43 
Fig. 2. Drift paths of 45 air-dropped data buoys between January 1979 and December 1981. The 
buoys are positioned by ARGOS several times a day to an accuracy better than 1 km. They con- 
tain quartz-oscillator pressure sensors whose readings are accurate to +1 mb, with a drift of 
less than 0.2 mb per year (adapted from Untersteiner and Thorndike, 1982). The stippled 
arrows indicate an early (Gordienko, 1958) estimate of the mean circulation of the upper several 
hundred meters of water in the Arctic Basin. (From Air-Sea-Ice Research Program for the 
1980's, APL-Univ. of Washington, 1983). 
Sea ice can be driven by wind on its upper surface or ocean currents on its lower sur- 
face. In Fram Strait mean annual winds are southward and the ice moves southward, even on the 
Spitsbergen side where the currents are northward (Fig. 3). Oceanographic conditions are 
sharply contrasting across the Strait with the colder, less saline East Greenland Current (EGC) 
flowing southward on the western side and the warmer, more saline West Spitsbergen Current 
flowing northward on the east side. The combined effect of wind and the cold EGC carry ice far 
southward off the coast of Greenland. But off Spitsbergen the southward-moving ice is melted 
by waters with temperatures above freezing. Oceanographic surveys by helicopter during FRAM 
experiments showed a horizontal boundary layer beneath the ice in which the WSC is melting 
polar pack ice, reducing its thickness from 3 m to zero in a distance of 50 to 100 km. The 
export of sea ice from the Arctic Ocean to the North Atlantic will be affected by both wind and 
current regimes. Mean winds in this region may be considered a part of the polar anticyclone 
and would be altered if the global meridional temperature gradient changed. Ocean currents here 
are driven by the density contrast between the low-salinity Arctic Ocean fed by river runoff 
from northern Eurasia and the saline waters which have been carried northward from the tropi- 
cal Atlantic. Any changes in discharge of the Siberian Rivers or transport of the Gulf Stream 
would also have an effect on ice discharge from the Arctic Ocean. 
