Over the past few winter seasons, a number of research projects have been conducted by NASA's Glenn Research Center to investigate aircraft icing environments. The data collected are valuable to a host of researchers including numerical modelers who benefit by comparing the observed data against similar data output by the microphysics package of the model. Unlike most model studies which end up comparing precipitation amount and type reaching the ground, this work concentrates equally on the research-quality aircraft data to compare observed and model-simulated locations and amounts of supercooled liquid water, the culprit of icing.

The main focus of this study is numerical simulations (using MM5) of clouds and precipitation as they relate to aircraft icing and comparisons to observed data. Unlike past model studies which emphasized a single case, this paper includes a variety of icing environments among multiple case studies. Included in the case studies are a few freezing drizzle/rain events either aloft or at the surface (sometimes both). Furthermore, both types of precipitation initiation (classical and non-classical) are included among the cases. The case studies in this paper and other past field projects (including the recent IMPROVE-1/2 project) are heavily used as the basis for model improvements in the MM5 and RUC numerical models.