RECENT DECREASE OF SEA-LEVEL PRESSURE IN THE CENTRAL ARCTIC

Arctic sea level pressure data from the period of the Arctic Ocean Buo y Program show a significant decrease in the annual mean. In every cal endar month, the annual mean is lower in the second half of the 1979-1 994 period than in the first. The changes of the annual means are larg er in the central Arctic than anywhere else in the Northern Hemisphere . The decreases are largest and statistically significant in the autum n and winter. The annual anomalies became negative relative to the 16- yr mean in the 1980s and have been negative in every year since 1988. Correspondingly, the mean anticyclone in the Arctic pressure field has weakened and the vorticity of the gradient wind held over the central Arctic Ocean has became mere positive than at any time in the past se veral decades. The pressure decrease, which has been compensated by pr essure increases over the subpolar oceans, implies that the wind forci ng of sea ice contains an enhanced cyclonic component relative to earl ier decades.