NUMERICAL EXPERIMENT ON MID-LATITUDE SST ANOMALY AND VARIATION IN CIRCULATION PATTERN

By means of simulation experiments with a two-dimensional zonal-mean model,a study is made of the influence of the western North-Pacific midlatitude sea-surface temperature(SST) anomalies on the circulation pattern and wet-seasonal precipitation over the East-China Changjiang-Huaihe reaches and the North-China plain.The SST anomalies are divided into two types,one being "colder in the south and warmer in the north" and the other just opposite,depending on season.Results show that the occurrence of the anomalies is followed by considerable changes in the position of the subtropical high happening for 3-5 months to come.For instance,the spring "colder in the south and warmer in the north" anomalous type(i.e.,colder for 20-35°N,and warmer north of 35°N) leads to the intensification of the summer subtropical high,with the ridge line moved slightly northward,resulting in drought over Changjiang reaches for July-August and in excessive rainfall in the North-China plain,and vice versa.