THE ANATOMY OF THE ARCTIC FRONTAL ZONE IN THE GREENLAND SEA

From a series of two-dimensional expendable bathythermograph (XBT) sur veys, conductivity-temperature-depth (CTD) sections, surface drifters, and acoustic Doppler current profiler (ADCP) observations, the proper ties and structure of the Arctic Frontal Zone in the Greenland Sea hav e been determined. The Arctic Frontal Zone appears to be a large-scale , climatic ''multifrontal'' frontal zone. The structure of the frontal zone can be discerned from subsurface as well as from surface hydrogr aphic parameters, even in summer, when a seasonal thermocline covers t he subsurface hydrographic structure. The Arctic Frontal Zone consists of two semipermanent frontal interfaces with warm, saline Norwegian A tlantic Water to the east and Arctic Water from the Greenland Sea gyre to the west. The two frontal interfaces are bounding a band of shallo w cyclonic cold eddies and anticyclonic warm eddies with horizontal sc ales of the order of 40-50 km. The typical diameter of the eddies can be scaled with the local internal Rossby radius of deformation. The ed dy kinetic energy of the surface flow in the fronta zone is of the ord er of 60 to 85 cm(2) s(-2). The zonal density gradient in the Arctic F rontal Zone maintains a mean northward geostrophic transport of 3.8 Sv , averaged over a number of cruises. This transport is mainly connecte d with the frontal interface on the western side of the warm and salin e Norwegian Atlantic Water. The estimated cross-frontal eddy transport s of heat and salt appear to be of considerable importance for the con ditioning of the Greenland Sea gyre.