Improving low-quality satellite remote sensing reflectance at blue bands over coastal and inland waters

• Published in: Remote sensing of environment Vol. 250; p. 112029
• Main Authors: Wei, Jianwei, Yu, Xiaolong, Lee, Zhongping, Wang, Menghua, Jiang, Lide
• Format: Journal Article
• Language: English
• Published: New York Elsevier Inc 01.12.2020; Elsevier BV
• Subjects: Algorithms; Atmospheric correction; Blue bands; Coastal waters; color; environment; Inland waters; MODIS; Ocean color; Reflectance; Remote sensing; Remote sensing reflectance; Satellites; SeaWiFS; Spectra; Spectral shape; Uncertainty; VIIRS; Wavelengths; SeaWiFS; Blue bands; Spectral shape; Atmospheric correction; VIIRS; Remote sensing reflectance; MODIS
• ISSN: 0034-4257; 1879-0704
• DOI: 10.1016/j.rse.2020.112029

The satellite remote sensing reflectance (Rrs(λ)) at two short blue bands (410 or 412 nm and 443 nm) are prone to large uncertainties in coastal and inland waters, prohibiting algorithms from generating reliable ocean color products associated with these bands. In this study, we developed an algorithm to estimate Rrs(41×) and Rrs(443) when the satellite Rrs(λ) in blue bands suffer from large uncertainties. The algorithm first determines the Rrs(λ) spectral shape from the satellite-measured Rrs(λ) values at three wavelengths of 48× (486, 488, or 490), 55× (547, 551, or 555), and 67× (667, 670, or 671) nm. The algorithm then derives Rrs(41×) and Rrs(443) from the estimated Rrs(λ) spectral shape with algebraic formulations. We assessed the algorithm performance with satellite (SeaWiFS, MODISA, and VIIRS-SNPP) and in situ Rrs(λ) matchups from global waters. It is shown that the uncertainties of estimated Rrs(41×) and Rrs(443) are substantially smaller than the original satellite products when applicable. Besides, implementation of the algorithm contributes to a significant increase in the number of utilizable Rrs(41×) and Rrs(443) values. The algorithm is relatively stable and is best applicable to the satellite Rrs(λ) spectra for which the Rrs(48×) and Rrs(55×) measurements are subject to small uncertainties. The demonstrations support the application of the blue-band estimation algorithm to a wide range of coastal waters. •A spectral shape based algorithm is developed to estimate Rrs(41×) and Rrs(443).•The algorithm can greatly increase the satellite Rrs data quality and quantity.•It allows for more accurate and increased number of valid ocean color retrievals.