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Moradi, Masoud ; Arabi, Behnaz ; Hommersom, Annelies ; van der Molen, Johan ; Samimi, Cyrus:
Quality control tests for automated above-water hyperspectral measurements : Radiative Transfer assessment.
In: ISPRS Journal of Photogrammetry and Remote Sensing.
Bd. 215
(2024)
.
- S. 292-312.
ISSN 0924-2716
DOI: https://doi.org/10.1016/j.isprsjprs.2024.07.011
Abstract
Automated above-water hyperspectral observations are often subject to inaccuracies caused by instrument
malfunction and environmental conditions. This study evaluates the influence of atmospheric and water surface
conditions on above-water hyperspectral measurements through statistical methods and Radiative Transfer (RT)
modelling. Initially, we developed a general quality control method based on statistical assessment to detect the
suspicious spectra. Subsequently, Radiative Transfer (RT) models were used to assess low light conditions, dis-
tortions in the spectral shape of above-water solar downwelling irradiance (ES(λ), mW m−2 nm−1) particularly
those caused by intense atmospheric scattering and/or reddish hue of dusk or dawn radiation, the effect of at-
mospheric humidity and precipitation on the intensity and shape of spectra, and the influence of sun glint and
surface perturbations on sky (LS(λ), mW m−2 nm−1 sr−1) and water surface (LT(λ), mW m−2 nm−1 sr−1) radiances.
The proposed methods were applied to the entire archive of automated above-water hyperspectral measurements
collected every ten minutes from 2020 to 2022 at the Royal Netherland Institute for Sea Research (NIOZ) at Jetty
Station (NJS) located in the Marsdiep tidal inlet of the Duch Wadden Sea, the Netherlands. The findings
demonstrate that low light conditions are characterized by ES(λ)max ≤ 25 mW m−2 nm−1. Red-shifted or distorted
spectra are indicated by a ratio of ES(48 0)/ES(68 0) ≤ 1.0 and ES(λmax)/ ES(86 5) ≤ 1.25. High humidity/pre-
cipitation conditions are identified by the ratio of ES(94 0)/ES(865), which varies with the Solar Zenith Angle
(SZA). Furthermore, significant sun glint and surface perturbations, such as whitecaps and foam, are indicated
when the minimum ratio of LT(800 nm-950 nm)/ES(800 nm-950 nm) > 0.025 sr−1, and the ratio of LT(850 nm)/
ES(850 nm) ≥ 0.025 sr−1.