Climatological Study to Determine the Impact of Icing on the Low Level Windshear Alert System. Volume I. Analysis.

PDFTech ReportDOT-TSC-FAA-89-02Wind shearIcingIce formationsAirportsWarning systemsWeather and climateUnited StatesUnited States. Federal Aviation AdministrationVilcans, JanisBurnham, David C.John A. Volpe National Transportation Systems Center, (U.S.)NTL-AVIATION-Airports and FacilitiesNTL-AVIATION-AVIATIONNTL-AVIATION-Aviation Safety/AirworthinessNTL-SAFETY AND SECURITY-Aviation Safety/AirworthinessNTL-SAFETY AND SECURITY-SAFETY AND SECURITYVolpe National Transportation Systems Center, Technical Reference CenterThe climatological study was performed to determine the impact of icing on the performance of Low Level Windshear Alert System (LLWAS).This report presents the icing statistical profile in the form of data tables and histograms of 106 LLWAS sites. The icing statistical data were derived using freezing rain and freezing drizzle hourly reports obtained from the National Climatic Data Center magnetic tape records. The meteorological data cover a 24 year history of the time period between January 1, 1965 to December 31, 1988. The statistics include: icing reports and duration (actual time of freezing precipitation in hours), glazing duration (an extension of freezing weather following precipitation up to a 48 hour limit), freezing duration (combination of both icing and glazing with and without weighting). Also presented is the ranking of all LLWAS sites based on the above listed parameter combinations including a contour map showing icing intensity of all site locations. Finally, the extent of the freezing effect on windshear sensors is demonstrated by using a graph from field test measurements collected during a period of light freezing rain