GeoSTAR - A hurricane observatory

Among the 15 Earth missions the National Research Council recommended that NASA undertake in the next decade is the “Precipitation and All-weather Temperature and Humidity” (PATH) mission, which will place a microwave sounder in geostationary orbit. A prototype for the “MW array spectrometer” that the NRC identified as the required payload for PATH, the Geostationary Synthetic Thinned Aperture Radiometer (GeoSTAR), was developed at NASA's Jet Propulsion Laboratory in 2005 under the NASA Instrument Incubator Program. A second phase of risk reduction and development of elements required for a space mission is now under way. GeoSTAR is a microwave sounder with the same capabilities as those of the Advanced Microwave Sounding Unit (AMSU) system now operating on low-earth-orbiting (LEO) satellites but with the additional capability of providing continuous observations of the entire hemisphere. Providing such a capability in geostationary orbit (GEO) has long been a goal for NOAA, NASA and other space agencies, since GEO offers key advantages over LEO. With NASA's stated commitment to implement the NRC “Decadal Survey” missions, a confluence of common interests with NOAA and other agencies, and the growing maturity of the necessary technology, it is likely that PATH and GeoSTAR will be implemented in the next decade, and plans for a PATH/GeoSTAR mission are now under development. There is a strong need for an atmospheric sounder in GEO, and the possibility of flying GeoSTAR on one of the first GOES-R satellites as a “Mission Of Opportunity” is being discussed. A joint effort by NASA and NOAA, where NASA would provide the instrument and NOAA would provide the platform and launch, would be a compelling demonstration of a new “Research to operations” paradigm. GeoSTAR will provide a number of measurements that are key in monitoring and predicting hurricanes and severe storms – including hemispheric 3-dimensional temperature, humidity and cloud liquid water fields, rain rates and rain totals, tropospheric wind vectors, sea surface temperature, and parameters associated with deep convection and atmospheric instability – everywhere and all the time, even in the presence of clouds. Configuring a GeoSTAR mission as a hurricane observatory is the most compelling. One scenario being investigated is to "focus" GeoSTAR on the Caribbean-Gulf region to monitor developing and mature hurricanes that pose a threat to US coastal communities. With GeoSTAR it is possible to derive a number of key parameters of great importance to the assessment and predcition of hurricanes: 3-dimensional convective structure, precipitation structure, atmospheric winds, temperature, water vapor, cloud liquid water and ice, maximum surface wind, and a number of other related parameters. This is possible because a microwave sounder is not hampered by clouds and measures all three phases of water substance in the atmosphere. This includes some so-called microphysical parameters. Together these are of crucial importance to the "intensification" problem, and GeoSTAR can therefore be viewed as a key hurricane observatory.