ISSN 1006-9895

CN 11-1768/O4

A Case Study Comparing WRF-Model-Simulated Cloud Microphysics and Precipitation with Aircraft Measurements in Stratiform Clouds with Embedded Convection in Northern China
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    Abstract:

    To verify the cloud microphysical scheme and to simulate cloud microphysics and precipitation, the authors used the Weather Research and Forecasting (WRF) model to simulate their characteristics in stratiform clouds with embedded convection for April 18 2009, and then compared the results with data obtained during the Beijing Cloud Experiment (BCE). The results indicate that the distributions of the cloud system, radar echo, and precipitations simulated by the WRF model are in good agreement with our observations. The simulated liquid water content (LWC) is consistent with aircraft measurements, and the maximum LWCs at the -8℃ and 3℃ layers observed by the aircraft are 1.5 g m-3 and 0.8 g m-3, and those simulated by model are 1.1 g m-3 and 0.78 g m-3, respectively. Vertical distributions below the -5℃ layer (most cloud water is LWC) were properly simulated, and it included the melting layer. The ice water content (IWC) simulated by the model was higher than that of the observations in the range of -6 to -10℃ layer because the simulated riming process is excessive at this layer, and the aggregation process occurred in a higher layer. As such, modifications are required for cold simulation processes. At the -8℃ layer, both the intercept and slope of the particle size distributions (PSDs) simulated by the model were lower than those of the observations due to the simulated snow mass concentrations being higher than observed. At the -5℃ layer, both the simulated intercept and slope were consistent with observations. At the 3℃ layer, the simulated slope was consistent with observations, but the simulated intercept was higher than the observed value due to the decreasing concentration of small particles in the cloud, which suggests that the spectrum-shape parameter could change with cloud height.

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History
  • Received:January 22,2014
  • Revised:May 23,2014
  • Adopted:
  • Online: March 12,2015
  • Published: