黄海典型气旋与反气旋式海洋涡旋特征及影响机制模拟研究

为探讨黄海海洋涡旋的三维结构特征、能量输送与转换及影响机制,对黄海海域典型台风海洋气旋与近海海湾反气旋式涡旋个例进行数值模拟和时空诊断分析。采用FVCOM(Finite Volume Community Ocean Model)区域海洋数值模式精细化描述台风海洋涡旋与近海海洋中小尺度涡旋系统。对涡旋能量传输特征模拟显示,气旋式和反气旋式海洋涡旋中,非对称强流区动能能量下传比涡旋中心部位的强度更强,维持时间更长,下传深度更深。反气旋式海洋涡旋因Ekman流动形成的向中心辐合作用,造成此类差异更显著。气旋涡的动能主要来源于台风的近海面风应力动能和海洋涡旋有效位能的转换,反气旋涡旋区域风动力偏弱,其动能强度维持在低位,其涡旋增强伴随着有效位能的增加。环境因子影响机制从风浪,底摩擦和地形三方面讨论。结果显示:耦合波浪模块后,台风强风应力和风浪的综合作用扩大台风海洋涡旋尺度,并增强涡旋环流强度,同时对相邻的反气旋涡有压缩和减弱作用。风浪效应对台风海洋涡旋有正贡献。强台风过程表层环流响应台风应力而浅水地形和底摩擦强烈影响涡旋下层,造成台风海洋涡旋结构在垂直方向上偏移,并影响到下层环流速度减小,流向与表层相反。在海洋气旋涡和反气旋涡的显著辐散区,其混合层下方有温盐要素的涌升对应,辐合区有温盐要素的下沉对应;同时海底地形的升降也造成温盐强迫上升与下降,其强度与地形起伏尺度成正比,较环流系统作用更强。

A study using simulation to determine the characteristics and influencing mechanisms of cyclonic and anti-cyclonic ocean eddies in the Yellow Sea

In this study,numerical simulation and temporal-spatial analysis are carried out on the typical typhoon-induced ocean eddy and offshore anti-cyclonic eddy in the Yellow Sea in order to investigate its three-dimensional structural characteristics,energy transference,energy conversion,and influence mechanisms of the ocean eddies.Utilizing the advantage of simulating small and meso-scale offshore ocean systems,the FVCOM (Finite Volume Community Ocean Model) regional ocean numerical model is employed as the model.According to the simulation results,the core component of both the cyclonic and anti-cyclonic ocean eddies transfers less energy than the asymmetric strong current,which also has a longer sustaining time and a deeper transmission depth.Due to the convergence of Ekman flow,this difference is more obvious in the anti-cyclonic ocean eddy.The kinetic energy of typhoon wind stress and the available potential energy of the ocean eddy are mostly converted to create the kinetic energy of the cyclone eddy.Since the wind speed over the anti-cyclonic eddy region is low,the anti-cyclonic eddy system maintains a low level of kinetic energy,and its intensity increases according to its available potential energy.The influence mechanism of environmental factors is mainly in three aspects:wind and waves,bottom friction and terrain.The results show that adding the coupled wave module allows the combined effects of typhoon strong wind stress and wind waves to increase the magnitude of the typhoon-induced ocean eddy,speed up the eddy circulation,and decrease the adjacent anti-cyclonic eddy.The wind wave contributes positively to the typhoon-induced ocean eddy.During strong typhoon processes,the surface circulation of the typhoon ocean eddy reacts to typhoon stress.and the domain topography and bottom friction both have a significant impact on the lower portion of the eddy structure.The top and bottom features cause the structure of the ocean eddy to shift vertically,slowing down bottom circulation and producing an opposing flow direction between the upper and lower part of the eddy region.Under the mixed layer,there is high temperature and salt content,and the upwelling responds to the strong divergence areas of the cyclonic and the anti-cyclonic ocean eddies,while the downwelling react to the convergence areas of the eddy regions.Meanwhile the rolling topography changes the temperature and salt levels of the upwelling and downwelling,with their intensity corresponding to the terrain scale.