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VIIRS-NOAA21 Ocean Color Reprocessing 2025.0 (Calibration Update)
VIIRS–NOAA21 Ocean Color Reprocessing 2025.0
Introduction
The Ocean Biology Processing Group (OBPG) performed a calibration‑only reprocessing for VIIRS on NOAA‑21. Unlike full‑mission reprocessings that incorporate algorithm and product changes, this cycle is limited to improvements in instrument characterization and vicarious calibration.
Scope: This is a calibration update only. No sensor‑independent product or algorithm changes are included in this cycle.
Sensor‑specific Processing Details
Instrument Calibration
Refined on‑orbit (solar/lunar) calibration time series and modeling of radiometric degradation.
Improved relative detector normalization to mitigate band‑dependent striping and inter‑detector biases.
Vicarious Calibration
Updated vicarious calibration coefficients are derived from HyperNAV in situ radiometry systems, replacing the earlier provisional approach that combined a limited early‑mission dataset with an ocean reflectance model. The HyperNAV‑based update reduces residual bias in Rrs and derived products in oligotrophic waters.
Expected Impacts
Remote Sensing Reflectance (Rrs): small, spectrally consistent adjustments; greatest stability expected in blue‑green bands (e.g., 445 and 555 nm).
Chlorophyll‑a (Chl): modest shifts in oligotrophic regimes consistent with revised absolute calibration; time‑series continuity preserved.
Striping/Detector artifacts: reduced visibility from improved normalization.
Note: Quantitative impacts will be finalized after full archive assessment; figures below use 2025.0 test run (J2VT08) results.
Quick‑look Figures (test run J2VT08)
The following are figures from oligotrophic water for a quick look of the reprocessing results.
