亚洲南部地区海陆分布对亚洲冬季风影响的数值试验

利用美国国家大气研究中心研制的第三代公共气候模式CCM3/NCAR,设计了一系列数值试验,研究非洲大陆、印度半岛、中南半岛与其周围的阿拉伯海、印度洋和孟加拉湾及南海海陆交叉分布对亚洲冬季风环流形成的重要作用.试验结果表明:亚洲南部地区的阿拉伯海、孟加拉湾和南海冬季风及其越赤道气流的存在与非洲大陆-阿拉伯海-印度半岛-孟加拉湾-中南半岛-南海的海陆热力差异有关;并且冬季热带地区北风分量的产生也与次行星尺度海陆热力差有关,同时这些次行星尺度海陆热力差也对副热带和高纬度冬季风形成有明显作用.试验结果也表明中南半岛不仅对临近的冬季风有局地的影响,对冬季风的传播也有重要的作用,中南半岛的存在减弱了流向孟加拉湾和印度的冬季偏东风气流,使部分气流在南海转向,形成了南海冬季风;另外,非洲陆地、印度半岛和中南半岛的存在都能对其高空的副热带急流产生重要的影响,尤其是印度半岛和中南半岛的存在对高原南支副热带急流的维持有重要的作用;另外也讨论了这些陆地与海洋间的热力差对冬季地面气温和降水的影响.

Impact of ocean-continent distribution over southern Asia on the formation of winter monsoon

Using the CCM3/NCAR,a series of numerical experiments are designed to explore the oceanland interlaced distribution of Africa-Arabian Sea(AS)-India Peninsula-Bay of Bengal(BOB) -Indochina Peninsula-South China Sea(SCS) on the form ation of the Asian Winter Monsoon circulation.The results show that:(1) the oceanOland thermal difference over southern Asia is the primary mechanism that maintains the AS,BOB and SCS winter monsoon circulation and the associated cross-equatorial currents,and its deter minant effect on the formation of the tropical winter north wind component is also revealed;the subplanetary scale thermal contrast likewise exerts pronounced effects on the formation of subtropical and highOlat itudes monsoon;(2) the presence of Indo china Peninsula is liable for a southw ard shift of the continental winter monsoon at SCS during its west ward propagation as to form SCS winterm onsoon,indicating that Indochina Peninsula not only af fects the neighbo ring local winter monsoon,but has an important influence on its propagation.Moreover,because of its more adjacent to the source region of winter monsoon than India and Africa,the elimination of Indochina Peninsula would result in greater variations of winter monsoon in the lower reaches;(3) the presence of Africa,Indian subcont inent and Indochina Peninsula also actsas a crucial role in the formation of the upperair subtropical jets.In addition,the impacts of these thermal contrasts on the distribution of the winter precipitation and surface temperature are also investigated.