Variability of adjacency effects in sky reflectance measurements

Philipp M.M. Groetsch; Peter Gege; Stefan G.H. Simis; Marieke A. Eleveld; Steef W.M. Peters

doi:10.1364/OL.42.003359

Variability of adjacency effects in sky reflectance measurements

Philipp M.M. Groetsch^*, Peter Gege, Stefan G.H. Simis, Marieke A. Eleveld, Steef W.M. Peters

^*Corresponding author for this work

Research output: Contribution to Journal › Article › Academic › peer-review

Abstract

Sky reflectance R_sky(λ) is used to correct in situ reflectance measurements in the remote detection of water color. We analyzed the directional and spectral variability in R_sky(λ) due to adjacency effects against an atmospheric radiance model. The analysis is based on one year of semi-continuous R_sky)λ) observations that were recorded in two azimuth directions. Adjacency effects contributed to R_sky)λ) dependence on season and viewing angle and predominantly in the near-infrared (NIR). For our test area, adjacency effects spectrally resembled a generic vegetation spectrum. The adjacency effect was weakly dependent on the magnitude of Rayleigh- and aerosol-scattered radiance. The reflectance differed between viewing directions 5.4 ± 6.3% for adjacency effects and 21.0 ± 19.8% for Rayleigh- and aerosol-scattered R_sky(λ) in the NIR. Under which conditions in situ water reflectance observations require dedicated correction for adjacency effects is discussed. We provide an open source implementation of our method to aid identification of such conditions.

Original language	English
Pages (from-to)	3359-3362
Number of pages	4
Journal	Optics Letters
Volume	42
Issue number	17
DOIs	https://doi.org/10.1364/OL.42.003359
Publication status	Published - 1 Sept 2017

Funding

Acknowledgment. European Commission H2020 TAPAS. We thank the two anonymous reviewers for their constructive criticism.

Funders	Funder number
Horizon 2020 Framework Programme	678396

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

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title = "Variability of adjacency effects in sky reflectance measurements",

abstract = "Sky reflectance Rsky(λ) is used to correct in situ reflectance measurements in the remote detection of water color. We analyzed the directional and spectral variability in Rsky(λ) due to adjacency effects against an atmospheric radiance model. The analysis is based on one year of semi-continuous Rsky)λ) observations that were recorded in two azimuth directions. Adjacency effects contributed to Rsky)λ) dependence on season and viewing angle and predominantly in the near-infrared (NIR). For our test area, adjacency effects spectrally resembled a generic vegetation spectrum. The adjacency effect was weakly dependent on the magnitude of Rayleigh- and aerosol-scattered radiance. The reflectance differed between viewing directions 5.4 ± 6.3% for adjacency effects and 21.0 ± 19.8% for Rayleigh- and aerosol-scattered Rsky(λ) in the NIR. Under which conditions in situ water reflectance observations require dedicated correction for adjacency effects is discussed. We provide an open source implementation of our method to aid identification of such conditions.",

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AU - Groetsch, Philipp M.M.

AU - Gege, Peter

AU - Simis, Stefan G.H.

AU - Eleveld, Marieke A.

AU - Peters, Steef W.M.

PY - 2017/9/1

Y1 - 2017/9/1

N2 - Sky reflectance Rsky(λ) is used to correct in situ reflectance measurements in the remote detection of water color. We analyzed the directional and spectral variability in Rsky(λ) due to adjacency effects against an atmospheric radiance model. The analysis is based on one year of semi-continuous Rsky)λ) observations that were recorded in two azimuth directions. Adjacency effects contributed to Rsky)λ) dependence on season and viewing angle and predominantly in the near-infrared (NIR). For our test area, adjacency effects spectrally resembled a generic vegetation spectrum. The adjacency effect was weakly dependent on the magnitude of Rayleigh- and aerosol-scattered radiance. The reflectance differed between viewing directions 5.4 ± 6.3% for adjacency effects and 21.0 ± 19.8% for Rayleigh- and aerosol-scattered Rsky(λ) in the NIR. Under which conditions in situ water reflectance observations require dedicated correction for adjacency effects is discussed. We provide an open source implementation of our method to aid identification of such conditions.

AB - Sky reflectance Rsky(λ) is used to correct in situ reflectance measurements in the remote detection of water color. We analyzed the directional and spectral variability in Rsky(λ) due to adjacency effects against an atmospheric radiance model. The analysis is based on one year of semi-continuous Rsky)λ) observations that were recorded in two azimuth directions. Adjacency effects contributed to Rsky)λ) dependence on season and viewing angle and predominantly in the near-infrared (NIR). For our test area, adjacency effects spectrally resembled a generic vegetation spectrum. The adjacency effect was weakly dependent on the magnitude of Rayleigh- and aerosol-scattered radiance. The reflectance differed between viewing directions 5.4 ± 6.3% for adjacency effects and 21.0 ± 19.8% for Rayleigh- and aerosol-scattered Rsky(λ) in the NIR. Under which conditions in situ water reflectance observations require dedicated correction for adjacency effects is discussed. We provide an open source implementation of our method to aid identification of such conditions.

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Variability of adjacency effects in sky reflectance measurements

Abstract

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UN SDGs

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