The overturning circulation in the Red Sea exhibits a distinct seasonally reversing pattern and is studied using high-resolution MIT general circulation model simulations. In the first part of this study, the vertical and horizontal structure of the summer overturning circulation and its dynamical mechanisms are presented from the model results. The seasonal water exchange in the Strait of Bab el Mandeb is successfully simulated, and the structures of the intruding subsurface Gulf of Aden intermediate water are in good agreement with summer observations in 2011. The model results suggest that the summer overturning circulation is driven by the combined effect of the shoaling of the thermocline in the Gulf of Aden resulting from remote winds in the Arabian Sea and an upward surface slope from the Red Sea to the Gulf of Aden set up by local surface winds in the Red Sea. In addition, during late summer two processes associated, respectively, with latitudinally differential heating and increased salinity in the southern Red Sea act together to cause the reversal of the contrast of the vertical density structure and the cessation of the summer overturning circulation. Dynamically, the subsurface northward pressure gradient force is mainly balanced by vertical viscosity resulting from the vertical shear and boundary friction in the Strait of Bab el Mandeb. Unlike some previous studies, the three-layer summer exchange flows in the Strait of Bab el Mandeb do not appear to be hydraulically controlled.
展开▼
机译:红海的倾覆环流表现出明显的季节性反转模式,并使用高分辨率的MIT常规环流模型模拟进行了研究。在本研究的第一部分中,从模型结果中给出了夏季俯覆环流的垂直和水平结构及其动力学机制。成功模拟了Bab el Mandeb海峡的季节性水交换,入侵的亚丁湾次表层水下水的结构与2011年的夏季观测结果吻合良好。模型结果表明,夏季的上覆环流是由水汽驱动的。阿拉伯海中偏远风造成的亚丁湾浅层跃层的综合作用以及红海中局部地面风造成的从红海到亚丁湾的上表面坡度的综合影响。此外,在夏末期间,分别与纬度差加热和南红海盐度增加相关的两个过程共同作用,导致垂直密度结构反差的逆转和夏季翻转环流的停止。在动力学上,地下的北向压力梯度力主要由竖向黏度平衡,竖向黏度是由Bab el Mandeb海峡的垂直切变和边界摩擦引起的。与先前的一些研究不同,巴布勒曼德布海峡的三层夏季交换流量似乎没有受到水力控制。
展开▼