A microwave instrument for temperature and humidity sounding from geosynchronous orbit

Significant weather is often located in cloudy areas where infrared (IR) soundings are degraded or fail, and since numerical weather models are often hypersensitive to such baroclinic regions, microwave sounders can improve predictions by providing needed data. Both theoretical studies and data from polar weather satellites make clear the superiority of combined IR and microwave sounder systems relative to either system operating alone. To date, the size and weight of microwave sounders have limited their use to low Earth orbit. The use of higher frequencies can provide reduced antenna size so that a useful microwave sounder using a ~2-meter diameter aperture can be packaged on a geosynchronous satellite. This article describes the design of such an instrument