GOES-West Operational Interleave began today (8/1) at 1700 UTC, and will continue through Sep 6. What does this mean to NWS users? GOES-West ABI Imagery (single-band imagery, band differences, RGBs) is now from GOES-18. Other GOES-West products, such as from GLM, and ABI derived products (cloud products, TPW, DMWs, etc) remain from GOES-17. Hence, “Interleave”. Why? GOES-18 ABI Imagery reached Provisional Validation maturity on July 28, meaning it is suitable for the broad user community. We are also entering a GOES-17 ABI Warm Period, which results in degraded GOES-17 LWIR imagery due to the cooling system failure. Therefore, the GOES-18 imagery will be distributed instead of that from GOES-17 from 8/1 to 9/6. The transition on 8/1 was successful, with GOES-18 imagery appearing in NWS AWIPS, as well as webpages like CIRA SLIDER and the STAR GOES Image Viewer.
From an AWIPS SBN perspective, no changes were needed at the individual locations. GOES-West imagery (from GOES-18) is loaded from the menu system as one normally would. Procedures containing GOES-West imagery load as usual. If you load imagery from the product browser, you will notice the addition of GOES-18 to the “Satellite” drop-down. The GOES-18 label will now appear in the product legend. GOES-West meso sector requests will continue as usual, with the meso sector imagery coming from GOES-18.
One may notice vertical striping at night in the Nighttime Microphsyics RGB and Nighttime Fog Difference. Details of the subtle GOES-18 Ch07 “Barcode Artifact” can be found here.
The transition from GOES-17 to GOES-18 imagery at 1700 UTC is shown below in various Imagery products. All examples begin with GOES-17, and transition to GOES-18 after 1700 UTC (midway through each animation). All examples are saved from AWIPS (SBN dataflow), with the exception of Geocolor, which was captured from CIRA SLIDER. Since we are already entering the warm period, the imagery degradation can be seen in the impacted GOES-17 imagery.
Starting with Ch08 Water Vapor imagery, the transition from GOES-17 to GOES-18 at 1700 UTC is obvious, as the horizontal striping associated with the cooling system failure is apparent in the GOES-17 portion of the animation, but abruptly disappears in the GOES-18 portion. The GOES-18 imagery appears as one would expect, similar to that from GOES-16.
GOES-17 Ch13 is not as impacted by the cooling system failure, and therefore, the transition to GOES-18 is very smooth with no noticeable changes in imagery.
Split Window Difference imagery, which is used for the detection of blowing dust and moisture gradients, appears significantly cleaner in the GOES-18 imagery. Channel differences typically enhance noise present in imagery.
The Airmass RGB, which includes multiple LWIR channel differences, is also notably improved with the transition to GOES-18.
The Nighttime Microphsyics RGB, which also employs multiple IR channel differences, exhibits significant noise in the GOES-17 portion, and very little in the GOES-18 portion. Note, this animation is during the daytime, so influence of the ch07 “Barcode Artifact” is not apparent here in GOES-18 imagery.
GOES-17 to GOES-18 1-min mesoscale sector imagery is shown in the next animation. The transition to GOES-18 after 1700 UTC is not discernible.
The transition is also seamless in Geocolor imagery, shown in the final figure from GOES-17 and GOES-18 full disk imagery.
Bill Line, NESDIS/STAR and CIRA