Method of determining the volume scattering function of ocean waters in the backward direction using a satellite ocean color sensor

6,868,361

10/628287

July 29, 2003

A method of determining the Volume Scattering Function of Ocean Waters in the backward direction using a Satellite Ocean Color Sensor the said method made to exploit the geometry of the sun-ocean-satellite detector to function as a backscatter system comprising of the sun [1] as a source of radiation, the ocean as the sampling volume [2], and the satellite ocean color sensor [3] as the detector of the backscattered flux from the ocean emanating from separate ocean pixels arranged on a scan line across the track of the satellite payload and arriving at corresponding pixels on the CCD array detector of the satellite sensor [3]; the output signals from each electronic pixel of the detector is shown to be related to the Volume Scattering Function at a fixed scattering angles (ψ) which bears a direct relation to the cosines of the solar incident angle (θs) and the angle (θp) of the upwelled flux at the ocean surface, the Remotely Sensed Reflectance (Rrs), and the diffuse attenuation coefficient (Kd) thereby resulting in a new product of the Volume Scattering Function at fixed backscattering angles.

Desa, Elgar (Goa, IN); Desa, Ehrlich (Goa, IN); Suresh, Thayapurath (Goa, IN)

Council of Scientific and Industrial Research (New Delhi, IN)

1. A method for determining the Volume Scattering Function (VSF) of ocean waters in backward direction using a satellite ocean color sensor, said method comprising the steps of: (a) obtaining satellite view angle (θ sat), solar angle (θ s), remote sensed reflectance [Rrs (θ p ,λ)] and diffuse attenuation coefficient (K d) at each ocean pixel on a scaline using a satellite ocean color sensor; (b) calculating corrected look angle of a pixel of satellite ocean color sensor on an ocean pixel using: θ p =θ sat +sin −1 (0.113 tan θ sat); and (c) calculating the Volume Scattering Function of ocean waters in the backward direction at a given wavelength [β(ψ,λ)] using: β(ψ,λ)= Rrs (θ p ,λ) K d [cos θ s cos θ p ].

2. A method as claimed in claim 1 , wherein the satellite ocean color sensors include CCD array detectors, ocean color monitors and SeaWifs Oocean color sensors.

3. A method as claimed in claim 1 , wherein the detectors view a scan line of ocean pixels arranged along a swath of the ocean surface.

4. A method as claimed in claim 1 , wherein the swath “W” of the satellite is about 1420 Kms.

5. A method as claimed in claim 1 , wherein the about 3730 ocean pixels are covered in a satellite scan line.

6. A method as claimed in claim 1 , wherein Instantaneous Field of View (IFOV) of an ocean pixel about 360 meters across track and about 250 meters along track.

7. A method as claimed in claim 1 , wherein the Volume Scattering Function of ocean waters in the backward direction is dependent upon the wavelength (λ).

8. A method as claimed in claim 1 , wherein the Volume Scattering Function of ocean waters in the backward direction is obtained at a particular wavelength using appropriate wavelength depenedent products of remote sensed reflectance and diffuse attenuation coefficient.

9. A method as claimed in claim 1 , wherein the Volume Scattering Function of ocean waters in the backward direction is obtained at the wavelength of about 490 nm.

10. A method as claimed in claim 1 , wherein the method can be extended to contiguous scan lines along the satellite track to generate a high resolution two dimensional volume scattering surface at fixed backscattering angles.

11. A method as claimed in claim 1 , wherein the method can be extended to create a set of two dimensional volume scattering surfaces in several different visible bands by the satellite ocean color sensor.

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4416542 November 1983 Mooradian
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Zaneveld-J-R-V., “Remotely sensed reflectance and its dependence on vertical structure: a theoretical derivation”, Applied-Optics, vol. 21, No. 22, p. 4146-50, Nov. 15, 1982. cited by examiner

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