Light fields and optics in coastal waters - Bewerkingsoverzicht

Daphnisd op 19 mrt 2013 om 14:26

Daphnisd — Tue, 19 Mar 2013 14:26:31 GMT

Daphnisd: /* References */

Daphnisd — Tue, 19 Mar 2013 14:22:11 GMT

‎References

Daphnisd: /* Optical closure */

Daphnisd — Tue, 19 Mar 2013 14:20:59 GMT

‎Optical closure

Daphnisd: /* Optical closure */

Daphnisd — Tue, 19 Mar 2013 14:20:43 GMT

‎Optical closure

MaartenDeRijcke op 3 aug 2011 om 13:44

MaartenDeRijcke — Wed, 03 Aug 2011 13:44:43 GMT

Simon op 31 mrt 2009 om 10:36

Simon — Tue, 31 Mar 2009 10:36:36 GMT

Jackgeerlings: /* References */

Jackgeerlings — Fri, 28 Nov 2008 12:49:38 GMT

‎References

Jackgeerlings: /* References */

Jackgeerlings — Fri, 28 Nov 2008 12:49:15 GMT

‎References

Tasomerville op 21 sep 2008 om 12:22

Tasomerville — Sun, 21 Sep 2008 12:22:46 GMT

Wouter Kreiken op 21 jul 2008 om 12:24

Wouter Kreiken — Mon, 21 Jul 2008 12:24:34 GMT

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 <references/>
-{{2Authors
+<div style = "float: center">
-|AuthorID1=14356
+{| style="border:1px solid #abd5f5; background:#f1f5fc; margin:0em 0em 0em 5em;"
-|AuthorFullName1=Alex Cunningham
+|<center>The main authors of this article are [http://www.coastalwiki.org/imis/imis.php?module=person&persid=14356 Alex Cunningham] and Leanne Ramage<br><small>Please note that others may also have edited the contents of this article. </small> </center>
-|AuthorName1=Alex.cunningham
+----
-|AuthorFullName2=Leanne Ramage
-|AuthorName2=Leanne Ramage}}
 [[Category:Theme_9]]

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 |AuthorName2=Leanne Ramage}}
-[[Category:Articles by Leanne Ramage]]
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 [[Category:Hydrological processes and water]]
 [[Category:Techniques and methods in coastal management]]
 [[Category:Remote Sensing in Coastal and Marine Research]]

