一次南亚高压中期活动过程的数值研究

A NUMERICAL EXPERIMENT ON THE MEDIUM-TERM ACTIVITIES OF SOUTH ASIAN HIGH

利用国家气象中心从ECMWF引进的中期数值预报准业务模式(T42L9),在对其中的云-辐射过程改进的基础上,以1979年6月14日12GMT的FGGE-Ⅲb资料为初始场.对1979年6月14日至19日期间南亚高压北跳过程中青藏高原的热力和动力作用以及云-辐射作用的贡献进行了数值试验研究。分别在有地形非绝热、有地形绝热、无地形绝热以及不考虑云-辐射反馈情形下进行了五天数值预报试验.模拟结果指出,青藏高原南侧的热力作用是这次北跳加强过程的主要原因,而大地形的动力作用不利于南亚高压的北跳加强(两者共同作用造成南亚高压的中期振荡)。云-辐射相互作用有利于南亚高压的北跳加强。

Initialized with FGGE - Ⅱ b data at 1 2 0 0 GMT on June 1 4 , 1 9 7 9 , a quasi - operational medium - term NWP model ( T 4 2 L 9 ) , introduced from ECMWF and with its cloud - radiation scheme modified , was used to investigate into the relative contribution by thermodynamic and dynamic forcings and cloud-radiative effects for the Tibetan Plateau during the northward advancement and enhancement of the South Asian High from June 14 - 19,1979. The 5 - day . experiment was done under the conditions of diabatic or adiabatic heatingg with or without topographic effects and in the absence of cloud-radiation feedback. The resu It shows that the thermodynamic forcing south of the Plateau is the main cause behind the northward advancement and enhancement while the dynamic forcing acts as an unfavourable factor, both contributing to the medium-term oscillation of the High. Cloud-radiation interaction is another favourable factor.