An overview of the GOES-N science test

The next three Geostationary Operational Environmental Satellite (GOES): GOES-N/O/P will have similar instruments than the GOES-8/12 instruments, but will be on a different spacecraft bus. The new bus will allow improvements both to the navigation and registration, as well as the radiometrics. The first of this new series, GOES-N will be launched in the summer of 2005. Current plans call for GOES-N to become operational after the on-orbit spare, GOES-11, is used. By supplying data through the eclipse, the GOES-N/O/P system addresses one of the major current imager limitations which are eclipse and related outages. This is possible due to spacecraft batteries. Outages due to Keep Out Zones (KOZ) will be minimized.

There will be radiometric improvements. The GOES-N+ instruments (imager and sounder) will be less noisy. A colder patch temperature is the main driver. In addition, there is a potential reduction in striping to be achieved through increasing the Imager scan-mirror's dwell time on the blackbody from 0.2 sec to 2 sec. There will be improvements in both the navigation and registration on GOES-N+. The GOES-N navigation will be improved due to the new spacecraft bus and the use of star trackers (as opposed to the current method of edge-of-earth sensors). In general, the navigation (at nadir) will go from between 4-6 km with today's imager to less than 2 km with those on the GOES-N/O/P satellites. Both within-frame and frame-frame registration will also be improved.

All these enhancements will be monitored during the NOAA post-launch science test. As with other GOES check-outs, there are several main goals for the GOES-13 science test. First, the quality of the GOES-13 data will be investigated. This may be accomplished by comparison to other satellite measurements or by calculating the signal-to-noise ratio. The second goal will be to generate products from the GOES-13 data stream and compare to those produced from other satellites. These products may include several Imager and Sounder products: visible and shortwave albedo, land skin temperatures, temperature/moisture retrievals, total precipitable water, lifted index, cloud-top pressure, atmospheric motion vectors, and sea surface temperatures. The third goal is to investigate the impact of the recent instrument changes. For example, the better navigation, improved calibration and the operation through eclipse periods will be investigated. In addition, rapid scan imagery of both severe weather and hurricane/tropical storm cases will be investigated as part of GOES-R Risk Reduction activities.