Estimation of Mass Balance Components of a Summer-Accumulation Type Glacier in the Nepal Himalaya

Patterns of annual variation of air temperature in the world provide two types of the patterns of ablation rate of the glacier, namely the “summer-maximum” and the “non-maximum” through a year, while those of precipitation and air temperature provide three types of accumulation rate, namely, the above two and the “winter-maximum”. In six combinations of these types, annual variation of balance rate can be classified into the types of the winter-maximum, the non-maximum and the summer-maximum. The “summer-accumulation type glaciers” in the Nepal Himalaya, which have more accumulation in summer than winter in the whole area of a glacier, belong to the non-maximum type of balance rate.In the case of this type glacier, direct observations of accumulation and ablation are quite difficult, since accumulation and ablation mainly occur simultaneously in summer. Therefore, the methods of estimation of accumulation and ablation are discussed. Accumulation can be estimated on the basis of the linear relation between surface air temperature and the probability of occurrence of solid precipitation in all cases of precipitation. Local characteristics of melting process of precipitation elements which control such relation are described. For the estimation of ablation, the effect of high albedo of new snow is important for the summer-accumulation type. The variation of mass balance through the balance year in the case of the summer-accumulation type is compared with that of the winter-accumulation type.