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| Titel |
Modelling of underwater light fields in turbid and eutrophic waters: application and validation with experimental data |
| VerfasserIn |
B. Sundarabalan, P. Shanmugam |
| 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. 1 ; Nr. 11, no. 1 (2015-01-09), S.33-52 |
| Datensatznummer |
250117124
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| Publikation (Nr.) |
 copernicus.org/os-11-33-2015.pdf |
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| Zusammenfassung |
| A reliable radiative transfer (RT) model is an essential and indispensable tool
for understanding the radiative transfer processes in homogenous and
layered waters, analyzing measurements made by radiance sensors and
developing remote-sensing algorithms to derive meaningful physical
quantities and biogeochemical variables in turbid and productive coastal
waters. Existing radiative transfer models have been designed to be
applicable to either homogenous waters or inhomogeneous waters. To overcome
such constraints associated with these models, this study presents a
radiative transfer model that treats a homogenous layer as a diffuse part
and an inhomogeneous layer as a direct part in the water column and combines
these two parts appropriately in order to generate more reliable underwater
light-field data such as upwelling radiance (Lu), downwelling irradiance
(Ed) and upwelling irradiance (Eu). The diffuse model assumes the
inherent optical properties (IOPs) to be vertically continuous and the light
fields to exponentially decrease with depth, whereas the direct part
considers the water column to be vertically inhomogeneous (layer-by-layer
phenomena) with the vertically varying phase function. The surface and
bottom boundary conditions, source function due to chlorophyll and solar
incident geometry are also included in the present RT model. The performance
of this model is assessed in a variety of waters (clear, turbid and
eutrophic) using the measured radiometric data. The present model shows an
advantage in terms of producing accurate Lu, Ed and Eu profiles
(in spatial domain) in different waters determined by both homogenous and
inhomogeneous conditions. The feasibility of predicting these underwater
light fields based on the remotely estimated IOP data is also examined using
the present RT model. For this application, vertical profiles of the water
constituents and IOPs are estimated by empirical models based on our in situ
data. The present RT model generates Lu, Ed and Eu spectra
closely consistent with the measured data. These results lead to a
conclusion that the present RT model is a viable alternative to existing RT
models and has an important implication for remote sensing of optically
complex waters. |
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