MODIS Data Degradation Notice

[OB.DAAC - amscott]

Dear Ocean Color community,

The Ocean Biology Processing Group has identified significant degradation with the science quality of MODIS-Aqua and MODIS-Terra Ocean Color data products starting in 2023. The degradation is related to our ability to track and correct for instrument calibration changes via the solar diffuser and fixed ground targets, as the platforms are now drifting from their nominal orbit node crossing times of 13:30 and 10:30 mean local time, respectively. For more details see:

Twedt, K., Xiong, X., Geng, X., Wilson, T., and Mu, Q., “Impact of satellite orbit drift on MODIS Earth scene observations used in calibration of the reflective solar bands”, Earth Observing Systems XXVIII, 2023, vol. 12685. doi:10.1117/12.2676873.

The effects of these calibration issues on the derived ocean color products (e.g., negative bias in chlorophyll-a retrievals) are evident beginning in early 2023 and continue to worsen with time. We are actively working to improve our on-orbit calibration approach to resolve these issues, but until we are able to produce an updated calibration and reprocess, the MODIS ocean color data products starting in 2023 should be regarded as reduced quality.

Regards,
The Ocean Biology Processing Group