Modeled Variations of Precipitation over the Greenland Ice Sheet

Abstract

Abstract A parameterization of the synoptic activity at 500 hPa and a simple orographic scheme are used to model the spatial and temporal variations of precipitation over the Greenland Ice Sheet for 1963–88 from analyzed geopotential height fields produced by the National Meteorological Center (NMC). Model coefficients are fitted to observed accumulation data, primarily from the summit area of the ice sheet. All major spatial characteristics of the observed accumulation distribution are reproduced apart from the orographic accumulation maximum over the northwestern coastal slopes. The modeled time-averaged total precipitation amount over Greenland is within the range of values determined by other investigators from surface-based observations. A realistic degree of interannual variability in precipitation is also simulated. A downward trend in simulated ice sheet precipitation over the 26 years is found. This is supported by a number of lines of evidence. It matches the accumulation trends during this peri...