摘要
The spatial and temporal variation of cyclone activity in summer in East Asia have been studied,as well as the relationship between cyclone activity frequency,atmospheric circulation background field at 500 hPa and rainfall in China.The results showed that cyclone activity in summer was mainly distributed in three regions,and cyclone activity frequency in the north of 25° N before the middle of 1970s was continuously higher than that after the middle of 1970s.The decadal variation of cyclone activity frequency was closely related to the anomaly of atmospheric circulation at 500 hPa.There was obvious negative anomaly in middle and high latitudes of East Asia before the middle of 1970s,prevailing meridional circulation,with the increase of cyclone activity.However,the atmospheric circulation situation was reverse after the middle of 1970s.Summer rainfall in Shandong Peninsula had significant decadal variability,experiencing wet and dry season,and wet(or dry) season was fit to the period of higher(or lower) cyclone activity frequency in the north of 25° N.
The spatial and temporal variation of cyclone activity in summer in East Asia have been studied,as well as the relationship between cyclone activity frequency,atmospheric circulation background field at 500 hPa and rainfall in China.The results showed that cyclone activity in summer was mainly distributed in three regions,and cyclone activity frequency in the north of 25° N before the middle of 1970s was continuously higher than that after the middle of 1970s.The decadal variation of cyclone activity frequency was closely related to the anomaly of atmospheric circulation at 500 hPa.There was obvious negative anomaly in middle and high latitudes of East Asia before the middle of 1970s,prevailing meridional circulation,with the increase of cyclone activity.However,the atmospheric circulation situation was reverse after the middle of 1970s.Summer rainfall in Shandong Peninsula had significant decadal variability,experiencing wet and dry season,and wet(or dry) season was fit to the period of higher(or lower) cyclone activity frequency in the north of 25° N.
