Annual Periodicity in Ocean Color Observations Across Diverse Oceanic Regions

• DOI: 10.1364/opticaopen.28907291.v1
• Publication Date: 2025-05-02T05:36:40Z
• Authors: E. Blocker; Paul Jeremy Werdell; Amir Ibrahim; Michael Behrenfeld; Kelsey Bisson; Emmanuel Boss; Bryan Franz; Robert Frouin
• Keywords: Ocean color

The annual periodicity present in spectral remote sensing reflectances (Rrs(λ)) derived from ocean color satellite data processed by NASA's Ocean Biology Processing Group has been shown to diverge that observed situ, with the source of discrepancies remaining unresolved. Here we investigate such four sensors and seven situ locations. Periodicity time series Rrs(λ) spectra are examined without prior assumption main constituent frequency through application floating-mean Lomb-Scargle periodogram. We show a 1-term sinusoidal function specified at constant offset reproduces seasonal trends various regional oceanic sites. Although unique features mean, amplitude, phase generally well captured measurements, perpetuate into satellite-to-in matchup difference. Specifying origin discrepancy is challenging because significantly contained many physical corrections, ancillary required for retrievals. Until differences amplitude between reduced, improved uncertainty estimates should be incorporated downstream product analyses.