Comparison of radiance and polarization values observed in the Mediterranean Sea and simulated in a Monte Carlo model

Adams, James T.; Aas, Eyvind; Højerslev, Niels K.; Lundgren, Bo

doi:10.1364/ao.41.002724

Cited by 32 publications

(17 citation statements)

References 12 publications

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“…An analytic description of the radiance distributions has been suggested by Aas and Højerslev (1999). It supports the quality of the measurements so that when the in situ values were compared to radiances and polarizations simulated in a Monte Carlo model by Adams et al (2002), a remarkably good agreement was observed. Another agreement was found for Q as a function of the solar angle in a comparison between the simulations of Morel and Gentili (1996) and our Mediterranean measurements Højerslev 1999, Morel et al 2002).…”

Section: Datasets Of Field Measurementsmentioning

confidence: 55%

Conversion of sub-surface reflectances to above-surface MERIS reflectance

Aas

H⊘jerslev

2009

International Journal of Remote Sensing

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Factors for converting sub-surface reflectances to above-surface MERIS reflectances have been determined both as analytic functions and average numbers for solar zenith angles in the range 30 -75 , wind speeds up to 10 m s -1 , and the spectral domain 400-700 nm. The conversion factors have been obtained by numerical and statistical computations based on field observations of spectral radiance and irradiance, above and below the surface of the sea. The estimated maximum errors of the different algorithms range from 0.1% up to 10%, depending on the chosen method and the types of optical quantities that are available. The errors are smallest for solar zenith angles between 30 and 60 and increase when the solar zenith angle approaches 75 . The influence of the wind on the conversion factors is practically negligible. The algorithms, which have been derived for conditions representative of the Skagerrak and the adjacent seas, are assumed to be valid for both Case 1 and 2 waters.

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Section: Datasets Of Field Measurementsmentioning

confidence: 55%

Conversion of sub-surface reflectances to above-surface MERIS reflectance

Aas

H⊘jerslev

2009

International Journal of Remote Sensing

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“…The data were stored as graphs on paper rolls from printers. Through the years the recordings were read off and tabulated (Lundgren 1971;, and analyses were made Aas and Højerslev, 1999;Adams et al, 2002 ).…”

Section: Observations Of Sub-surface Radiance and Irradiancementioning

confidence: 99%

Estimates of radiance reflected towards the zenith at the surface of the sea

Aas

2010

Ocean Sci.

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Abstract. Remote sensing of water colour by ship-mounted sensors represents an important tool for the validation of satellite products and the monitoring of water quality. The recorded radiance from the sea has to be corrected for the surface-reflected radiance from sun and sky in order to obtain the water-leaving radiance. Here the simple case of radiance reflected towards the zenith is studied. A set of observed sky radiance and solar irradiance data from Oslo has been used together with a Gaussian slope distribution for the sea surface in order to estimate the reflected radiance. The spectral range studied is 405-650 nm, the solar zenith angles are in the range 37 • -76 • , and the wind speeds are up to 10 m s −1 . The analysis of the results show that the reflected radiance has to be separated into three contributions: sky radiance and sun rays reflected at the foam-free surface and irradiance reflected by whitecaps and foam. It is then demonstrated that by using four input values, namely the downward irradiance, the sky radiance from the zenith, the solar zenith angle and the wind speed, it is possible to obtain by simple expressions estimates of the reflected radiance that only differ from the former calculated values by relative errors of less than 5%. The analysis also indicates that for the spectral range studied neither the water-leaving radiance nor the surface-reflected radiance can be disregarded relative to the other one in the Case 2 waters of the Oslofjord-Skagerrak area. The results form a first step towards the study of reflected radiance in viewing angles differing from the nadir direction.

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“…Unfortunately only two theoretical works using this program were created by its author [1,2]. And another only one work [3], comparing the results of the Monte Carlo code containing the polarization and the measured data was published so far. It seemed expedient to create the second independent program of its kind in the world, specifically targeted to study phenomena related to surface of the sea.…”

Section: Introductionmentioning

confidence: 99%

Signal of single scattering albedo in water leaving polarization

Piskozub

Freda

2013

J. Eur. Opt. Soc.-Rapid Publ.

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The purpose of this article is to examine whether the change in single scattering albedo in the surface layer of the sea will cause significant changes in the polarization of light emerging from the sea. The results of a polarization resolving Monte Carlo radiative transfer calculations are presented. Bubble clouds of different bubble concentrations are used to achieve a wide range of single scattering albedo variability. The variability of the polarization signal is largest in the direction looking towards the sun which is unfortunate due to sun reflection. However the variability is also significant at direction perpendicular to solar azimuth angle which should it make possible to use this signal in remote sensing. The polarization degree of water leaving radiation, together with reflectance can be used to determine the backscattering ratio of the observed sea water.

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Comparison of radiance and polarization values observed in the Mediterranean Sea and simulated in a Monte Carlo model

Cited by 32 publications

References 12 publications

Conversion of sub-surface reflectances to above-surface MERIS reflectance

Conversion of sub-surface reflectances to above-surface MERIS reflectance

Estimates of radiance reflected towards the zenith at the surface of the sea

Signal of single scattering albedo in water leaving polarization

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