв. (1995–2017 гг.) увеличились изменчивость и частота экстремальных явлений. Рассмотрены тенденции изменения снеголавинного режима в Приэльбрусье за последние десятилетия, показана их связь с изменениями климата.
Оценка возраста гряд торосов в замерзающих морях
Get PDFA method of estimating the ice ridge age proposed in the 1990s was analyzed and some disadvantages of this method were shown. Analysis of the ice thickness distribution in the ice ridges demonstrated that in many cases the average value of the thickness used in the above mentioned method did not correspond to the thickness of an ice floe of which the ice blocks were formed. The ice floe thickness is characterized by the modal value of the ice thicknesses. After the ice ridge has been formed the ice block thickness in its above-water part does not change while the thickness of the ice floe on which the ice ridge is located continues to increase. Our study has shown that the difference between thickness of the plane ice and the modal value of the ice block thickness may be used as a characteristic of the ice growth for the period of the ice ridge existence. This period can be determined by one of the calculation formulas at the known initial and final ice thickness. Calculation by formula of the ice growth thickness make possible to derive the date of ice ridge formation based on the average air temperatures. The updated method of estimating the time of ice ridge formation can be used for the ice-covered seas. Analysis of the estimated ice ridge ages showed a significant dependence of thickness of the minimal consolidated layer on the time of the ice ridge formation. A comparative analysis of (the) ages of ice ridges and the flexural strength of ice samples made it possible to determine important tendency - the increased ice strength in ice ridges of early formation. This allows us in further studies to derive a formula of relationship between an ice ridge age and a strength of its ice. In some cases the ice strength measurement in ice ridges can be replaced by a less laborious estimating of strength basing on data of the age.Предложен уточнённый способ определения возраста гряды торосов на основе сравнения модальной толщины блоков льда, слагающих её надводную часть, и толщины поля ровного льда, на котором расположена гряда в момент измерений. Возраст гряды торосов связан с толщиной консолидированного слоя. Установлена важная тенденция - для торосов раннего образования характерна повышенная прочность льда на изгиб
Байкальская ледниковая система, новые находки
Get PDFThree glaciers and other small glacial formations, which are not mentioned in the USSR Catalog of glaciers as well as in any published article, were found in the area of the Verkhneangarsky (upper Angara) Range on satellite images. Earlier, researchers from the Institute of Geography of Siberian Branch of RAS described a group of glaciers on the Baikal Mountains and the Barguzin Range, which together with the above group of the Verkhneangarsky Range are related to the Baikal basin by the climate conditions. Ogdynda-Maskit Glacier has been described on the spot in 2017, while other glaciers and snow patches are to be investigated in situ in 2018. Together with the above Baikal and Barguzin glaciers, new data allow identification of the Baikal Glacial system. The article presents analysis of climate changes in the region. Trends in mean annual temperature range from 1 to 4 °C/50 years, while the same of summer temperatures change from 1 to 3 °C/50 years, but without any evident spatial distribution between them. Another situation takes place in the spatial distribution of precipitation: trends in total precipitation decrease towards the Baikal Lake, while precipitation of the cold period, on the contrary, slightly increases towards the Lake, but with rather small trend – 10–40 mm per 50 years. The last fact confirms the influence of the Baikal basin on the alimentation of glaciers and snow patches on the Verkhneangarsky Range. Currently, glaciers of the Verkhneangarsky Range undergo a slow regression. На космических снимках Landsat‑8 обнаружены три ледника в районе Верхнеангарского хребта, которые не упоминаются в Каталоге ледников СССР и научной литературе. Ледник Огдында-Маскит описан в 2017 г. Вместе с уже известными ледниками Байкальского и Баргузинского хребтов новые находки позволяют выделить Байкальскую ледниковую систему, климатически связанную с оз. Байкал. Описаны орографические и климатические условия существования ледников этого района
Суровость современного климата в Сибирском Заполярье
