Launch Weather Decision Support System

The maximum dynamic stress on a launch vehicle (Max Q) typically depends on winds and air density at 10 to 15 km altitude. NASA operates a 48 MHz Doppler radar wind profiler at Kennedy Space Center to monitor winds up to 20-km height proximate to the launch trajectory. Radiosondes are used to measure temperature and humidity profiles, from which air pressure and density profiles are calculated. However, these balloons often drift 100-km or more from the launch trajectory, introducing uncertainty in air density information used for the Max Q calculation. More accurate Max Q estimation can improve launch operation safety and efficiency.

A Launch Weather Decision Support System (LWDSS) based on microwave profiler (MP) and related one-dimensional variational analysis (1DVAR) was demonstrated at the Cape Canaveral Air Force Launch Complex during 24-31 March 2018. Preliminary statistical comparisons of 25 collocated radiosonde and MP-1DVAR profiles up to 20-km height showed pressure (bias, standard deviation) <0.8, 0.8 mb, temperature <1, 1.8 ^oC, and vapor density <1.2, 2 g/kg. Further evaluation of LWDSS profile accuracies is planned via comparison of launch trajectory and radiosonde ascent path gridded analysis. Comparison with aircraft and dropsonde measurements is also possible.

Other LWDSS features include improved lightning risk identification based on forecast index time series derived from MP-1DVAR soundings, and Launch Commit Criteria (LCC) refinement based on MP cloud base height, cloud base temperature and integrated liquid water measurements.

The National Weather Service (NWS) Denver Weather Forecast Office (WFO) uses MP-1DVAR soundings to improve air traffic advisories to the Denver FAA Air Route Traffic Control Center (ARTCC). Opportunities to improve additional ARTCC and drone corridor weather advisories are under consideration.