不同观测资料在西南地区数值预报中的应用

Application of Different Observations in Numerical Weather Prediction of Southwest China

利用3.4版WRF同化与预报系统开展自动站、探空、GPS大气可降水量和云迹风资料的同化对比试验,了解现有业务中已同化观测资料在新版系统中的应用效果,确定资料同化优选方案,为西南区域中心数值预报业务改进提供参考。试验表明:(1)自动站资料测站多、分布不均,对初猜场低层要素调整作用大,会减小温度、相对湿度误差;探空资料站点少、垂直信息丰富,对初猜场各层误差减小均有贡献;云迹风资料垂直分布不均,集中在对流层中高层,因此对初猜场的最大调整集中在中高层,会减小位势高度误差;GPS测站少,被剔除的比例高,对初猜场调整作用很小;(2)单独同化试验发现探空、云迹风资料有助于该地区降水预报改进,而自动站和GPS资料对降水预报有负作用;(3)同时同化探空、云迹风资料有利于西南地区降水预报准确率提高,尤其对大降水中心预报。

Using the 3.4 version of WRF assimilation and forecasting system, the assimilation comparison tests about auto- matic weather stations （AWS）, radiosonde, GPS atmospheric precipitation and atmospheric motion vectors （AMVs） data in southwest China were carried out. The purpose is to understand the application effect of these observations used in Southwest Regional Centre ntimerical prediction system, give a better assimilation scheme when using these observations, and provide a reference for Southwest Regional Centre numerical prediction improvement. Tests show that ： ! ） There are many AWS stations, but these stations are distributed unevenly. Assimilating AWS mainly adjusts the low elements of first guess field. There are relatively few radiosonde stations, but the vertical observations are rich, so all levels of first guess field can be adjusted after as- similating radiosonde. AMV data are mainly in the 200 - 300 hPa and the main effect lies in 200 - 300 hPa to first guess field. GPS data have only 25 stations and more than half are excluded, so a little of adjustment to first guess field ; 2） The tests of as- similation alone find that radiosonde and AMVs data can improve precipitation forecasts, other two observations have the nega- tive effects to NWP; 3 ） Using radiosonde and AMVs data at the same time can improve precipitation forecasts in southwest re- gion, especially heavy precipitation center＇ s forecast.