Petrakov D.,Moscow State University |
Shpuntova A.,Moscow State University |
Aleinikov A.,ETC ScanEX |
Kaab A.,University of Oslo |
And 6 more authors.
Science of the Total Environment
The observed increase in summer temperatures and the related glacier downwasting has led to a noticeable decrease of frozen water resources in Central Asia, with possible future impacts on the economy of all downstream countries in the region. Glaciers in the Ak-Shyirak massif, located in the Inner Tien Shan, are not only affected by climate change, but also impacted by the open pit gold mining of the Kumtor Gold Company. In this study, glacier inventories referring to the years 2003 and 2013 were created for the Ak-Shyirak massif based on satellite imagery. The 193 glaciers had a total area of 351.2 ± 5.6 km2 in 2013. Compared to 2003, the total glacier area decreased by 5.9 ± 3.4%. During 2003-2013, the shrinkage rate of Ak-Shyirak glaciers was twice than that in 1977-2003 and similar to shrinkage rates in Tien Shan frontier ranges. We assessed glacier volume in 2013 using volume-area (VA) scaling and GlabTop modelling approaches. Resulting values for the whole massif differ strongly, the VA scaling derived volume is 30.0-26.4 km3 whereas the GlabTop derived volume accounts for 18.8-13.2 km3. Ice losses obtained from both approaches were compared to geodetically-derived volume change. VA scaling underestimates ice losses between 1943 and 2003 whereas GlabTop reveals a good match for eight glaciers for the period 2003-2012. In comparison to radio-echo soundings from three glaciers, the GlabTop model reveals a systematic underestimation of glacier thickness with a mean deviation of 16%. GlabTop tends to significantly underestimate ice thickness in accumulation areas, but tends to overestimate ice thickness in the lowermost parts of glacier snouts. Direct technogenic impact is responsible for about 7% of area and 5% of mass loss for glaciers in the Ak-Shyirak massif during 2003-2013. Therefore the increase of summer temperature seems to be the main driver of accelerated glacier shrinkage in the area. © 2016 Elsevier B.V. Source
Hausler H.,University of Vienna |
Scheibz J.,University of Vienna |
Leber D.,University of Vienna |
Kopecny A.,University of Vienna |
And 3 more authors.
Austrian Journal of Earth Sciences
The 2009 expedition led to the Inylchek Glacier in eastern Kyrgyzstan, the largest glacier of the Tien Shan with a length of 60,5 kilometers. In this paper we present the results of our investigations in the surroundings of the Northern Inylchek Glacier, namely in the Peremitschka, the seasonally flooded plain situated between the Southern Inylchek Glacier and Upper Lake Merzbacher. During the summer, this plain is flooded by melt water discharged from the Northern Inylchek Valley, creating the up to 120 m deep Lower Lake Merzbacher, which regularly bursts out and releases its water through an englacial piping system of the Southern Inylchek Glacier in. It is due to this unique phenomenon that Lower Lake Merzbacher has been the subject of study by scientists on numerous expeditions during the last century. As a mapping basis for our field works, we used an enlarged scene acquired in September 2005 from the Quickbird satellite with 60 cm ground resolution. For identification of advancing and retreating parts of the Inylchek Glacier system, a pan-sharpened Landsat 7 ETM+ scene (bands 1, 4 and 7) with a ground resolution of 15 m acquired in 2006 was used. A time series analysis of aerial photos dating from 1943 and 1956 was compared to the Quickbird scene from 2005 and revealed first the retreat and later the rapid advance of the Northern Inylchek Glacier along a distance of at least two kilometres. Since neither indications of a glacier lake outburst around Upper Lake Merzbacher nor stretched ogives or erosional scars in the Northern Inylchek Glacier implying a rapid surge could be detected, the mechanism of this fluctuating glacier is subject to ongoing investigations. Our helicopter-supported campaign in the Peremitschka at altitudes between 3300 and 3500 meters lasted only four days. For the glaciogeologic and geomorphologic interpretation of remote sensing imageries we used geophysical methods such as electric resistivity tomography (ERT) and frequency domain electromagnetics (FDEM). The 800 m long ERT-profile crossing the Peremitschka plain revealed resistivities ranging from 6 Ohmmeter (ohm.m) in the near subsurface to 100.000 ohm.m down to a depth of 45 meters. A series of thin, undulated, low-resistivity layers are underlain by a thick high-resistivity layer, which has been interpreted as dead ice from the formerly advancing Northern Inylchek Glacier. A small river flows down the Northern Inylchek Valley, here termed "Merz Rivulet" or "Merzbach", with a flow of about 30 m3 /second. Along its course it has locally eroded the Peremitschka plain to a depth of 20-25 meters. This steep slope within the Peremitschka reveals an intercalation of silty calcareous lake deposits with ice layers and ice lenses respectively. These outcrops have been interpreted as near subsurface permafrost layers, which can be correlated with the undulated low-resistivity layer of the ERT-profile. Additionally, high resolution mapping of this permafrost zone using frequency domain electromagnetics with 2525 Hertz (Hz) and 5025 Hz revealed cone-like depressions, which were interpreted as glacier karst. Source
Barandun M.,University of Fribourg |
Huss M.,University of Fribourg |
Huss M.,ETH Zurich |
Sold L.,University of Fribourg |
And 7 more authors.
Journal of Glaciology
Abramov glacier, located in the Pamir Alay, Kyrgyzstan, is a reference glacier within the Global Terrestrial Network for Glaciers. Long-term glaciological measurements exist from 1968 to 1998 and a mass-balance monitoring programme was re-established in 2011. In this study we re-analyse existing mass-balance data and use a spatially distributed mass-balance model to provide continuous seasonal time series of glacier mass balance covering the period 1968-2014. The model is calibrated to seasonal mass-balance surveys and then applied to the period with no measurements. Validation and recalibration is carried out using snowline observations derived from satellite imagery and, after 2011, also from automatic terrestrial camera images. We combine direct measurements, remote observations and modelling. The results are compared to geodetic glacier volume change over the past decade and to a ground-penetrating radar survey in the accumulation zone resolving several layers of accumulation. Previously published geodetic mass budget estimates for Abramov glacier suggest a close-to-zero mass balance for the past decade, which contradicts our results. We find a low plausibility for equilibrium conditions over the past 15 years. Instead, we suggest that the glacier's sensitivity to increased summer air temperature is decisive for the substantial mass loss during the past decade. Source
Kronenberg M.,University of Fribourg |
Barandun M.,University of Fribourg |
Hoelzle M.,University of Fribourg |
Huss M.,University of Fribourg |
And 8 more authors.
Annals of Glaciology
This 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 ± 10mw.e. a-1. This result agrees well with the geodetic balance of -0.48 ± 0.07mw.e. a-1over the same period. Source