Measurement and estimative models of glacier mass balance in China

Attributed to high altitude and inland location, the glaciers in China are characterized by very low temperature. The non-negligible contribution of u p to 25% of superimposed ice to the net balance has been taken into account in the mass budget calculation. So too has the internal the accumulation i n the infiltration zone of the accumulation area. The prevailing monsoon climate delivers most of the annual precipitation ov er glaciated areas of China in the summer, making the major accumulation on those glaciers coincide with the ablation period. Therefore, the annual ma ss balance should be calculated neither by giving the place of annual accum ulation to winter balance, nor annual ablation to summer balance. Rather, i t is better done by net accumulation and net ablation during the year. In o rder to get the annual accumulation and the annual ablation on a glacier, t he summer precipitation should be measured at the same time. Frequent snowfall in the summer season results in intensive fluctuation of surface albedo. This means that, for lack of data on the extremes of ablati on, reconstruction of mass balance is unsatisfactory when based on the rela tionships of accumulation and ablation to precipitation and temperature. Th e establishment of models, either on the relationship of multi-year mass ba lance to the equilibrium line and the mass balance gradient of a glacier in steady-state, or on the maximum entropy principle and the hydrometeorologi cal data. helps to estimate the multi-year mass balance of the glacierized area in a mountain range or drainage basin.