印度洋海盆模对南北半球太平洋副热带高压非对称的影响及机制  

Influence and Mechanism of Indian Ocean Basin Model on the Asymmetry of Pacific Subtropical High in the Northern and Southern Hemispheres

作　　者：杨雨欣 袁潮霞 李艳[1] YANG Yuxin;YUAN Chaoxia;LI Yan(College of Atmospheric Sciences,Lanzhou University,Lanzhou 730030,Gansu,China;School of Atmospheric Sciences,Nanjing University of Information Science&Technology,Nanjing 210044,Jiangsu,China)

机构地区：[1]兰州大学大气科学学院,甘肃兰州730030 [2]南京信息工程大学大气科学学院,江苏南京210044

出　　处：《高原气象》2023年第6期1589-1603,共15页Plateau Meteorology

基　　金：国家自然科学基金项目(41775051)。

摘　　要：副热带高压对于我国天气气候具有重要影响,它的形成受到印度洋海温异常的影响,但其中的影响机制并不十分清楚。因此,本文利用1980-2020年NCEP/NCAR再分析资料,研究了印度洋海盆模(Indian Ocean Basin Model,IOBM)异常偏强对于太平洋副热带高压的影响;然后从能量角度分析IOBM引起南北半球太平洋海域副热带高压不对称性的物理机制;最后利用GFDL AM2.1模式进行模拟验证。为了说明印度洋海温异常对副热带高压的独立作用,对ENSO信号进行了滤除。结果表明:(1)夏季的印度洋暖海温暖异常会激发东传的Kelvin波,在西北太平洋地区低层出现反气旋异常,使西太副高较常年偏强,我国南海到菲律宾东部降水偏少;冬季IOBM正位相时,澳洲地区东风异常,热带西太平洋地区有大范围的降水负异常。印度洋海盆模对太平洋副热带高压非对称结构的影响在环流和降水场上均有体现。(2)根据能量诊断结果发现IOBM正位相时,夏季西北太平洋低层季风风场辐合区与扰动动能增长区相重合,有利于该地反气旋异常发展,从而使得副高偏强;冬季澳洲地区季风的风场辐合区与扰动动能增长区不能很好地配合,没有明显的反气旋异常。(3)利用数值模式模拟得到的结果能够验证沿赤道对称的印度洋海温异常在西太平洋地区引起的反气旋性环流和降水异常,无论位置还是强度都表现出极强的不对称性。因此,印度洋海盆模(IOBM)对于太平洋副热带高压南北半球非对称结构的形成具有重要作用,并进而对东亚及澳洲地区降水的异常分布产生影响,这为印度洋海盆模对西太副高的影响提供了理论基础。Subtropical anticyclone has an important influence in weather and climate in China,which is affected by the tropical sea surface temperature(SST)anomaly in the Indian Ocean for its formation.However,there is limited studies for the corresponding influence mechanism.In order to probe impact as well as the mechanism of the SST anomaly over the Indian Ocean on the subtropical high,the El Nino-Southern Oscillation(ENSO)signal is filtered out.By using the reanalysis data from the National Centers for Environmental Prediction/National Center for Atmospheric Research(NCEP/NACR)from 1980 to 2020,this study tries to explore the influence and mechanism of the Indian Ocean basin model(IOBM)on subtropical high in the Pacific Ocean through dynamical diagnose in perspective of energy,and verifies the results by numerical model simulation by the Geophysical Fluid Dynamics Laboratory Atmospheric Model(GFDL AM2.1).The results show that eastern-spreading of the Kelvin wave is motivated by the SST anomaly in the Indian Ocean in summer.Meanwhile,low-level anticyclone anomaly appears in the northwest Pacific Ocean,resulting in the subtropical anticyclone is stronger than the climatological mean.Thus,the precipitation is less in regions from the South China Sea to Eastern Philippines.In winter,during the positive phase of the IOBM,the east wind anomalies are stimulated in Australia,resulting in large-area negative anomalies of precipitation occurred over the western Pacific.Non-uniform distribution of precipitation is caused by the asymmetry in circulation of subtropical high over the Pacific Ocean in the northern and southern hemispheres.Result by the dynamical diagnose reveals that when the phase of IOBM is positive,the wind field convergence zone is superposed by the disturbance energy growth area,whereas in winter such two regions do not cooperate with each other.As a result,the subtropical high is abnormally strong in the northwestern Pacific in summer and with indistinct abnormally in Australia in winter.The numerical simulation

关 键 词：印度洋海盆模 西北太平洋副热带高压 KELVIN波 中国降水异常 

分 类 号：P461[天文地球—大气科学及气象学]