基于DERF2.0产品的重庆月动力延伸期预测分析及应用

Analysis and Application of Monthly Dynamic Extension Forecast in Chongqing Based on DERF2.0 Data

根据2015年国家气候中心实时下发的第二代月动力延伸模式(DERF2.0)逐日资料和历史回算资料,统计构建不同时间起报的月500 hPa高度场格点数据序列,针对重庆2月气温和8月降水量方差和预测难度较大的事实,分别分析2010—2014年逐年1月和7月16日、21日、26日、31日起报的2月和8月500 hPa高度场预报场与同期NCEP资料实况场的分布型。结果表明:预测效果低纬好于中高纬,8月总体好于2月;基于上述滚动的500 hPa预报场,试验了4个关键区和5种统计降尺度方法,对重庆2010—2015年2月气温和2010—2014年8月降水量进行回报预测和检验。结果表明,16日起报的模式场对2月气温有较好的参考价值,配合最好的关键区为本区上空,而降尺度方案中Lamb方法效果最佳,二者结合的预测效果最好;虽然8月降水预测效果不如2月气温,但在预测关键区取自定义关键区时,车氏方法的降尺度方案预测效果相对较好。

Based on latest and historical daily data of National Climate Centre second-generation monthly Dynamic Extended Range Forecast operational system （DERF2.0）,monthly 500 hPa geopolitical height sequences were built at different initial forecasting time. Focused on the facts that variances of temperature in February and precipitation in August are larger in Chongqing and they were hard to be forecasted correctly, we analyzed the differences between 500 hPa geopolitical height field forecasted on 16th, 21th, 26th and 31th in February and August seperated during 2010-2014 and NCEP data in the same term, It is concluded that the patterns foredcasted in the lower latitude are better than that in the higher latitude, while generally better in February than that in August. on basis of on the forecasted 500 hPa geopolitical height fields showed above, the forecasted temperature in Februray and the precipitation in Auguest during 2010-2015 in Chongqing are historically recalculated and reviewed in four key regions using five statistical downscaling methods. It indicated that the forecasted model fields initialized on Jane 16th is a preferable reference for predicting temperature in February with the best key region on the local upper air, while the lamb method was proved to be the best statistical downscaling method, and the most precise forecast value can thus be generated with the forecasted model fields initialized on 16th using Lamb. It is also showed that the forecasting effects of precipitation in August were worse than temperature in February, and Chebysev method is suprior to the other method in chosing userdefined region on August precipitation forecasting in Chongqing.