ATMOSPHERIC CIRCULATION AROUND THE GREENLAND CREST

The Greenland Ice Sheet Program 2 (GISP2) required meteorological supp ort for the layout of the field camp, ice core site, landing strip, sn ow sampling sites, and air sampling sites. An automatic weather statio n installed in May 1987 provided the initial data for the support of s everal components of the program using the 2 year wind speed and direc tion distributions. The automatic weather station (AWS) network was ex panded to six sites with four sites located approximately 100 km from the highest point in Greenland in the cardinal directions and sites lo cated at GISP2 and at the air sampling site. The wind direction and sp eed wind roses for August and September 1994 show that there is consid erable variation in the wind field around the Greenland Crest. The con stancy (ratio of the vector wind speed to the scalar wind speed) of th e monthly wind vectors was lowest at the southern site and increased a s one moved clockwise around the crest to the eastern site. Vorticity and divergence were determined from triangles formed by three AWS site s. The mean horizontal divergence for August and September 1994 was 1. 4 x 10(-5) s(-1), and the vorticity was -3.7 x 10(-5) s(-1). Apparentl y, the flow around the Greenland Crest is most influenced by topograph y when the 500 hPa contours indicate a pressure ridge over central Gre enland. The surface winds showed anticyclonic flow, positive horizonta l divergence, and negative vertical vorticity. In the mean, this confi guration indicates the presence of an inversion wind, especially at th e sites located on the slopes to the west and east of the crest.