Spectral measurements of underwater downwelling radiance of inland water bodies
The apparatus exploited in this work is composed of an optical cable linked to a portable FieldSpec UV/VNIR that records the spectral downwelling radiance in underwater environment, allowing us to calculate the shortwave attenuation coefficient in water. Results for three inland water bodies are pre...
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2013-11-01
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doaj-198d2dbcc3dd45f6a4b542e09702c2952020-11-25T01:55:15ZengTaylor & Francis GroupTellus: Series A, Dynamic Meteorology and Oceanography0280-64951600-08702013-11-0165011110.3402/tellusa.v65i0.20774Spectral measurements of underwater downwelling radiance of inland water bodiesMiguel PotesMaria João CostaRui SalgadoDaniele BortoliAntãNio SerafimPatrick Le MoigneThe apparatus exploited in this work is composed of an optical cable linked to a portable FieldSpec UV/VNIR that records the spectral downwelling radiance in underwater environment, allowing us to calculate the shortwave attenuation coefficient in water. Results for three inland water bodies are presented under different atmospheric conditions (sun zenith angle and wind speed) and water composition (chlorophyll α concentration and turbidity). We show that the spectral downwelling zenith radiance profiles under high sun elevations present a positive slope in the upper layers due to relatively high scattering of direct sunlight compared to attenuation. For deeper layers, attenuation overcomes the scattering of sunlight leading to a constant negative logarithmic slope. For low sun elevations, a negative slope is observed in the entire water column since the scattering of direct sunlight is always lower than attenuation. Whenever a negative logarithmic constant slope is observed, the attenuation coefficient was computed. A relation was observed between attenuation coefficient in the photosynthetically active radiation (PAR) spectral region and water turbidity, for the three water bodies under study.www.tellusa.net/index.php/tellusa/article/download/20774/pdf_1apparatusspectroradiometerinland waterunderwater radiance profilesattenuation coefficient |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
Miguel Potes Maria João Costa Rui Salgado Daniele Bortoli AntãNio Serafim Patrick Le Moigne |
spellingShingle |
Miguel Potes Maria João Costa Rui Salgado Daniele Bortoli AntãNio Serafim Patrick Le Moigne Spectral measurements of underwater downwelling radiance of inland water bodies Tellus: Series A, Dynamic Meteorology and Oceanography apparatus spectroradiometer inland water underwater radiance profiles attenuation coefficient |
author_facet |
Miguel Potes Maria João Costa Rui Salgado Daniele Bortoli AntãNio Serafim Patrick Le Moigne |
author_sort |
Miguel Potes |
title |
Spectral measurements of underwater downwelling radiance of inland water bodies |
title_short |
Spectral measurements of underwater downwelling radiance of inland water bodies |
title_full |
Spectral measurements of underwater downwelling radiance of inland water bodies |
title_fullStr |
Spectral measurements of underwater downwelling radiance of inland water bodies |
title_full_unstemmed |
Spectral measurements of underwater downwelling radiance of inland water bodies |
title_sort |
spectral measurements of underwater downwelling radiance of inland water bodies |
publisher |
Taylor & Francis Group |
series |
Tellus: Series A, Dynamic Meteorology and Oceanography |
issn |
0280-6495 1600-0870 |
publishDate |
2013-11-01 |
description |
The apparatus exploited in this work is composed of an optical cable linked to a portable FieldSpec UV/VNIR that records the spectral downwelling radiance in underwater environment, allowing us to calculate the shortwave attenuation coefficient in water. Results for three inland water bodies are presented under different atmospheric conditions (sun zenith angle and wind speed) and water composition (chlorophyll α concentration and turbidity). We show that the spectral downwelling zenith radiance profiles under high sun elevations present a positive slope in the upper layers due to relatively high scattering of direct sunlight compared to attenuation. For deeper layers, attenuation overcomes the scattering of sunlight leading to a constant negative logarithmic slope. For low sun elevations, a negative slope is observed in the entire water column since the scattering of direct sunlight is always lower than attenuation. Whenever a negative logarithmic constant slope is observed, the attenuation coefficient was computed. A relation was observed between attenuation coefficient in the photosynthetically active radiation (PAR) spectral region and water turbidity, for the three water bodies under study. |
topic |
apparatus spectroradiometer inland water underwater radiance profiles attenuation coefficient |
url |
http://www.tellusa.net/index.php/tellusa/article/download/20774/pdf_1 |
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