INTERCOMPARISON OF IN-FLIGHT ICING ALGORITHMS - PART-I - WISP94 REAL-TIME ICING PREDICTION AND EVALUATION PROGRAM

The purpose of the Federal Aviation Administration's Icing Forecasting Improvement Program is to conduct research on icing conditions both i n flight and on the ground. This paper describes a portion of the in-f light aircraft icing prediction effort through a comprehensive icing p rediction and evaluation project conducted by the Research Application s Program at the National Center for Atmospheric Research. During this project, inflight icing potential was forecast using algorithms devel oped by RAP, the National Weather Service's National Aviation Weather Advisory Unit, and the Air Force Global Weather Center in conjunction with numerical model data from the Era, MAPS, and MM5 models. Furtherm ore, explicit predictions of cloud liquid water were available from th e Eta and MM5 models and were also used to forecast icing potential. T o compare subjectively the different algorithms, predicted icing regio ns and observed pilot reports were viewed simultaneously on an interac tive, real-time display. To measure objectively the skill of icing pre dictions, a rigorous statistical evaluation was performed in order to compare the different algorithms (details and results are provided in Part II). Both the subjective and objective comparisons are presented here for a particular case study, whereas results from the entire proj ect are found in Part II. By statistically analyzing 2 months worth of data, it appears that further advances in temperature and relative-hu midity-based algorithms are unlikely. Explicit cloud liquid water pred ictions, however, show promising results although still relatively new in operational numerical models.