Cyclone Activity around the Greenland Ice Sheet for Last 50 Years

Cyclone Activity around the Greenland Ice Sheet for Last 50 Years

Lin Li and David H. Bromwich

Polar Meteorology Group, Byrd Polar Research Center

And

Atmospheric Sciences Program, Department of Geography

The Ohio State University, Columbus Ohio 43210

The Greenland ice sheet has significant impacts on the climate of the North Atlantic Ocean. The ice sheet accumulation is related to the regional precipitation, synoptic-scale circulation and downslope katabatic winds. Studies show that the North Atlantic Oscillation (NAO) is highly correlated with the cyclone activity near Greenland, and hence affects the precipitation pattern. When NAO is positive, the precipitation is less than normal, particularly over southern Greenland, and vice versa.

Fifty years of NCEP/NCAR and ECMWF Reanalysis (ERA) datasets from 1950 to present are used to track cyclones around and over Greenland. These 6 hourly sea level pressure fields are analyzed by the Serreze (1995) tracking algorithm which has been optimized. Because of the high elevation of the Greenland ice sheet, analyses based on mean sea level pressure are distorted due to the pressure reduction to the sea level. The modified tracking algorithm then is applied to the equivalent geopotential in sigma coordinates which accurately accounts for the impact of elevated terrain on atmospheric analyses (Chen and Bromwich 1999). The results from both variables (SLP and equivalent geopotential) are compared to display the cyclone activity variation around and over the ice sheet during the last 50 years.