Tropical cyclones are among the most destructive natural disasters. However, lack of detailed observations and the simplifications inherent in operational ocean models, lead to incomplete knowledge of underlying ocean processes. Using high-fidelity large-eddy simulations and moored observations away from the storm track, we show that mutually interacting shear and convective processes, govern the evolving state of the upper ocean. Our simulation agrees well with observed sea surface temperature and sea surface salinity. Shear driven turbulence due to surface wind stress erodes stratification, deepens the ocean mixed layer and transports freshwater into the mixed layer during rain events. Concurrently, surface buoyancy loss also aids in ocean mixing via convective entrainment. The mixing efficiency and the associated eddy diffusivity shows high spatiotemporal variability throughout the water column during cyclone passage. Thus, a better insight into the upper ocean mixing mechanisms is necessary for developing improved mixing parameterizations for tropical cyclone intensity forecasts.

中文翻译：

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热带气旋袭港期间海洋混合加剧


热带气旋是最具破坏性的自然灾害之一。然而，缺乏详细的观测和业务海洋模型中固有的简化，导致对潜在海洋过程的了解不完整。使用高保真大涡模拟和远离风暴路径的系泊观测，我们表明相互相互作用的切变和对流过程控制着上层海洋的演变状态。我们的模拟与观测到的海面温度和海面盐度非常吻合。由于表面风应力引起的剪切驱动湍流侵蚀了分层，加深了海洋混合层，并在降雨期间将淡水输送到混合层中。同时，表面浮力损失也有助于通过对流夹带进行海洋混合。混合效率和相关的涡流扩散率表明，在气旋通过期间，整个水柱的时空变化很大。因此，更好地了解上层海洋混合机制对于为热带气旋强度预报开发改进的混合参数化是必要的。