非绝热过程对热带副热带环流和天气影响的数值预报试验

本文用p—σ混合坐标系原始方程模式,对1982年5月8日至10日的一次天气过程进行了数值预报试验。试验方案有两类,一类是湿绝热预报方案,另一类是非绝热预极方案,即模式中除考虑水汽凝结所产生的潜热外,还包含了海陆分布、地形以及不同的土壤下垫面物理特征所引起的各种非绝热物理过程。文中着重比较和讨论了非绝热加热过程对于北半球热带副热带地区环流和天气现象的影响。结果指出,非绝热物理过程对于高空温压场形势的短期影响不明显,对于低层气压形势以及风场的影响较大,对孟加拉湾及高原东部影响甚大,两种方案的风矢差变率可达到100%。忽略非绝热过程,会使青藏高原热低压大为减弱,风场的气旋性环流和辐合均大为减小,西南气流也被削弱。对于降水分布和降水量来说,忽略非绝热物理过程可使孟加拉湾地区不出现降水区,我国东南部沿海地区以及西太平洋中的降水也被减少甚至消失。 

NUMERICAL PREDICTION EXPERIMENTS OF EFFECTS OF DIABATIC HEATING PROCESS ON CIRCULATION AND WEATHER IN THE TROPICAL AND SUBTROPICAL REGIONS

Numerical prediction experiments are made by use of a p—σ incorporated coordinate system model with primitive equations and a case study of May 8, 1982 is analysed in some details. There are two kinds of experimental schemes. One is the moist adiabatic prediction scheme and the other is the diabatic heating scheme in which the latent heating from the vapour condensation is included. Besides there are also various diabatic physical processes induced by the land- sea distribution , the topography and the underlying surfaces with different physical properties. The focus of this paper is the comparisons and discussions of the diabatic heating effects on circulation and weather in the trpoical-subtropical regions. The results show that the diabatic heating effects on the upper level temperature and height fields are not very evident, but the effects on the low level fields are larger, especially large are the effects on the wind field in the boundary layer in the Bay of Bengal area and the region south of the Tibetan Plateau, the variation rate in the twoschemes reaches 100%. Omitting diabatic heating processes will result in the weakening of the Tibetan Heat Low, the cyclonic circulation and the convergence of the wind field, as well as the southwesterlies. For the precipitation amount and distribution, the precipitation area over the Bay of Bengal disappears and the amount in the coastal regions of East China and over the western Pacific decreases, even no precipitation takes place in the scheme without diabatic heating processes.