Climatic control on the peak discharge of glacier outburst floods

Lakes impounded by natural ice dams occur in many glacier regions. Their sudden emptying along subglacial paths can unleash similar to 1 km(3) of floodwater, but predicting the peak discharge of these subglacial outburst floods ('jokulhlaups') is notoriously difficult. To study how environmental factors control jokulhlaup magnitude, we use thermo- mechanical modelling to interpret a 40- year flood record from Merzbacher Lake in the Tian Shan. We show that the mean air temperature during each flood modulates its peak discharge, by influencing both the rate of meltwater input to the lake as it drains, and the lake- water temperature. The flood devastation potential thus depends sensitively on weather, and this dependence explains how regional climatic warming drives the rising trend of peak discharges in our dataset. For other subaerial ice- dammed lakes worldwide, regional warming will also promote higher- impact jokulhlaups by raising the likelihood of warm weather during their occurrence, unless other factors reduce lake volumes at flood initiation to outweigh this effect

Баланс массы льда ледникового купола Беллинсгаузен в 2007–2012 гг. (о. Кинг‐Джордж, Южные Шетландские острова, Антарктика)

Mass balance researches on Bellingshausen Ice Dome (King George Island, archipelago Southern Shetland Islands, Antarctica) were spent during five summer seasons in 2007–1012 and one winter in 2011. The analysis of received data has shown that in 2007/08 and 2008/09 ice mass balance on Bellingshausen Ice Dome was almost closed to zero, in 2009/10, 2010/11 and 2011/12 it was positive. ELA in 2007/08 and 2008/09 was situated a little below top of the Ice Dome (about 225 m a.s.l.), in 2009/10 ELA has lowered practically up to sea level, in 2010/11 it was equal 180 m a.s.l., in 2011/12 – 220 m a.s.l. Good correlation between snow and ice melting and mean summer air temperature give possibility to renew ice melting conditions for all period of observations at Bellingshausen weather station (1969–2011). Ice mass balance for Bellingshausen Ice Dome was also renewed for similar period. Analysis of received data allow to suppose that tendency of climate cooling is outlined in last years.Масс-балансовые измерения на ледниковом куполе Беллинсгаузен проводились в течение пяти летних сезонов 2007–2012 гг. и одного зимнего в 2011 г. Анализ полученных данных показал, что в 2007/08, 2008/09 и 2011/12 гг. баланс массы льда на куполе был отрицательным, а в 2009/10 и 2010/11 гг. – положительным. Высота границы питания в 2007/08 и 2008/09 гг. располагалась несколько ниже вершины ледникового купола (около 225 м над ур. моря), в 2009/10 г. она опустилась практически до уровня моря, в 2010/11 г. проходила на высоте 180 м над ур. моря, а в 2011/12 г. – около 220 м. Хорошая связь таяния снега и льда со средней летней температурой воздуха позволила восстановить условия таяния на куполе и баланс массы льда по данным метеостанции Беллинсгаузен за весь период наблюдений (1969–2011 гг.). Анализ полученных данных позволяет предположить, что в последние годы наметилась тенденция к похолоданию климата

Glaciers of the northern massif of the Suntar-Khayata Mountains: current state and dynamics since the end of 1950s

The estimation of glaciers of the Suntar-Khayata Mountains (the Northeastern Siberia) in the context of previously published data is presented. Under the background of current warming the glaciers in this region retreat enough quickly, they decrease not only in a real size, but also by the ice thickness. In this paper the mean summer temperature and solid precipitation of the key factors for glaciation, which indicate unfavorable conditions for the glacier existence at present time are presented as spatial distribution of trends (for 45 years, until 2012). The glaciers of the northern massif of the Suntar-Khayata have a negative ice mass balance as their entire surface is below the equilibrium line altitude. Mean thickness of superimposed ice on the glaciers of this massif was about 17 cm. Based on the assumption of climate variation in the Northern Pacific data it is suggested about the beginning of more favorable climatic conditions for the Suntar-Khayata glaciers

