摘要
利用NCEP 1°×1°再分析格点资料和浙江省自动站降水资料,分析了2007年"罗莎"台风能量频散的波动特征与浙江省远距离台风降水之间的关系。结果表明:1)由于浙江省所处纬度相对较低,其远距离台风降水的形成过程与北方(西北和华北)典型的远距离台风暴雨存在本质区别,浙江省远距离台风降水主要是台风能量频散的波动效应所引起,而北方远距离台风暴雨的形成过程主要是西风槽和台风外围环流相互作用的结果。2)影响浙江省远距离降水的台风在整个台风环流登陆前有向降水区的能量频散过程,这种能量频散过程在对流层中低层波动特征不明显,因而能量频散的距离相对较小;在对流层中高层,台风能量频散表现出清楚的波动特征,能够影响到较远距离外的天气系统,从而引起局地降水的增加。3)台风能量频散的波动效应在远距离降水区的上空形成一个正涡量区,之后该正涡量区以波动的形式向下传播,导致降水区对流层中下层气旋性涡旋形成,造成局地降水或降水增加。
Based on the NCEP l^xl~ reanalysis data and the precipitation data from AWS in Zhejiang Province, the relationship between precipitation resulting from distant typhoon （PDT） and the perturba- tion kinetic energy dispersion （PKED） of typhoon Krosa is analyzed.The results show that the mecha- nism of PDT in Zhejiang Province is different from that in north region of China because the PDT here is formed by the distant propagation of disturbance kinetic energy of typhoon while the PDT in north re- gion of China results from the interaction between westerly trough and outer circulation of typhoon.The PKED of typhoon occurs both before and after its IandfaIling in Zhejiang Province.The intensity of dis- turbance kinetic energy is different at lower, middle, and upper levels in troposphere.The larger the am- plitude of disturbance kinetic is, the longer of the wave propagation distance will be. The intensity of disturbance kinetic energy at middle and upper levels is larger than that at lower level in troposphere, so the PKED at middle and upper levels in troposphere can exert impact on the precipitation in Zhejiang Province when the typhoon location is far from it but that at lower level can not.The PKED from distant typhoon can produce a positive vorticity area at the upper level in precipitation region.And then the lo-cal cyclonic circulation comes into being because of the downward propagation of the positive vorticity from upper level.Finally, the combination of local cyclonic cell with the moisture flow from the east sea of China leads to the enhancement of local precipitation.
出处
《大气科学学报》
CSCD
北大核心
2014年第1期57-64,共8页
Transactions of Atmospheric Sciences
基金
2013浙江省科技厅公益项目(2013C33037)
浙江省重大科技专项(2011C13044)
2013年中国气象局预报员专项(CMAY-BY2013-028)
关键词
天气学
台风远距离降水
诊断研究
能量频散
波动
synoptic meteorology
PDT
diagnostic study
kinetic energy dispersion
wave
