Patterns and variations of snow accumulation over Greenland, 1979-98, fromECMWF analyses, and their verification

ECMWF monthly climate analyses were used to retrieve surface temperature, p recipitation, evaporation/sublimation, and in conjunction with a simple met eorological model, snow accumulation over Greenland for 1979-98. The modele d snow accumulation is compared with existing observational maps of Greenla nd accumulation and mass balance, and with widely distributed coincident an d contemporaneous ice-core data, primarily from NASA's Program in Arctic Re gional Climate Assessment (PARCA) program. ECMWF-derived accumulation gave more realistic values for substantial (2-3-km elevation) areas of the "inte rmediate'' inland plateau than previous methods, although the estimates are still (similar to 20%-30%) too low over central Greenland. Overall, this E CMWF-driven model provides a reasonable first-order depiction, among the be st currently available, of snow accumulation and its interannual variations . Mean annual ECMWF precipitation (snow accumulation) for the whole island (Greenland area >2 km) was 0.314 (0.260) m yr(-1), with standard deviations (demarcating interannual variation) of 0.108 (0.098) m yr(-1). The underly ing cumulative 20-yr changes in precipitation and accumulation of, respecti vely, +0.044 and +0.019 m yr(-1) (20 yr)(-1) are therefore insignificant, n either are there any striking trends for the individual monthly (January-De cember) series. However, in line with other recent results, accumulation de creased substantially in southeast and northwest Greenland and increased in the southwest and northeast. Notable [similar to2 degrees -4 degreesC (20 yr)(-1)] rises in 2-m air temperature in April, September, and November, po ssibly related to changes in the length of the melt season, may have increa sed ablation of the ice sheet and require key attention in determining the surface mass balance.