【作者】 张润琼；

【导师】 沈桐立；

【作者基本信息】 南京信息工程大学 ， 气象学， 2006， 硕士

【摘要】 受高原东移小槽、低涡切变和地面静止锋的共同影响,2002年6月17-20日贵州中部、北部及贵州、重庆、湖南三省交界地区出现了一次连续性暴雨—大暴雨天气过程,过程最大降雨量达362mm,造成了严重山洪、泥石流灾害。 本文利用MM5(V3)中尺度模式对这次暴雨天气过程(简称贵州02619暴雨)进行了数值模拟。首先利用模式输出的基本物理量分析了相当位温、位势稳定度及垂直速度,并计算出了垂直螺旋度、干位涡以及湿位涡的值。通过对它们的诊断分析研究发现:贵州02619大暴雨天气过程发生在高温高能区。倒灌回流的东路冷空气,阻挡暖湿气流向东扩散、使低涡切变与静止锋增强。在冷平流侵入下,辐合区内的上升运动加剧,对流不稳定能量和潜热大量释放,造成大暴雨;暴雨中心位于最大垂直速度中心附近,南北两支闭合经向垂直环流对于暴雨区的低空入流和高空出流具有非常重要的作用。垂直螺旋度的变化对暴雨的强度变化有很好的指示性,暴雨区位于垂直螺旋度等值线密集处北侧。中高纬干位涡高值区反映西风槽弱冷空气和西南涡的活动,干位涡低值区反映低纬偏南气流活动,暴雨发生时,对流层高层干位涡具有向对流层低层延伸和低层干位涡具有向上伸展的特点,当高层、低层干位涡减弱,两者相互作用减弱时,降水趋于结束。贵州大暴雨与500hPa“漏斗”形MPV1高值区同位相变化。而且还发现高低层MPV1“正负值区垂直叠加”的配置是暴雨发生、发展的有利形势。500hPa上MPV2正值区与对流性降水区对应很好,而且强度变化也一致。同时,通过MM5数值模拟,研究了云贵高原对贵州大暴雨影响,发现地形降低和削平会使南北气象要素差异减小,西南涡和低空急流东移,导致暴雨区东移。更多还原

【Abstract】 During 17-20, June in 2002, there occurred an infrequent heavy rain in the north and mid-part of Guizhou , and on the common boundary of guizhou,Hunan and Chongqin, resulting from the united effects of trough to the east of Plateau, low shear and quasi-stationary front on surface, which results in serious disaster.A rainstorm process is simulated in Guizhou during 18-20, June in 2002, based on meso-scale numerical model MM5 (V3). With the basic physical parameters from the modeled output, the potential equivalent temperature and vertical velocity are analyzed, and calculation of the helicity and the barotropic and baroclinic moist potential vorticity(MPV) are made. The diagnosis results are as follows:The center of rainstorm is adjacent to the center of the maximum vertical velocity;the south and north meridional-vertical circulations are significant to the in-and out-flow on the lower and upper level, respectively. The changes of the helicity is a favorable index for the evolution of the rainstorm intensity. The rainstorm area is to the dense part of helicity isograms;Both the dry and moist potential( PV) can well present the features of the weather systems. The dry PV reflect both the cold and warm air flow activities, It is favorable for causing the heavy rainstorm when the upper tropospheric dry PV tends downward to lower- levels and vice versa for the lower- level troposheric dry PV.But once the PV weakens in upper-and lower- levels the precipitations will be ended soon. The heavy rainfall over Guizhou start, get stronger and weaker with the high value area’ s formation, strengthen and perish of MPV1" funnel" at 500hPa. it is also found that plus MPV zone just over minus one will make for the taking place and development of the heavy rainfall. The plus MPV zone at 500hpa is in accordance with the convective rainfall area, as well as the variable strength.更多还原