12 research outputs found
Changes of the Abramov Glacier (Alay Ridge) from 1850 to 2014
Get PDFThe purpose of this study was to determine the nature and rate of changes of the Abramov glacier over the period from 1850 to 2014. The glacier is located on the Alay Ridge in Kyrgyzstan. Its borders were estimated by means of interpretation and analysis of space images from the satellites Landsat-2, 5, 7, 8, KH-4А and KH-9 (program Corona), Geoеye-1 together with aerial photographs and topographical maps, and with addition of results of the field survey of the glacier’s tongue by GPS instruments. As a result, we could find that the longstanding degradation of the glacier continued over the whole period under investigation, and against the background of that there were periods of relative stabilization of the front of the tongue as well as the periods of the glacier advances of different duration and intensity. In 1850, the total area of the glacier accounted for 26.4 km2, but by 2014 it reduced by 3.65 km2, or 13.8%, and became equal to 22.75 km2. Thus, annual reduction of the glacier area was equal approximately to 0.02 km2 per a year, and its length decreased by almost 2950 m, i.e., the glacier contracted, on the average, by 18 m per a year. It should be noted that changes of the glacier area were similar during both the initial and final periods of observations, and it means that no intensification of anthropogenic impact upon the glacier was observed. Obviously, this fact is indicative of the prevalence of natural factors in the change of the glacier, expressed in irregular duration of cyclic changes
Изменения ледника Абрамова (Алайский хребет) c 1850 по 2014 г.
Get PDFThe purpose of this study was to determine the nature and rate of changes of the Abramov glacier over the period from 1850 to 2014. The glacier is located on the Alay Ridge in Kyrgyzstan. Its borders were estimated by means of interpretation and analysis of space images from the satellites Landsat-2, 5, 7, 8, KH-4А and KH-9 (program Corona), Geoеye-1 together with aerial photographs and topographical maps, and with addition of results of the field survey of the glacier’s tongue by GPS instruments. As a result, we could find that the longstanding degradation of the glacier continued over the whole period under investigation, and against the background of that there were periods of relative stabilization of the front of the tongue as well as the periods of the glacier advances of different duration and intensity. In 1850, the total area of the glacier accounted for 26.4 km2, but by 2014 it reduced by 3.65 km2, or 13.8%, and became equal to 22.75 km2. Thus, annual reduction of the glacier area was equal approximately to 0.02 km2 per a year, and its length decreased by almost 2950 m, i.e., the glacier contracted, on the average, by 18 m per a year. It should be noted that changes of the glacier area were similar during both the initial and final periods of observations, and it means that no intensification of anthropogenic impact upon the glacier was observed. Obviously, this fact is indicative of the prevalence of natural factors in the change of the glacier, expressed in irregular duration of cyclic changes.Цель данного исследования – определить характер и скорость изменения ледника Абрамова. Методика определения границ ледника за 1850–2014 г. предусматривала дешифрирование и анализ космических снимков спутников Landsat-2, 5, 7, 8, KH-4А, KH-9 программы Corona, Geoеye-1, аэрофотоснимков и топографических карт, а также съёмку в полевых условиях границ языка ледника с помощью GPS-приборов. В эти годы продолжалась деградации ледника Абрамова, его площадь сократилась на 3,65 км2, т.е. на 13,8%. Средняя скоростью сокращения площади ледника составила около 0,02 км2/год
Multi-decadal mass balance series of three Kyrgyz glaciers inferred from transient snowline observations
No full textAbstract. Glacier mass balance observations in the Tien Shan and Pamir mountains are sparse and often discontinuous. Nevertheless, glaciers are one of the most important components of the high-mountain cryosphere in the region; they strongly influence water availability in the arid, continental and intensely populated downstream areas. This study provides reliable and continuous mass balance series for selected glaciers located in the Tien Shan and Pamir-Alay. A combination of three independent methods was used to reconstruct for the past two decades the mass balance of the three benchmark glaciers, Abramov, Golubin and No. 354. By applying different approaches, it was possible to compensate for the limitations and shortcomings of each individual method. This study proposes the use of transient snowline observations throughout the melting season obtained from satellite imagery and terrestrial automatic cameras. By combining modelling with remotely acquired information on summer snow depletion, it was possible to infer glacier mass changes for unmeasured years. Multi-annual mass changes based on high accuracy digital elevation models and in situ glaciological surveys were used to validate the results for the investigated glaciers. Substantial mass loss was confirmed for the three studied glaciers by all three methods, ranging from −0.30 ± 0.19 m w. e. a−1 to −0.41 ± 0.33 m w. e. a−1 over the 2004–2016 period. Our results indicate that integration of snowline observations into mass balance modelling significantly narrows the uncertainty ranges of the estimates, and hence highlights the potential of the methodology for application to inaccessible glaciers at larger scales for which no direct measurements are available.
