Knowledge of spring warm pool in the Bay of Bengal (BoBWP) is key for further understanding the climate variability in this region and beyond, but little is known about the BoBWP climatological state and the related mechanisms. In this study, we investigate the spatial structure and evolution of the BoBWP using daily Optimum Interpolation SST data from 1982-2022 in combination with multi-source data. Our analysis shows that the BoBWP is located in the central bay (6°-13°N) with a thickness around 20 m ~ 40 m. Composite analysis indicates that the BoBWP emerges in early April, peaks in early May and dissipates in early June. During the developing period, the net heat flux dominates the formation of spring warm pool through significant air-sea coupling processes, and induces the warming rate of 0.27°C/10d in the mixed layer, which is far larger than the contribution of oceanic dynamical processes (0.01°C/10d). During the decaying period, the net heat flux also plays a dominant role, with a cooling rate of -0.21°C/10d, meanwhile ocean dynamical processes contribute to the cooling of the warm pool with a rate of -0.01°C/10d. Additionally, the SST and the area of the BoBWP are significantly correlated with ENSO (r=0.66 and 0.73, p=0.05). During El Niño decaying year, the BoBWP primarily expands in a southward direction, with a 75% increase in area. Conversely, during La Niña decaying year, the BoBWP almost disappears, with a 52% decrease.

中文翻译：

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孟加拉湾春季暖池演化特征及机制


了解孟加拉湾春季暖池（BoBWP）对于进一步了解该地区及其他地区的气候变化至关重要，但人们对BoBWP的气候状态和相关机制知之甚少。在本研究中，我们利用1982-2022年每日最佳插值海温数据并结合多源数据研究了BoBWP的空间结构和演变。分析表明，BoBWP位于海湾中央（6°-13°N），厚度约为20 m~40 m。综合分析表明，BoBWP 在 4 月初出现，5 月初达到峰值，6 月初消散。发育期，净热通量通过显着的海气耦合过程主导春季暖池的形成，并引起混合层0.27℃/10d的增温速率，远大于海洋动力的贡献。过程（0.01°C/10d）。在衰减过程中，净热通量也起主导作用，冷却速率为-0.21℃/10d，同时海洋动力过程对暖池的冷却速率为-0.01℃/10d。此外，SST和BoBWP面积与ENSO显着相关（r=0.66和0.73，p=0.05）。厄尔尼诺衰减年，BoBWP主要向南扩展，面积增加75%。相反，在拉尼娜现象减弱的年份，BoBWP 几乎消失，下降了 52%。