Observed seasonal variability of barrier layer in the Bay of Bengal
Observed seasonal variability of barrier layer in the Bay of Bengal
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DOI：
10.1029/2006jc003651
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发表时间：
2007-02
影响因子：
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通讯作者：
P. Thadathil;P. M. Muraleedharan;R. Rao;Y. K. Somayajulu;G. Reddy;C. Revichandran
中科院分区：
文献类型：
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作者：
P. Thadathil;P. M. Muraleedharan;R. Rao;Y. K. Somayajulu;G. Reddy;C. Revichandran
利用最全面的数据集，对孟加拉湾观测到的障壁层（BL）的形成和障壁厚度（BLT）的季节变化进行了研究。厚BL （~ 40 m）于6月首先出现在东北湾沿岸地区，并随着夏季风的发展向西扩散。在印度东海岸，BL的形成及其变率受东印度海岸流的控制。厚BL （~ 50 m）在11月沿印度东海岸出现，此时EICC向赤道流动，并在12月得到空间组织。到1月份，当EICC逆转时，它会减弱。在2月，副热带反气旋环流（SAG）在海湾地区建立良好，BLT的成熟期在振幅（~ 60 m）和空间范围上都出现。在夏季和冬季季风季节，地表环流和低咸水的再分布对观测到的BLT分布都有主要影响。其他过程，如沿东部边界传播的开尔文波所强迫的埃克曼泵送和传播罗斯比波，也对调制其变率有重要作用。BLT的年模态在11 - 12月达到最大值，半年模态在2 - 3月和8 - 9月达到峰值。2 - 3月的峰值是由内部的Ekman泵送和中部海湾的辐合引起的，而8 - 9月的峰值是由东部边界向西传播的下行Rossby波引起的。
[1] The observed formation of barrier layer (BL) and the seasonal variability of BL thickness (BLT) in the Bay of Bengal are examined utilizing the most comprehensive data set. Thick BL (∼40 m) first appears in the coastal region of the northeastern bay in June and spreads westward as the summer monsoon progresses. Along the east coast of India the BL formation and its variability are controlled by the East India Coastal Current (EICC). Thick BL (∼50 m) appears along the east coast of India in November when the EICC flows equatorward and gets spatially organized by December. By January it weakens when the EICC reverses. The mature phase of BLT, both in amplitude (∼60 m) and in spatial extent occurs during February, when the Subtropical Anticyclonic Gyre (SAG) is well established in the bay. During both the summer and winter monsoon seasons the surface circulation and the redistribution of low saline waters show a dominant influence on the observed BLT distribution. Other processes such as Ekman pumping and propagating Rossby waves forced by the propagating Kelvin waves along the eastern boundary also contribute significantly in modulating its variability. The annual mode of BLT shows maxima during November–December, whereas the semiannual mode peaks during February–March and August–September. The peak in February–March is attributed to the interior Ekman pumping and the associated convergence in the central bay, whereas the peak during August–September is due to the westward propagating downwelling Rossby waves from the eastern boundary.