孟加拉湾SST季节循环双峰结构的热收支诊断

Heat Budget for the Double Peak of SST Seasonal Cycle in the Bay of Bengal

孟加拉湾海表温度(SST)存在显著的季节变化,它在春季和秋季出现两个峰值,而且春季峰值要高于秋季。本研究利用孟加拉湾中部的浮标观测资料,结合卫星遥感资料对2009年孟加拉湾混合层热收支进行诊断分析,揭示了两个SST峰值的形成机制及不对称的原因。结果表明:春、秋季孟加拉湾增暖过程呈现不同机制,春季增暖主要是热通量项的强加热效应的造成的,而秋季增暖是热通量项和温度平流输运共同加热造成的。SST在春季和秋季的峰值不对称主要是由热通量的加热效应不对称所造成的。对热通量项的进一步分析表明,春、秋季被混合层吸收的热通量和混合层深度的不对称共同造成了热通量加热效应的不对称。

Two SST peaks occur respectively in spring and autumn in the Bay of Bengal （BOB）, and the temperature in the spring peak is higher than that in the autumn peak. Buoy dataset together with satellite data collected in the central area of BoB in 2009 are used to diagnose the heat budget of mixed layer in BoB and hence to reveal the formation mechanisms and the asymmetry reasons of the SST double-peak struc- ture. The results indicate that different mechanisms of SST warming processes exist in spring and autumn in BOB. In spring the SST warming is mainly forced by heat flux, whereas in autumn it is mainly attribu- ted to the joint effort of heat flux and advection transportation. The asymmetry of the SST warming in spring and autumn is mainly caused by the asymmetric heating effect of the heat flux term, and the asym- metric heating effect of heat flux is mainly due to that the heat flux absorbed by the mixed layer and the depth of the mixed layer are both asymmetric in spring and autumn.