1. Front page of the realtime GOES-12 site, showing all of the latest Sounder spectral bands (18 infrared and 1 visible) over the central and Eastern US
All bands from the Sounder: 1 through 19
1. The “official” NOAA Science Test for GOES-12 (aka GOES-M at its launch on 23 July 2001) was conducted from 23 Sep 2001 through 27 Oct 2001.
2. Two major changes occurred with the Imager: (1) CO2 band “6” at 13.3 um took the place of (old) split-window band “5” at 12.0 um (with expected effects on SST, volcanic ash, and cloud products); and, (2) water vapor band “3” at 6.7 um had its spatial resolution increased to 4x4 km, along with slight spectral shifting and broadening. No significant changes were made to the Sounder (although hopefully, the spectral integrity for GOES-12 would be markedly better than the aging, and de-grading, GOES-8).
N.B. - At CIMSS, emphasis is on SOUNDINGS; thus, real-time web displays during the Test period were basically limited to data and product imagery from only the Sounder.
3. The most routinely available area covered by GOES-12 (located at 90 W over the equator) was over the central and eastern US, although the scheduling permitted various coverage scenarios (such as including the Caribbean, Central America, or other locations). Thus, the decision was made to emphasize that region (cen/E US) for routine hourly displays of GOES-12 Sounder data and products on the web.
4. For easy visual comparisons with GOES-8, where considerable overlap was possible, the decision was to re-map imagery from both satellites to a common (Mercator) projection. Three animation options generally were provided for the imagery: (1) a loop of the last 24 hours; (2) a shorter loop of just the last 4 hours; and (3) a “toggling” loop between the most recent GOES-12 and GOES-8 data.
5. For background on the “19 panel” display of all Sounder channels, see the description on the CIMSS Realtime Page (at For a quick summary, remembering that just one color enhancement is applied to all the IR channels:
- bands 1-5 (CO2) go from the stratosphere down to the lower troposphere, generally warming.
- bands 6-8 show more progressively transparent windows, seeing surface features.
- bands (H2O) show increasingly higher heights through the troposphere. Note characteristically detailed and often continuous moisture patterns versus the thermal patterns in similarly high CO2 channels (12 v 3, 11 v 4, 10 v 5).
- bands (4.5um CO2) largely mimic bands 5-3 (14um CO2) but are noticeably “noisier”.
- bands (4um windows) largely mimic bands 6-8 (11-12um windows) but are sensitive to reflected solar (daylight) radiation.

2. Comparing GOES-12 Sounder Derived Product Imagery of total precipitable water versus that from GOES-8
GOES-12 (central)
GOES-8 (east)
1. Four primary displays of GOES-12 Sounder data were regularly shown:
(1) all spectral bands (ordered by decreasing wavelength) with one common color enhancement. See previous slide (and its notes) for more information.
(2) “derived product imagery” (DPI) of total precipitable water vapor. The DPI combines TPWV in clear, retrievable locations with 11um window channel values (“cloud top temperatures”) in the cloudy locations. Atmospheric profiles are retrieved by a physical algorithm for 3x3 field-of-view “boxes”.
(3) DPI of lifted index (LI), a stability parameter.
(4) DPI of cloud top pressure (CTP). The CTP DPI combines cloud (pressure) heights with 11um window channel “surface temperatures” in the clear locations.
2. The TPWV DPI shown are color enhanced to indicate moisture content, with increasing amounts (0 to 75mm) in this order: beige, blue, (dark) green, (bright) yellow, red, magenta, very light magenta. Clouds are in gray.
3. The “toggling” comparison between commonly re-mapped (Mercator) projections from GOES-12 and -8 clearly shows generally good agreement between the satellites. From considerable cloudiness across the northern sections, through dry air (<5-10mm) from the mid Atlantic coast back to the central Rockies, to very moist air (25-40mm) surging from the Gulf of Mexico into east Texas and the lower Mississippi Valley, agreement in patterns dominates. Differences are more evident as biases, with GOES-12 typically appearing a bit moister. (This may partially be due to insufficient time during the Test period to fully incorporate regular radiance bias adjustment procedures.)
Animated toggling between the commonly re-mapped images (in Mercator projection) provides for easy comparison.