The Advanced Microwave Sounding Unit (AMSU) sensor system that has been operated in space since 1998 has demonstrated the great value of microwave sounders both in research, by NASA's AIRS-AMSU system on Aqua, and in operations, by NOAA's HIRS-AMSU on the polar-orbiting operational environmental satellites (POES). Both are in low-earth orbits (LEO), which provide only twice-daily snapshots of any given location but at relatively high resolution. NASA has used atmospheric state vectors derived from AIRS-AMSU to advance our understanding of atmospheric weather and climate processes with great success, and NOAA has found that AMSU observations have one of the greatest positive impacts on weather forecast accuracy among satellite data sources. The Advanced Technology Microwave Sounder (ATMS) on the NPP platform forming the first of the Joint Polar Satellite System (JPSS) represents the next generation of these sensors through a modest step forward in technology and capabilities. The nest big step forward, however, is in getting similar capabilities in geostationary orbit (GEO), where it is possible to dwell on the scene below indefinitely and therefore add the hitherto missing time dimension. The value of this has been demonstrated with imagers operating in the visible and infrared, but those sensors cannot penetrate clouds and probe into “interesting” weather. We will discuss the Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR), a sensor design under development by NASA at the Jet Propulsion Laboratory that will provide the same capabilities in GEO as now exist in LEO. Initially GeoSTAR will be part of a NASA research mission, possibly in the 2017 time frame, and later it will be part of the NOAA operational systems. We will discuss issues related to the development of GeoSTAR and its transition from research to operations.

Copyright 2011 California Institute of Technology. Government sponsorship acknowledged.