中文摘要：

以华中区域中尺度业务模式WRF3D为平台,使用MYJ、ACM2边界层方案完成了2012年7月的批量敏感试验,并与高时空分辨率实况降水数据作对比,重点关注不同边界层方案对中国中东部地区降水日变化的影响。结果表明,两种方案下的降水预报均对我国中东部地区清晨和午后并存的降水双峰值有所表现,且两者对清晨降水峰值的预报差异不大,但预报的午后降水峰值差异明显,尤其表现在峰值幅度上,位相上也略有差异。总体而言,ACM2方案下的降水日变化特征更接近实况。进一步对高分辨率模式输出的诊断表明,午后降水峰值主要由隐式降水决定。在此基础上,从模式中隐、显式降水产生机制的角度考察了不同边界层方案下降水日变化差异的可能原因。

英文摘要：

The planetary boundary layer（PBL）is an important part of the numerical weather prediction model.Previous sensitive studies of the PBL schemes are mainly focused on the typical typhoon or heavy rainfall cases,but it is not clear how the PBL schemes impact the diurnal variation of precipitation in the operational model.Based on the operational central China regional mesoscale model WRF3 D,sensitivity experiments have been made in July 2012 by using two PBL schemes named MYJ and ACM2 respectively.Then the impact of different schemes on the diurnal variation of precipitation in central eastern China has been studied by comparing the forecasted precipitation with the high-resolution observation provided by the National Meteorological Information Center.Furthermore,because of WRF3 D is not a cloud-resolving model due to the limit of computing resources,the interaction of implicit and explicit precipitation processes should also be studied by deeply diagnosing the model outputs.The result showed that the precipitation forecasts by both schemes can reflect the double peaks observed in central eastern China to a certain extent.For the early morning precipitation peak,the difference between these two forecasts is little.But the difference in the late afternoon peak is distinct.Specifically,the late afternoon peak forecasted by the MYJ scheme is 4h ahead of the observation with an exaggerated amplitude,while it is only 1h ahead and the amplitude is reasonable by using the ACM2 scheme.In general,the diurnal variation of precipitation forecasted by ACM2 is more close to the observation.Dividing the forecasted precipitation into the implicit and explicit part,it shows that the late afternoon precipitation peak is mainly composed of the implicit one.In addition,the area-averaged implicit（explicit）precipitation forecasted by the MYJ scheme is more（less）than ACM2 at all times.Furthermore,detailed analysis of the high-resolution model outputs shows that,the over-predicted implicit precipitation by the MYJ scheme is mai