热带太平洋、印度洋海温异常在菲律宾海异常反气旋建立过程中的作用

A study of the effects of anomalous SSTs over the tropical Indian Ocean and the tropical Pacific on the establishment of the anomalous Philippine Sea anticyclone

利用NCEP/NCAR的1948—2000年逐月再分析资料、NOAA气候诊断中心的1948年1月—2000年1月的海表温度扩展重建资料、美国NOAA2-CIRES气候诊断中心提供的1974年6月—2008年1月向外长波辐射资料,采用诊断分析方法主要探讨了热带太平洋、印度洋海温异常事件在热带低层异常反气旋东移发展最后到达菲律宾海成为菲律宾反气旋过程中的作用。结果表明:(1)初秋南亚印度洋上发展起来的低层异常反气旋在东部干冷西部湿热的水平不对称分布和热带西太平洋海洋性大陆上存在的大尺度辐散异常条件下都会向东移动发展,而上述条件与热带海表温度异常及其演变特征有着密切联系。(2)单纯厄尔尼诺事件,单纯印度洋正偶极子事件下的海温异常分布特征有利于形成东部干冷西部湿热的水平不对称分布和热带海洋大陆上的大尺度辐散异常。相对于厄尔尼诺事件,印度洋正偶极子事件是一个较弱且短暂的海洋事件,因此单纯印度洋正偶极子事件下到达菲律宾海地区的低层异常反气旋(即菲律宾异常反气旋)相对较弱,持续时间短。(3)在有印度洋正偶极子发生的厄尔尼诺事件中,两大洋的海温异常分布和显著的大尺度辐散异常更加有利于低层异常反气旋东移发展,在两大洋共同作用下使到达菲律宾海的低层异常反气旋(即菲律宾异常反气旋)相对于在单纯的某种海温异常事件作用的菲律宾异常反气旋强度更大,持续时间更长。

Based on the NCEP/NCAR reanalysis data,the sea surface temperature（SST） data from the NOAA and the outgoing longwave radiation（OLR） from the NOAA2-CIRES,the influence of SST anomaly（SSTA） of the tropical Pacific and the tropical Indian Ocean on the process of the development and eastward passage of the tropical low-level anomalous anticyclone （LAAC） which eventually anchors in the Philippine Sea（named PSAC） is investigated in this paper.The results show that（1） The LAAC was developing in the Indian Ocean in earlier fall.The eastward passage of the LAAC appears to be the results from the horizontal asymmetry of moisture and temperature anomalies as well as the existence of the large-scale divergent center over the maritime continent.The two conditions are significantly correlated with the SSTA over the tropical ocean and the SSTA evolvement.（2） For single E1 Nino events and single positive Iudian Ocean Dipole（IOD） events,the distribution pattern and the SSTA evolvement benefit the formation of the horizontal asymmetry of moisture and temperature anomalies as well as the large-scale divergence anomaly over the maritime continent.Compared to the E1 Nino events,the positive IOD events are much weaker with shorter duration.As the result,the PSAC is much weaker and has shorter lifecycle.（3） When an E1 Nino event occurring with a positive IOD event,the SSTAs over the two oceans and the divergent center over the maritime continent more avail the moving and development of the LAAC.As the result of the combined influence of positive IOD and E1 Nino events, the PSAC was stronger and sustained for a longer time than those in the case of the single E1 Nino events or single positive IOD events.