西北太平洋台风路径业务预报误差初步分析

Preliminary Analysis on the Track Error of Typhoon Operational Forecasts in the Western North Pacific

本文通过总结3个业务预报中心(中国中央气象台(以下简称NMC)、日本东京台风中(心以下简称TYPH)和美国联合台风预警中心(以下简称JTWC))官方台风路径预报,分析发现,过去12a(1997—2008年)中,24 h和48 h的台风路径预报精度有较大改进,其中48 h的预报效果改进更为明显。但路径预报的主要改进出现在2000—2004年,近几年(2005—2008年)台风预报路径改进相对缓慢。分类分析表明,较弱的热带风暴和强热带风暴等级台风(以下简称STS类)个例24 h平均路径预报误差(本文所指的路径预报误差均为距离绝对误差)比台风及以上等级(以下简称TY类)个例平均误差大约50 km,而STS类48 h预报平均误差则比TY类个例预报平均误差大约50～100 km。但近12a来STS类预报水平要比TY类改进幅度大,24 h平均误差由2000年前后的超过100 km减小至2006—2008年的约50 km,48 h路径预报误差也有类似表现。区域分析表明:纬度较高的我国华东北部及黄海地区,以及日本以东洋面的台风预报误差比较大,而热带附近的台风路径预报误差较小。综合而言,3个官方预报水平逐步接近,但是不同方法对于不同区域的台风预报效果各有优劣。对于南海台风,JTWC的24 h预报精度比TYPH的要好,NMC效果居中。近12a来,对于中国大陆区域的台风个例NMC方法24 h预报改进最大,而48 h预报误差也已经减少至200 km左右,这可能意味着NMC对于影响我国的台风预报能力已经非常接近国际先进水准。相对而言,NMC方法在日本附近海域台风预报效果比其他两个要略差一些。

Through a detail analysis based on the subjective forecast information of National Meteorological Center(NMC),TYPH and JTWC,the results show that the operational track forecast has been improved largely during the past 12 years(1997-2008).And more advances are gained for the 48 h forecast than the 24 h forecast.But most of the improvements of track forecast happen in the early years of this century(2000-2004),and few progresses are made in recent years(2005-2008).Further analyses show that 24 h track forecast error of weak typhoons(STS and TS) is 40-50 km larger than that of strong typhoons(TY,STY and SPTY),and that the forecasts of typhoons located in the difference regions have different skills.To the typhoons of the South China Sea,the 24 h forecast results of NMC and JTWC are more accurate than that of TYPH.In the 12 years,the improvements of the NMC 24 h forecast are the highest for the typhoons near China's Mainland,and the 48 h forecast error is decreased to be about 200 km,which might mean that NMC has good typhoon forecast ability which is near internationally top standard.But the NMC forecast skill score is much lower than the other two forecasts for the typhoons near the Japan Sea area.