Feasibility And Design Considerations Of A Global Wind Sensing Coherent Infrared Radar (WINDSAT)

Since 1977, NOAA has been investigating the feasibility of a global wind-sensing lidar in response to the need for altitude profiles of the wind vector to serve as input to global circulation models. The lidar technique obtains the wind information by assessing the Doppler information contained in CO2 laser radiation backscattered from the atmospheric aerosol (particulates, droplets, etc.). The results of studies undertaken to define the proposed system concept and hardware for a space-shuttle-borne demonstration flight are presented. Resulting from considerations of wind vector accuracy, area coverage and sampling density, signal detectability and space shuttle compatibility requirements were a continuous conical scan of the telescope with a half cone angle of 62° centered on nadir, telescope diameter (1.25 m), laser pulse energy (10 J), pulse repetition frequency (8 Hz), pulse duration (6 ins) and laser wavelength (9.11 pm). Requirements that the concept imposes on platform stability, navigation and attitude determination, line-of-sight pointing and lag angle compensation, on-board Doppler processing, prime power and thermal dissipation are discussed. The system configuration intended for a hardware design study is presented.