Высота границы питания на куполе Беллинсгаузен, Антарктика

We present an analysis of the equilibrium line altitude (ELA) on the Bellingshausen Ice Dome on King George Island (Waterloo), Antarctica, derived only from ground-based glaciological surveys for the period 2007–2012 and 2014–2023. A good relationship was found between ELA and mean summer air temperature (XII-II months) with a coefficient of determination of about 0.8. Assuming the stability of this relation in the past, the changes in the ELA during the entire period of observations at Bellingshausen weather station (from 1968) were reconstructed. Since negative ELA values were obtained for some years, which is physically impossible, they were artificially adjusted to sea level. A good correlation of air temperature between the Bellingshausen and Deception Island weather stations allowed extending the reconstruction of ELA for a longer period (from 1947).By cleaning up the strong interannual f luctuations in ELA using five-year moving averages, two complete periods of ELA change (from minimum to minimum) were identified for approximately 20 years (1947–1968) and 45 years (1968–2013). From 2014 to present time, the third period has been continuing. At the apogee of each period, the ELA was higher than the Bellingshausen Ice Dome height, which indicates that in these years the ice dome completely lost accumulation area. For the Bellingshausen and Warsaw ice domes, a pattern of higher ELA position on the western and southern slopes compared to the eastern slopes was revealed, which is probably applicable to the entire King George Island.Since the ELA variations on King George Island are generally synchronous with its variations on Livingston Island, the reconstructed ELA on the Bellingshausen Ice Dome can probably be useful for reconstructing the glaciation history of the South Shetland Islands. Получены данные о высоте границы питания (ELA) для ледникового купола Беллинсгаузен на острове Кинг-Джордж (Ватерлоо) в Антарктике за 2007–2012 и 2014–2023 гг. Восстановлен характер изменения ELA для купола с 1947 г. по настоящее время. Выявлена синхронность изменения ELA на островах Кинг-Джордж и Ливингстон

Внутренняя дренажная система ледника Альдегонда, Шпицберген, по данным спелеологических исследований

The systems of internal drainage of glaciers have been studied mainly by indirect methods. In order to reveal the structure of the internal drainage network inside Aldegondabreen, moulins and glacial caves were investigated by speleological methods in 2001–2021, which was accompanied by a semi-instrumental topographic survey in the cavities. This allowed us to see the change in the glacial cavities over time. There are three types of moulins in Aldegondadreen: active, dead and healed ones. We visited active and dead moulins. The depth of the entrance pits in the moulins varies from 52 to 65 m (moulin group No 1), from 70 to 75 (moulin group No 2) and from 45 to 60 m (moulin group No 3). The depth of moulins is equal to the thickness of the cold ice layer. Using the structure of the moulins, we show that the water from moulin group No 1 flows to the right marginal part of the glacier tongue. The water from moulin groups No 2 and No 3 flows to the left margin part of the glacier tongue, which is confirmed by the mapping of healed moulins locations. We find that the number of active and dead moulins has been decreasing since 2001, while the number of healed moulins has increased. We attribute this to a decrease in the thickness of the temperate ice layer at the base of the glacier due to climate change. Many moulins have narrow meanders at the lower part of the entrance pits, which usually finish by siphons. None of the moulins reaches the glacier bed, their lower parts are usually located in clean transparent ice. The lifetime of the moulins usually does not exceed 6 years. Our study of the caves on the glacier tongue revealed that they can be englacial or subglacial, and they originate along sub-horizontal thrusts located in the ice. We assume that the moulins reach the slip planes along thrusts close to the glacier bed. The water from the moulins flows along these slip planes as a film in early summer and turns into channels in mid- or late summer. The presence of thrusts in the ice depths can explain the development of internal drainage systems in glaciers (regardless of their size), outbursts of glacial lakes, surges and the formation of eskers. Clastic material for eskers formation can penetrate into a cave channel from the contact areas of the thrusts with uplifts on the bed. The results obtained can help in the interpretation of the available geophysical data for this glacier.В 2001–2021 гг. на леднике Альдегонда проводились исследования ледниковых колодцев и пещер спелеологическими методами для выяснения внутренней дренажной сети ледника. Рассмотрены положение в пространстве и строение обследованных полостей. Выявлено, что пещеры на языке ледника формируются по надвигам в толще льда. Поскольку все обследованные колодцы не достигают ложа ледника, высказано предположение, что вода из колодцев движется к языку ледника по надвигам, которые служат плоскостями скольжения. Полученные результаты могут помочь в интерпретации имеющихся геофизических данных для этого ледника

Летний баланс массы ледникового купола Беллинсгаузен на острове Кинг-Джордж, Антарктика

