Abstract
Abstract. Simulations of a squall line system which occurred on 12 August 2004 near Munich, Germany are performed using a fine grid version of the Weather Research and Forecasting (WRF) model with five different microphysical schemes. Synthetic dual polarization observations are created from the model output and compared with detailed observations gathered by the DLR polarimetric radar POLDIRAD located near Munich. Synthetic polarimetric radar scans are derived from the model forecasts employing the polarimetric radar forward operator SynPolRad. Evaluations of the microphysical parameterization schemes are carried out comparing Plan Position Indicator (PPI) and Range Height Indicator (RHI) scans of reflectivity and the spatial distribution of hydrometeor types. The hydrometeor types are derived applying a hydrometeor classification scheme to the observed and simulated polarimetric radar quantities. Furthermore, the Ebert-McBride contiguous rain area method of verification is tested in a variety of ways on the reflectivity output from the simulations. It is found that all five schemes overestimate reflectivity in the domain, particularly in the stratiform region of the convective system. All four schemes including graupel as a hydrometeor type produce too much of it. Differences are seen among the schemes in their depiction of reflectivity in the convective line and their representation of radar bright bands.
Highlights
Improvements in computational power in recent years have allowed for increasing use of fully explicit numerical models for weather prediction
When the EbertMcBride technique (EMT) was applied at 18:00 UTC to each simulation, it was found that only WMS6 did not have a high bias in the number of points with positive reflectivity values
Five high resolution Weather Research and Forecasting (WRF) simulations using different microphysical schemes were compared with detailed observations of a German squall line gathered by the DLR polarimetric radar POLDIRAD
Summary
Improvements in computational power in recent years have allowed for increasing use of fully explicit numerical models for weather prediction. 1◦ PPI scan of reflectivity [dBZ] at 18:00 UTC (a) observed by POLDIRAD, and simulated by (b) Lin, (c) Thompson-old, (d) Using 25 dBZ as the threshold for which the EMT scheme determines its CRAs (Table 1), Lin best depicted the squall line, with an overestimate of integrated reflectivity of around
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