GOES-10 replaces GOES-12

December 5th, 2007 |

On 04 December 2007, GOES-12 (the operational GOES-East satellite at 75º W longitude) experienced an anomaly in spacecraft attitude following a North-South station keeping maneuver; initial efforts to restore GOES-12 to a normal on-orbit mode were unsuccessful. As a result, GOES-10 (at 60º W longitude) was reassigned from South American operations to replace GOES-12 as the operational GOES East satellite on the following day (05 December). •• For the latest information on GOES operations and status, refer to the Satellite Services Division GOES Special Bulletins site.

Due to the age of GOES-10 (which was launched in 1997), increasing satellite inclination (currently more than 2 degrees) was causing more “wobble” to be noted in image animations — as a result, the GOES-10 imager “eXtended GOes High Inclination” (XGOHI) operations were initiated in October 2007. XGOHI re-maps the GOES-10 GVAR data before the satellite imagery is re-broadcast to users, which may have a slight impact on data latency. One important issue with XGOHI is the fact that 3.9 µm “hot spot” detection capability is somewhat diminished using GOES-10.

The image examples shown here demonstrate a few of the subtle differences between GOES-12 and GOES-10, and the early artifacts of the satellite transition.

AWIPS GOES water vapor channel images (Anmated GIF)

GOES-12 had the new 4-km resolution, spectrally-wider 6.5 µm “water vapor” channel; the 8-km resolution, spectrally-narrow 6.7 µm “water vapor” channel on GOES-10 is the same as the corresponding water vapor channel on GOES-11. As a result, composites of GOES-11 and GOES-10 water vapor images will exhibit less of a “seam” where the data from the two satellites are merged (see: 16:30 UTC 04 Dec 2007 image | 17:30 UTC 05 Dec 2007 image). Prior to GOES-10 data beginning to appear in AWIPS as of about 17:30 UTC on 05 December, there was only GOES-11 coverage for approximately 24 hours (above).

AWIPS GOES IR images (Animated GIF)

The 10.7 µm IR “window” channels are identical on GOES-11 and GOES-10 . Prior to GOES-10 data beginning to appear in AWIPS as of about 17:30 UTC on 05 December, there was only GOES-11 IR channel coverage for approximately 24 hours (above).

GOES-10 11-12 µm IR difference

GOES-12 replaced the 12.0 µm IR channel (the so-called “dirty IR window” channel) with a 13.3 µm “CO2 absorption” IR channel. This new 13.3 µm channel was used to derive cloud height information using the GOES-12 imager, which was also employed for height assignment of GOES-12 water vapor and visible/IR cloud drift winds (atmospheric motion vectors or AMVs). As a result, the GOES-10 (GOES-East) AMV height assignments will not be quite as good without the 13.3 µm channel (instead relying on the less-accurate IR window and water vapor intercept height assignment methods).

The 12.0 µm IR channel on the older GOES (GOES-10 and GOES-11) is useful for detecting volcanic ash or airborne dust/sand using the 11-12 µm IR difference product (above) — so this ash/dust detection capability has returned to GOES East (for the time being). Note, however, that the product in AWIPS is incorrectly labeled as “11µ-13µ” for NWS forecast offices localized to use GOES-East (since GOES-12 had the 13.3 µm channel)

Due to the high satellite viewing angle from GOES-10, GOES sounder coverage will not be available over portions of the central US (affecting sounder-derived products such as Total Precipitable Water). NWS forecast offices who have added CIMSS MODIS products to their local AWIPS (via LDM subscription) can access that particular product suite to help fill in the gap (below).

Total Precipitable Water (GOES Sounder + MODIS)

Note: GOES-12 was returned to service as the operational GOES-East satellite on 17 December 2007. 

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