For the first time the summer mass balance of the Bellingshausen Ice Cap, the King George Island (Water-loo) in Antarctica, was estimated for the period of summer seasons 2007–2012 and 2014–2020. Measurements were carried out over a network of 29 ablation stakes. The contribution to the summer mass balance on the dome includes melting of snow (77%), glacial ice (15%), and superimposed ice (8%). Altitude gradients of snow and ice melting on slopes of different exposition were determined, which changed from –1.5 mm of water equivalent (w.e.) per 1 m on western slope in years with annual positive ice mass balance to –11 mm w.e. per 1 m on southern slope in years with negative ice mass balance. The summer mass balance on the cap was calculated using: 1) the average summer air temperature; 2) the sum of positive daily temperatures from data of the Bellingshausen weather station, 3) sum of average monthly air temperatures. Based on a comparison of colder (2009/10) and warmer (2019/20) years, the average melting coefficient for snow and ice for the glacier was calculated to be 9.5 mm/°C per day (Day Degree Factor – DDF). The high value of the DDF is probably due to intensive summer condensation during periods of frequent foggy weather on King George Island. A good correlation was found between the summer mass balance on the cap and the average summer air temperature at the Bellingshausen weather station for December–March (R2 = 0.9). This shows that the air temperature is the decisive factor of the change in the summer mass balance. Using this correlation, the dynamics of the summer mass balance on the cap was restored for the observation period (1969– 2020), which approximately corresponds to the trends in the annual mass balance on the cap. According to observations, it was found that positive deviation of the average summer air temperature by 0.5 °C from its climatic average value (~1 °C) increases the summer mass balance by 56%, while its negative deviation by 0.5 °C decreases the summer mass balance by 36%. This demonstrates a very high sensitivity of the summer mass balance on the glacier cap to climate changes.По данным полевых наблюдений на куполе Беллинсгаузен (Антарктика) в сезоны абляции 2007–2020 гг. даны оценки общего суммарного таяния, изменения таяния с высотой, определены также доля таяния снега, наложенного и ледникового льда, изменение плотности снега в течение периода абляции, вертикальные градиенты таяния снега и льда на склонах разной экспозиции и температурный коэффициент таяния. На основании полученных данных восстановлен летний баланс массы льда на куполе на период с 1968 по 2020 г. и прогноз изменения летнего баланса при изменении климата

Ледники северного массива гор Сунтар-Хаята: современное состояние и динамика с конца 1950-х годов

The estimation of glaciers of the Suntar-Khayata Mountains (the Northeastern Siberia) in the context of previously published data is presented. Under the background of current warming the glaciers in this region retreat enough quickly, they decrease not only in a real size, but also by the ice thickness. In this paper the mean summer temperature and solid precipitation of the key factors for glaciation, which indicate unfavorable conditions for the glacier existence at present time are presented as spatial distribution of trends (for 45 years, until 2012). The glaciers of the northern massif of the Suntar-Khayata have a negative ice mass balance as their entire surface is below the equilibrium line altitude. Mean thickness of superimposed ice on the glaciers of this massif was about 17 cm. Based on the assumption of climate variation in the Northern Pacific data it is suggested about the beginning of more favorable climatic conditions for the Suntar-Khayata glaciers.В основу работы положены результаты обработки космических снимков Bing Map 2011  г. и материалы полевого сезона 2013  г. Оценено состояние ледников северного массива гор Сунтар-Хаята в продолжение ранее опубликованных работ [4, 5]. На фоне потепления на Северо-Востоке России ледники исследуемого района достаточно быстро деградируют, уменьшается не только их площадь, но и толщина. Полевые исследования показали, что все ледники этого массива в 2011–2013 гг. имели отрицательный баланс массы. За время с малого ледникового периода ледники № 28–31 потеряли около 0,38 км3 льда

