Weather support to deicing decision making (WSDDM): A winter weather nowcasting system

This paper describes a winter weather nowcasting system called Weather Supp ort to Deicing Decision Making (WSDDM). designed to provide airline, airpor t. and air traffic users with winter weather information relevant to their operations. The information is provided on an easy to use graphical display and characterizes airport icing conditions for nonmeteorologists. The syst em has been developed and refined over a series of winter-long airport demo nstrations at Denver's Stapleton International Airport, Chicago's O'Hare In ternational Airport. and New York's LaGuardia Airport. The WSDDM system uti lizes commercially available weather information in the form of Next Genera tion Weather Radar WSR-88D radar reflectivity data depicted as color coded images on a window of the display and Aviation Routine Weather Report (META R) surface weather reports from Automated Surface Observating System statio ns and observers. METAR information includes wind speed and direction, air temperature, and precipitation type/rate, which are routinely updated on an hourly basis or more frequently if conditions are changing. Recent studies have shown that the liquid equivalent snowfall rate is the most important factor in determining the holdover time of a deicing fluid. However, the cu rrent operational snowfall intensity reported in METARs is based on visibil ity, which has been shown to give misleading information on liquid equivale nt rates in many cases due to the wide variation in density and shape of sn ow. The particular hazard has been identified as high visibility-high snowf all conditions. The WSDDM system addresses this potentially hazardous condi tion through the deployment of snow gauges at an airport. These snow gauges report real-time estimates of the liquid equivalent snowfall rate once eve ry minute to WSDDM users. The WSDDM system also provides 30-min nowcasts of liquid equivalent snowfall rate through the use of a real-lime calibration of radar reflectivity and snow gauge snowfall rate. This paper discusses t he development of the system, including the development of new wind shields for snow gauges to improve catch efficiency, as well as the development of the above mentioned real-time method to convert radar reflectivity to snow fall rate on the ground using snow gauges. In addition, we discuss results from a user evaluation of the system, as well as results from an efficiency and safety benefits study of the system.