GOES-17 Cooling System Impacts Update

February 2020

2 minute read 

 

As you may know, the GOES-17 Advanced Baseline Imager (ABI) has an issue with its cooling system, known as the Loop Heat Pipe (LHP), which causes the longwave IR channels (channels 8-16) to become saturated at certain times of the year.  During those times, GOES-17 satellite imagery in those channels will degrade and eventually become unusable for short periods of time each day (i.e. late night into morning). The graph below in Figure 1 represents the daily maximum estimated temperature of the GOES-17 ABI IR detectors throughout the year.

 

Figure 1. GOES-17 Predicted Peak Longwave Infrared Focal Plane Temperature* 

*For more predictive reference information, download the PDF by clicking here.

 

The GOES-17 ABI operates with a focal plane temperature higher than intended. Near the latter half of January, temperature begins to rise during the overnight hours due to the LHP issue. This will begin to manifest itself in “striping” of the satellite imagery.  As January progresses into February, the graph shows the peak ABI temperature continues to increase. This will result in striping and then complete saturation in most IR bands of the ABI.

Impact to the IR Bands 

The water vapor bands, channels 8-10, are some of the first channels to fully saturate.  Expect to lose these channels entirely, for up to six hours per day, during peak saturation periods.  Below is a photo of what saturation for channel 8, the 6.19um channel, looks like in AWIPS. This is a full disk image taken at 13:00 UTC on February 3, 2020.  Note that in cases of extreme saturation, some imagery looks essentially blank in AWIPS.

 

Figure 2. AWIPS GOES-17 Full Disk image of channel 8 (6.19um) water vapor band

 

The "Clean IR” band (channel 13) and the “Legacy IR” band (channel 14) will never fully saturate, however there will be some striping evident when the sensor reaches its peak heating near the end of February.

After peak heating around February 26, 2020, the saturation of the IR channels will rapidly improve to low amounts around the Vernal Equinox due to eclipse.  Following that period, they will rapidly degrade again until about mid-April. From there, you can expect gradual improvement until all the channels have completely recovered near the end of May.

Short Video on the LHP Issue 

Last fall, the NWS Operations Proving Ground (OPG) created a short video that addresses the LHP issue and also provides an overall GOES-17 orientation. Preview what is expected in AWIPS when these infrared satellite channels degrade and improve on a daily basis. This video can be downloaded here.

We want to hear from you! 

Did you experience a case where degraded or missing imagery affected the forecast or warning process? If so, please send us your feedback, including imagery examples, on the GOES-17 Loop Heat Pipe impacts. You can also route any related questions or comments to the TOWR-S team on NWSChat here by joining the “towrs” group.