华南汛期降水与南半球关键系统低频演变特征

利用1960—2008年华南地区71个站逐日降水量和NCEP/NCAR南半球逐日海平面气压 (SLP) 场再分析资料，采用多锥度方法-奇异值分解 (MTM-SVD) 统计诊断方法，重点分析了华南地区4—9月汛期降水及同期南半球关键系统低频演变特征。MTM-SVD的LFV谱分析表明:华南汛期降水具有30~60 d低频振荡和5~7 d的变化特征；南半球澳大利亚高压系统具有30~60 d低频振荡、10~20 d双周振荡及5~7 d和2~3 d的变化特征；马斯克林高压系统则具有30~90 d低频振荡和双周振荡特征; 跟踪华南汛期降水与南半球SLP场的30~60 d低频振荡的时空耦合演变过程显示，南半球马斯克林高压和澳大利亚高压系统由强 (弱) 到弱 (强) 的演变过程对应华南降水的多雨带由西南 (东北) 向东北 (西南) 的转移。华南南部多雨带的变化与马斯克林高压和澳大利亚高压变化趋势及位相一致，而北部多雨带则和马斯克林高压和澳大利亚高压SLP场的变化趋势相反。

Low Frequency Oscillations of Southern Hemispheric Critical Systems and Precipitation During Flood Season in South China

By using daily precipitation data over South China and the NCEP/NCAR daily mean reanalysis data of SLP in Southern Hemisphere during 1960—2008, the low frequency oscillations of Southern Hemispheric critical systems and precipitation during raining seasons in South China are investigated by means of statistical method, for example, MTM-SVD, and so on. The LFV spectrum results show a 30—60 days low frequency oscillation and variation of 5—7 days for the precipitation during raining seasons in South China. Australian high in Southern Hemisphere can also be decomposed into 30—60 days low frequency oscillations, 10—20 days bi-weekly oscillations and variations of 5—7 days and 2—3 days. Mascarene high has 30—90 days low frequency oscillations and characteristics of bi-weekly oscillations. The MTM-SVD method can identify coupled spatial and temporal evolving signal by using both phase and amplitude information. Tracking the spatial and temporal coupling evolution of low-frequency oscillation with 30—60 days, it is found that the Mascarene and Australian high from strong to weak is corresponding to the rainy zone transfer from southwest to northeast in South China, and vice versa. South rain belt of precipitation in South China coincides with the variations and phase of the Mascarene and Australian high very well, but North rain belt is opposite with the Mascarene and Australian high. When the SLP of Mascarene and Australian high are positive from the usual, southern rain belt in South China is usually strong and northern rain belt tends to by weak, and vice versa.