亚洲夏季风季节内振荡对云南主汛期降水的影响Ⅱ:云南主汛期季节内振荡活动过程及其对MJO活动的响应  

Impact of Intra-Seasonal Oscillation in Asian Summer Monsoon on Precipitation in Main Rainy Season of Yunnan Ⅱ:Intra-Seasonal Oscillation Activity Process in Main Rainy Season of Yunnan and Its Response to MJO Activity

作　　者：李汀[1] 琚建华[2] 

机构地区：[1]中国科学院大气物理研究所大气科学和地球流体力学数值模拟国家重点实验室,北京100029 [2]云南省气象局,云南昆明650034

出　　处：《高原气象》2013年第3期626-634,共9页Plateau Meteorology

基　　金：国家公益性行业(气象)专项(GYHY201306022);中国科学院南海海洋研究所热带海洋环境国家重点实验室开放课题(LTO1203);中国气象科学研究院灾害天气国家重点实验室开放课题(2012LASW-A02)共同资助

摘　　要：利用NCEP OLR、风场再分析资料和日本APHRO_MA_V1003R1降水资料,针对云南主汛期季节内振荡(ISO)活跃年分析了对应低频对流场、环流场和降水的异常特征,以及热带印度洋大尺度振荡MJO分别激发孟加拉湾西南季风ISO和南海热带季风ISO,从而对云南主汛期ISO和降水产生的影响。在云南主汛期ISO活跃年,低频对流场和环流场在云南ISO波动的1～3位相和4～6位相呈反位相特征,这主要由热带印度洋低频对流东传、北传和副热带西太平洋低频对流西传造成的。热带印度洋的低频对流在发展过程中,一方面沿孟加拉湾西岸向西南—东北方向传播,激发了孟加拉湾西南季风ISO活跃并继续向云南传播;另一方面沿孟加拉湾以南继续东传到南海,激发了南海热带季风ISO活跃并北传到副热带中国东部地区,再沿副热带西传至云南,越过云南后与沿孟加拉湾西岸从东北方向传来的低频对流在孟加拉湾以北地区交汇,完成了一个经纬向接力传播的周期。云南主汛期降水在1～3位相由于副热带低频对流西传和孟加拉湾低频对流东北向传播而处于正距平(第2位相降水最多);在4～6位相,由于副热带低频对流抑制区西传和孟加拉湾低频对流抑制区东北向传播而降水减少(第5位相降水最少),云南主汛期降水与当地低频对流有较好的对应关系。当热带印度洋MJO较强时,4-7月以两条路径向云南的三次传播增强和提前,使得云南主汛期ISO活动也加强,对应产生三次低频对流活跃期,这种MJO由热带印度洋向云南的传播需要30～40天的时间。因此,正是热带印度洋MJO分别对孟加拉湾西南季风ISO和南海热带季风ISO的激发,使得东亚夏季风和南亚夏季风这两个亚洲夏季风系统共同作用于云南主汛期ISO,影响当地降水。Using OLR and wind reanalysis data from NCEP and precipitation data from APHRO_MA_ V1003R1 in Japan, the responding Low Frequency （LF） convection and circulation fields and precipitation anomaly features in ISO active years in main rainy season of Yunnan, and the impact of Intra-Seasonal Os- cillation （ISO） in monsoon systems of Bay of Bengal （BOB） and South China Sea （SCS） which excited by tropical Indian Madden and Julian Oscillation（MJO） on Yunnan ISO during main rainy season have been analyzed. The results show that, in ISO active years in main rainy season of Yunnan, LF convection and circulation fields shows negative feature in phase 1~3 and phase 4~6 of Yunnan ISO wave, which caused by eastward and northward propagations of tropical Indian LF convection and westward propagation of subtropical western Pacific LF convection. In developing process of tropical Indian LF, on the one hand, it propagates along western bank of BOB in southwest-northeast directions, which excites Southwest Mon- soon ISO of BOB active and to propagate to Yunnan; on the another hand, it propagates eastward from southern BOB to SCS and excites South China Sea Summer Monsoon（SCSSM）ISO active and to propagate northward to sub-tropical eastern China, where ISO turns to propagate westward to Yunnan. When it pas- ses Yunnan and meets LF convection which propagates northeastward along western bank of BOB, a circle of relay propagation along zonal and meridional directions is accomplished. Besides, the precipitation in Yunnan shows positive abnormal in phase 1~3 （in phase 2 it is the most） caused by sub-tropical LF con- vection propagating westward to Yunnan and BOB LF convection propagating northeastward to Yunnan; and in phase 4~6 the precipitation shows negative abnormal （in phase 5 it is the least） caused by sub-trop- ical LF convection inhibiting region propagating westward to Yunnan and BOB LF convection inhibiting re- gion propagating northeastward to Yunnan, so precipitation in main rainy season of Yun

关 键 词：季节内振荡(ISO) 热带印度洋MJO 云南主汛期降水 孟加拉湾西南季风 南海热带季风 

分 类 号：P461[天文地球—大气科学及气象学]