2021/05/25- 分享人:冯 杰 秦南南
发布时间: 2021-05-25

题目Impact of increasing horizontal and vertical resolution during the HWRF hybrid EnVar data assimilation on the analysis and prediction of Hurricane Patricia (2015)

报告人:冯杰复旦大学青年研究员

报告摘要:Although numerous studies have demonstrated that increasing model spatial resolution in free forecasts can potentially improve tropical cyclone (TC) intensity forecasts, studies on the impact of model resolution during data assimilation (DA) on TC prediction are lacking.In this study, using the ensemble-variational DA system for Hurricane Weather Research and Forecasting (HWRF) model, we investigated the individual impact of increasing the model resolution of first guess (FG) and background ensemble (BE) forecasts during DA on initial analyses and subsequent forecasts of Hurricane Patricia (2015).The impacts were compared between horizontal and vertical resolutions and also between the tropical storm (TS) and hurricane assimilation during Patricia.

  

题目:Evolution of the Moat Associated with the Secondary Eyewall Formation in a Simulated Tropical Cyclone

报告人:秦南南,南京信息工程大学气象学博士,导师张大林。美国马里兰大学大气与海洋科学系2年联合培养博士,1年博士后交流,交流导师为Da-Lin Zhang。现复旦大学大气院博士后,合作导师吴立广。主要研究方向为台风动力学。

报告摘要:Previous studies have focused on the formation and maintenance of spiral rainbands in the secondary eyewall formation (SEF) of tropical cyclones (TCs). In this study, a semi-idealized numerical experiment is conducted to understand the SEF by focusing on the evolution of the moat. It is found that the occurrence and subsequent evolution of the moat in the simulated TC are closely associated with the inner-eyewall structure. As the eyewall updraft becomes strong and the eyewall anvil is well developed, the upper-level inflow develops below the eyewall anvil in response to the diabatic warming in the eyewall anvil. The warming-induced inflow causes a drying effect and promotes the sublimation cooling below the anvil, inducing strong subsidence between the inner eyewall and the spiral rainband through the resulting negative buoyancy. Moreover, the resulting subsidence is enhanced by the compensated downward motion in the outer edge of the inner eyewall. Further analysis indicates that the rapidly decreasing vertical shear of environmental wind and the rapid filamentation zone outside the inner eyewall also play important role in the axisymmetrization of the rainband and the moat subsidence.