非地转强迫对Fitow(0114)暴雨的影响  

THE EFFECT OF AGEOSTROPHIC FORCING ON TYPHOON FITOW(0114) HEAVY RAIN

作　　者：李江南[1] 闫敬华[2] 魏晓琳[1] 吴池胜[1] 侯尔滨[3] 王安宇[4] 

机构地区：[1]广州中山大学大气科学系,季风与环境研究中心,广州510275 [2]中国气象局广州热带海洋气象研究所,广州510080 [3]澳门地球物理暨气象局 [4]广州中山大学大气科学系季风与环境研究中心,广州510275

出　　处：《气象学报》2005年第1期69-76,共8页Acta Meteorologica Sinica

基　　金：国家科技部社会公益研究项目"我国南方致洪暴雨预警系统研究";中山大学青年教师科研启动基金资助项目。

摘　　要：利用非静力中尺度模式MM5对 0 114号台风Fitow从 2 0 0 1年 8月 31日 0 0时～ 9月 2日 0 0时 (UTC ,下同 )的降水过程进行了模拟研究。结果表明 ,MM5对Fitow登陆过程中暴雨落区和强度的模拟与实况比较一致。模拟结果较好地再现了暴雨的中尺度特征。正是维持少动的台风倒槽和嵌入其中的中小尺度系统相互作用造成了暴雨的发生、发展 ,而高、低空中尺度散度场的配置对暴雨有很好的指示意义。在华南台风暴雨区无论是高层还是低层 ,都存在很强的非地转作用 ,非地转涡度项对散度倾向项是重要的强迫因素 ;但非地转作用的实现与中高纬度地区有本质的区别 ,在低层非地转作用是由于强的位势场气旋涡度 (- 2  <0 )与弱的流场气旋涡度 (fζ >0 )不平衡产生的 ;而高层非地转作用是由于强的位势场反气旋涡度 (- 2  >0 )与弱的流场反气旋涡度 (fζ <0 )不平衡产生的。非地转作用是暴雨中尺度系统上升运动发展的触发机制。从动力学角度解释了用非地转 Q矢量散度场来判断暴雨落区要比用准地转 Q矢量散度场好的原因。With PSU/NCAR nonhydrostatic mesoscale model MM5, the rainfall process of typhoon Fitow(0114) is simulated during 00UTC31 Auguest-00UTC2 September 2001, Analyses on the model results show that MM5 model well reproduced the position and intensity of heavy rain. Mesoscale characters of heavy rain were quite distinct in rainfall time scale, rainfall area, stream field and divergence at lower and upper levels. the interaction between inverted Typhoon trough and these mesoscale systems leads to heavy rain happening. The distribution of divergence fields at lower and upper levels can have a kind of indication meaning for the heavy rain. The ageostrophic effect on heavy rain area were very strong at lower and upper levels. The ageostrophic vorticity forcing was an important factor for divergence tendency. The achieving of the ageostrophic effect on heavy rain in South China is distinct from the mid high latitude area, The ageostrophic effect at lower levels was caused by the unbalance between strong geopotential field cyclonic vorticity (- 2<0) and weak stream field cyclonic vorticity (fζ>0) , The ageostrophic effect at upper levels was caused by the unbalance between strong geopotential field anticyclonic vorticity (- 2>0) and weak stream field anticyclonic vorticity (fζ<0) . The ageostrophic effect was trigger mechanism for ascending motion development in heavy rain mesoscale system. The cause that ageostrophic Q vector are better than quasi geostrophic Q vector divergence fields responding to the rainfall area was represented dynamically.

关 键 词：中尺度模式MM5 2001年8月 中小尺度系统 中高纬度地区 准地转Q矢量 暴雨落区 中尺度特征 中尺度系统 散度场 模拟研究 降水过程 登陆过程 模拟结果 相互作用 台风倒槽 指示意义 触发机制 上升运动 不平衡 位势场 反气旋 

分 类 号：P426.51[天文地球—大气科学及气象学] P458.121.1