Remote sensing of ocean color: assessment of water-leaving radiance bidirectional effects on atmospheric diffuse transmittance

Yang, Haoyu; Gordon, Howard R.

doi:10.1364/ao.36.007887

Cited by 79 publications

(47 citation statements)

References 26 publications

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“…L w BOA is the water-leaving radiance at the bottom of atmosphere and t u is the upward radiance transmittance which accounts for the light propagation through the atmosphere from the bottom to the top (Yang and Gordon, 1997).…”

Section: Top-of-atmosphere Signal and Water-leaving Radiancementioning

confidence: 99%

Sunglint correction of the Multi-Spectral Instrument (MSI)-SENTINEL-2 imagery over inland and sea waters from SWIR bands

Harmel

Chami

Tormos

et al. 2018

Remote Sensing of Environment

132

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correction of the Multi-Spectral Instrument (MSI)-SENTINEL-2 imagery over inland and sea waters from SWIR bands. Remote Sensing of Environment, Elsevier, 2018, 204, pp.308-321 A B S T R A C TRemote sensing of inland and sea waters depends on the quality of the retrieval of the water-leaving radiance from the top-of-atmosphere measurements. The water-leaving radiance can be difficult to observe due to the reflection of direct sunlight on the air-water interface (sunglint) in the direction of the satellite field of view. The viewing geometry of Sentinel-2 satellite (European Space Agency) makes it vulnerable to sunglint contamination. In this paper, an original method is proposed to correct Sentinel-2-like imagery for sunglint contamination. The sunglint contribution is first estimated from the shortwave-infrared (SWIR) part of the spectrum and then extrapolated toward the near-infrared and visible bands. The spectral variation of the sunglint signal is thus revisited for a wide spectral range (from 350 to 2500 nm). The bidirectional reflectance distribution function related to the sunglint is shown to vary by > 28% from the SWIR to the blue bands of Sentinel-2. The application of the proposed algorithm on actual Sentinel-2 data demonstrates that sunglint patterns are satisfactorily removed over the entire images whatever the altitude of the observed target. Comparison with in situ data of water-leaving radiances (AERONET-OC) showed that our proposed algorithm significantly improves the correlation between satellite and in situ data by 55% (i.e., from R 2 = 0.56 to R 2 = 0.87). In addition, the discrepancies between satellite and in situ measurements are reduced by 60%. It is also shown that the aerosol data provided by the Copernicus Atmosphere Monitoring Service (CAMS) can be safely used within the proposed algorithm to correct the Sentinel-2-like satellite data for both sunglint and atmospheric radiances. Improvements of the proposed method potentially rely on simultaneous retrievals of the aerosol optical properties. The proposed method is applicable to any satellite sensor which is able to measure in SWIR spectral bands over aquatic environments.

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Section: Top-of-atmosphere Signal and Water-leaving Radiancementioning

confidence: 99%

Sunglint correction of the Multi-Spectral Instrument (MSI)-SENTINEL-2 imagery over inland and sea waters from SWIR bands

Harmel

Chami

Tormos

et al. 2018

Remote Sensing of Environment

132

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“…are the atmospheric transmittance factors for aerosol and Rayleigh effects 28,29 for ozone absorption and for oxygen absorption, 30 respectively. To model aerosol and water-leaving reflectances independently of ozone content Eq.…”

Section: A Standard Seawifs Atmospheric Correctionmentioning

confidence: 99%

Atmospheric correction of SeaWiFS imagery for turbid coastal and inland waters

Ruddick¹,

Ovidio²,

Rijkeboer³

2000

Appl. Opt.

526

287

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The standard SeaWiFS atmospheric correction algorithm, designed for open ocean water, has been extended for use over turbid coastal and inland waters. Failure of the standard algorithm over turbid waters can be attributed to invalid assumptions of zero water-leaving radiance for the near-infrared bands at 765 and 865 nm. In the present study these assumptions are replaced by the assumptions of spatial homogeneity of the 765:865-nm ratios for aerosol reflectance and for water-leaving reflectance. These two ratios are imposed as calibration parameters after inspection of the Rayleigh-corrected reflectance scatterplot. The performance of the new algorithm is demonstrated for imagery of Belgian coastal waters and yields physically realistic water-leaving radiance spectra. A preliminary comparison with in situ radiance spectra for the Dutch Lake Markermeer shows significant improvement over the standard atmospheric correction algorithm. An analysis is made of the sensitivity of results to the choice of calibration parameters, and perspectives for application of the method to other sensors are briefly discussed.