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Mass-balance reconstruction for Glacier No. 354, Tien Shan, from 2003 to 2014
No full textThis study presents a reconstruction of the seasonal mass balance of Glacier No. 354, located in the Akshiirak range, Kyrgyzstan, from 2003 to 2014. We use a distributed accumulation and temperature-index melt model driven by daily air temperature and precipitation from a nearby meteorological station. The model is calibrated with in situ measurements of the annual mass balance collected from 2011 to 2014. The snow-cover depletion pattern observed using satellite imagery provides additional information on the dynamics of mass change throughout the melting season. Two digital elevation models derived from high-resolution satellite stereo images acquired in 2003 and 2012 are used to calculate glacier volume change for the corresponding period. The geodetic mass change thus derived is used to validate the modelled cumulative glacier-wide balance. For the period 2003–12 we find a cumulative mass balance of –0.40∓10 m w.e. a–1. This result agrees well with the geodetic balance of –0.48∓0.07 m w.e. a–1 over the same period
Multi-decadal mass balance series of three Kyrgyz glaciers inferred from modelling constrained with repeated snow line observations
Get PDFGlacier surface mass balance observations in the Tien Shan and Pamir are
relatively sparse and often discontinuous. Nevertheless, glaciers are one of
the most important components of the high-mountain cryosphere in the region
as they strongly influence water availability in the arid, continental and
intensely populated downstream areas. This study provides reliable and
continuous surface mass balance series for selected glaciers located in the
Tien Shan and Pamir-Alay. By cross-validating the results of three
independent methods, we reconstructed the mass balance of the three benchmark
glaciers, Abramov, Golubin and Glacier no. 354 for the past 2 decades. By
applying different approaches, it was possible to compensate for the
limitations and shortcomings of each individual method. This study proposes
the use of transient snow line observations throughout the melt season
obtained from satellite optical imagery and terrestrial automatic cameras. By
combining modelling with remotely acquired information on summer snow
depletion, it was possible to infer glacier mass changes for unmeasured
years. The model is initialized with daily temperature and precipitation data
collected at automatic weather stations in the vicinity of the glacier or
with adjusted data from climate reanalysis products. Multi-annual mass
changes based on high-resolution digital elevation models and in situ
glaciological surveys were used to validate the results for the investigated
glaciers. Substantial surface mass loss was confirmed for the three studied
glaciers by all three methods, ranging from −0.30 ± 0.19 to
−0.41 ± 0.33 m w.e. yr−1 over the 2004–2016 period. Our
results indicate that integration of snow line observations into mass balance
modelling significantly narrows the uncertainty ranges of the estimates.
Hence, this highlights the potential of the methodology for application to
unmonitored glaciers at larger scales for which no direct measurements are
available
Spatiotemporal climate and atmospheric circulation variability in Asia inferred from tree rings
No full textObserved 20th century warming trends accompanied by more frequent weather extremes such as droughts or intense rainfall events have consequences for societies and environments alike. In Asia, where the majority of the population depend on agricultural productivity, recent climate change is likely to increase societal hardships. In order to quantify future climate variability, it is vital to understand past climate variability with respect to its magnitude, frequency and more importantly, its underlying physical processes. Since instrumental data scarcely extends into the pre-1950 era in Asia, annually resolved proxy data such as tree rings provide unique and continuous estimates of past climate and atmospheric circulation variability.
