台风“山竹”（1822）引发华南暴雨过程机制分析

利用NCEP/NCAR 1°×1°的FNL再分析资料、CMORPH（CPC MORPHing technique）卫星-地面自动站融合降水数据以及FY-2G卫星反演的TBB（black-body temperature，云顶亮温）对1822号台风“山竹”在华南造成强降水过程进行了分析。结果表明：西北太平洋副热带高压和南亚高压的稳定维持有利于台风残涡持续影响华南地区；低层来自孟加拉湾的低空急流与西北太平洋副热带高压南侧偏东风汇合后建立起一条连接华南的水汽通道；在登陆台风影响下，大气视热源和视水汽汇主要来自于垂直运动释放的凝结潜热；湿位涡诊断分析表明强的水平风垂直切变导致低层大气斜压性增强，出现显著的对流不稳定。

Analysis on mechanism of torrential rain in South China induced by Typhoon MANGKHUT (2018)

Based on NCEP/NCAR FNL reanalysis data(1°×1°), CMORPH-AWS merged hourly gridded precipitation product, and FY-2G TBB (black-body temperature), the mechanism of the torrential rain caused by Typhoon MANGKHUT (2018) is analyzed. The results show that the maintenance of the western North Pacific subtropical high and the South Asia high is beneficial to the continuous influence of typhoon residual vortex on South China. The low-level jet stream from the Bay of Bengal converges with the easterly wind on the south side of the subtropical high, setting up a water vapor channel accessing South China. The apparent heat source and apparent vapor sink are mainly generated with latent heat release of condensation by vertical motion under the influence of Typhoon MANGKHUT.The diagnosis of moist potential vorticity (MPV) indicates that vertical shear of strong horizontal wind leads to the enhancement of baroclinicity at lower level and significant convective instability.