Get PDFOver the period 1981–2015 severe climatic conditions on the North of Siberia (area within 66–162° E above the Polar Circle) were characterized by significant space-time variations of air temperature at the cold period of the year. This conclusion is made on the basis of analysis of observations made about 13 hour of local time. Positive changes in the mean seasonal air temperature were observed here in October–April. The largest rates of air temperature rise with a pronounced gradient to the West were noted in high latitudes, i.e. in Arctic glacial and polar desert landscapes. The change in weather severity which is one of characteristics of the climate discomfort was analyzed by means of the Arnoldi index (TA). This index reflects the combined effect of negative temperatures and stiff wind on the thermal state of the open surface of the human body. Together with the space-time dynamics of the actual TA values, important values of TA are its threshold values (more than 30 and more than 45 units) which determine a degree of discomfort. Duration of these periods, limiting a possibility of a person's stay in the open air, is also extremely important as well. In recent decades (1981–2015), the spatial differentiation of the number of days (from 80 to 160) limiting the human’s stay in the open air reflects in the main fluctuations of the air temperature and wind regime in polar landscapes. Slight warming (a rise of the air temperature) and small wind speed variability during the period from October to April in 1981–2015 resulted in a certain decrease in the index of weather severity in relation to the period 1966–1980, since the last one did not did not go beyond limit of the interannual variability. Despite the stable increase in the air temperature in 1981–2015, no tendency to reduction of the number of days limiting human’s stay in the open air was noted. The duration of this period for 1981–2015 is similar to that observed in 1936–1964, and we believe that this is suggestive of manifestation of the cyclicity of atmospheric processes and is agreed with a gradual decrease in the rate of the temperature rise. In the last period duration of the period limiting human stay in the open air in the considered area remains high and ranges from 3.5 (to the west of 80° E) to 5 months on islands and capes of the region. So, as is demonstrated by the above example of space-time dynamics of the weather severity index at the time about 13 hours of local time, no decrease in the level of discomfort in polar Siberia is found.Исследованы изменения температуры воздуха и скорости ветра в холодный период. Повышение температуры воздуха и небольшие отклонения скоростей ветра за период 1981–2015 гг. способствовали некоторому снижению жёсткости погоды по показателю Арнольди. Но пространственная дифференциация числа дней, ограничивающих пребывание человека на открытом воздухе, остаётся высокой. Поэтому дискомфортность на заполярных территориях Сибири не снижается.
Расчёты формирования снежного покрова на основе модели взаимодействия поверхности суши с атмосферой SWAP
Get PDFIn framework of the project «The Earth system Models – Snow Models Intercomparison Project» (ESMSnowMIP), calculations of snow storages were carried out on ten experimental sites organized for longterm monitoring of the snow cover variability in various regions of the globe. The calculation method is based on the physical and mathematical description of heat and moisture exchange processes occurring within the system «ground water – soil – vegetation cover/snow cover – surface layer of the atmosphere», and it is implemented in the form of the model of interaction between the land surface and the atmosphere (SWAP). The model was developed at the Institute of water problems (IWP) of Russian Academy of Sciences. The model makes possible to calculate components of water and heat balances and different characteristics of the hydrological regime of terrestrial ecosystems and river basins having different spatial scales and located in different natural conditions. Good quality of reproduction of the snow storages variability on all considered sites is reached that allows consideration of the SWAP model as one of the best models of the snow cover formation. Thus, the SWAP model has a sufficiently optimal degree of complexity of the algorithm for reproducing the dynamics of snow cover, which is necessary and sufficient in global and regional hydrological models describing formation of the water balance of the land in the cold regions of the planet, and can be used to create scenario forecasts of snow dynamics (as the important part of the cryosphere). This conclusion is verified by the results of using the SWAP model to reproduce long-term variability of snow storages in basins of the River Lena and the River Ob (with its tributary Irtysh) which are the two largest rivers of the Russian Federation. The calculated and measured characteristics of snow cover dynamics for these basins are shown to be in good agreement.Расчёты снегозапасов на десяти экспериментальных площадках в разных районах земного шара показали, что модель SWAP входит в число лучших мировых моделей формирования снежного покрова. Расчёты по этой модели многолетней динамики снегозапасов в бассейнах рек Лены и Оби (с её притоком р. Иртыш) подтвердили вывод о способности модели SWAP адекватно воспроизводить формирование снегозапасов в крупных речных бассейнах.
