First validation of retrieved rain rates and snow covered mask of the 183-WSL retrieval method

Improvements of the 183-WSL retrieval method allow to better describe the precipitating clouds as to rain distribution, type and amount. The 183-WSL method is physically based on the water vapor absorption band at 18331 GHz and retrieves the rain rates upon discriminating the convective/stratiform characteristics of the observed precipitation. The current version of the retrieval scheme was upgraded with a dedicated module for the identification of the snow cover pixels, which are often responsible for false alarms because of the strong scattering from the frozen surfaces. The 183-WSL snow cover module, currently in the testing stage, produces a snow cover mask per each satellite overpass, distinguishing between regions of wet and dry snow. The validation of rain rates is carried out by using two years of data of the European Radar Network NIMROD while the snow cover product is compared with 6 months of maps from the Interactive Multisensor Snow and Ice Mapping System (IMS) operational product over the Baltic Regions. Furthermore, the 183-WSL retrievals were compared with other satellite retrieval methods using the NORDRAD radar network measurements as ground truth over 2 months. The analysis reveals that the 183-WSL new computational scheme shows high match ups with radar data with high values of the statistical indices. Although the new version of the 183-WSL performs better than the previous with the integration of the snow cover mask module into the main retrieval scheme, it tends to overestimate the retrieved rain rates especially those with intensities lower than 1 mm h-1. This threshold is crucial especially during the winter season.