2011年江西汛期降水低频分量的延伸期预报试验

摘要

Based on the daily rainfall series and 850 hPa meridional wind of the NCEP reanalysis data from February to August in 2011,a multivariable lagged regressive(MLR)model was constructed.The model was applied to do the daily extended forecast of low frequency rainfall over Jiangxi Area from May to July.The results show that there are two distinct oscillations in Jiangxi which are about 10-30 days and 50-70 days respectively.The predictive skill of the 50-70 days low-frequency rainfalls is distinctly better then that of the 10-30 days.The forecast score of 50-70 days low frequency rainfall is up to 86%,which is able to accurately predict the positive and negative phase conversion of low frequency rainfall.This can provide extended range forecast signal for the heavy rainfall process in Jiangxi.%利用2011年2—8月逐日降水量序列及东亚地区850 hPa经向风场资料建立多变量时滞回归(multivariable lagged regression,MLR)模型,对5—7月江西降水10~30 d和50~70 d低频分量分别进行延伸期逐日预报实验.结果表明:2011年江西降水存在显著的10~30 d和50~70 d的振荡周期.降水50~70 d低频分量延伸期预报技巧明显优于10~30 d低频分量延伸期预报技巧,平均预报技巧高达0.86.降水50~70 d低频分量延伸期预报可准确预报降水低频位相的正负转换,能为江西延伸期强降水过程发生的时段预测提供预报信号.