Distribution and Cloud Free Evaluations of the GOES-17 ABI Radiance Anomalies

The Advanced Baseline Imager (ABI), a state-of-the-art imager with unprecedented capabilities, has so far been deployed on two geostationary satellite platforms. These are NOAA’s GOES-16 (2016) and most recently NOAA’s GOES-17 (2018). While the ABI on GOES-16 is operating nominally, the loop heat pipe (LHP) on GOES-17 is malfunctioning making cooling the ABI to acceptable levels a significant challenge at certain times of the year and times of the day. While NOAA provides a number of reports and daily tracking sites for quality monitoring and validation, this work provides some further granularity characterizing the degradations of the mid-level water vapor bands (8-10) at those times when excess heat becomes a significant problem.

In particular, we look at a comparison of the distribution of radiances between the ABI on GOES-16 and GOES-17 during the worst and best period. This was done by looking at an equatorial region of interest in the overlap Region of Interest (ROI). In light of the recent calibration corrections, this provides some insight that even when the mean values of the ROI are consistent for both ABI during the times when heat is a problem, the distributions of values over the range have significant differences. We also evaluate the 6.2, 6.9, and 7.3-micrometer water vapor channels restricted to cloud-free grid cells since these are the locations where the observations are most useful. Evaluating the effect of the loop heat pipe problem on these critical bands is an important step in mitigation strategies.