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 WRF3D, 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 WRF3D 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 mainly due to its own local closure, making the lower troposphere too wet, resulting in the larger CAPE and slightly smaller CIN appear some time earlier, and eventually triggering the KF cumulus parameterization scheme to produce the heavier and earlier implicit precipitation compared with ACM2. On the other hand, there is energy competition between the processes of implicit and explicit precipitation, inducing the much less hydrometeors forecasted by the MYJ scheme and leading to the less explicit precipitation compared with ACM2. It is concluded that there's important impact of the PBL schemes on the forecasted diurnal variation of precipitation in central eastern China. This result is intended to provide a reliable basis for the optimization of the PBL scheme in WRF3D.
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