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“…This effect is realized mainly for low concentrations of phytoplankton and in the blue region of the electromagnetic spectrum. The assumption of a uniform distribution of water-leaving radiance, as reported by Yang and Gordon (1997), leads to an error of up to 4% (1 = 0.443 & 0.555 pm) for observation angles 0" I 8 I 60" and 0" I $ I 180", and aerosol optical thicknesses za(h) I 0.2 for a range of solar zenith angles 40" I 80 s 60". Likewise, Zhao and Nakajima (1997) report errors in simultaneously retrieved water-leaving reflectance and aerosol optical thickness in the range of 10%.…”

Section: Introductionmentioning

confidence: 96%

“…The anisotropy of the radiance field just above the ocean surface has practical consequences for the interpretation of the ocean signal detected remotely either by aircraft or satelliteborne radiometers, and affects retrieved products such as ocean color and aerosols. For example, a theoretical study by Yang and Gordon (1997) shows that the error in water-leaving radiance caused by assuming the upwelling radiance beneath the ocean surface to be reflected uniformly in all directions is significant in comparison to other errors expected in the water-leaving radiance. This effect is realized mainly for low concentrations of phytoplankton and in the blue region of the electromagnetic spectrum.…”

Section: Introductionmentioning

confidence: 99%

Airborne Spectral Measurements of Ocean Directional Reflectance

Gatebe

County

King

et al. 2005

Journal of the Atmospheric Sciences

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The Cloud Absorption Radiometer (CAR) was flown aboard the University of Washington Convair 580 (CV-580) research aircraft during the Chesapeake Lighthouse and Aircraft Measurements for Satellites (CLAMS) field campaign and obtained measurements of bidirectional reflectance distribution function (BRDF) of the ocean in July and August 2001 under different illumination conditions with solar zenith angles ranging from 15° to 46°. The BRDF measurements were accompanied by concurrent measurements of atmospheric aerosol optical thickness and column water vapor above the airplane. The method of spherical harmonics with Cox–Munk wave-slope distribution is used in a new algorithm developed for this study to solve the atmosphere–ocean radiative transfer problem and to remove the effects of the atmosphere from airborne measurements. The algorithm retrieves simultaneously the wind speed and full ocean BRDF (sun’s glitter and water-leaving radiance) from CAR measurements and evaluates total albedo and equivalent albedo for the water-leaving radiance outside the glitter. Results show good overall agreement with other measurements and theoretical simulations, with the anisotropy of the water-leaving radiance clearly seen. However, the water-leaving radiance does not show a strong dependence on solar zenith angle as suggested by some theoretical studies. The spectral albedo was found to vary from 4.1%–5.1% at λ = 0.472 μm to 2.4%–3.5% for λ ≥ 0.682 μm. The equivalent water-leaving albedo ranges from 1.0%–2.4% at λ = 0.472 μm to 0.1%–0.6% for λ = 0.682 μm and 0.1%–0.3% for λ = 0.870 μm. Results of the validation of the Cox–Munk model under the conditions measured show that although the model reproduces the shape of sun’s glitter on average with an accuracy of better than 30%, it underestimates the center of the sun’s glitter reflectance by about 30% for low wind speeds (<2–3 m s−1). In cases of high wind speed, the model with Gram–Charlier expansion seems to provide the best fit.

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Remote sensing of ocean color: assessment of water-leaving radiance bidirectional effects on atmospheric diffuse transmittance

Cited by 79 publications

References 26 publications

Sunglint correction of the Multi-Spectral Instrument (MSI)-SENTINEL-2 imagery over inland and sea waters from SWIR bands

Sunglint correction of the Multi-Spectral Instrument (MSI)-SENTINEL-2 imagery over inland and sea waters from SWIR bands

Atmospheric correction of SeaWiFS imagery for turbid coastal and inland waters

Airborne Spectral Measurements of Ocean Directional Reflectance

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