Loop Heat Pipe Anomaly Impacts on GOES-17 ABI Band 8

July 30, 2020

2 minute read

What is happening to Band 8?

Over the next few days, users of GOES-17 imagery from ABI Band 8 (Upper-level Water Vapor IR) will begin to notice the degradation of the imagery as a result of the seasonal loop heat pipe anomaly. A visual representation of the anticipated daily impacts for Band 8 can be found here and in Figure 1, below. A yellow cell with a "1" indicates estimated minimal to moderate degradation in the imagery for a given hour on a given day. Similarly, a red cell with a "2" indicates estimated severe degradation to the point that the imagery becomes unusable. The hour of day is at the top along the horizontal axis in UTC. The date is to the left along the vertical axis in ascending order.

Figure 1:  Anticipated impacts for Band 8 from July 24 - September 7

In Figure 1, above, the horizontal axis ranging from 0 to 23 (top) is the hour of the day in UTC
and the vertical axis is the calendar date from July 24 to September 7, 2020 in ascending order.​

 

Operational Impacts to Band 8

Band 8 (6.19 µm) is one of three mid-level water vapor bands on the ABI. The water vapor bands are IR bands that sense the mean temperature of a variable-depth layer of moisture. This altitude can vary depending upon the atmosphere's temperature and moisture profile, as well as the satellite's viewing angle (this band has maximum sensitivity in the 300-400 hPa range). Some of its uses include tracking upper tropospheric winds, identifying jet streams, forecasting hurricane track and mid-latitude storm motions, as well as identifying areas where the potential for turbulence exists. The impact of the loop heat pipe anomaly degradation to this band is on the ability to identify features such diffluent flow aloft that may suggest vertical motion and thunderstorms, and validating numerical weather prediction model initialization. More information on Band 8 can be found in this quick guide from CIMSS and this article published in the Journal of Operational Meteorology.

 

Impacted Data Products

The table below includes the GOES-17 data products that will be impacted by the degradation of Band 8. A quick guide for each data product is linked in the right column.

Data Product Link to Quick Guide
Derived Motion Winds CIMSS Quick Guide for Derived Motion Winds
Derived Stability Indices CIMSS Quick Guide for Derived Stability Indices
Legacy Vertical Moisture and Temperature Profiles CIRA Quick Guide for Legacy Vertical Profiles
Rainfall Rate/QPE NASA SPoRT Quick Guide for QPE
Total Precipitable Water CIRA Quick Guide for Total Precipitable Water
Airmass RGB CIMSS Quick Guide for Airmass RGB
Differential Water Vapor RGB CIRA Quick Guide for Differential Water Vapor RGB
Simple Water Vapor RGB CIRA Quick Guide for Simple Water Vapor RGB
Split Water Vapor Brightness Temperature Difference CIMSS Quick Guide for Split Water Vapor Difference

 

More Information on the Loop Heat Pipe Anomaly

For additional information regarding this seasonal loop heat pipe anomaly event, including the upcoming supplemental GOES-15 operations and the GOES-17 Mode 3 cooling timeline operations, refer to the article linked here. Mark your calendars for August 20th when Dave Pogorzala from the GOES-R Program will be presenting in the Satellite Book Club on the loop heat pipe anomaly. Stay tuned for more details on that session!