ISCCP CATALOG OF DATA AND PRODUCTS Section 3.3

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3.3 GOES-EAST

The task of processing GOES-East (75W) B1 data sets was performed by the Space Science and Engineering Center (SSEC) at the University of Wisconsin - Madison until the demise of GOES-5 on July 29, 1984. The Atmospheric Environment Service (AES) of the Canadian Climate Center is the current SPC for GOES-East, beginning with the GOES-7 spacecraft from April 1987 to August 1994 and continuing with GOES-8 in April 1996. CSU processed GOES-8 from December 1994 through March 1996, until AES was ready to continue this task.

The raw data are transmitted from the U.S. geostationary satellites to the NOAA/NESDIS Command and Data Acquisition Ground Station at Wallops Island, Virginia. These data are then processed into stretched VISSR (Visible and Infrared Spin Scan Radiometer) and VAS (VISSR Atmospheric Sounder) data before being retransmitted back to the satellite for relay to AES and NESDIS ground systems. The processing includes the calibration of the IR data to correspond to predetermined data values versus temperature tables which are computed and maintained by NESDIS. A set of predicted navigation parameters is also appended to the data.

The A-level VISSR data frame consists of data transmitted from eight visible detectors (sensitive to the 0.54-0.70 micron band) and one of two IR detectors, or an average of two of the IR detectors (sensitive to the 10.5-12.6 micron band). The basic full resolution VISSR data frame, which is transmitted every three hours contains data collected during nominally 1821 scans of the earth by the VISSR instrument. The visible data are quantized as 6 bits, and the IR data as 8 bits.

For GOES-7, the full resolution image (8 x 8 array of 1 km VIS pixels) are reduced to 8 km resolution by performing an rms averaging of all 64 pixels at once to yield the 8 km B1 VIS pixel. The rms averaging takes the square root of the sum of the squares of each of the 64 individual pixels. As much as possible, this method preserves the value of the brightest pixels of the 64 and does not dull them by averaging with dimmer pixels. Note that the visible counts for GOES-7 are 7-bits, instead of the 8-bits intended. The IR data were simply sampled every other pixel to yield an 8 km B1 pixel.

For GOES-8, the averaging is performed identical to the GOES-West SPC at CSU. An 8 x 8 array of 1 km VIS pixels are averaged 7 horizontal by 4 vertical scans and sampled at a rate of 7 in 16 horizontal pixels and 4 in 8 vertical scans which yields a 4 x 4 km pixel sampled at 9.1 x 8 km. If no more than 2 scans of the VIS are missing, the remaining scans are averaged into the B1 pixel. The IR data are sampled to match the resultant 9.1 x 8 km pixel of the VIS B1 pixel.

The B1 data sets are available at three-hour intervals, nominally 2345, 0245, 0545, 0845, 1145, 1445, 1745, and 2145 UTC. The B1 data products produced from GOES-8 are archived on IBM 3480 cartridges with two days of data per cartridge.

From May 1992 to January 1995, the European Space Agency provided METEOSAT-3 data from the satellite located at 50 W and 75 W. A B1 data set with 10 km sampling and 5 x 5 km pixels was collected by CIRA. The dataset contains the three METEOSAT channels and navigation information. The basic calibration was provided by ESA.