Distribution of the tropical Pacific surface zonal wind anomaly and its relation with two types of El Niño
Distribution of the tropical Pacific surface zonal wind anomaly and its relation with two types of El Niño
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DOI：
10.1007/s00343-013-2294-9
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发表时间：
2013-09
影响因子：
--
通讯作者：
Yang Wang;Jinnian Chen;Hongna Wang
中科院分区：
文献类型：
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作者：
Yang Wang;Jinnian Chen;Hongna Wang
利用旋转经验正交函数（REOF）方法，首次将厄尔尼诺事件分为东太平洋型（EP）和中太平洋型（CP）。利用超前/滞后回归和旋转奇异值分解（RSVD）分析方法，研究了热带太平洋地面纬向风（SZW）异常与海表温度（SST）异常的关系。提出了一个可能的物理过程的CP厄尔尼诺。对于EP厄尔尼诺，强西风异常持续向东传播，产生一个以165°W为中心的异常海洋纬向辐合带（ZCZ）。这种SZW异常模式有利于极向和向东Sverdrup输送在赤道。对于CP厄尔尼诺，西风异常和ZCZ主要局限于西太平洋，东风异常吹在东太平洋。这种SZW异常型抑制赤道Sverdrup向极和向东的输送，但在5°N附近存在向东的Sverdrup输送，有利于热带太平洋东北部的增暖。结果表明，次表层暖水（部分来自Ekman辐合和ZCZ引起的下沉流）向东传播的缓慢是由于中央海盆的潜流减缓所致，而中太平洋的垂直平流对CP厄尔尼诺的形成和消失可能具有重要作用。
El Niño events with an eastern Pacific pattern (EP) and central Pacific pattern (CP) were first separated using rotated empirical orthogonal functions (REOF). Lead/lag regression and rotated singular value decomposition (RSVD) analyses were then carried out to study the relation between the surface zonal wind (SZW) anomalies and sea surface temperature (SST) anomalies in the tropical Pacific. A possible physical process for the CP El Niño was proposed. For the EP El Niño, strong westerly anomalies that spread eastward continuously produce an anomalous ocean zonal convergence zone (ZCZ) centered on about 165°W. This SZW anomaly pattern favors poleward and eastward Sverdrup transport at the equator. For the CP El Niño, westerly anomalies and the ZCZ are mainly confined to the western Pacific, and easterly anomalies blow in the eastern Pacific. This SZW anomaly pattern restrains poleward and eastward Sverdrup transport at the equator; however, there is an eastward Sverdrup transport at about 5°N, which favors the warming of the north-eastern tropical Pacific. It is found that the slowness of eastward propagation of subsurface warm water (partly from the downwelling caused by Ekman convergence and the ZCZ) is due to the slowdown of the undercurrent in the central basin, and vertical advection in the central Pacific may be important in the formation and disappearance of the CP El Niño.