FRESH-WATER BUDGET OF POLAR-REGIONS - ESTIMATES FROM MODELS OF THE ATMOSPHERIC GENERAL-CIRCULATION

Within the framework of the international Atmospheric Model Intercompa rison Project (AMIP), the components of the freshwater budget are anal yzed for three polar regions-the Arctic Ocean, Greenland, and Antarcti ca. The results of modeling precipitation, evaporation, and snow-mass evolution (on the sea ice and glaciers) on the basis of 23 models of t he atmospheric general circulation are compared with each other and wi th available observational data. There are great discrepancies in exis ting climatologies of precipitation in polar regions. In the regions u nder consideration, most models overestimate precipitation and the dif ference between precipitation and evaporation. The models demonstrate a wide scatter in annual mean values and seasonal variability of the a bove components of the freshwater budget, which is frequently greater than the uncertainty of estimates obtained from observational data. Pa rticular emphasis is given to the evolution of snow masses on glaciers . The significance of different elements of the hydrologic cycle of Gr eenland and Antarctica is discussed from the standpoint of their mass balance.