摘要
理性分析和利用NCEP/NCAR资料进行统计分析表明:大气环流的季节变化和越赤道气流即两半球的相互作用首先是由于赤道面与黄道面有交角而使太阳辐射有年变化所致,行星热对流环流是热带季风的“第一推动力”,而地表面特性差异(海陆热力特性差异以及地形高度等)所导致的准定常行星波为“第二推动力”。如以推动大气质量跨纬圈传输的效力来看,平均来说二推动力的功效之比为2:1。第二推动力在亚澳季风区与第一推动力合拍,使热带季风在亚澳区内最明显,而各经圈环流圈的上下及南北关联及与中高纬准定常行星波的配置则使全球范围内从低纬到高纬、从低空到高空有地域性的明显季节变化区,从而构成三度空间的全球季风系统。
Based on the theoretical consideration and the statistical analysis of NCEP/NCAR reanalyses data, it is clear that the causes of seasonal variations of atmospheric general circulation, the cross-equatorial air flows and the interactions between the Northern and Southern Hemispheric atmospheres are primarily due to the seasonal variations of incoming solar radiation. The primary driving forcing of the tropical monsoon, characterized by the cross-equatorial meridional wind component, is the planetary thermal convection, and the semi-permanent planetary waves due to the seasonal variation of the differences between the thermal characters of earth surface (ocean and continent) are the secondary forcing. The calculation results show that the efficiency ratio of the first to second forces, on the average, is 2:1. The two forces are in phase in the eastern hemisphere, resulting in pronounced Asian-Australian monsoon prevails, but out of phase in the western hemisphere, resulting in weak seasonal variations and monsoon over the tropical Atlantic and the tropical eastern Pacific. Besides, the semi-permanent planetary waves in the middle-high latitudinal zones owing to the seasonal variations of thermal contrast of land and ocean and the incoming solar radiation are favourable for the Asian-Australian monsoon to extend to the extratropical regions. At high altitudes, the air flows compensating the low-level monsoons also undergo significant seasonal variations. Thus there is a clear picture of globally three-dimensional general monsoon system.
出处
《大气科学》
CSCD
北大核心
2002年第4期433-448,共16页
Chinese Journal of Atmospheric Sciences
基金
国家自然科学基金资助项目49735160
国家重点基础研究发展规划项目G1998040900共同资助
关键词
南北两半球
大气
相互作用
季风
大气环境
planetary thermal convection
driving force
cross-equatorial flow
seasonal variation
monsoon
