青藏高原东北侧干旱的数值试验

用谱方法（Ｔ４２）求解半球球面无辐散正压涡度方程，采用实际的干旱环流资料，分别在有地形和无地形的情况下，求出其对应的干旱环流型的强迫场，模拟了在强迫场的作用下干旱环流的形成、维持情况及在强迫场消失后干旱环流型的崩溃情况。结果表明：（１）强迫场在干旱环流型的形成、维持及崩溃过程中起重要作用；（２）青藏高原的存在使其东北侧干旱形成和崩溃均加快。

NUMERICAL STUDY ON THE DROUGHT OVER THE NORTHEAST REGION OF TIBETAN PLATEAU

The nondivergent barotropic vorticity equation on a Hemisphere is solved by the spectral method (T42) with the real drought circulation data to calculate the forced field of the drought circulation pattern under circumstances with and without the topographic forcing. The formation and maintenance of drought circulation pattern under the effect of the forced field and the collapsing process after the dissipation of the forced field are numerically simulated. The results show that the forced field plays an important role in the processes of formation, maintenance and collapse of the drought circulation pattern, and the Tibetan Plateau's topographic forcing makes the drought circulation's formation and collapsing faster over its northeast region.