青藏高原表面过程对夏季青藏高压的影响--数值试验

利用IAP/LASGGOALS气候模式设计了两组敏感性试验,分别考察青藏高原表面感热输送和表面摩擦拖曳对夏季青藏高压的影响.结果表明,表面感热输送显著增强了高原近地层气柱中正涡度的制造和气旋性环流,同时增强了高原上空气柱高层的负涡度制造和反气旋性环流.另一方面,高原表面摩擦拖曳虽然使得低层的辐合略有增加,但施加给整层气柱以反气旋性涡度.因而高原表面的感热输送和表面摩擦拖曳对夏季青藏高压都有增强的作用.表面摩擦拖曳对上空环流的影响随着高度升高而减弱,而表面感热输送引起的高层负涡度的增加与低层正涡度的增加在数值上相当甚至更大.

How the Surface Processes over the Tibetan Plateau Affect the Summertime Tibetan Anticyclone -Numerical Experiments

Numerical simulations by using IAP/ LASG GOALS climate model are carried out to in- vestigate how the surface sensible heat flux and surface friction force over the Tibetan Plateau affect the summertime South Asia high. It is shown that the surface sensible heat flux enhances both the lower-level convergence in the Plateau area and the upper-level divergence outward, intensifies the ris- ing motion over the Plateau, thus strengthens the South Asia high. The surface friction force exerts ab- normal an anticyclonic circulation to the whole air column over the Plateau, hence causes the intensifi- cation of the South Asia high in summer. The influence of surface friction on atmospheric circulation decreases with height, whereas the impact of surface sensible heat flux on the circulation at higher level is comparable to that at the lower level.