三维变分同化机载雷达资料对飓风预报的影响研究——2012年Isaac试验

A Study of the Impact of Airborne Radar Data Assimilated by 3DVar on the Prediction of Hurricane——Isaac 2012

随着气旋内部资料(Inner core data)在热带气旋预报中的使用,其重要性逐渐受到人们越来越多的关注。为了研究该资料中尾部机载雷达(Tail Doppler Radar,TDR)资料在业务系统中的应用效果,本文利用2012年飓风等级热带气旋Isaac期间的TDR资料,采用业务HWRF(Weather Research and Forecasting model for Hurricane)数值模式与业务GSI(Grid-point Statistical Interpolation system)三维变分同化(Three-Dimensional Variational Data Assimilation,3DVar)系统对TDR资料进行了同化,展开了一系列预报试验,并对其效果进行了分析和研究。结果表明与HWRF的业务预报相比,GSI系统同化TDR资料后对热带气旋的路径和强度预报有明显改进;但其同化效果同时也表明业务三维变分中的静态背景误差协方差在TDR资料的应用中仍需要进一步的改进。

Given the increasingly important role of inner-core data in tropical cyclone（TC） forecasting, the present paper investigates the impact of assimilating Tail Doppler Radar（TDR） data on the prediction of hurricanes. A series of experiments are conducted using the operational Weather Research and Forecasting model for Hurricane（HWRF） and grid-point statistical interpolation（GSI） 3D variational（3DVar） system for Hurricane Isaac（2012）. It is found that the assimilation of TDR data can correct the storm center to a better position compared to without TDR assimilation. Furthermore, the better inner-core structures in the results of the experiments that assimilated the TDR data have a positive impact on the intensity forecasts. In general, the TDR data improve the TC track and intensity forecast compared to the official forecasts from the operational HWRF, and the forecasts without assimilating the TDR data. The study also suggests that further reducing the background error covariances to be consistent with the dynamical and thermodynamical structures of the hurricanes is needed to further improve analyses and predictions of TCs.