造成北京连续高温的河套高压结构分析

就2000年7月11~14日北京连续4天≥35 ℃的高温天气，分析了与之相关的700 hPa河套高压的水平和垂直结构，指出它是与我国西部干旱区大范围暖空气东移相关联的一个深厚的负涡度系统。由于河套高压是一个水平尺度较小的移动性系统，所以高温持续天数较短。作为一个暖性高压，河套高压所对应的负涡度系统在垂直方向可达到对流层上层。极锋急流出口区和副热带急流入口区的高空辐合机制使位于南北两条急流之间的河套高压为下沉运动控制，它所伴随的晴空区辐射增温和绝热增温有利于高温天气的形成。文章最后提出了河套高压的形成还可能和高空急流的动力加压有关。

A Case Study of the Structure of the Hetao High which Caused Long-lasting Hot Weather in Beijing

Based on the severe hot weather case taken place on July 11-14, 2000 in Beijing, we analysed the horizontal and vertical structure of the Hetao High on 700hPa associated with the hot weather. The result shows that the High is a deep negative vorticity system and related with a large-scale, eastward moving warm air mass in western arid region. The Hetao High is a relatively small and locomotive system, so hot weather usually sustains only several days.As a warm high, the Hetao High reached the high level of troposphere in vertical direction. Located between the exit region of Polar-front jet and the entrance region of subtropical jet, the upper level convergence makes Hetao High under the control of downward current. Adiabatic warming because of sinking and radiation heating are in favor of hot weather. At last, the paper pointed out that the formation of the Hetao High might be associated with dynamically pressure increase.