Looking down: large microwave apertures for meteorological and oceanographic remote sensing

Abstract

The design strategy for environmental satellite constellations relies upon low orbiting satellites to provide global, high-resolution synoptic data and geostationary satellites to provide continuous observations of rapidly evolving local events. The latter category includes storm systems and, with the advent of cloud-track and water vapor winds, winds aloft. This division of labor is an architectural convenience for visual and infrared sensors but a necessity for microwave sensors. In fact, the typical ground resolution of microwave sensors on low orbiters is barely acceptable. Unfortunately, microwave sensors are preferable to visual and infrared systems for many applications including sea-surface temperature and wind measurement and the only viable method for remotely sensing sea surface salinity. Microwave sensors are also preferable for some atmospheric sounding applications because they are relatively insensitive to cloud cover. The most important cases where microwave sensors are preferred, those related to diagnosing the evolution of severe storm activity, require the highest spatial resolution and are best done with geostationary satellites. In particular, microwave sounding would be an ideal capability for a geostationary weather satellite.