海洋性大陆区域OLR的气候低频振荡及其与中国降水的可能联系  

THE CLIMATOLOGICAL LOW-FREQUENCY OSCILLATIONS IN MARITIME CONTINENT REGION AND THEIR POSSIBLE RELATIONS WITH PRECIPITATION CHANGES IN CHINA

作　　者：靳振华[1,2] 管兆勇[1] 

机构地区：[1]气象灾害省部共建教育部重点实验室/南京信息工程大学,江苏南京210044 [2]天津市滨海新区气象局,天津300457

出　　处：《热带气象学报》2013年第5期705-716,共12页Journal of Tropical Meteorology

基　　金：国家自然科学基金项目(41175062;40475028);江苏省PAPD项目;青蓝工程创新团队项目共同资助

摘　　要：利用1979-2009年NCEP/NCAR再分析资料和地面观测站降水资料,研究了海洋性大陆（Maritime Continent,MC）区域的低频振荡气候学特征及其与中国东部降水扰动的关系.结果表明：气候平均状况下MC 区域存在显著的低频振荡（CLFO）,30 ～ 60 d季节内振荡在4-9月强度最大,且MC区域为低频OLR方差贡献率大值区.低频时间尺度上,MC区域OLR在4-9月有4次比较明显的活跃过程,在1～4（5～8）位相,对流相对较弱（活跃）.OLR的CLFO在热带地区显著东传,在南北方向亦存在位相的传播.从MC区域经南海、菲律宾群岛至中国长江流域存在类似于EAP波列（或P-J型遥相关）的扰动环流分布.不同位相上,低频环流及加热场的变化表明,中国降水的扰动在4-9月间受到MC区域CLFO的可能影响.低频热力场在南北方向上呈现EAP波列状或P-J型遥相关状分布.在OLR的CLFO的峰（谷）位相时,MC区域低层辐散（辐合）,高层辐合（辐散）,低频对流相对较弱（较强）,在MC区域至日本海激发EAP波列（或P-J型遥相关）；在对流层上层南亚高压因低频气旋（反气旋）而位置偏东（偏西）；中国的江南及河套地区降水偏少（偏多）,西南及青海、甘肃等地降水增加（减少）.在转换位相时,MC区域低频对流在部分地区更为活跃,在对流层低层激发低频的气旋-反气旋-气旋的波列,南亚高压偏南,长江中上游、吉林地区出现明显的辐合区,降水偏多,黄淮之间及云贵地区降水偏少.这些结果有助于人们深刻认识气候学意义上的低频振荡特征及LFO的季节锁相问题,有利于进一步认识中国不同地区降水扰动的成因.Using the NCEP/NCAR reanalysis and in situ precipitation data from 1979 to 2009,the authors have investigated the climatological characteristics of Low-Frequency Oscillation（CLFO） in Maritime Continent Regions（MC） and their association with the precipitation disturbances in China.Our results demonstrate that climatologically,the apparent LFO exists in MC with a period of 30～60 days as derived from Outgoing Long-wave Radiation data from April to September.During the period from phases 1 to 4（5 to 8） of the Low-Frequency,the variations of OLR in MC show that the convection in MC is relatively weak （active）.The climatological low frequency OLR is found to propagate eastward in the tropics,and also has a phase propagation in the meridional direction.The wave train-like pattern is found from MC to the Philippine islands and then the Yangtze River in China and across the South China Sea,which looks similar to the EAP or P-J teleconnection.The Low-Frequency circulations and heating disturbances in different phases suggest some linkages between the CLFO in MC and the precipitation disturbances in China during the period from April to September.In the peak phase,the low-frequency convection is relatively weak due to divergence in the lower troposphere along with convergence in the upper troposphere,which excites the EAP wave train from MC to the Sea of Japan.The South Asia high shifts eastward due to the low-frequency anticyclone in southem China.As a result,less precipitation is observed in both the south of Changiiang River valley and Hetao area in China.More precipitation is found in southwestern China,Qinghai and Gansu provinces.In the transition phase from the valley to the peak of CLFO of OLR,the low-frequency cyclone-anticyclone-cyclone wave train is also be excited,resulting in South Asia high shifting southwestward.The convergence takes place in the upper and middle reaches of Yangtze River and Jilin Area,which facilitates more rainfall in these regions.Meanwhile,less rainfall is received in the

关 键 词：气候低频振荡 夏季降水 海洋性大陆 向外长波辐射 中国 

分 类 号：P426.6[天文地球—大气科学及气象学]