Реконструкция зимней температуры воздуха в голоцене по стабильным изотопам из ледяных жил в районе города Анадырь
Get PDFThe object of research is syncryogenic Holocene strata on the coast of the Onemen Bay, 2 km from the town of Anadyr. In July 2017, the outcrop of the first marine terrace uncovered by strong storms was examined. The stratigraphy of the outcrop was represented mainly by sandy loam (5–7 m thick) covered by peat (1–1.5 m) and underlain by sand. Numerous ice wedges were opened in the upper part of this outcrop. Along with that another outcropping of transect of a lakemarsh basin represented by a peat bog of 2–2.5 m thick underlain by sandy loam was also investigated. Ice wedges occur below the polygonal trenches. The present-day narrow ice wedges were found in the upper part of the peat bog. Two representative fragments of both the above outcrops were thoroughly examined. Radiocarbon dating had shown that accumulation of peat on surface of the first marine terrace started in early Holocene (about 8 ka BP). Accumulation of peatland within the lake-marsh basin was also dated to the beginning of the Holocene (about 9 ka BP). In the middle of the Holocene, it was most likely interrupted as a result of thermokarst processes and bogging of the surface. Formation of peatlands in Chukotka during the Holocene is known to be accompanied by active growth of the ice wedges inside them, so the age of the wedges studied by us was estimated as the beginning of the Holocene. The analysis of stable oxygen and hydrogen isotopes in the Holocene and the modern ice wedges had allowed establishing mainly the atmospheric type of moisture feeding of the wedges (due to melted snow) and lack of noticeable isotope fractionation during the ice formation. It has been found that δ18О and δ2Н values in the Holocene ice wedges were lower than in the modern wedges and snow by an average 2–3 and 7–12 ‰, respectively. Paleotemperature reconstructions performed on the basis of isotopeoxygen data showed that the air temperature of the coldest winter month in the first half of the Holocene in the Onemen Bay area was lower than the present-day ones by an average 2–3 °C, which is in a good agreement with the trend of rising winter temperatures throughout the Chukotka Peninsula, as well as in other areas of Eastern Siberia and Alaska. Объект исследований – синкриогенные голоценовые толщи на побережье залива Онемен, в 2 км от г. Анадырь. Изучены повторно-жильные льды, вскрытые в двух фрагментах обнажения первой морской террасы. При радиоуглеродном датировании вмещающего торфа установлено, что жилы начали активно формироваться в раннем голоцене (около 9–8 тыс. лет назад). Согласно палеотемпературным реконструкциям на основе изотопно-кислородных данных, температура воздуха самого холодного зимнего месяца в первой половине голоцена в районе залива Онемен была ниже современной на 2–3 оС
Влияние потепления климата на прочностные характеристики льда в Обской губе
Get PDFThe article presents results of investigation of the climate warming effects in the northern polar region of the Earth, in particular on some characteristics of ice in the northern part of the Ob Bay (the area of the most active economic activity of the Russian Federation in the last decade). It is determined that over the past 40 years, morphometric and strength characteristics of ice have significantly changed. Estimates of ice thickness obtained using simple empirical formulas (depending on the sum of the degree-days of frost) show that the ice thickness decreased here by an average of 10 15%. The strength characteristics of ice were analyzed for two periods: the maximum strength of ice (for this area it is March) and the maximum development of ice thickness (usually it is May). It was found that the strength properties of ice (bending and compression) for both periods decreased by 10-12%. Thus, in recent decades, under the influence of climate warming in the Ob Bay, the thickness and strength of the ice cover have significantly decreased. This circumstance will be favorable for further development of the considered water area by Russian oil and gas companies.Рассматриваются изменения прочностных и морфометрических характеристик припайного льда в Обской губе за последние 30–40 лет. Использованы расчётные метеорологические характеристики, полученные по наблюдениям регулярной сети Росгидромета России. Установлено, что в Обской губе толщина припайного льда уменьшилась на 10–15%, а его прочностные характеристики снизились на 10–12%