Evaluating icing nowcasts using cloudsat

The Current Icing Product (CIP) is a model/observation fusion tool to diagnose aircraft icing probability and severity. Implemented at the Aviation Weather Center, it is used by forecasters to assess icing conditions and improve aviation support over the contiguous United States and southern Canada. However, given the three dimensional nature of the icing threat, it has been difficult to completely assess CIP effectiveness. CloudSat is a low-earth orbiting satellite containing a 3 mm cloud radar (94 GHz) that gives a two dimensional vertical profile of cloud along the orbital track of the satellite. When combined with temperature profile information, CloudSat can be used to infer information about the location and vertical structure of supercooled liquid water. Therefore, it can be used to compare to CIP. In this study first we compare CIP and CloudSat in several case studies to illustrate CIP‟s strengths and limitations. In the process we illustrate that CloudSat products are powerful observational tools in their own right, allowing unprecedented cross-sectional views of cloud systems which contain aviation hazards. Second, we compare CloudSat and CIP cloud heights statistically. For low cloud systems in particular, CIP tends to analyze cloud tops that are too high, leading to vertical overestimation of the icing hazard.