SPATIAL AND TEMPORAL VARIABILITY OF ANTARCTIC PRECIPITATION FROM ATMOSPHERIC METHODS

The spatial and temporal variability of net precipitation (precipitati on minus evaporation/sublimation) for Antarctica derived from the Euro pean Centre for Medium-Range Weather Forecasts operational analyses vi a the atmospheric moisture budget is assessed in comparison to a varie ty of glaciological and meteorological observations and datasets. For the 11-yr period 1985-95, the average continental value is 151 mm yr(- 1) water equivalent. Large regional differences with other datasets ar e identified, and the sources of error are considered. Interannual var iability in the Southern Ocean storm tracks is found to be an importan t mechanism for enhanced precipitation minus evaporation (P - E) in bo th east and west Antarctica. In relation to the present findings, an e valuation of the rawinsonde method for estimating net precipitation in east Antarctica is conducted. Estimates of P - E using synthetic rawi nsondes derived from the analyses are found to compare favorably to gl aciological estimates. A significant upward trend of 2.4 mm yr(-1) is found for the Antarctic continent that is consistent with findings fro m the National Centers for Environmental Prediction, formerly the Nati onal Meteorological Center, and the National Center for Atmospheric Re search Reanalysis precipitation dataset. Despite large regional discre pancies, the general agreement on the main features of Antarctic preci pitation between studies suggests that a threshold has been reached, w here the assessment of the smaller terms including evaporation/sublima tion and drift snow loss is required to explain the differences.