THE RELATIONSHIP BETWEEN MEIYU IN THE MID- AND LOWER REACHES OF THE YANGTZE RIVER VALLEY AND THE BOREAL SPRING SOUTHERN HEMISPHERE ANNUAL MODE

1 INTRODUCTION As confirmed by many studies, sea surface pressure is of interannual variations in subtropical Southern Hemisphere, which is defined as the Southern-hemisphere Annual Mode （SAM）. It is in fact a seesaw effect of sea surface pressure symmetric longitudinally between the South Pole region and austral middle latitudes. SAM is in fact a correction to the Antarctic Atmospheric Oscillation （AAO）. At present, more attention is paid to the structure of SAM and its influence on the climate in mid- and higherlatitudes of SH than to the links between SAM and anomalies of boreal general circulation and climate. This work focuses on the relation among SAM in boreal spring （April - May）, Mei-yu （sustaining rains） in the middle and lower reaches of the Yangtze River and East Asian monsoon.