我国东部季风区夏季持续非绝热加热的特征分析和数值试验

Feature Analysis and Numerical Experiments of the Persistent Diabatic Heating in the Summer Monsoon Regions in Eastern China

首先用NCEP/NCAR再分析资料统计了我国东部季风区华南、江淮、华北的夏季持续非绝热加热情况,然后针对非绝热加热的主要贡献因子凝结潜热进行不同区域的数值试验,从而探讨了各区凝结潜热加热对大气环流的可能影响途径。所有数值试验都揭示了凝结加热可以首先在对流层中低层的加热区附近激发气旋性异常,然后异常向东北传播,并最终在中高纬地区形成正负中心相间的波列状结构,这在一定程度上体现了潜热加热能的向东向极频散过程。此外,不同个例年试验结果的差异说明了大气环流对凝结加热的最初响应情况比较复杂,很大程度上依赖于加热初始阶段的大气环流场,而呈现出与垂直环流结构相类似的异常分布是可能的响应方式之一。

The NCEP/NCAR reanalysis data is firstly used to analyse the persistent diabatic heating in the summer monsoon regions including South China, the Changjiang River-Huaihe River valley and North China. Seeing that condensation heating is the main part of diabatic heating in the monsoon region, then related numerical experiments in the above three regions are made so as to discuss the possible impacting approaches of condensation heating on general circulation. All numerical experiments reveal that, the condensation heating can firstly induce cyclonic a- nomaly nearby the heating region in the mid-low troposphere, then the anomaly propagates northeastward, and the wave train forms in mid-high latitudes finally, which indicates the northeastward dissipation of latent heat energy. Moreover, the difference of instance experiments shows that the initial response of atmosphere to the condensation heating depends a lot on the general circulation in the initial stage of heating, and the anomaly distribution similar to the vertical circulation structure may be one of the possible response modes.