FY 2023 How many independent quantities can be extracted from ocean color? Cael, B.B., K. Bisson, E. Boss, and Z.K. Erickson Limnol. Oceanogr. Lett., 8(4), 603-610, doi: 10.1002/lol2.10319, View online at ASLO/Wiley (external link, open access) (2023) Products derived from remote sensing reflectances (RTS (λ)), for example, chlorophyll, phytoplankton carbon, euphotic depth, or particle size, are widely used in oceanography. Problematically, RTS (λ) may have fewer degrees of freedom (DoF) than measured wavebands or derived products. Here, we show that a global sea surface hyperspectral RTS (λ) dataset has DoF = 4. MODIS-like multispectral equivalent in situ data also have DoF = 4, while their SeaWiFS equivalent has DoF = 3. Both multispectral-equivalent datasets predict individual hyperspectral wavelengths' RTS (λ) within nominal uncertainties. Remotely sensed climatological multispectral RTS (λ) have DoF = 2, as information is lost by atmospheric correction, shifting to larger spatiotemporal scales, and/or more open-ocean measurements, but suites of RTS (λ)-derived products have DoF = 1. These results suggest that remote sensing products based on existing satellites' RTS (λ) are not independent and should not be treated as such, that existing RTS (λ) measurements hold unutilized information, and that future multi- or especially hyper-spectral algorithms must rigorously consider correlations between RTS (λ) wavebands. Feature Publications | Outstanding Scientific Publications Contact Sandra Bigley | Help
