Ocean color products for the PACE Ocean Color Instrument (OCI) have been reprocessed to version 3.2. You can now acquire them via Earthdata Search.
Changes from Version 3.1 to Version 3.2:
- The new version incorporates the V3.0.2 instrument calibration update.
- OCI has low polarization sensitivity, but a small correction was implemented and first applied in V3.0. That implementation did not properly compute the geometry across the scan, and that issue has now been corrected. This has a very small impact on cross-track and latitudinal variation of Rrs.
- In V3.1 (and prior versions), the bi-directional reflectance (BRDF) correction was not correctly accounting for the change in relative azimuth across the scan. This has been corrected, resulting in a significant improvement in accuracy and cross-track stability of the Rrs retrievals.
- The absorbing gas corrections were recomputed using the latest HITRAN database.
- The vicarious calibration (SVC) gains were updated to account for impact of small changes in the atmospheric correction algorithm, and to incorporate additional OCI observational match-ups with measurements from the HyperNAV SVC sites.
- Level-2 ocean color retrievals are flagged for presence of coccolithophores, as the derived bio-geochemical properties are likely biased in these highly scattering conditions. All ocean color Level-3 products in V3.1 (and earlier) were masked for coccolithophores. In V3.2, that masking has been disabled for the AOP products as it was determined that the Rrs retrievals in the presence of moderate coccolithophore concentrations are valid. At high concentrations, the AOP products can still be masked for atmospheric correction failure.
- All Level-2 products from the OC_AOP suite are now consolidated into one Level-3 mapped product called AOP. Previously RRS, nFLH, AVW, etc. were distributed as separate Level-3 mapped products.
Known Issues:
- Performance of Rrs retrieval in the UV (below 400nm) has not been validated and is likely to contain significant biases and erroneous variability.
- Corrections for absorbing gases continue to improve, but Rrs variability, especially in the red, is still likely to contain residual artifacts from water vapor and oxygen absorption.
- The current processing extends to higher view zenith angles than the heritage sensors. The atmospheric correction becomes increasingly difficult at these extreme geometries, and erroneously elevated reflectance has been observed in red wavelengths near scan edge. These data are flagged in Level-2 and masked in Level-3 (above 60-degrees).
- Chlorophyll Fluorescence Line Height (nFLH) is displaying impacts of the erroneously elevated reflectances at the scan edge and, in extreme cases, is also impacted by the O2 b-band absorption artifacts in 680nm region.