Hue-Angle Product for Low to Medium Spatial Resolution Optical Satellite Sensors

Woerd, H.J. van der; Wernand, Marcel Robert

doi:10.3390/rs10020180

Cited by 85 publications

(94 citation statements)

References 26 publications

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“…Any pair of x, y coordinates of an upwelling radiance spectrum can be identified by the hue angle (α), which is the angle of the line drawn from the white point to the x, y coordinate and the x-axis of the plot in anticlockwise direction. We calculate α using the four quadrant arctangent function atan2 in Matlab (Equation (7) in [22]):…”

Section: Calculation Of Chromaticitymentioning

confidence: 99%

“…Van der Woerd and Wernand [21,22] describe that in first approximation the tristimulus values can be reconstructed based on a linear weighted sum of the bands R, in this case, the four bands of OLI X = 11.053 (443) + 6.950 (482)…”

Section: Calculation Of Chromaticitymentioning

confidence: 99%

“…Algorithms have been developed for the retrieval of colour information from ocean-colour sensors and a suite of medium resolution sensors [21,22]. This colour information is based only on the remote sensing reflectance and can be retrieved accurately and consistently from sensors with four or more spectral bands in the visual domain.…”

Section: Introductionmentioning

confidence: 99%

“…Remote sensing has the potential to address this knowledge gap by providing current baseline information and historic data for any lake large enough to be resolved by the footprint of satellite sensors. Here, we derive water colour using the hue angle method of Woerd and Wernand [22] Remote Sens. 2018, 10, 1273 4 of 22 from over 1400 lakes across New Zealand using atmospherically corrected reflectance derived from Landsat 8 OLI images that were captured between April 2013 and February 2018.…”

Section: Introductionmentioning

confidence: 99%

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Colour Classification of 1486 Lakes across a Wide Range of Optical Water Types

et al. 2018

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Remote sensing by satellite-borne sensors presents a significant opportunity to enhance the spatio-temporal coverage of environmental monitoring programmes for lakes, but the estimation of classic water quality attributes from inland water bodies has not reached operational status due to the difficulty of discerning the spectral signatures of optically active water constituents. Determination of water colour, as perceived by the human eye, does not require knowledge of inherent optical properties and therefore represents a generally applicable remotely-sensed water quality attribute. In this paper, we implemented a recent algorithm for the retrieval of colour parameters (hue angle, dominant wavelength) and derived a new correction for colour purity to account for the spectral bandpass of the Landsat 8 Operational Land Imager (OLI). We used this algorithm to calculate water colour on almost 45,000 observations over four years from 1486 lakes from a diverse range of optical water types in New Zealand. We show that the most prevalent lake colours are yellow-orange and blue, respectively, while green observations are comparatively rare. About 40% of the study lakes show transitions between colours at a range of time scales, including seasonal. A preliminary exploratory analysis suggests that both geo-physical and anthropogenic factors, such as catchment land use, provide environmental control of lake colour and are promising avenues for future analysis.

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Section: Calculation Of Chromaticitymentioning

confidence: 99%

Section: Calculation Of Chromaticitymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Colour Classification of 1486 Lakes across a Wide Range of Optical Water Types

et al. 2018

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“…Surface water optical and physical properties observed in situ reveal the optical and physical characteristics of the ventilating water mass (Figure 3b). First, the surface water chromaticity coordinates were transformed to the hue angle (0-360°; Woerd & Wernand, 2018). There are two depressions in the hue angle,…”

Section: Satellite Image and Poststorm Surveymentioning

confidence: 99%

The Optical Signature of a Bottom Boundary Layer Ventilation Event in the Northern Gulf of Mexico's Hypoxic Zone

Jolliff

Jarosz

Ladner

et al. 2018

Geophysical Research Letters

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Oceanographic observations in the northern Gulf of Mexico captured an unusual combination of atmospheric forcing and shelf frontal dynamics that brought about the surface ventilation of sediment‐laden bottom waters. Colorimetric analysis of in situ optical data indicates a specific turquoise‐white color signature for turbid and low‐oxygen bottom waters that match a coincident shelf‐wide feature detected in Moderate Resolution Imaging Spectroradiometer satellite true color images. The physical processes leading to this ventilation event are simulated using the Coupled Ocean Atmosphere Mesoscale Prediction System, which includes an integrated surface wave model. The combined model‐data analysis suggests that low‐oxygen, bottom water ventilation may occur episodically during boreal spring and summer in the northern Gulf of Mexico following the passage of high‐energy atmospheric systems, and these events may be identified in the historical satellite record based on the unique bottom water optical characteristics.

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