大氣與海洋年代震盪特徵分析

本文採用NCEP/NCAR再分析資料之近地面風場、最佳化內差月平均海平面溫度資料，利用奇異值分解法來探討大氣與海洋系統耦合特徵。大氣海洋系統最顯著之耦合特徵為「年代震盪」，其海溫空間分佈在太平洋地區呈現東太平洋和北太平洋反相位分佈，暖（冷）年代時東太平洋海溫升高（降低），北太平洋海溫降低（升高），和ENSO成熟期結構類似。我們的研究也發現，年代震盪結構之季節變化不明顯，與ENSO訊號透過大氣海洋交互作用強烈地被鎖定在北半球冬季顯然不同，顯示年代震盪為大氣海洋系統整個氣候態的轉變。冷、暖年代ENSO演變差異若從時間來看，主要發生在消散期，暖年代ENSO消散較冷年代慢；若從空間來看，暖年代時ENSO消散較冷年代慢主要區域在南美秘魯外海（Ninol+2區）。年代震盪扮演調和ENSO角色，使得暖（冷）年代ENSO強度較強（弱），持續時間較長（短），發生ENSO頻率較低（高）。

關鍵字

年代震盪；聖嬰／南方震盪

並列摘要

In this paper, NCEP/NCAR reanalysis near-surface monthly winds and Optimum Interpolation monthly sea surface temperature (SST) are used to examine the coupled characteristics in atmosphere-ocean system by employing the Singular Value Decomposition (SVD) method. The most dominant coupled mode of the atmosphere-ocean system is the so-called ”decadal oscillation”. Its SST spatial pattern exhibits opposite phase between eastern Pacific and North Pacific, with warm (cold) SST in the eastern Pacific while cold (warm) SST in the North Pacific during ”warm epoch” (”cold epoch”), similar to the ENSO variability. Our result also indicates that the seasonal change of decadal pattern is modest, much different from the ENSO evolution whose amplitude is strongly locked in northern winter season, which shows that the decadal oscillation involves an entire shift of climate state from one to another. Difference of ENSO evolution between cold and warm epoch can be seen. From the temporal point of view, ENSOs in warm epoch decay much slower than those in cold epoch. From the spatial point of view, the slow decay of ENSOs in warm epoch results from warming trend off the coast of Peru (Nino1+2) during the decaying stage of ENSOs. The decadal oscillation can modulate ENSOs by intensifying (weakening) and lengthening (shortening) ENSO evolution, as well as decreasing (increasing) ENSO frequency in warm (cold) epoch.

並列關鍵字

Decadal oscillation ； El Nino/Southern Oscillation

國際替代計量

大氣與海洋年代震盪特徵分析

全文下載

主題瀏覽