基于降尺度方法的入海中尺度对流过程模拟

利用海-气-浪耦合模式和动力降尺度方法模拟并分析了2018年5月12日和7月13日两次东移进入渤海湾的中尺度对流过程，分别为入海减弱型和入海增强型。两次过程均发生在低空西南气流强盛，且地面处于暖舌控制的环境下，具有较好的水汽和能量条件。结果表明:海-气-浪耦合模式能较好地模拟减弱型过程的变化趋势，而对增强型过程的模拟效果较差，且模拟的两次过程对流强度整体偏弱；但经动力降尺度模拟后，两次过程的模拟效果均明显提升。敏感性试验对比表明:采用海-气-浪耦合模式结果为动力降尺度提供初边界条件具有一定优势，适用于入海中尺度对流过程模拟；两次过程对流系统入海前对流有效位能条件均较好，但垂直风切变条件增强型过程优于减弱型过程；对流系统入海后的冷池效应在减弱型过程中明显，而在增强型过程中强度较弱但范围较大；海洋下垫面为对流发展提供的热量和水汽输送在减弱型过程中较少，在增强型过程中明显。

Simulation of Mesoscale Convection Process into Sea Based on Downscaling Method

Two processes of mesoscale convection moving eastward into the Bohai Bay on 12 May and 13 Jul in 2018, which are weakened process and enhanced process respectively, are simulated and analyzed by using the ocean-atmosphere-wave coupling model and dynamic downscaling method. Both processes occur under the control of strong southwesterly at low level and warm tongue near surface, which bring abundant water vapor and heat. The results show that the coupling model can simulate the right trend of the weakened process, but the wrong trend of the enhanced process, and the simulated intensity is overall weak. The simulation effects are improved obviously after the spatial resolution of the model increasing by using dynamic downscaling method twice. Through the comparison of sensitivity experiments, it is indicated that the coupling model has certain advantages in providing better initial and boundary conditions for the dynamic downscaling, which is suitable for the simulation, compared with the general atmospheric WRF model. Through the diagnosis and analysis of the simulation results, it's concluded that before the convection systems entering the sea, the convective available potential energy (CAPE) is large in the Bohai Bay and coastal areas. As the convection systems moving eastward into the sea, the CAPE is gradually consumed, but the supplement of CAPE in the enhanced process is stronger than that in the weakened process. The 0-6 km vertical wind shear condition of the enhanced process is also stronger than that of the weakened process in the Bohai Bay before the convection systems entering the sea, which is another favorable factor for the development of the convection. In the weakened process, the cold pool effect is increasingly stronger with an obvious rear inflow, and there is an obvious wind velocity convergence in the front of the cold pool during the convection systems moving. In the enhanced process, however, the strength of the cold pool is weaker, but the range is larger compared with the weakened process, and there is an obvious wind direction convergence in the front of the cold pool. In the weakened process, the underlying surface of the ocean provide less water vapor and heat energy for the convection region, making the convection difficult to maintain or further develop, while in the enhanced process the sea surface provides mass water vapor and heat energy transfer to the convective region when the convection system moving over the sea.