Re-analysis of seasonal mass balance at Abramov glacier 1968–2014

Abstract

ABSTRACT. 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.

Mass balance observations and reconstruction for Batysh Sook Glacier, Tien Shan, from 2004 to 2016

“…354 (Kronenberg et al, 2016), the measured mass balance of Tuyuksu and Urumqihe No.1 (e.g. WGMS, 2014), reconstructed values for Gregoriev Glacier (Fujita et al, 2011) located in the Tien Shan, and Abramov in the Pamir-Alay (Barandun et al, 2015). For all glaciers, annual mass balances were negative, with the exception of the hydrological year 2008/09, in which a positive or an almost balanced mass budget was found.…”

“…From the delineation of the snowline it becomes possible to calculate the snow-covered area fraction (SCAF), which is the glacier area covered by snow in relation to the total area of the glacier at this time. Comparison of the SCAF derived from remotely sensed images with the modelled SCAF for the exact same date enables an independent model validation to be performed (Barandun et al, 2015;Kronenberg et al, 2016). We found a total of 57 Landsat scenes with sufficient visibility for observing SCAFs (Table 1).…”

Review of the status and mass changes of Himalayan-Karakoram glaciers

“…However, remote-sensing estimates themselves carry their own uncertainty, as illustrated by the fact that the glacier-wide mass balance in the Langtang area (Nepal) had to be revisited by Ragettli and others (2016) compared with a similar earlier assessment by Pellicciotti and others (2015). Two major sources of uncertainty in DEM-based geodetic mass-balance estimates are the poor quality of DEM in the texture-less accumulation areas (Ragettli and others, 2016) and the unknown penetration of the SRTM C-band and X-band radar signal into dry snow and firn (Barandun and others, 2015;Kääb and others, 2015;Dehecq and others, 2016;Round and others, 2017).…”

Observation-Based Estimates of Global Glacier Mass Change and Its Contribution to Sea-Level Change

“…By all means, satellites provide information that is complementary to field observations, in particular when it comes to complete spatial coverage and remote regions. Moreover, they also provide observations for time periods that are not covered by field observations (Barandun et al 2015) or products that are difficult to obtain in the field or from airborne remote sensing. For the time period they cover, their particular strength is in global scale observations with consistent and reproducible methods.…”

“…Finally, estimates of the mass balance may be obtained by determining the accumulation area ratio through remote sensing (Rabatel et al 2008;Barandun et al 2015). However, because of the required manual delineation of the snow line, this is not done frequently.…”