【摘要】 利用逐日NCEP/NCAR再分析资料分析了春夏过渡季节青藏高原非绝热加热和大气环流季节变化以及亚洲季风爆发的关系。结果表明,过渡季节的早期（5月中旬以前）青藏高原总非绝热加热与感热加热的时间演变曲线趋势一致,感热加热在过渡季节早期的环流演变中有很重要的作用。青藏高原非绝热加热的时间演变与北半球环流的季节变化和亚洲夏季风爆发有很好的相关。在过渡季节里,青藏高原非绝热加热的变化引起了海-陆热力差异对比的变化,给亚洲夏季风的爆发建立了有利的背景环境,对亚洲夏季风爆发有明显的影响。结果还表明,用各区域纬向风垂直差异的时空分布能更准确地表示季节变化的区域差异。更多还原

【Abstract】 The relationship between the evolutions of the Asian monsoon circulation and the diabatic heating over the Tibetan Plateau during spring is investigated by using the daily NCEP/NCAR reanalysis data. The result shows that there is distinct seasonal variation of diabatic heating over the Tibetan Plateau. During early transition season (before mid-May) over the Tibetan Plateau, the temporal variation of total diabatic heating is in phase with sensible heating. The features of the variation of total diabatic heating and sensible heating over the Tibetan Plateau show that the sensible heating is important to the seasonal variation of the Northern Hemispheric circulation. Of the particular importance, the temporal variation of diabatic heating over the Tibetan Plateau is closely coupled to the Asian summer monsoon onset and the seasonal transition from winter to summer of the atmospheric circulation of the Northern Hemisphere. In the transition season, the change of the diabatic heating over the Tibetan Plateau leads to the changes in land-sea thermal contrast, which builds up a favorable background for the Asian summer monsoon onset. It is also shown that, due to the large domain used, the Webster-Yang monsoon index cannot present the regional characteristics of the seasonal transition in the Asian monsoon area. More over the spatial difference in seasonal transition in the area can be depicted reasonably well by using the local zonal wind difference between 850 hPa and 200 hPa.更多还原