Unique Uses Of Weather Radar For Space Launch

The Air Force's 45th Weather Squadron (45 WS) provides weather services to the Eastern Range (ER) and the Kennedy Space Center (KSC) in support of more than 30 countdowns per year for space launch and ballistic missile tests by the Department of Defense (DOD), National Aeronautics and Space Administration (NASA), and commercial launch customers. The weather radars used by the 45 WS are the modified WSR-74C at Patrick AFB, owned and operated by the USAF, and the WSR-88D at National Weather Service(NWS)/Melbourne, owned and operated by the NWS. The 45 WS uses these radars for the typical operational applications of radar, such as severe weather warnings, precipitation forecasting and general weather surveillance. In addition to these routine uses, the 45 WS has several unique weather radar applications for the special requirements of space launch. These unique weather radar applications include forecasting and evaluating Lightning Launch Commit Criteria (LCC), lightning forecasting, and downburst prediction. The Lightning LCC are a set of weather rules to avoid natural and rocket triggered lightning to in-flight rockets. Other operational weather offices predict downbursts and lightning, but the 45 WS supports uniquely stringent warning requirements with long lead-times, precise locations, and multiple speed thresholds. Additionally, the ER and KSC's location in east central Florida leads to the operational need for detailed identification of mesoscale boundary line interactions for thunderstorm prediction during the summer, particularly when large scale, synoptic dynamics are not important. To meet these needs, the WSR-74C has been modified, including doubling the antenna spin rate to provide 2.5 min volume scans, a customized scan strategy, and the Integrated Radar Information System post-processor and display.

As the 45th WS WSR-74C is nearing the end of its lifecycle, plans have begun for acquiring a new weather radar that will include dual polarization capabilities. Significant improvements in forecasting downbursts and lightning, and evaluating Lightning LCC are anticipated with dual polarization capability. In addition, dual Doppler capability with the WSR-88D/Melbourne will allow true 3-D wind fields to help initialize the local numerical weather prediction model. Bistatic receivers are also being considered to optimize the dual Doppler wind fields. Operational research is required to create tools to optimize use the dual polarization and dual Doppler capabilities for the unique weather space launch applications.

Weather radar is one of the most important tools for weather support to America's space program. This paper presents an overview of the unique weather radar applications used by 45 WS including their special tools and techniques, the modifications to the local weather radar, and plans to use its dual polarization and dual Doppler capabilities.