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 Ideally, it should be possible to construct a light field model of a coastal water column using measured values of the IOPs which would precisely replicate radiometric measurements made at the same time.  This is known as <u>‘optical closure’</u>.  It is difficult to achieve in practice for two main reasons.  First, it places great demands on the appropriate calibration and deployment of the measuring instruments.  Second, some key IOPs such as the scattering phase function are difficult to measure [[in situ]], and are usually estimated from the backscattering ratio (bb/b) using analytical functions. Figure 3 shows a typical attempt to achieve optical closure for a shelf sea station in the Irish Sea with constituent concentrations of: Chl 1.6 mg m<sup>-3</sup>, MSS 1.9 mg l<sup>-1</sup>, CDOM a440 0.2m<sup>-1</sup>.  In this instance the match between measured and modelled E<sub>d</sub> values is reasonably good, but the L<sub>u</sub> plots diverge significantly below 5 m. The symbols in Figure 3 represent measurements made with a profiling radiometer (Satlantic SPMR) and are spaced at 1 m intervals from the sea surface. The lines indicate the output of Hydrolight calculations of downward irradiance (upper plot) and upward radiance (lower plot) which used [[in-situ]] measurements of IOPs as inputs.  Absorption and scattering coefficients were measured using a dual tube photometer (Wet Labs ac-9) and backscattering coefficients measured using a Hydroscat 2 (HobiLabs) backscattering meter.
-<blockquote style="background: rgb(245, 245, 245); border: 1px solid rgb(153, 153, 153);padding: 1em; width:600; margin:0 auto">
+<blockquote style="background: rgb(245, 245, 245); border: 1px solid rgb(153, 153, 153);padding: 1em; width:600px; margin:0 auto">
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 Ideally, it should be possible to construct a light field model of a coastal water column using measured values of the IOPs which would precisely replicate radiometric measurements made at the same time.  This is known as <u>‘optical closure’</u>.  It is difficult to achieve in practice for two main reasons.  First, it places great demands on the appropriate calibration and deployment of the measuring instruments.  Second, some key IOPs such as the scattering phase function are difficult to measure [[in situ]], and are usually estimated from the backscattering ratio (bb/b) using analytical functions. Figure 3 shows a typical attempt to achieve optical closure for a shelf sea station in the Irish Sea with constituent concentrations of: Chl 1.6 mg m<sup>-3</sup>, MSS 1.9 mg l<sup>-1</sup>, CDOM a440 0.2m<sup>-1</sup>.  In this instance the match between measured and modelled E<sub>d</sub> values is reasonably good, but the L<sub>u</sub> plots diverge significantly below 5 m. The symbols in Figure 3 represent measurements made with a profiling radiometer (Satlantic SPMR) and are spaced at 1 m intervals from the sea surface. The lines indicate the output of Hydrolight calculations of downward irradiance (upper plot) and upward radiance (lower plot) which used [[in-situ]] measurements of IOPs as inputs.  Absorption and scattering coefficients were measured using a dual tube photometer (Wet Labs ac-9) and backscattering coefficients measured using a Hydroscat 2 (HobiLabs) backscattering meter.
-<blockquote style="background: rgb(245, 245, 245); border: 1px solid rgb(153, 153, 153);padding: 1em;">
+<blockquote style="background: rgb(245, 245, 245); border: 1px solid rgb(153, 153, 153);padding: 1em; width:600; margin:0 auto">
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← Oudere versie		Versie van 31 mrt 2009 om 10:36
Regel 196:		Regel 196:
	[[Category:Hydrological processes and water]]		[[Category:Hydrological processes and water]]
	[[Category:Techniques and methods in coastal management]]		[[Category:Techniques and methods in coastal management]]
		+	[[Category:Remote Sensing in Coastal and Marine Research]]

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 <math>a_{total} = a_{water}\, +\, a_{Phyt}\, +\, a_{MSS}\, +\, a_{CDOM}\, +\, a_{OSS} </math>
-The scattering coefficient (b), attenuation coefficient (c) and phase function (&beta;) can all be partitioned in a similar manner.  In practice, however, the optical contributions of these four classes of material may not be completely distinct: [[algal blooms|blooms]] formed by phytoplankton groups such as coccolithophores and diatoms may generate significant concentrations of mineral particles (calcite and silica respectively), and organic detrital material may form flocs which incorporate suspended minerals.
+The scattering coefficient (b), attenuation coefficient (c) and phase function (&beta;) can all be partitioned in a similar manner.  In practice, however, the optical contributions of these four classes of material may not be completely distinct: [[algal bloom|blooms]] formed by phytoplankton groups such as coccolithophores and diatoms may generate significant concentrations of mineral particles (calcite and silica respectively), and organic detrital material may form flocs which incorporate suspended minerals.
 ===Specific optical properties and characteristics of constituents===

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 {{featured}}
-The quantitative study of underwater light fields in coastal waters and shelf seas has important applications in ecology, engineering and [[remote sensing]]. This article introduces the theoretical basis of optical measurements. Attention is paid to descriptors of light fields, optical properties of natural waters and light field modelling. For more information about the measurement of light field, see also the article [[Optical measurements in coastal waters]].
+The quantitative study of underwater light fields in coastal waters and shelf seas has important applications in ecology, engineering and [[remote sensing]]. This article introduces the theoretical basis of optical measurements. Attention is paid to descriptors of light fields, optical properties of natural waters and light field modelling. For more information about the measurement of light fields, see also the article [[Optical measurements in coastal waters]].
 ==Introduction of underwater light fields==