【摘要】 选取了2001年8月发生于北京市的具有不同大尺度环流强迫特征的两次强降水过程,利用MM5模式和国家气象中心的T213预报资料,分析了模式非绝热物理过程对北京市暴雨数值预报的影响特征和不确定性,探讨了解决暴雨预报不确定性的集合预报方法,进行了多物理模式集合预报试验。试验结果表明:模式非绝热物理参数化方案对精细化预报结果有明显影响,包括局地降水强度、空间分布型态、时间演变特征等;在高分辨率模式中,采用积云对流参数化方案后,会出现更多的小量级降水预报,且不论是大尺度强迫较强的暴雨,还是大尺度强迫较弱的暴雨,对流参数化方案都是造成降水预报不确定性的重要因素。多物理集合预报的初步试验结果表明,高分辨率集合预报可提供有价值的预报信息,是解决灾害性天气预报不确定性的一种有效的技术方法,但就目前的模式水平而言,可重点发展降水集合预报,特别是强降水集合预报系统,以反映模式在降水预报中存在的不确定性。更多还原

【Abstract】 The 29th Olympic Games will be held in Beijing during Aug 8—24 2008 when the local weather is under the control by East Asia Monsoon system with hot and wet weather.Heavy rainfall and flood often occur in monsoon season in Beijing and are a main high impact weather factor on the Olympic Games matches and schedules.It’s very important for meteorologists to forecast the heavy rainfall events and floods for Olympic Games weather service.However,heavy rainfall events are closely related not only to the development of mesoscale and micro-mesoscale convective weather systems,but also to diabatic physics processes.Researches show that diabatic physics processes have a great impact on the uncertainty of heavy rainfall prediction and can not be simulated very well by mesoscale model.Ensemble prediction is a new encouraging prediction technology and a method to improve the heavy rainfall prediction skill and could give the reliability of prediction in recent years.The construction scheme of ensemble prediction system is a key factor for a skilled ensemble system.Initial perturbation scheme and model perturbation scheme are popular methods.Recent researches show that ensemble system constructed by different convective parameterization schemes and planetary boundary layer parameterizations is good for heavy rainfall events occurring in the situation of weak baroclinic circulation.But heavy rainfall often occurs under strong baroclinic circulation.To establish a good ensemble prediction system during Olympic Games,further researches should be done to understand the characteristics of the impact of diabatic physics process on heavy rainfall in Beijing.In the context of PSU/NCAR non-hydrostatic mesoscale model(MM5),the impact of convective parameterization schemes on uncertainty in mesoscale numerical prediction of Beijing heavy rainfall events is explored.Two mesoscale heavy rainfalls are selected to study the impact of different convective parameterization schemes and different planetary boundary layer schemes on the predictions.One case occurs in strong large scale forcing environment during Aug 3—4,2001 and the other case in weak large scale forcing environment during Aug 17—18,2001.The results show the physical process of convective parameterization schemes on heavy rainfall makes much more differences of the timing,locations and strength of mesh scale and subgrid scale precipitation in two different large scale forcing environments.By using different convective parameterization and planetary boundary layer schemes,different model parameters are constructed as ensembles system.The results indicate that the ensemble simulations can provide more uncertainty information of location and strength of the heavy rainfall.The single determinate predictions of heavy rain are unstable;physics ensemble predictions can reflect the uncertainty of heavy rains,providing more useful guidance and have more high application value.更多还原