摘要
用合成及ＳＶＤ方法，对冬季风异常在南海地区的风场和热力场中所产生的影响进行了研究，并探讨了这种相互联系的可能机制。结果表明，冬季风异常对流场的影响可以从冬季持续至春、夏季。在强冬季风年，南海夏季风爆发偏早、偏强且突发性显著；而在弱冬季风年则相反。长江流域的情况则与此相反，强冬季风时，该地区夏季对流偏弱，降水减少；弱冬季风时相反。南海地区风场的变化与该地区大气及下垫面热状态的改变有关。强、弱冬季风所对应的同期及后期的海温截然不同。在强冬季风年，热带海温场上呈现 Ｌａ Ｎｉｎａ型的异常分布，而在亚洲大陆近海及南海地区，则维持较强的负距平，海水温度明显偏低，强度以春季为最强。它所形成的南海及邻近地区海陆之间的温度梯度有利于夏季风的早爆发和加强；而在弱季风年，则完全相反。与异常冬季风相关联的大气的热状态同样具有季节的持续性。春、夏季季风区中大气热状态的改变，影响了夏季风特别是南海夏季风爆发的早晚及其强度的变化。由冬季风异常引起的热源变化可能也是环流隔季相关的重要纽带之一。
The influence of the anomalous winter monsoon in the eastern Asia on the South China Sea (SCS) summer monsoon is studied. Based on the investigation of the variations of SST and heat sources of atmosphere, the possible mechanism of the linkage between the winter and summer monsoon is also discussed. The main results are as follows: the influence of anomalous winter monsoon on the wind field in SCS region may persist from winter to summer. In the strong winter monsoon years, the strength of SCS summer monsoon will be stronger. And its onset will be earlier and on a more abrupt manner. In the weak years, the reverse holds. While in the Yangtze River Valley, following a strong winter monsoon, the convection in summer will be less active, and the precipitation, decrease. This kind of connection between the winter and summer monsoon may result from the variation of SST and heat sources in the atmosphere especially around the SCS region in spring and summer. The signs of SSTA distributions are largely contrary between strong and weak winter monsoon both in winter and coming seasons. For the strong winter monsoon cases, a La Nina type pattern appears in the tropical area. However, in the SCS and coastal area of Asia, it maintains a region of negative SSTA from winter to summer, reaching its maximum in spring around SCS region. The strong land-sea thermal contrast is favorable to the onset and strengthening of SCS summer monsoon. The reverse can be found for the weak winter monsoon cases. The anomaly of the heat sources of atmosphere is also clear from winter to summer associated with the anomalous winter monsoon. The distribution of the heat sources in summer for the strong winter monsoon cases is conducive for the strengthening of SCS summer monsoon.
出处
《气候与环境研究》
CSCD
2000年第4期400-416,共17页
Climatic and Environmental Research
基金
国家科技部攀登项目 A"南海季风试验研究"
国家自然科学基金资助项目!49775261共同资助
