Mass balance of Muji Glacier, northeastern Pamir, and its controlling climate factors

•Mass balance on Muji Glacier was slightly negative, with an average value of −276 mm w.e. yr−1.•Muji Glacier could readily reach a zero mass balance under present climate conditions.•Used a method to assess mainly factors controlling interannual variability of glacier mass balance.•Precipitation is a stronger control than air temperature on interannual changes in mass balance of Muji Glacier. The lack of glacier mass balance and meteorological data limit our knowledge of the spatial pattern of glacier changes in the Pamir. Based on meteorological measurements and mass balance records for Muji Glacier in the northeastern Pamir during 2011–2017, the temporal variations in energy and mass balance, and the response of mass balance to climate variations, were investigated using the energy-mass balance model. The model was assessed by the measurements of seasonal mass balance and snow thickness at different altitudes and seasonal glacier-wide mass balance. Results reveal that glacier-wide mass balance was slightly negative (mean: −276 mm w.e. yr−1) on Muji Glacier which could readily reach a zero mass balance under the present climatic conditions. In addition, a method is proposed for assessing whether melt-season air temperature (Ta) or precipitation (P) is more important for controlling interannual variability of glacier mass balance on the Tibetan Plateau, based on limited observations. This method is based on sensitivity analysis and the interannual variability of Ta and P, and shows that P (particularly P in the melt season) is a stronger control than Ta on interannual changes in mass balance variations of Muji Glacier, through the influence of P on albedo, melt energy and snow accumulation. In addition, a comparative analysis shows that smaller snowfall (resulting from lower P) and larger melt (linked to higher incoming longwave radiation and Ta) cause the more negative glacier mass balance in the northeastern Pamir than in the western Kunlun mountains.