Effects Of Eurasian Snow Cover On Atmospheric Circulation In The Northern Hemisphere

Abstract

Effects of Eurasian snow cover were first noted by Blanford (1884) who found an inverse relationship between summer monsoon rainfall over India and winter snow cover over the Himalayas. Hahn and Shukla (1976) confirmed it by using satellite-derived data and their work stimulated succeeding studies on the interaction between large-scale snow cover and atmosphere. Matson and Wiesnet (1981) showed that interannual variation of northern hemisphere snow cover is dominated by Eurasian snow cover, both showing similar trends and fluctuations during 1967–79. Recent studies (Barnett, 1988) also noted that Eurasian snow cover has a greater feedback potential than that of North America on hemispheric-scale climatic anomalies. Though the importance has been thus recognized, not many studies have been done on the interaction between Eurasian snow cover and large-scale atmospheric circulation anomalies. Morinaga and Yasunari (1987) studied lag correlations between satellite-derived snow-cover extent over central Asia and the 500 mb-geopotential height field in the Northern Hemisphere (1967–84), and indicated that so-called Eurasian pattern (Wallace and Gutzler, 1981) in December brings large snow-cover extent in February; in turn, February snow cover has a considerable lingering effect on the atmosphere in April. This study present further results on the time-lag teleconnections of the atmosphere associated with Eurasian snow-cover anomalies and their physical implications including the evaluation of snow-hydrological process.