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ABSTRACT. This study presents a reconstruction of the mass balance (MB) of Chhota Shigri glacier, Western Himalaya, India, and discusses the regional climatic drivers responsible for its evolution since

International audienceLittle is known about the Himalayan glaciers, although they are of particular interest in terms of future water supply, regional climate change and sea-level rise. In 2002, a long-term monitoring programme was started on Chhota Shigri Glacier (32.2°N, 77.5°E; 15.7 km2, 6263-4050 m a.s.l., 9 km long) located in Lahaul and Spiti Valley, Himachal Pradesh, India. This glacier lies in the monsoon-arid transition zone (western Himalaya) which is alternately influenced by Asian monsoon in summer and the mid-latitude westerlies in winter. Here we present the results of a 4 year study of mass balance and surface velocity. Overall specific mass balances are mostly negative during the study period and vary from a minimum value of -1.4 m w.e. in 2002/03 and 2005/06 (equilibrium-line altitude (ELA) ∼5180 m a.s.l.) to a maximum value of +0.1 m w.e. in 2004/05 (ELA 4855 m a.s.l.). Chhota Shigri Glacier seems similar to mid-latitude glaciers, with an ablation season limited to the summer months and a mean vertical gradient of mass balance in the ablation zone (debris-free part) of 0.7 m w.e. (100 m)-1, similar to those reported in the Alps. Mass balance is strongly dependent on debris cover, exposure and the shading effect of surrounding steep slopes

International audienceMass-balance and dynamic behaviour of Chhota Shigri Glacier have been investigated between 2002 and 2010 and compared to data collected in 1987/1989. During the period 2002/2010, the glacier experienced a negative glacier-wide mass balance of -0.67 ± 0.40 m/a w.e. Between 2003 and 2010, elevation and ice flow velocities are slowly decreasing in the ablation area leading to a 24 to 37% reduction in ice fluxes, an expected response of the glacier dynamics to its recent negative mass balances. The reduced ice fluxes still remain far larger than the balance fluxes calculated from the year 2002 to 2010 average surface mass balances. Therefore, further slow down, thinning and terminus retreat of Chhota Shigri Glacier are expected over the next years. Conversely, the 2003/2004 ice fluxes are in good agreement with ice fluxes calculated assuming that the glacier-wide mass balance is zero. Given the limited velocity change between 1987/1989 and 2003/2004 and the small terminus change between 1988 and 2010, we suggest that the glacier has experienced a period of near zero or slightly positive mass balance in the 1990s, before shifting to a strong imbalance in the 21st century. This result challenges the generally accepted idea that glaciers of Western Himalaya have been shrinking rapidly for the last decades

Abstract. Few glaciological field data are available on glaciers in the Hindu Kush-Karakoram-Himalayan (HKH) region, and remote sensing data are thus critical for glacier studies in this region. The main objectives of this study are to document, using satellite images, the seasonal changes of surface albedo for two Himalayan glaciers, Chhota Shigri Glacier (Himachal Pradesh, India) and Mera Glacier (Everest region, Nepal), and to reconstruct the annual mass balance of these glaciers based on the albedo data. Albedo is retrieved from Moderate Resolution Imaging Spectroradiometer (MODIS) images, and evaluated using ground based measurements. At both sites, we find high coefficients of determination between annual minimum albedo averaged over the glacier (AMAAG) and glacier-wide annual mass balance (B a ) measured with the glaciological method (R 2 = 0.75). At Chhota Shigri Glacier, the relation between AMAAG found at the end of the ablation season and B a suggests that AMAAG can be used as a proxy for the maximum snow line altitude or equilibrium line altitude (ELA) on winteraccumulation-type glaciers in the Himalayas. However, for the summer-accumulation-type Mera Glacier, our approach relied on the hypothesis that ELA information is preserved during the monsoon. At Mera Glacier, cloud obscuration and snow accumulation limits the detection of albedo during the monsoon, but snow redistribution and sublimation in the post-monsoon period allows for the calculation of AMAAG. Reconstructed B a at Chhota Shigri Glacier agrees with mass balances previously reconstructed using a positive degreeday method. Reconstructed B a at Mera Glacier is affected by heavy cloud cover during the monsoon, which systematically limited our ability to observe AMAAG at the end of the melting period. In addition, the relation between AMAAG and B a is constrained over a shorter time period for Mera Glacier (6 years) than for Chhota Shigri Glacier (11 years). Thus the mass balance reconstruction is less robust for Mera Glacier than for Chhota Shigri Glacier. However our method shows promising results and may be used to reconstruct the annual mass balance of glaciers with contrasted seasonal cycles in the western part of the HKH mountain range since the early 2000s when MODIS images became available.