Mass- and Energy-Balance Modeling and Sublimation Losses on Dokriani Bamak and Chhota Shigri Glaciers in Himalaya Since 1979

Available surface energy balance (SEB) studies on the Himalayan glaciers generally investigate the melt-governing energy fluxes at a point-scale. Further, the annual glacier-wide mass balance (B-a) reconstructions have often been performed using temperature-index (T-index) models. In the present study, a mass- and energy-balance model is used to simulate the B-a on Dokriani Bamak Glacier (DBG, central Himalaya) and Chhota Shigri Glacier (CSG, western Himalaya) using the bias-corrected ERA5 data from 1979 to 2020. The model is calibrated using in-situ B-a and validated against available in-situ altitudinal and geodetic mass balances. DBG and CSG show mean B-a of -0.27 +/- 0.32 and -0.31 +/- 0.38 m w.e. a(-1) (meter water equivalent per year), respectively, from 1979 to 2020. Glacier-wide net shortwave radiation dominates the SEB followed by longwave net radiation, latent heat flux, and sensible heat flux. The losses through sublimation are around 22% on DBG and 20% on CSG to the total ablation with a strong spatial and temporal variability. Modeled B-a is highly sensitive to snow albedo -with sensitivities of 0.29 and 0.37 m w.e. a(-1) for 10% change in the calibrated value-on DBG and CSG, respectively. The sensitivity of the modeled mean B-a to 1 degrees C change in air temperature and 10% change in precipitation, respectively is higher on DBG (-0.50 m w.e. a(-1 degrees)C(-1), 0.23 m w.e. a(-1)) than the CSG (-0.30 m w.e. a(-1 degrees)C(-1), 0.13 m w.e. a(-1)). This study provides insights into the regional variations in mass-wastage governing SEB fluxes at a glacier-wide scale, which is helpful for understanding the glacier-climate interactions in the Himalaya and stresses an inclusion of sublimation scheme in T-index models.

Automated summary

This study uses a balance model to simulate the glacier-wide mass balance on Dokriani Bamak Glacier and Chhota Shigri Glacier, revealing significant spatial and temporal variability in their B-a.