GRAPES_TYM模式对TC路径及环境引导气流预报检验分析

Test and Analysis of GRAPES_TYM Model for TC Track and Environmental Steering Flow Forecast

对2012—2013年GRAPES_TYM模式热带气旋路径预报结果进行检验,结果表明:模式对所有类型路径预报在24h、48h和72h预报时效的平均距离误差分别为94.3km,143.7km和260.8km,并且存在偏北的系统性偏差;对于南海TC,模式对TC移向预报较实况偏右,移速误差较小,移向偏差是路径偏差的主要原因;另外统计得到模式对TC移向的预报偏差与对其环境引导气流预报偏差有密切的关系,以1213号台风"启德"为例进一步通过移向误差诊断方程探讨了环境引导气流预报偏差(包括环境风场预报偏差、环境引导气流半径偏差及环境引导气流厚度偏差)对TC移向偏差的影响,而环境引导气流预报误差来源与模式对大尺度天气系统、TC大小及强度的预报偏差有关。

Tropical cyclone path forecast results are checked for 2012 to 2013using the GRAPES_TYM model.The results show that the average distance errors of the model is 94.3,km,143.7km and 260.8km,in 24 h,48hand,72 h,respectively;there exist farther-northern systematic biases for all types of TC forecast paths for the GRAPES_TYM model;for TC in the South China Sea,the TC moving direction prediction by GRAPES_TYM model slants to the right,and the moving speed error is less.The moving direction deviation is the main source of the path deviation.In addition,the statistic prediction model bias toward TC and TC environmental steering flow forecast bias are closely related.Taking the TyphoonKaitak＂as an example,according to the moving direction error diagnosis equation,the environmental steering flow forecast deviations（including environment wind field deviation,the impacts of the environment directing flow radius deviation,and environmental steering flow thickness deviation）on the TC moving direction prediction error are investigated;however,the environmental steering flow forecasting error sources are related with the model forecasting errors of large-scale weather systems and the size and strength of TCs.