Interannual variability (IAV) in the barrier layer thickness (BLT) and forcing mechanisms in the eastern equatorial Indian Ocean (EEIO) and Bay of Bengal (BoB) are examined using monthly Argo data sets during 2002–2017. The BLT during November–January (NDJ) in the EEIO shows strong IAV, which is associated with the Indian Ocean dipole mode (IOD), with the IOD leading the BLT by two months. During the negative IOD phase, the westerly wind anomalies driving the downwelling Kelvin waves increase the isothermal layer depth (ILD). Moreover, the variability in the mixed layer depth (MLD) is complex. Affected by the Wyrtki jet, the MLD presents negative anomalies west of 85°E and strong positive anomalies between 85°E and 93°E. Therefore, the BLT shows positive anomalies except between 86°E and 92°E in the EEIO. Additionally, the IAV in the BLT during December–February (DJF) in the BoB is also investigated. In the eastern and northeastern BoB, the IAV in the BLT is remotely forced by equatorial zonal wind stress anomalies associated with the El Niño-Southern Oscillation (ENSO). In the western BoB, the regional surface wind forcing-related ENSO modulates the BLT variations.

中文翻译：

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赤道东印度洋和孟加拉湾屏障层的年际变化和强迫机制

使用2002-2017年期间的每月Argo数据集，对赤道东印度洋（EEIO）和孟加拉湾（BoB）的阻挡层厚度（BLT）的年际变化（IAV）和强迫机制进行了研究。EEIO在11月至1月（NDJ）期间的BLT显示出强大的IAV，这与印度洋偶极子模式（IOD）有关，IOD领先BLT两个月。在负IOD阶段，驱动下行Kelvin波的西风异常增加了等温层深度（ILD）。此外，混合层深度（MLD）的变化是复杂的。受Wyrtki喷气机影响，MLD在85°E以西呈现负异常，在85°E与93°E之间呈现强正异常。因此，除了EEIO中的86°E和92°E之间，BLT都显示出正异常。另外，还调查了BoB在12月至2月（DJF）内BLT中的IAV。在东部和东北的BoB中，BLT中的IAV受与厄尔尼诺-南方涛动（ENSO）相关的赤道纬向风应力异常的强加作用。在西部的BoB中，与地表风强迫有关的ENSO调节了BLT的变化。