RAMMB CIRA 3rd Quarter Report |
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April May June 2007 |
Feedback was provided on two different calibration issues: 1) An observation of banding in the GOES-11 Imager was noticed in image products that utilized band differences. In particular, the split-window difference product suffered from banding, or areas where the product values changed significantly for a large number of lines. This was discovered to be due to a change in the blackbody temperature for the GOES-11 Imager and the resulting change in the calibration mode being used before instrument stabilization took place. 2) Additional feedback on GOES-13 Sounder striping has been provided for a dataset that will be analyzed by Satellite Operations. The results will allow comparison of the methods used by different groups who are sharing results in order to determine the source of the excessive striping. (D. Hillger, B. Connell)
Software has been written to create (McIDAS) AREA files for simulated GOES-R ABI radiances generated by model output. The particular case of interest consists of artificial fire hot spots, to see how they will appear in future GOES imagery. This required the use of McIDAS 2007 which includes (simulated) ABI calibration and navigation modules. Radiances were supplied by Louis Grasso and Manajit Sengupta and output was sent to Elaine Prins and Scott Lindstrom. These first files were mainly for testing the correct coding and delivery of the fire radiances. One interesting aspect that needs to be investigated is how identical fires (with the same size and temperature) will appear as the expected GOES-R ABI grid samples the fires in different ways. Also, fires will not saturate for GOES-R ABI band-7 (3.9 μm) until 400 K, compared to about 340 K for current GOES imagery. (D. Hillger) Click on image to enlarge.
Figure 1: Simulated band-7 (3.9 μm) GOES-R ABI image (2 km resolution) of artificial hot spots laid out in a rectangular grid. Fires become generally larger from west to east and hotter from south to north. Black pixels are fires with effective temperatures up to 330 K, the limit for the display of 1-byte GOES imagery, and close to the maximum fire temperature for current GOES. White pixels are fires with temperatures over 330 K, those that would be saturated with current GOES imagery. (The skew in the image is due to the area of interest being centered at 97°W and the GOES sub-satellite location at 75°W.)