Bay of Bengal salinity stratification and Indian summer monsoon intraseasonal oscillation: 1. Intraseasonal variability and causes: SALINITY STRATIFICATION AND MISO
Bay of Bengal salinity stratification and Indian summer monsoon intraseasonal oscillation: 1. Intraseasonal variability and causes: SALINITY STRATIFICATION AND MISO
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孟加拉湾盐度分层和印度夏季季风季节内振荡： 1. 季节内变化和原因：盐度分层和 MISO
DOI：
10.1002/2017jc012691
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
Lee, Tong
中科院分区：
文献类型：
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作者：
Li, Yuanlong;Han, Weiqing;Ravichandran, M.;Wang, Wanqiu;Shinoda, Toshiaki;Lee, Tong
印度夏季风(ISM；5-10月)的巨大淡水通量在孟加拉湾(BOB)引起强烈的盐度层结，导致浅混合层和厚屏障层，这可能影响季风(MISO)的季节内振荡。在这项研究中，利用ARGO浮标和系泊浮标的现场观测和海洋环流模式(OGCM)，研究了混合层深度(MLD)和障碍层厚度(BLT)的季节内变化。在间歇期，∼的平均MLD一般为20-30米，而BLT则从5-6月的10米增加到9-10月的20-40米。MISO引起MLD和等温层深度(ILD)的同相变化，在MISO活跃期，两者均加深8~15m，而BLT变化较小，在ARGO数据采集误差范围内。在北(南)湾，MISO期间，由于ILD的加深大于MLD，BLT增加了∼5m(2m)。进行了OGCM实验以了解其潜在的机制。在BOB，MLD、ILD和BLT的季节内变化主要是由海洋内部不稳定引起的，而MISO引起的季节内变化较弱。MISO过程中MLD和ILD的同相变化是由不同的工艺引起的。MLD加深主要是由风应力强迫引起的，而ILD加深主要是由地面冷却的地表热通量驱动的。BLT的有限变率是由于不同强迫过程的抵消。
The huge freshwater flux of the Indian summer monsoon (ISM; May–October) gives rise to strong salinity stratification in the Bay of Bengal (BoB), causing a shallow mixed layer and a thick barrier layer, which potentially affects intraseasonal oscillations of the monsoon (MISOs). In this study, intraseasonal variability of the mixed‐layer depth (MLD) and barrier layer thickness (BLT) is investigated using in situ observations from Argo floats and moored buoys and an ocean general circulation model (OGCM). The average MLD in the BoB is typically 20–30 m during the ISM, while the BLT increases from ∼10 m in May–June to 20–40 m in September–October. MISOs induce in‐phase variations in MLD and isothermal layer depth (ILD), both of which are deepened by 8–15 m during MISO active phase, while the change of BLT is small and within the error range of Argo data sampling. In the northern (southern) bay, BLT increases by ∼5 m (2 m) during MISOs owing to a larger deepening of ILD than MLD. OGCM experiments are performed to understand the underlying mechanism. In the BoB intraseasonal variations of MLD, ILD and BLT arise largely from ocean internal instability, whereas those induced by MISOs are weaker. The in‐phase variations of MLD and ILD during MISOs are induced by different processes. The MLD deepening is primarily caused by wind stress forcing, while the ILD deepening is driven by surface heat fluxes via surface cooling. The limited variability of BLT is due to the offsetting of different forcing processes.