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Groetsch, PMM, Gege, P, Simis, SGH, Eleveld, MA and Peters, SWM 2017 Validation of a spectral correction procedure for sun and sky reflections in above-water reflectance measurements. Optics Express, 25 (16). A742. https://doi.org/10.1364/OE.25.00A742
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Text (published paper)
groetsch et al 2017 OE.pdf - Published Version Available under License Creative Commons Attribution. Download (7MB) | Preview |
Abstract/Summary
A three-component reflectance model (3C) is applied to above-water radiometric measurements to derive remote-sensing reflectance Rrs (λ). 3C provides a spectrally resolved offset Δ(λ) to correct for residual sun and sky radiance (Rayleigh- and aerosol-scattered) reflections on the water surface that were not represented by sky radiance measurements. 3C is validated with a data set of matching above- and below-water radiometric measurements collected in the Baltic Sea, and compared against a scalar offset correction Δ. Correction with Δ(λ) instead of Δ consistently reduced the (mean normalized root-mean-square) deviation between Rrs (λ) and reference reflectances to comparable levels for clear (Δ: 14.3 ± 2.5 %, Δ(λ): 8.2 ± 1.7 %), partly clouded (Δ: 15.4 ± 2.1 %, Δ(λ): 6.5 ± 1.4 %), and completely overcast (Δ: 10.8 ± 1.7 %, Δ(λ): 6.3 ± 1.8 %) sky conditions. The improvement was most pronounced under inhomogeneous sky conditions when measurements of sky radiance tend to be less representative of surface-reflected radiance. Accounting for both sun glint and sky reflections also relaxes constraints on measurement geometry, which was demonstrated based on a semi-continuous daytime data set recorded in a eutrophic freshwater lake in the Netherlands. Rrs (λ) that were derived throughout the day varied spectrally by less than 2 % relative standard deviation. Implications on measurement protocols are discussed. An open source software library for processing reflectance measurements was developed and is made publicly available.
| Item Type: | Publication - Article |
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| Subjects: | Earth Observation - Remote Sensing |
| Divisions: | Plymouth Marine Laboratory > Science Areas > Earth Observation Science and Applications |
| Depositing User: | Dr Stefan Simis |
| Date made live: | 04 Jul 2017 14:03 |
| Last Modified: | 25 Apr 2020 09:58 |
| URI: | https://plymsea.ac.uk/id/eprint/7469 |
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