Atmospheric Circulation Anomaly Prior To Drought/flood of Summer in North China and Its Relations to North Pacific SST

The atmospheric circulation anomaly and North Pacific SSTA in spring prior to drought/flood of summer in North China are analysed and the relationships between SSTA and atmospheric circulation anomaly are discussed. Then numerical simulation forced by heat source anomaly in Kuroshio current area is made by using OSU-AGCM. The results show that rainy summers in North China would occur if arctic low vortices weaken significantly and zonal circulations strengthen in middle-high latitudes in Eurasian continent and West Pacific subtropical high lies northerly and westerly, and remarkable negative PNA-pattern exists in springs. Otherwise, there would be dry summer in North China. At the same period positive and negtive SST departures exist in the Western North Pacific and in equatorial East Pacific, respectively, which is closely related to atmospheric circulation anomaly in springs. SSTA in Kuroshio current area has great influence upon subtropical atmospheric circulations as well as those of its northside in the Northern Hemisphere. Positive SSTA in Kuroshio current area is an important factor for the anomalous atmospheric circulation pattern prior to flood of summer in North China