GOES-17 Cooling System Impacts Update

January 2019

 2 minute read

As you know, the GOES-17 Advanced Baseline Imager (ABI) has an issue with its cooling system (called the Loop Heat Pipe, [LHP]) that causes the longwave IR channels (channels 8-16) to become saturated at certain times of the year.  During those times, satellite imagery in those channels will become brighter and eventually become unusable in AWIPS for short periods of time each day. Below is a graph representing the estimated temperature of the GOES-17 ABI throughout the year.

 

 

The ABI usually operates at an ambient temperature of 81K.  Near the latter half of January, that temperature begins to rise during specific time intervals throughout the day 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.

The water vapor bands, channels 8-10, are some of the first channel to fully saturate.  As a forecaster, you can expect to lose these channels entirely, for a maximum of 4-5 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 8:00 UTC on 10/26/18.  Note that in cases of extreme saturation, some imagery looks essentially blank in AWIPS.

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 near the end of February, the saturation of the IR channels will rapidly improve to low amounts around the Vernal Equinox.  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.

As you may be aware, 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. In addition, you can get a preview of what you may expect to see in AWIPS when these infrared satellite channels degrade and improve on a daily basis. This video can be downloaded here.