青藏高原对形成江南“倒春寒”过程的影响的数值试验

利用一个有较高水平分辨率的有较完整物理过程的五层谱模式（T42L5），研究了青藏高原对形成长江以南的“倒春寒”过程的影响。结果表明，在春季，青藏高原的动力作用有利于北来冷空气沿其东侧南下，又有利于其东南侧的南支低槽的形成和维持，而高原东侧的背风坡作用利于南支槽的加深及东移而影响长江以南地区，使之易于出现并维持低温过程，并有倒春寒天气过程发生。

Numerical Study of Influence of the Qinghai-Xizang Plateau on the Late Spring Cold Spell Event South of the Changjiang River

By employing the improved T42L5 spectral model and utilizing the ECMWF data of12 UTC 25 March 1985 as the initial field,a numerical study of the effect of the Qing-hai-Xizang Plateau on the formation of the cold spell in the late spring south of theChangjiang River has been made.The results show that the dynamic effect of the Plateaucan help the cold air move along the east of the Plateau from the north to south and thesouth trough with generation and maintenance on the southeast side of the Plateau.Dueto the dynamic effect of the lee wave east of the Plateau,the south trough becomes deep-er and moves towards the east,with the result that the low temperature process can re-main in the south of the lower reaches of the Changjiang River.