This thesis presents a comprehensive assessment of the relationship between tree growth and environmental factors using local to continental-scale tree-ring networks in Asia. In this regard, new tree-ring chronologies were developed for Central Asia in order to increase the spatial coverage of the existing proxy network. Analyses of five tree-ring width networks were conducted to identify the dominant climate and atmospheric circulation patterns that influence tree growth in Asia.
Based on 38 newly developed juniper (Juniperus sp.) tree-ring chronologies including 1069 trees from the northern Pamir-Alay and Tien Shan mountain ranges in Central Asia, the first detailed study of spatial patterns and temporal trends in species- and site-specific climate response was conducted. Our results show that juniper growth at lower elevation sites was significantly limited by drought conditions, which has increased in intensity over the past decades, hence, making those sites highly suitable for drought reconstructions. The majority of juniper trees at high elevation sites, however, showed a distinct growth-climate response shift. In the early to mid- 20th century, juniper growth was favored by warm summer temperatures, while in the most recent decades, it was negatively affected by increasing summer aridity.
By calculating a new index that represents the tree growth relevant circulation pattern at the site during the summer, it was possible to describe leading patterns of the atmospheric circulation for a regional- and a continental-scale tree-ring network in Asia. The main results indicate that pressure anomalies over northwestern Russia had a major impact on tree growth not only in continental regions but also in monsoon influenced parts of Asia. The identified tree growth relevant circulation patterns show a significant spatiotemporal resemblance to leading patterns of pressure anomalies from climate data. Furthermore, the tree growth derived circulation patterns show strong linkages to the North Atlantic sector even further back in time (as far as AD 1600), and can be linked to the Northern Hemisphere atmospheric circulation system.
The findings presented in this thesis enhance our understanding of the influence of environmental factors on tree growth in Asia. Moreover, tree rings are shown to be a highly suitable proxy for reconstructing and investigating past climate and atmospheric circulation variability in Asia
Climate Change Increases Drought Stress of Juniper Trees in the Mountains of Central Asia.
Get PDFAssessments of climate change impacts on forests and their vitality are essential for semi-arid environments such as Central Asia, where the mountain regions belong to the globally important biodiversity hotspots. Alterations in species distribution or drought-induced tree mortality might not only result in a loss of biodiversity but also in a loss of other ecosystem services. Here, we evaluate spatial trends and patterns of the growth-climate relationship in a tree-ring network comprising 33 juniper sites from the northern Pamir-Alay and Tien Shan mountain ranges in eastern Uzbekistan and across Kyrgyzstan for the common period 1935-2011. Junipers growing at lower elevations are sensitive to summer drought, which has increased in intensity during the studied period. At higher elevations, juniper growth, previously favored by warm summer temperatures, has in the recent few decades become negatively affected by increasing summer aridity. Moreover, response shifts are observed during all seasons. Rising temperatures and alterations in precipitation patterns during the past eight decades can account for the observed increase in drought stress of junipers at all altitudes. The implications of our findings are vital for the application of adequate long-term measures of ecosystem conservation, but also for paleo-climatic approaches and coupled climate-vegetation model simulations for Central Asia
Методика оценки лавинного питания (на примере трёх ледников Тянь-Шаня)
Get PDFThe contribution of snow avalanches to the seasonal snow accumulation on a glacier is among the least studied components of the glacier’s mass balance. The methods for the numerical assessment of avalanche accumulation are still under development, which is related to poor avalanche data availability and difficulties in obtaining such data on most of mountain glaciers. We propose a possible methodology for the numerical assessment of snow avalanche contribution to snow accumulation at mountain glaciers based on DEM and weather data analysis using GIS and numerical modeling of snow avalanches. The developed methodology consists of the following steps: terrain analysis; weather data analysis; snow avalanche volume assessment during an analyzed balance year; numerical simulation of snow avalanches using RAMMS; evaluation of snow avalanches contribution into a glacier accumulation. The proposed methodology was tested on three glaciers located in the Inner Tien Shan: Batysh Sook, № 354 and Karabatkak during the 2015/16 balance year. To evaluate snow avalanche contribution to the seasonal