2006年广东汛期大气环流场的低频特征  

THE CHARACTERISTICS OF ATMOSPHERIC LOW FREQUENCY OSCILLATION OVER GUANGDONG DURING THE RAINY SEASON IN 2006

作　　者：梁巧倩[1] 蔡洁云[1] 纪忠萍[1,2] 林良根[1] 方一川[1] 

机构地区：[1]广州中心气象台,广东广州510080 [2]中国气象科学研究院灾害天气国家重点实验室,北京100081

出　　处：《热带气象学报》2011年第2期219-229,共11页Journal of Tropical Meteorology

基　　金：中国气象局气象新技术推广预报员专项(CMATG2007Y04);广东省科技厅项目(2006B37202004);广东省气象局项目(2008A02);公益性行业(气象)科研专项经费项目(GYHY200706037;GYHY201006018)共同资助

摘　　要：利用2006年NCEP/NCAR再分析资料和广东省86个测站的逐日降水资料,分析了广东汛期降水的大气环流低频特征。结果表明,华南汛期的降水主要有7～20天和60天左右的周期振荡,广东汛期的明显降水过程主要出现在60天左右低频振荡的正位相中,当7～20天振荡与60天左右的低频振荡正位相同相叠加时,广东降水明显增强。前汛期华南及其附近地区的低频系统配置和气旋性涡旋有联系,850和500 hPa上,在华南及其邻近地区都存在一个气旋性涡旋,涡旋中心位于华东沿海,广东受其环流南侧的影响,有利于低层西南风带来的水汽在华南汇合从而产生降水;200 hPa亚洲大陆上气旋和反气旋涡旋在100～110°E地区形成较一致的西北风场,在华南地区转辐散的偏西风场。间歇期的低频系统及其配置和前汛期的相似,但气旋性和反气旋性涡旋的位置正好相反。后汛期的低频系统配置与前汛期的相似,但系统的位置总体偏西、偏南。前汛期850 hPa正涡度主要是由南往北传播到达华南,后汛期正涡度源于自东往西和南北方向传播的波列;前后汛期降水盛期500 hPa正涡度的传播方向在纬向上是相反的,前汛期有自西往东传播的特征;200 hPa散度在前汛期有自南往北传播的特征,在后汛期在华南上空近乎静止。In this paper,the characteristics of atmospheric low-frequency oscillation over Guangdong during the rainy season in 2006 are studied by using the NCEP/NCAR reanalysis data and daily precipitation data of 86 stations in Guangdong.The results are shown as follows.Heavy rainfall mainly occurs in the positive phase of a 60-day low frequency oscillation;when the positive phases of oscillations with periods of 7~20 days and 60 days appear at the same time,the precipitation increase significantly.Analysis of the 60-day low-frequency oscillation circulation indicated that,during the annually first rainy season,there was a cyclonic vortex near the south of China which played an important role in the rainfall process.At 850 hPa and 500 hPa,two cyclonic vortexes were located at coastal East China,with the south part of the vortex having great effect on the convergence of the moisture brought by a southwesterly at low levels.The divergence area between the couple of cyclonic and anticyclonic vortexes at 200 hPa maintained the heavy rainfall.The locations of cyclonic and anticyclonic vortexes were reversed during the break,and were more westward and southward during the annually second rainy season.The 60-day low-frequency oscillating vorticities at 500 hPa mainly moved to the east in the early rainy season but to the west in the late one.The divergence at 200 hPa in South China moved northward during the early rainy season but almost stationary in the late one.

关 键 词：汛期 暴雨 低频振荡 

分 类 号：P458.1[天文地球—大气科学及气象学]