Atmospheric circulation around the Greenland Crest

Abstract

The Greenland Ice Sheet Program 2 (GISP2) required meteorological support for the layout of the field camp, ice core site, landing strip, snow sampling sites, and air sampling sites. An automatic weather station installed in May 1987 provided the initial data for the support of several components of the program using the 2 year wind speed and direction distributions. The automatic weather station (AWS) network was expanded to six sites with four sites located approximately 100 km from the highest point in Greenland in the cardinal directions and sites located at GISP2 and at the air sampling site. The wind direction and speed wind roses for August and September 1994 show that there is considerable variation in the wind field around the Greenland Crest. The constancy (ratio of the vector wind speed to the scalar wind speed) of the monthly wind vectors was lowest at the southern site and increased as one moved clockwise around the crest to the eastern site. Vorticity and divergence were determined from triangles formed by three AWS sites. The mean horizontal divergence for August and September 1994 was 1.4×10−5 s−1, and the vorticity was −3.7×l0−5 s−1. Apparently, the flow around the Greenland Crest is most influenced by topography when the 500 hPa contours indicate a pressure ridge over central Greenland. The surface winds showed anticyclonic flow, positive horizontal divergence, and negative vertical vorticity. In the mean, this configuration indicates the presence of an inversion wind, especially at the sites located on the slopes to the west and east of the crest.