5th GOES Users' Conference


Remapping GOES Imager Instrument Data for South American Operations, Implementing the XGOHI System

Shahram Tehranian, Nortel Government Solutions, Lanham, MD; and J. L. Carr, S. Yang, H. Madani, S. Vasanth, K. Mckenzie, T. J. Schmit, A. Swaroop, and R. DiRosario

Operational weather forecasting depends critically on the Geostationary Operational Environmental Satellite (GOES) system. The GOES constellation consists of an eastern satellite stationed at 75°W longitude, a western satellite stationed at 135°W longitude, plus in-orbit spares. Currently, GOES-12 occupies the eastern slot while GOES-11 occupies the western slot. National Oceanic and Atmospheric Administration (NOAA) replaced GOES-10 with GOES-11 as the operational GOES-W satellite in June of 2006. The GOES-10 satellite is still functioning well, but has exhausted its north-south station-keeping fuel. The GOES-10 spacecraft completed its eastward drift from longitude 135°W to 60°W in early December 2006 where it will continue to operate in a high-inclination mission to provide coverage over South America. Other GOES satellites may also be operated in high-inclination missions when they exhaust their station-keeping fuel, extending their operational lifetimes and enhancing the return on the public investment in the GOES system. The high-inclination mission for the GOES satellite is expected to help protect lives and property in Central and South America by significantly improving satellite detection of severe storms, floods, drought, volcanic ash clouds, wildfires and other natural hazards. Without GOES-10 data, and when the GOES-East is in a rapid-scan operations mode, large regions of South America only relieved GOES imagery every three hours. The GOES-10 effort is part of the implementation of the Global Earth Observation System of Systems (GEOSS)-Americas. Repositioning GOES-10 for better satellite coverage over the southern part of the Western Hemisphere was one of the first major activities to take place under the GEOSS-Americas initiative. Implementation of Image Motion Compensation (IMC) via ground processing through resampling is an integral part of the high-inclination mission operations concept. The objective of the on-ground IMC implementation is to provide the same level of Image Navigation and Registration (INR) performance that is achieved with on-board IMC. Normally, the GOES Imager is operated in fixed-grid mode, meaning that Image Motion Compensation (IMC) is applied in space to control the Imager scan mirror to compensate for image distortion caused by deviations of the orbit and attitude from their reference values. Current GOES operational spacecrafts (east and west) operate within a 0.5 degree inclination limit that allows the on-board IMC system to scan imagery as if from a “perfect GOES projection” from a fixed point in orbit. This limitation on inclination limits the life of GOES spacecrafts in that older spacecrafts (with lower fuel reserves) cannot be maintained within the 0.5 degree inclination limit. As part of the Extended GOES High Inclination (XGOHI) mission, the current generation of GOES ground system was enhanced to accommodate on-ground IMC implementation operating on IMC OFF data received from the GOES-10 spacecraft. Considering that the GOES-10 orbital inclination has already reached the 2° saturation point, the XGOHI system will be operational in early September 2007. The GOES VARiable (GVAR) format adaptations are transparent to the users since spare words are used for XGOHI specific parameters within GVAR. Several resampling methods have been considered such as nearest-neighbor and bicubic resampling depending on the needs of the user community. Fundamentally, all high-order resampling methods such as the bicubic resampling are convolutions of raw image pixels with resampling kernel functions. The selection of horizontal and vertical resampling kernels can be done independently of the implementation of resampling. A resampling impact study is ongoing by the Advanced Satellite Products Branch (ASPB) and the Cooperative Institute for Meteorological Satellite Studies (CIMSS) at Space Science and Engineering Center (SSEC) at University of Wisconsin for evaluating and recommending appropriate kernels for the user community. As of July 2007, the XGOHI system has gone through Integration Level Testing (ILT) and is transitioning into operations at Wallops Command and Data Acquisition Station (WCDAS).

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Poster Session 1, Fifth GOES Users' Confererence Poster Session
Wednesday, 23 January 2008, 2:30 PM-4:00 PM, Exhibit Hall B

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