摘要 : <正> I. INTRODUCTION During summer, the lower tropospheric circulation is observed as a belt of high pressure ridge surrounding a low pressure center over the Qingzang plateau. It is found that the northern high pressure belt brea... 展开 <正> I. INTRODUCTION During summer, the lower tropospheric circulation is observed as a belt of high pressure ridge surrounding a low pressure center over the Qingzang plateau. It is found that the northern high pressure belt breaks into 3 distinct centers, the so-called Hexi high, Nanjiang high and Central Asia high, and a relatively weak ridge uns along the southern side of the plateau. 收起