利用热带太平洋关键区海表面盐度指标区分两类厄尔尼诺

Distinguishing two types of El Ni?o in the Tropical Pacific using key region sea surface salinity index

文章利用强化海洋数据(enhanceoceandata,简称EN4.4.1.f)1980—2016年的再分析逐月资料,根据海表盐度异常(SSSA)指标,找出与厄尔尼诺关系最为重要和密切的盐度变化区域,并区分两类厄尔尼诺。利用海表面温度作为两类厄尔尼诺的时间相关系数指标,通过研究其水平分布发现:在热带太平洋存在着多个能指示两类厄尔尼诺的盐度变化区域,在东部(EP)型厄尔尼诺时期,最显著的SSSA关键区主要出现在日界线附近的西太平洋暖池区域东边缘,并以赤道和日界线为轴线呈中心对称分布;而在中部(CP)型时期,关键区在日界线以西的赤道太平洋,且在日界线以东的SSSA分布则呈现沿赤道的经向非对称性,这种非对称性在东南太平洋出现了与EP型厄尔尼诺时期相比更为显著不同的正SSSA关键区。文章以此找到关键区域中能够较好代表并区分两类厄尔尼诺的区域,对挑选出的多个关键区进行有机组合,定义了一组以SSSA为指标进行有效区分两类厄尔尼诺的方法,并以此指数对近年来发生的两类厄尔尼诺进行合理再现。

In this paper, the sea surface salinity anomaly (SSSA) index from the EN4 reanalysis data during 1980-2016 is used to distinguish two types of El Nino. We identify the salinity variation region which has a close contact with two types of El Nino in the tropical Pacific. We demonstrate that salinity time series in different boxes are related sea surface temperature variation, and can indicate two types of El Nino. Depending on the key salinity field contrast of their correlation coefficient of temporal and horizontal distribution. Evidently, the region of SSS field is mainly located in the equatorial region with symmetric distribution in the western tropical Pacific during the eastern Pacific (EP) El Nino. One significant region of SSS field is migrated westward, another skewing southward east of the dateline as asymmetric distribution during the central Pacific El Ni?o, which is different from the EP El Ni?o. Based on these characteristics, we find key areas of an index that represents two types of El Nino and distinguishes them. Finally, we use this index to reproduce recent El Nino events.