SUPERIMPOSED ICE IN GLACIER MASS-BALANCE ON THE TIBETAN PLATEAU

The relations between mass balance and meltwater refreezing were exami ned on the basis of glaciological observations carried out in summer 1 993 on Xiao Dongkemadi Glacier, Tanggula Mountains, central Tibetan Pl ateau. On this glacier, a part of meltwater refreezes at the snow/ice interface as superimposed ice. The amount of superimposed ice formatio n was determined by both meltwater supply and temperature condition of the glacier. Snow-layer thickness on the glacier ice body is less tha n 2 m, even in the higher accumulation zone. About 60% of meltwater ge nerated in the accumulation zone for the period May-September was trap ped at the snow/ice interface by refreezing, and was not discharged ou t of the glacier. About 26% of accumulated snow to the glacier surface was replaced on the snow/ice interface by refreezing in the accumulat ion zone. These facts indicate that superimposed ice formation is quit e significant for water retention in glaciers under low-precipitation conditions.