WindSat Payload Description

Click for detail.

The WindSat radiometer operates in discrete bands at 6.8, 10.7, 18.7, 23.8, and 37.0 GHz. Table 1 provides key design and performance parameters of the system. The 10.7, 18.7, and 37.0 GHz channels are fully polarimetric. The 6.8 channel is dual-polarization (vertical and horizontal), and is more sensitive to sea surface temperature (SST) than to winds. Thus it is used to remove environmental noise due to variations in SST. Similarly, the 23.8 channel has dual-polarization and is highly sensitive to atmospheric water vapor. Thus, measurements at 23.8 GHz enable algorithms to correct for the effects of atmospheric attenuation on signals from the ocean surface.

WindSat uses a 1.8-m offset reflector antenna fed by 11 dual-polarized feed horns. The antenna beams view the Earth at incidence angles ranging from 50 to 55°. Table 1 shows the nominal beamwidth and resulting surface spatial resolution of each band. The Coriolis satellite orbits Earth at an altitude of 840 km in a Sun-synchronous orbit. The satellite completes just over 14 orbits per day. The orbit and antenna geometry result in a forward-looking swath of approximately 1000 km and an aft-looking swath of about 350 km. The fully integrated WindSat payload stands 10 ft tall and weighs approximately 675 lbs.

Table 1. WindSat Configuration

Band (GHz)	Polarization	Bandwith (MHz)	Earth Incidence Angle (deg.)	Horizontal Spactial Resolution (Km)
6.8 10.7 18.7 23.8 37.0	V,H V,H ±45,L,R V,H,±45,L,R V,H V,H,±45,L,R	125 300 750 500 2000	53.5 49.9 55.3 53.0 53.0	39 X 71 25 X 38 16 X 27 20 X 30 8 X 13