North Atlantic Oscillation and northern hemispheric warming

Abstract

In this paper, the effect of Winter-NAO on northern hemispheric temperature and snow-cover is studied because North Atlantic Oscillation (NAO) fluctuations are strongest in the winter season. The correlation analysis, for the period 1973-2003, suggests that winter-NAO is inversely associated with Northern hemispheric snow-cover from winter through summer and the correlation coefficients are significant at 5% level. Moreover, NAO is showing direct relationship with northern hemispheric temperature during winter season. This relationship is also significant at 5% level. The stability of this relationship is tested and found to be stable. The correlation analysis further suggests that winter-NAO and global temperature difference between land and ocean have direct association, which is significant at 5% level. The effect of rising trend in winter-NAO may have resulted in decreasing northern hemispheric snow-cover, which ultimately results in warming of northern hemispheric temperature. The study suggests that NAO plays an important role in warming of northern hemisphere through decreasing northern hemispheric snow-cover extent.