Mass-balance observation, reconstruction and sensitivity of Stok glacier, Ladakh region, India, between 1978 and 2019

Abstract

We present the first-ever mass-balance (MB) observation (2014-19), reconstruction (between 1978 and 2019) and sensitivity of debris-free Stok glacier (33.98°N, 77.45°E), Ladakh Region, India. In-situ MB was negative throughout the study period except in 2018/19 when the glacier witnessed a balanced condition. For MB modelling, three periods were considered based on the available data. Period I (1978-87, 1988/89) witnessed a near balance condition (-0.03 ± 0.35 m w.e. a-1) with five positive MB years. Whereas Period II (1998-2002, 2003-09) and III (2011-19) experienced high (-0.9 ± 0.35 m w.e. a-1) and moderate (-0.46 ± 0.35 m w.e. a-1) negative MBs, respectively. Glacier area for these periods was derived from the Corona, Landsat and PlanetScope imageries using a semi-automatic approach. The in-situ and modelled MBs were in good agreement with RMSE of 0.23 m w.e. a-1, R= 0.92, P < 0.05. The average mass loss was moderate (-0.47 ± 0.35 m w.e. a-1) over 28 hydrological years between 1978 and 2019. Sensitivity analysis showed that the glacier was more sensitive to summer temperature (-0.32 m w.e. a-1 °C-1) and winter precipitation (0.12 m w.e. a-1 for ± 10%). It was estimated that ~27% increase in precipitation is required on Stok glacier to compensate for the mass loss due to 1°C rise in temperature.