accumulation, we reconstructed avalanche release zones that were most probably active during the 2015/16 balance year and corresponding snow fracture height in each of these zones. The numerical simulations of most probable released snow avalanches during the winter period 2015/16 using avalanche dynamics software RAMMS were performed and compared with the field observations and UAV orthophoto image from July 2016. The outlines of avalanches deposits were realistically reproduced by RAMMS according to the results of field observation. The estimated share of snow avalanche contribution to the accumulation on the research glaciers during the 2015/16 balance year turned out to be: Batysh Sook – 7,4±2,5%; № 354 – 2,2±0,7%; Karabatkak – 10,8±3,6% of the total accumulation. The next step would be to test the proposed methodology based on the data and regional dependences from the Inner Tien Shan in other mountainous regions. This methodology is applicable in the regions where DEMs, regular meteorological observations as well as data on the regional avalanche formation factors are available.Предложена новая методика количественной оценки лавинного питания ледников, основанная на анализе рельефа и данных метеорологических наблюдений с использованием методов геоинформационного картографирования и математического моделирования. Рассмотрены результаты её применения на трёх ледниках Тянь-Шаня: Западный Суёк, № 354, Карабаткак
Результаты геодезических измерений баланса массы некоторых ледников Заилийского Алатау
Get PDFSummaryThe current state and mass balance of some glaciers of the Trans-Ili Alatau (Zailiyskiy Alatau, Tien Shan, Kazakhstan) is estimated in the paper. The remote sensing data (images of the Pléiades satellites) and detailed field geodetic measurements (differential global positioning system with the South G6 instrument)were used for the analysis. The field works were carried out in August-September 2021on the northern slope of the Zailiyskiy Alatau ridge. A digital relief model had been built for the analysis as well. Negative trends in the area of the studied glaciers have been revealed, which generally correspond to the average rate of degradation of the glaciation of the Trans-Ili Alatau from 1955 to the present. A comparison of glaciological (contact, i.e., obtained as a result of measurements made on the glacier) and geodetic (resulted from analysis of remote sensing data) methods for estimating the annual mass balance of the Central Tuyuksu glacier for the period 2016-2021 showed that the final values calculated by these two methods are very close in values. For example, the sum of annual balances calculated by the glaciological method for this period was -2.9 m w.e., or -0.58 a-1 m w.e. per a year, while the balance calculated by the geodetic method for the same period was - 0.63 a-1 m w.e. Thus, the results of comparison of the above methods of the glacier mass-balance investigation confirm that the geodetic one based on satellite measurements and the ground surveys using the South G6 instrument is in a good agreement with results of glaciological methods of measurements and calculations.Деградация оледенения вызывает изменения в горных экосистемах, оказывая непосредственное влияние на жизнедеятельность людей, вызывает изменения в гидрологическом режиме, биогеохимии рек и гляциальных озёр, влияя на качество и доступность водных ресурсов. Рассмотрены вопросы оценки баланса массы ледников северного склона Заилийского (Иле) Алатау посредством применения данных дистанционного зондирования Земли (ДЗЗ) в сочетании с полевыми исследованиями и измерениями
Re-establishing glacier monitoring in Kyrgyzstan and Uzbekistan, Central Asia
Get PDFGlacier mass loss is among the clearest indicators of atmospheric warming.
The observation of these changes is one of the major
objectives of the international climate monitoring strategy developed by the Global Climate Observing System (GCOS).
Long-term glacier mass
balance measurements are furthermore the basis for calibrating and validating models simulating future runoff of glacierised
catchments. This is essential for Central Asia, which is one of the driest continental regions of the Northern Hemisphere. In the
highly populated regions, water shortage due to decreased glacierisation potentially leads to pronounced political instability,
drastic ecological changes and endangered food security. As a consequence of the collapse of the former Soviet Union, however, many
valuable glacier monitoring sites in the Tien Shan and Pamir Mountains were abandoned. In recent years, multinational actors have
re-established a set of important in situ measuring sites to continue the invaluable long-term data series. This paper introduces the
applied monitoring strategy for selected glaciers in the Kyrgyz and Uzbek Tien Shan and Pamir, highlights the existing and the new
measurements on these glaciers, and presents an example for how the old and new data can be combined to establish multi-decadal mass
balance time series. This is crucial for understanding the impact of climate change on glaciers in this region
