GOES-R Band 2 (“red visible”) Calibration Changes
GOES-16 ABI Band 2 Visible Imagery (0.64 µm) at 1811 UTC on 21 April (before the calibration change) and at 1811 UTC on 25 April 2019 (after the calibration change) in and around Pima County (outlined in black) in southern Arizona (click to enlarge).
On 23 April 2019, a Ground Systems update resulted in a change to the ‘brightness’ (in the form of dimming) of the GOES-16 Band 2 (0.64 µm) visible imagery (as noted in this calibration events log). The calibration coefficients used for this band were determined in the lab before the launch. (Other calibration information is collected on-orbit.) GOES-R Advanced Baseline Imager (ABI) visible imagery have been compared to visible imagery from polar-orbiting satellites in the past several years (see this page), and GOES-R ABI Band 2 (0.64 µm) radiances were consistently larger than measurements from Suomi NPP and NOAA-20 using the Visible-Infrared Imaging Radiometer Suite (VIIRS).
ABI calibration coefficients for GOES-16 were modified on 23 April, using plausible values from pre-launch lab measurements. Thus, Band 2 radiances decreased by about 6.9%. This will have an impact on the computed albedo as shown above: the later date (after the calibation change) is slightly darker than the earlier (before the calibration change). This change means that Band 2 radiances and albedo are more closely aligned with values from other satellites. A similar toggle over Texas is shown below.
Note: A similar change for GOES-17 was implemented at 1540 UTC on 27 April 2019.
GOES-16 ABI Band 2 Visible Imagery (0.64 µm) at 1811 UTC on 21 April (before the calibration change) and at 1811 UTC on 25 April 2019 (after the calibration change) in and around Fayette County, TX (outlined in black), just west of metropolitan Houston (click to enlarge).