北半球夏季全球热带和副热带200hPa平均辐散环流的研究

STUDY OF THE GLOBAL 200hPa DIVERGENT CIRCULATIONS IN THE TROPICS AND SUBTROPICS IN SUMMER

摘要: 大气的运动场或风场包括两部分:一是旋转部分,另一是辐散部分。虽然旋转部分的方差占总运动场方差的大部分(约占80%),但与辐散风相联系的垂直环流对于天气系统的发展是重要的。Krishnamurti等人1,2最早研究了全球热带的辐散环流。最近他3的研究表明,辐散风场的大部分是属于纬向的行星尺度垂直环流的水平分支,这意味着行星尺度系统总是热力直接环流,并且以纬向环流为主。Van der Boogard4计算了7月多年平均的速度势场,发现对流层上层最强的辐散中心在中南半岛上空。

Abstract: Utilizing the wind data at 200hPa for recent 13 years, the global tropical divergent wind fields from May through October have been calculated. It has been found that the center of the strongest divergent wind is located in the region from the South China Sea to the West-Pacific. The maximum monthly variation, however, of the divergent wind fields is found in India and the region of the Bay of Bengal.