中文摘要：

用2011年5—7月逐日东亚地区850hPa经向风场资料建立主振荡预测模型（POP），对影响7月中旬长江下游地区强降水过程的主要低频经向风场（20-30d时间尺度）的时空变化进行10—30d延伸期独立预报试验。结果表明，在60次预测中提前20d预报的相关预报技巧在0．50以上。很好地预报了2011年7月18日长江下游特大暴雨过程对应的关键区20--30d时间尺度的低频经向风变化过程。

英文摘要：

Based on the low-frequency meridional wind of 850 hPa over East Asia for May-July in 2011 on the time scale of the 20-- 30 days, a series of the principal oscillation pattern （POP） models are built, and independent forecast experiments of POP models are carried out for the propagation of the low-frequency zone associated with the heavy precipita!ion over the lower reaches of the Yangtze River valley in Mid-July 2011 for the extended range of the 10--30 days. The results show that the skill score of the correlation prediction up to 20 days ahead of time can reach more than 0.50 in the 60 forecasts, and the variations of the low frequency meridional wind of the key region are well predicted in connection with a disastrous rain on July 18, 2011 over the lower reaches of the Yangtze River valley.