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| Titel |
Estimation of upward radiances and reflectances at the surface of the sea from above-surface measurements |
| VerfasserIn |
Ø. Kleiv, A. Folkestad, J. Høkedal, K. Sørensen, E. Aas |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1812-0784
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| Digitales Dokument |
URL |
| Erschienen |
In: Ocean Science ; 11, no. 5 ; Nr. 11, no. 5 (2015-10-02), S.779-788 |
| Datensatznummer |
250117293
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| Publikation (Nr.) |
 copernicus.org/os-11-779-2015.pdf |
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| Zusammenfassung |
During 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. |
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