“04·8”山东远距离台风暴雨成因的数值模拟

Numercial Simulation of Remote Typhoon Rainstorm in Shandong Province in August 2004

利用非静力平衡模式MM5,对由台风"艾利"和西风带冷空气相互作用造成的2004年8月26—28日山东大到暴雨天气过程进行了数值模拟,并对暴雨形成机理进行了分析。结果表明,"艾利"台风外围的急流带在华东沿海到山东南部地区产生深厚的湿层和强水汽辐合,从而导致不稳定能量的积聚;干冷空气从高层入侵使降水区对流不稳定增强,并使不饱和湿空气达到饱和,对降水具有增幅作用;低层正涡度和辐合作用的加强,导致中尺度低涡的形成和暴雨中心的产生。

Using the non-hydrostatic mesoscale model MM5,the rainstorm caused by the interaction between typhoon Aili and cold air in Shandong Province on 26—28 August 2004 is simulated,the formation mechanism of the rainstorm is analyzed.The results show that the jet stream in the peripheral of the typhoon led to deep moist air layer and intense water vapor convergence over the area from the East China Coast to the South of Shandong,i.e.the accumulation of unstable energy.The intrusion of dry/cold air at the upper levels over the rainfall areas resulted in intensified instability,and the saturation of unsaturaded moist air,thus enhancing the rainfall.The intensification of the positive vorticity and divergence at the low levels induced the formation of the meso-scale vortex and the center of torrential rainfall.