ユーラシア大陸の冬季積雪面と500hPa面の75°Eに沿うリッジの位置の相互関連について

抄録

The aim of this paper is to investigate the interaction between the Eurasian winter snow cover extent and the location of the April 500hPa ridge along 75°E for the period 1967 to 1986. Snow cover area and mean April ridge position data were from the NOAA/NESDIS Northern Hemisphere snow cover and ice charts and the normal upper-air charts of the India Meteorological Department (IMD) respectively. The relationship between the winter snow cover extent and the ridge location is negative (correlation coefficient =-0.63) and is significant above the 5% level. This preliminary result indicated that an extensive winter snow cover area was likely to maintain the April ridge position South of its 20-year mean location. An inverse relationship is more strong and significant (r=0.68) between the January snow cover and the April ridge at 500hPa position than the winter snow cover and the ridge. The regression equation between the January snow cover (S, in area) and the ridge location (R, in degrees) for the study period is R=33.68-0.65S. This relationship explains about 47% of the total variance. Finally, this interaction study suggested a considerable lingering effect of snow cover on the regional atmospheric circulation over India.