光流法对2011年“梅花”台风期间500hPa高度场预报的检验释用
Verification and Application for 500hPa Height Forecasts During the Period of Typhoon MUIFA(1109) Using the Optical Flow Technique
中文摘要：
利用光流技术，对2011年台风“梅花”期间ECMWF（简称EC）和T639两个数值天气预报模式的500hPa高度场预报进行了检验和释用。结果发现，EC的24、48和72h预报具有稳定的误差。EC的24h预报强度误差比观测低2～9gpm，角度误差在180°和240°之间（极坐标系），也就是西到西南向；EC的48h预报强度误差比观测低8～18gpm，角度误差同样在180°和240°之间。EC的72h预报强度误差比观测低－25～26gpm，角度误差在170°和290°之间。作为比较，T639的预报强度和预报角度误差则没有那么稳定。对预报位移误差而言，EC和T639的预报误差都比较稳定。利用基于光流技术的数值预报释用方法，将24h的预报误差用来订正48h的预报，结果表明，订正预报场比预报场本身更近似于观测场。
中文关键词：
光流技术，台风“梅花”，检验释用，位势高度
KeyWords：
optical flow technique, MUIFA, verification and application, geopotential height
Abstract：
Using the optical flow technique, 500hPa height forecasts of two numerical weather prediction (NWP) models ECMWF (EC for short) and T639 during the period of Typhoon MUIFA(1109) are verified and interpreted. The results show that EC has stable errors in 24h, 48h and 72h forecasts. Its 24h forecast intensities are 2-9gpm lower than observations, and angular errors are between 180° and 240°, which are between west and southwest. Its 48h forecast intensities are 8-18gpm lower than observations, and angular errors are also between 180° and 240°. Its 72h forecast intensities are mainly －25 to 26gpm lower than observations, and angular errors are mainly between 170° and 290°. By contrast, the intensity and angular errors of T639 are not so stable. As for displacement errors, the performances of EC and T639 are both stable. The similar disparities between observation fields and 24h, 48h and 72h forecast fields of the two models also show that EC has better forecasting performances than T639. Finally, an application technique is used to correct the 48h forecast fields according to the 24h forecasts errors. The results show that when the distortion errors of 24h forecasts obtained from the optical flow field are used to correct the 48h forecasts, the correction fields are more similar to the observation fields than the forecast fields themselves.