Remote detection of aircraft icing conditions using microwave radiometers

The potential role of ground-based remote sensors in the detection of atmospheric conditions conducive to aircraft icing is evaluated. Measurements of liquid water along a line of sight and profiles of atmospheric temperature were made by microwave radiometers located at Stapleton International Airport, Denver, Colorado. Radiometer data and sky cover observations for a 2-yr period were correlated with icing occurrences reported by aircraft pilots in the area. Data limitations in this study include the following: (1) the radiometer observations were made at one location and in the zenith direction only, whereas icing conditions may be highly variable in space; (2) pilot reports do not systematically verify the presence of icing conditions in all situations, because they vary greatly with time of day, aircraft route, etc. Given these limitations, it is concluded that the liquid measurement makes a critical contribution to the detection of icing conditions. This measurement is not generally (e.g., from rawinsondes) available, except from sensors like the radiometer.