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dc.contributor.authorKleiv, Øyvind
dc.contributor.authorFolkestad, Are
dc.contributor.authorHøkedal, Jo
dc.contributor.authorAas, Eyvind
dc.contributor.authorSørensen, Kai
dc.date.accessioned2018-07-06T07:30:02Z
dc.date.available2018-07-06T07:30:02Z
dc.date.issued2015-10-02
dc.description.abstractDuring 4 field days in the years 2009–2011, 22 data sets of measurements were collected in the inner Oslofjord, Norway. The data consist of recordings of spectral nadir radiances in air and water as well as spectral downward irradiance in air. The studied wavelengths are 351, 400, 413, 443, 490, 510, 560, 620, 665, 681, 709 and 754 nm. The water-leaving radiance and the reflected radiance at the sea surface have been obtained from the measured nadir radiances in air and water, where the latter radiance has been extrapolated upwards to the surface. For comparison we present a simpler and much faster method that determines the water-leaving and reflected radiances solely from above-surface measurements of upward nadir radiance and downward irradiance. This new method is based on an assumption about similarity in spectral shape of the radiance reflected at the surface, and it makes use of the small ratio between water-leaving and reflected radiances at 351 and 754 nm in the Oslofjord. A comparison between the quantities determined by the two mentioned methods shows that the average relative deviations between their results are less than or equal to 15 % for the reflected radiance, at the studied wavelengths. The average relative deviation of the water-leaving radiance at 560 nm is 24 %. These results are obtained for a cloudiness range of 1–8 oktas (12.5–100 %) and solar zenith angles between 37 and 51°. We consider these to be acceptable uncertainties for a first check of satellite products in the inner Oslofjord.en_US
dc.description.abstractDuring 4 field days in the years 2009–2011, 22 data sets of measurements were collected in the inner Oslofjord, Norway. The data consist of recordings of spectral nadir radiances in air and water as well as spectral downward irradiance in air. The studied wavelengths are 351, 400, 413, 443, 490, 510, 560, 620, 665, 681, 709 and 754 nm. The water-leaving radiance and the reflected radiance at the sea surface have been obtained from the measured nadir radiances in air and water, where the latter radiance has been extrapolated upwards to the surface. For comparison we present a simpler and much faster method that determines the water-leaving and reflected radiances solely from above-surface measurements of upward nadir radiance and downward irradiance. This new method is based on an assumption about similarity in spectral shape of the radiance reflected at the surface, and it makes use of the small ratio between water-leaving and reflected radiances at 351 and 754 nm in the Oslofjord. A comparison between the quantities determined by the two mentioned methods shows that the average relative deviations between their results are less than or equal to 15 % for the reflected radiance, at the studied wavelengths. The average relative deviation of the water-leaving radiance at 560 nm is 24 %. These results are obtained for a cloudiness range of 1–8 oktas (12.5–100 %) and solar zenith angles between 37 and 51°. We consider these to be acceptable uncertainties for a first check of satellite products in the inner Oslofjord.en_US
dc.description.sponsorshipThe field work and the first processing of the data was part of the PRODEX project C90383 <br>Validation of MERIS products – VAMP II, supported by ESA. <br>A minor part of the data processing was supported by the Department of Geosciences at the University of Oslo.en_US
dc.descriptionOpen Access, published under the <a href=https://creativecommons.org/licenses/by/4.0/> Creative Commons attribution License (CC BY 4.0)</a><p> Link to publishers version:<a href=https://www.ocean-sci.net/11/779/2015/>https://www.ocean-sci.net/11/779/2015/</a>en_US
dc.identifier.citationKleiv, Ø., Folkestad, A., Høkedal, J., Sørensen, K., and Aas, E.: Estimation of upward radiances and reflectances at the surface of the sea from above-surface measurements, Ocean Science. 2015; 11(5), p. 779-788. https://doi.org/10.5194/os-11-779-2015en_US
dc.identifier.issn1812-0784
dc.identifier.issn1812-0792
dc.identifier.otherFRIDAID 1293948
dc.identifier.other10.5194/os-11-779-2015
dc.identifier.urihttps://hdl.handle.net/10037/13166
dc.language.isoengen_US
dc.publisherEuropean Geosciences Unionen_US
dc.relation.journalOcean Science
dc.rights.accessRightsopenAccessen_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Geofag: 450::Oseanografi: 452en_US
dc.subjectVDP::Mathematics and natural science: 400::Geosciences: 450::Oceanography: 452en_US
dc.titleEstimation of upward radiances and reflectances at the surface of the sea from above-surface measurementsen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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