Barrier Layer Variability in the Central Equatorial Pacific Associated With ENSO Development

IF 4.6 1区地球科学 Q1 GEOSCIENCES, MULTIDISCIPLINARY

Geophysical Research Letters Pub Date : 2025-03-29 DOI:10.1029/2024GL113396

Cong Guan, Michael J. McPhaden, Shijian Hu, Fan Wang, Yuanlong Li, Manman Cui

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Abstract

Previous studies suggest that a thick barrier layer can strengthen surface warming during El Niño and vice versa for La Niña. Here we find barrier layer changes of up to 6 m in the central equatorial Pacific (CEP, 170°E−160°W, 5°S–5°N) in response to a 1°C change in the Niño 3.4 index using 19 years of Argo observations. Our analysis reveals that mixed layer variability due to strong interannual salinity anomalies determines the changes in CEP barrier layer thickness (BLT) during El Niño Southern Oscillation events since isothermal layer variations are minimal there. During El Niño, enhanced rainfall leads to anomalous surface freshening in the CEP especially west of the dateline, while anomalous vertical-sheared zonal current results in stronger vertical salinity stratification and thicker barrier layer east of the dateline in the CEP. Surface-layer zonal current advection in general contributes to a thicker barrier layer in the entire CEP.

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以前的研究表明，在厄尔尼诺现象期间，厚的阻挡层会加强地表变暖，反之亦然。在这里，我们利用 19 年的 Argo 观测数据发现，赤道太平洋中部（CEP，170°E-160°W，5°S-5°N）的阻挡层会随着尼诺 3.4 指数 1°C 的变化而发生高达 6 米的变化。我们的分析表明，在厄尔尼诺南方涛动事件期间，由强烈的年际盐度异常引起的混合层变化决定了中欧太平洋阻挡层厚度（BLT）的变化，因为那里的等温层变化很小。在厄尔尼诺现象期间，降雨量的增加导致大陆架界限以西地区的表层异常清新，而垂直切向带流的异常则导致大陆架界限以东地区的垂直盐度分层更强，阻挡层更厚。表层地带性海流平流总体上导致整个中欧太平洋的阻挡层增厚。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Geophysical Research Letters 地学-地球科学综合

CiteScore

9.00

自引率

9.60%

发文量

1588

审稿时长

2.2 months

期刊介绍： Geophysical Research Letters (GRL) publishes high-impact, innovative, and timely research on major scientific advances in all the major geoscience disciplines. Papers are communications-length articles and should have broad and immediate implications in their discipline or across the geosciences. GRLmaintains the fastest turn-around of all high-impact publications in the geosciences and works closely with authors to ensure broad visibility of top papers.