The effect of advanced satellite products on an icing nowcasting system

Products developed at the National Center for Atmospheric Research (NCAR) and disseminated by the U.S. National Weather Service provide nowcast and short-term forecast estimates of icing probability, severity, and the potential for supercooled large droplets (SLD). The Current Icing Product (CIP) system combines multiple data sources using fuzzy logic methods to produce a gridded, three-dimensional, hourly depiction of icing-related conditions. The CIP algorithms rely on basic satellite-derived information, such as a cloud mask and cloud top temperature estimate, as one source of input data. The goal of the NASA Advanced Satellite Aviation-weather Products (ASAP) program is to devise methods for incorporating more sophisticated satellite products into aviation weather diagnosis and forecast systems. In the icing component of the ASAP program, the objective is replacement of the satellite module in the CIP system with satellite-derived cloud products developed by the NASA Langley Research Center (LaRC) Cloud and Radiation Research Group.

In this paper we present comparisons of icing probability, severity, and potential for SLD from the operational CIP with the experimental version of CIP which includes the ASAP fields. In the experimental version the ASAP hydrometeor phase and effective temperature products give information on cloud presence and cloud top microstructure. The liquid and ice water path products assist with estimation of icing severity, and the effective radius product is used for adjusting the potential for SLD. Details of the algorithms are provided in a companion paper. Verification efforts have demonstrated an improvement in cloud top height estimates when compared to pilot reports, resulting in a reduction in the volume of airspace diagnosed to have icing potential. In this study we examine individual cases from the verification effort where the operational and experimental versions of CIP arrive at different estimates of icing probability, severity, and potential for SLD, and compare those results with independent data from pilot reports and research aircraft.