摘要
本文是系列文章的第二篇，首先分析了１９８９年亚洲夏季风爆发时期青藏高原及邻近地区地表感热通量和大气温度场季节变化的基本特征，着重讨论了春季高原地表感热加热和亚洲季风爆发的联系，然后分析了１９８０～１９８９年１０ａ南海季风爆发的气候学特征。上述工作表明，在春末初夏过渡季节，高原上空大气温度变化出现阶段性的跃升，并同亚洲夏季风阶段性的爆发有很好的对应关系。高原地表感热通量的持续增大导致了对流层高层局地反气旋式扰动环流的出现，使南亚反气旋北进的过程明显受到高原局地热力环流的调制，而热带东风急流入口区所产生的强烈的高层辐散，提供了有利于热带季风对流在南海地区首先爆发的动力学条件。此外，从５月份至６月中下旬，青藏高原、伊朗—阿富汗上空强大暖中心相继建立的结果，直接导致了热带地区上空大气南北温度梯度的反向依次在南海—孟加拉湾东部和阿拉伯海—印度次大陆由东向西相继建立，从而决定了亚洲季风建立的过程在不同地区爆发的时间不同。
This is the second part of a series of study on the possible physical mechanism towards the onset of the Asian summer monsoon. In this paper, including a case study of 1989 and climatological analyses of 1980-1989, special attention was paid to investigation of the temporal and spatial evolutions of the air temperature, general circulation and surface sensible heat flux from late spring to early summer over the Asian monsoon regions. The role of surface sensible heating over the Tibetan Plateau and surrounding areas was emphasised. It is shown that, during the transitional season the two abrupt increases of the air temperature over the Tibetan Plateau coincide well with the sequential onset of the Asian summer monsoon over South China Sea and the Indian Subcontinent, respectively. The intense warming due to sensible heating over Tibetan Plateau directly gives rise to a relatively strong disturbance of local anti cyclone at the high levels of the troposphere, and such regime greatly modulate the evolutions of the South Asia High and easterly jet over the northern tropics. It was shown that the strong divergence which appears in the entrance of the easterly jets plays a role in triggering the onset of intense convections. Moreover, it was found that the temporal and spatial evolutions of the tropic easterly jets were greatly affected by the reversals of the meridional temperature gradient on the southern sides of the Tibetan Plateau and the Afghanistan Iran region, where the warming centres developed in a spatial sequence from east to west.
出处
《气象学报》
CSCD
北大核心
1999年第1期56-73,共18页
Acta Meteorologica Sinica
基金
国家"八五"攀登B项目
国家自然基金
关键词
青藏高原
地表感热通量
亚洲
夏季风爆发
季风
Tibetan Plateau,Sensible heating,Onset of the Asian summer monsoon.
