热带气旋影响下浙江省强降水过程延伸期预报研究

Preliminary study on extended-range forecast for intensive precipitation processes over Zhejiang province induced by tropical cyclone:Model construction and examination

利用2000—2011年NCEP/NCAR水平风场逐日再分析资料以及浙江省逐日降水量资料,基于低频天气图工具,识别出3种与浙江省台风强降水过程相对应的典型低频大气环流型。通过合成分析,划分了与C型环流场和C+SN型环流场相适配的天气关键区。进而结合历史个例,研究了台风强降水期间关键区内低频系统的活动特征,初步建立了热带气旋影响下浙江省强降水过程预报模型,并提出依据模型开展延伸期过程预报的基本思路。对2012年的回报结果表明,模型表现出较好的性能,并针对强降水过程延伸期预报中需要解决的问题,提出了若干思考与建议。

Based on the daily NCEP/NCAR horizontal wind reanalysis datasets during 2000-2011 and synchronous daily precipitation data over Zhejiang province, the low-frequency synoptic chart was used to indentify three kinds of typical low-frequency atmospheric circulation pattern corresponding to in- tensive precipitation processes over Zhejiang province induced by tropical cyclone. Through composite a- nalysis, the synoptic key regions corresponding to the ＂C-type＂ and ＂ C＋SN-type＂ circulation pattern are built. Furthermore, combined with historic cases study, the characteristics of low-frequency system activities in key regions during heavy rainfall processes are investigated, and a preliminary forecast model for intensive precipitation process over Zhejiang province induced by typhoon is constructed, moreover, a fundamental method conducting extended-range forecast of such strong rainfall processes is proposed. The performance of forecast model in this paper generally satisfies the hindcast of important typhoon-induced intensive precipitation processes in 2012, but the problems in operational extended-range forecast remain open. Some thoughts and suggestions are raised finally.