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Ocean Color Inferred from Radiometers on Low-Flying Aircraft

View Article: PubMed Central - PubMed

ABSTRACT

The color of sunlight reflected from the ocean to orbiting visible radiometers has provided a great deal of information about the global ocean, after suitable corrections are made for atmospheric effects. Similar ocean-color measurements can be made from a low-flying aircraft to get higher spatial resolution and to obtain measurements under clouds. A different set of corrections is required in this case, and we describe algorithms to correct for clouds and sea-surface effects. An example is presented and errors in the corrections discussed.

No MeSH data available.


Measured (solid circles) and corrected (open circles) remote sensing reflectance RRS for clear (red) and overcast (blue) skies.
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f4-sensors-08-00860: Measured (solid circles) and corrected (open circles) remote sensing reflectance RRS for clear (red) and overcast (blue) skies.

Mentions: In the most basic atmospheric correction, we ignore foam and glint effects. For the clear data, we use the results from the previous section to get:(17)RRS(λ)=L(λ)−RF(0)LS(λ)E(λ),where LS was estimated using MODTRAN with the sub-arctic summer model atmosphere, the maritime aerosol model, and both the current and 24 hour averaged winds set to 2 m s-1. For the cloudy data:(18)RRS(λ)=L(λ)E(λ)−RF(0)π.Since these data collected during visual surveys, flights were only made during low-wind conditions for good visibility. These low winds also meant that there were few glints and foam patches, justifying the use of this basic correction. In a plot of the median values of the corrected reflectivities (Fig. 4), we see good overall agreement between the clear and cloudy cases, even though the correction for the cloudy cases is quite large. Since the clear and cloudy data were taken at different locations at different times, we would not necessarily expect them to be the same. However, Figure 2 shows that they had about the same mix of coastal and off-shore waters, so it is not too surprising that they are similar.


Ocean Color Inferred from Radiometers on Low-Flying Aircraft
Measured (solid circles) and corrected (open circles) remote sensing reflectance RRS for clear (red) and overcast (blue) skies.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3927510&req=5

f4-sensors-08-00860: Measured (solid circles) and corrected (open circles) remote sensing reflectance RRS for clear (red) and overcast (blue) skies.
Mentions: In the most basic atmospheric correction, we ignore foam and glint effects. For the clear data, we use the results from the previous section to get:(17)RRS(λ)=L(λ)−RF(0)LS(λ)E(λ),where LS was estimated using MODTRAN with the sub-arctic summer model atmosphere, the maritime aerosol model, and both the current and 24 hour averaged winds set to 2 m s-1. For the cloudy data:(18)RRS(λ)=L(λ)E(λ)−RF(0)π.Since these data collected during visual surveys, flights were only made during low-wind conditions for good visibility. These low winds also meant that there were few glints and foam patches, justifying the use of this basic correction. In a plot of the median values of the corrected reflectivities (Fig. 4), we see good overall agreement between the clear and cloudy cases, even though the correction for the cloudy cases is quite large. Since the clear and cloudy data were taken at different locations at different times, we would not necessarily expect them to be the same. However, Figure 2 shows that they had about the same mix of coastal and off-shore waters, so it is not too surprising that they are similar.

View Article: PubMed Central - PubMed

ABSTRACT

The color of sunlight reflected from the ocean to orbiting visible radiometers has provided a great deal of information about the global ocean, after suitable corrections are made for atmospheric effects. Similar ocean-color measurements can be made from a low-flying aircraft to get higher spatial resolution and to obtain measurements under clouds. A different set of corrections is required in this case, and we describe algorithms to correct for clouds and sea-surface effects. An example is presented and errors in the corrections discussed.

No MeSH data available.