大氣海洋系統年際變異度之初步分析

A Preliminary Examination of the Interannual Variability of Atmosphere - Ocean System

張振瑋(Cheng-Wei Chang) ； 余嘉裕(Jia-Yuh Yu)

《華岡理科學報》 20期 (2003/05) Pp. 209-227

https://doi.org/10.6364/HKJS.200305.0209

摘要

本文採用NCEP／NCAR再分析資料之風場、Reynolds最佳化海面溫度、以及CMAP降水資料，利用經驗正交函數和奇異值分解法來探討大氣海洋系統之年際變化特徵，其中又以分析熱帶太平洋地區大氣和海洋交界面處之耦合特徵為重心。　透過經驗正交函數分析發現，熱帶地區海溫年際變化主中心集中在太平洋盆地，主要是伴隨著ENSO事件發展，其中EOF1顯示ENSO成熟期變異量，主要暖海溫區位於赤道中、東太平洋，西太平洋與副熱帶太平洋則由馬蹄形負值區所籠罩。EOF2顯示的是ENSO＋１年春季特徵，暖海溫區東移到秘魯沿海附近，馬蹄形負值區移至中太平洋，西北太平洋沿岸地區出現顯著之暖海溫區。　透過奇異值分解探討大氣海洋交界面處之耦合關係發現，海溫與降水分佈有高度正相關，海溫升高（減低）伴隨著降水增加（減少）。海溫與風場耦合型態顯示，當ENSO成熟期時，在赤道區中太平洋暖水區有顯著之跨越赤道南風，引發北半球西風爆發。在ENSO＋１年春季，赤道中太平洋轉為跨赤道北風，並在菲律賓東方海面出現反氣旋環流。

並列摘要

In this paper, NCEP/NCAR reanalysis data of winds, Reynolds optimum interpolation sea surface temperature (SST), CMAP precipitation data are used to examine the interannual variability in atmosphere-ocean system. In particular, the coupled patterns of near the interface between atmosphere and ocean are emphasized. The empirical orthogonal function analysis indicates that major centers of SST interannual variability are located in the tropical Pacific, mainly associated with evolution of ENSO events. EOF1 of SST exhibits the mature phase of ENSO with warm SST located in the equatorial central and eastern Pacific. The western Pacific and subtropical Pacific are covered by a horse-shoe-like cold SST pattern. EOF2, On the other hand, exhibits spring phase of ENSO+ 1 year, with warm SST and the horse-shoe-like cold SST patterns migrating eastward to the coast of Peru and central Pacific, respectively. Significant warm SSTs appear along the coast of western north Pacific. The singular value decomposition analysis indicates that the distribution of SST is highly correlated to the precipitation pattern, with enhanced (weakened) precipitation over warm (cold) ocean. The coupled patterns of SST and winds indicate the appearance of cross-equatorial southerly over warm equatorial central Pacific during the mature phase of ENSO. During the spring of ENSO+ 1 year, however, the Southerly mentioned previously turns into cross-equatorial northerly over the same region and this is associated with the existence of a significant anti-cyclonic circulation to the east of Philippine Islands.