摘要
以MM5模式为基础,从预报模式的不确定性出发形成8个集合成员,建立了上海区域降水集合预报系统。该系统实现从资料收集、资料处理、模式预报到预报结果处理与产品输出的全自动化,于2005年8月1日开始业务运行,运行稳定可靠。对系统8—10月的运行结果进行检验,结果表明:集合预报系统对降水的总体预报效果尚可,其中对量级小的降水的总体预报效果更好,集合预报产品尤其是概率预报产品具有一定的参考价值,但系统还存在发散度偏小的问题,有待进一步改进。
The operational ensemble forecast system for Shanghai regional precipitation is established. The model is based on MM5 in the system, with a one-way two-nesting procedure. The coarse grid domain of 101×101 grid points has a horizontal grid spacing of 45 km, while the inner grid domain of 70×70 grid points has a horizontal grid spacing of 15 km. Both domains have 21 vertical sigma levels. Eight different configurations of MM5 are used to produce an 8-member ensemble forecast. The approach to generating eight members is to use different convective parameterization schemes and different PBL parameterization schemes of the inner grid domain. In this system, all steps from data collection, data processing and model running to output automatically are carried out by computer. The system starts operating on August 1,2005. The system operates twice everyday and each time it runs to 48 h forecast. The forecasts are then displayed on Website. Since the start of the operation, the system has shown stability and reliability. The forecasts from August to October are verified in the fields of ensemble mean, probabilistic forecast and spread. The results show the ensemble means of precipitations of low thresholds are more skillful than the ensemble means of precipitations of high thresholds. For precipitations of low thresholds, the larger the forecasting probability is, the larger the usefulness of probabilistic forecast is. For precipitations of high thresholds, the smaller the forecasting probability is, the larger the usefulness of probabilistic forecast is. The results also show the system has the problem of too small spread. In conclusion, the performance of the system is alright in forecasting precipitation. The precipitation forecasts of low thresholds seem better than the forecasts of high thresholds. The products of the system, especially the products of probability forecasts can be used as a reference. However, there are still some problems in the system, which should be improved in the future.
出处
《应用气象学报》
CSCD
北大核心
2007年第2期173-180,共8页
Journal of Applied Meteorological Science
关键词
集合预报系统
降水
检验
ensemble prediction system
precipitation
verification
