This study investigates the winter-to-winter recurrence (WWR) of sea surface temperature anomaly (SSTA) in the Bay of Bengal (BOB) and its causes. During 1948–2016, 36% years show WWRs, which occurred over the BOB north of 13° N. The WWR of net surface heat flux (Qnet), especially the latent heat flux (Qlat) associated with change of winter monsoon wind speed, is essential for all the SSTA WWR events. The interdecadal wintertime warming (cooling) of BOB SST before (after) 1976, which is induced by the weakened (enhanced) monsoon wind and latent heat flux associated with the Interdecadal Pacific Oscillation (IPO) and decadal variability of the Indian Ocean, are the causes for the observed interdecadal variability of warm (cold) SSTA WWR. However, nearly half (48%) of the WWR events are significantly contributed from the subsurface processes, which is equivalent to ~ 26% (42%) contribution to Qnet for the warm (cold) SSTA WWR events. Different from the mid-latitude subsurface re-emergence mechanism that depends critically on wintertime mixed layer deepening, the BOB subsurface effects on WWR of SSTA are associated with shoaling/deepening thermocline, forced remotely by winds along the equator and Ekman pumping within the BOB.

本研究调查了孟加拉湾（BOB）的海表温度异常（SSTA）的冬季到冬季复发（WWR）及其原因。在1948年至2016年期间，有36％的年发生WWR，发生在北纬13°N以北的BOB上。净水通量（Qnet）尤其是与冬季季风风速变化相关的潜热通量（Qlat）的WWR，对于所有SSTA WWR事件都是必不可少的。BOB SST 1976年之前（之后）的年代际冬季变暖（降温）是由与印度洋年代际太平洋涛动（IPO）和年代际变率相关的减弱（增强）的季风风和潜热通量引起的。导致观测到的暖（冷）SSTA WWR年代际变化的原因。但是，将近一半（48％）的WWR事件是由地下过程引起的，这相当于温暖（冷）的SSTA WWR事件对Qnet的贡献约为26％（42％）。与严重依赖于冬季混合层加深的中纬度地下再涌现机制不同，BOB对SSTA WWR的地​​下作用与浅滩/深层热跃层有关，后者是由沿赤道的风和BOB内的Ekman抽水远程推动的。