中文摘要：

以目前运行的上海区域业务数值预报模式为基础，从预报模式的不确定性出发构造8个预报成员，建立了上海区域数值预报模式集合预报系统的初步模型，并对2004年夏季进行了逐日48h预报试验。结果表明：集合平均对华东地区城市降水、温度、海平面气压等气象要素的总体预报能力与分辨率高3倍的业务模式相当，其中对雨量较大降水、最低温度、海平面气压（0～24h）的预报效果好于业务模式；集合预报还能提供客观化、定量化的降水概率预报，对降水的发生、尤其是特大降水的发生有着很好的提示作用。

英文摘要：

The initial model of Shanghai regional numerical ensemble forecast system is established based on Shanghai regional operational numerical forecast model. In this system, eight forecast members are created according to the model uncertainty. Daily 48 h experiments are made for summer 2004. The results show the ensemble mean forecasts of precipitation, temperature and sea level pressure for cities in East China are not worse than the forecasts of the operational model, although the horizontal resolution of the operational model is three times as the resolution of the ensemble model. The ensemble mean forecasts of large precipitation,minimal temperature and 0-24h sea level pressure are better than the forecasts of the operational model. Also objective and quantitative precipitation probability forecast can be obtained from the ensemble forecast. The precipitation probability forecasts have good directions for the. happening of large precipitation in the near future.