Изотопно-кислородный состав льда ледника № 30 в горах Сунтар-Хаята

The object of research is the mountain-valley glacier № 30, located in the central part of the Suntar-Khayatа Ridge – one of the largest centers of modern glaciation of the North-East of Russia. This glacier had been chosen due to lamination of ice on its surface, providing successive sampling of increasingly young ice upward the glacier slope. At the end of August 2013, surface ice of the glacier was sampled within the altitude range 2060–2510, an age of this ice here was estimated to be about 500 years old. Variations of δ18О values in the glacier ice amounted about 5.5‰: from −20.2 to −25.9‰ that is numerically consistent with isotopic values for the neighboring glaciers № 29 and 31. No essential relation between the ice isotopic composition and altitude, age or the change of the ice granularity was found. Absence of high-altitude isotope effect is explained by the fact that preciptation on the glacier № 30 falls at the same level of condensation as well as by intensive infiltration-congelation ice formation and fixation in the firn and snow cover of a part of the meltwater coming from higher and steeper areas on gently sloping sites of the glacier. The δ18О values of ice from glacier № 30 are rather «heavy» for glaciers being formed in severe climate conditions with average January temperature of −28 °C. According to Dansgaard's dependence δ18Оprecipitation – t °Cair the winter snow on the glacier № 30 should be hypothetically characterized by the δ18О values from −30 to −40‰ which are typical ones for the winter snow in Siberia. Oxygen isotope values of the ice show insignificant contribution of winter snow into formation of the glacier and prevalence of spring-autumn snowfalls. No definite trend of changes in the glacier alimentation and the ice-formation process was found for the last 500 years.Рассмотрен изотопно-кислородный состав поверхностного льда ледника №  30 в горах Сунтар- Хаята, отобранного в 2013  г. Вариации δ18О во льду ледника №  30 составили около 5,5‰. При этом не отмечено существенного изменения изотопного состава льда с высотой или с его возрастом. Сопоставлен изотопный состав льда ледника № 30 и зимнего снега, выпадающего в разных районах Сибири. На основании полученных изотопных данных показано, что питание ледника происходит преимущественно за счёт весенне-осенних осадков при незначительном участии зимнего снега

Ice mass balance of the Bellingshausen ice cap in 2007–2012 (King George Island, South Shetland Islands, Antarctica)

Mass balance researches on Bellingshausen Ice Dome (King George Island, archipelago Southern Shetland Islands, Antarctica) were spent during five summer seasons in 2007–1012 and one winter in 2011. The analysis of received data has shown that in 2007/08 and 2008/09 ice mass balance on Bellingshausen Ice Dome was almost closed to zero, in 2009/10, 2010/11 and 2011/12 it was positive. ELA in 2007/08 and 2008/09 was situated a little below top of the Ice Dome (about 225 m a.s.l.), in 2009/10 ELA has lowered practically up to sea level, in 2010/11 it was equal 180 m a.s.l., in 2011/12 – 220 m a.s.l. Good correlation between snow and ice melting and mean summer air temperature give possibility to renew ice melting conditions for all period of observations at Bellingshausen weather station (1969–2011). Ice mass balance for Bellingshausen Ice Dome was also renewed for similar period. Analysis of received data allow to suppose that tendency of climate cooling is outlined in last years

Oxygen isotopic composition of ice of the glacier № 30, Suntar-Khayata Mountains

The object of research is the mountain-valley glacier № 30, located in the central part of the Suntar-Khayatа Ridge – one of the largest centers of modern glaciation of the North-East of Russia. This glacier had been chosen due to lamination of ice on its surface, providing successive sampling of increasingly young ice upward the glacier slope. At the end of August 2013, surface ice of the glacier was sampled within the altitude range 2060–2510, an age of this ice here was estimated to be about 500 years old. Variations of δ18О values in the glacier ice amounted about 5.5‰: from −20.2 to −25.9‰ that is numerically consistent with isotopic values for the neighboring glaciers № 29 and 31. No essential relation between the ice isotopic composition and altitude, age or the change of the ice granularity was found. Absence of high-altitude isotope effect is explained by the fact that preciptation on the glacier № 30 falls at the same level of condensation as well as by intensive infiltration-congelation ice formation and fixation in the firn and snow cover of a part of the meltwater coming from higher and steeper areas on gently sloping sites of the glacier. The δ18О values of ice from glacier № 30 are rather «heavy» for glaciers being formed in severe climate conditions with average January temperature of −28 °C. According to Dansgaard's dependence δ18Оprecipitation – t °Cair the winter snow on the glacier № 30 should be hypothetically characterized by the δ18О values from −30 to −40‰ which are typical ones for the winter snow in Siberia. Oxygen isotope values of the ice show insignificant contribution of winter snow into formation of the glacier and prevalence of spring-autumn snowfalls. No definite trend of changes in the glacier alimentation and the ice-formation process was found for the last 500 years