Incorporating Diagnosed Intercept Parameters and the Graupel Category via Hydrometeor Classification within the ARPS Cloud Analysis System for the Initialization of Double-moment Microphysics

In this study, a new set of reflectivity equations is introduced into the ARPS (Advanced Regional Prediction System) cloud analysis system. This set of equations incorporates double moment microphysics information in the analysis by adopting a set of diagnostic relationships between the intercept parameters and the corresponding mass mixing ratios. A reflectivity- and temperature-based graupel classification scheme is also implemented according to a hydrometeor identification (HID) classification diagram. A squall line that occurred on 23 April 2007 over southern China containing a pronounced trailing stratiform precipitation region is used as a test case to evaluate the impacts of the enhanced cloud analysis scheme. It is found that using the enhanced cloud analysis scheme is able to better capture the characteristics of the squall line in the forecast. The predicted squall line exhibits a wider stratiform region and a more clearly defined transition zone between the leading convection and the trailing stratiform precipitation region agreeing better with observations in general, when using the enhanced cloud analysis together with the two-moment microphysics scheme. Quantitative precipitation forecast skill score is also improved.