This study addresses the air–sea interaction processes and mixed layer variability, which cause the intraseasonal oscillations in the sea surface temperature (SST) during January 2013–December 2014 using the Regional Ocean Modeling System (ROMS). We have analyzed the SST variability at three locations—northern Bay of Bengal (BoB)/15°N, 90°E (R15), central BoB/12°N, 90°E (R12), and equatorial Indian Ocean (EIO)/0°N, 80.5°E (R0). During northeast monsoon (NEM) and southwest monsoon (SWM), intraseasonal SST variability is respectively controlled by the intense outgoing fluxes (sum of longwave radiation, latent heat flux, and sensible heat flux) and zonal wind stress. The intraseasonal SST variability in spring and fall is modulated by intense incoming shortwave radiation. There is a profound impact of mixed layer depth (MLD) variations on the intraseasonal SST oscillations in the BoB and EIO. At R15, and R12, deepened simulated MLD is associated with the lowered SST variability in the NEM and SWM. In spring and fall, the shallow MLD variability corresponds to higher intraseasonal SST variability at the buoy locations. In the northern BoB, ROMS cannot capture barrier layer (BL) and temperature inversion (TI) accurately in the winter and premonsoon season due to salinity bias, resulting in the difference between simulated and actual MLD. But the simulated MLD bias does not affect the intraseasonal SST structures in the NEM and pre-SWM. In the northern BoB, the proper representation of salinity structure may represent BL, TI, and MLD, accurately in the simulation during the winter and premonsoon season.

本研究使用区域海洋模型系统（ROMS）来解决海-海相互作用过程和混合层变异性，这些过程和混合层变异性会导致2013年1月至2014年12月期间海面温度（SST）的季节内振荡。我们分析了三个地点的海表温度变异性：孟加拉北部湾（BoB）/ 15°N，90°E（R15），中部BoB / 12°N，90°E（R12）和赤道印度洋（EIO） /0°N，80.5°E（R0）。在东北季风（NEM）和西南季风（SWM）期间，季节内SST的变化分别由强烈的出射通量（长波辐射，潜热通量和显热通量之和）和纬向风应力控制。春季和秋季的季节内SST变异性受到强烈的短波辐射的调制。混合层深度（MLD）的变化对BoB和EIO中的季节内SST振荡有深远的影响。在R15和R12，加深的模拟MLD与NEM和SWM中SST变异性降低有关。在春季和秋季，MLD的浅层变异性对应于浮标位置较高的季节内SST变异性。在北部的BoB中，由于盐度偏差，ROMS在冬季和季风季节无法准确捕获阻挡层（BL）和温度反演（TI），从而导致模拟MLD与实际MLD之间存在差异。但是模拟的MLD偏差不会影响NEM和SWM之前的季节内SST结构。在北部的BoB中，盐度结构的正确表示可以在冬季和季风季节的模拟中准确地表示BL，TI和MLD。