Apparatus and methods for remote measurement of sea surface temperature
OwnerFredrick S. Solheiminventor
Life of this patent
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Abstract
Apparatus and methods are disclosed for highly accurate remote measurement of sea surface skin temperature. Thermal band 8 to 14 micron images of the surface of the ocean taken by a downward looking infrared camera are processed to determine the optimum segments of the image to utilize. The influence of contaminating reflection of the downwelling flux from the sky and other error sources are removed and from the data and/or otherwise corrected for making sea surface temperature accuracy within several tenths of a degree possible.
Claims19
A method for remote measurement of sea surface temperature comprising the steps of:
- capturing a time series of pitch and roll angles from an inertial measurement unit:
- fitting sinusoids to the time series of pitch and roll angles and determining mean angles therefrom;
- applying Fourier transform to the time series of pitch and roll angles and inspecting the dc component of the Fourier transform;
- comparing and assessing sinusoid fit to Fourier transform results;
- and
- determining geometric horizon from the mean angles;
- capturing a multi-pixel image in selected wavebands of a selected area of sea surface at a selected incidence angle, each pixel of the image having a fraction of a degree field-of-view width;
- sorting blackbody thermal values of the pixels, from warmest to coolest;
- locating coordinates of the warmest pixels relative to position of image capture and nadir angle thereto;
- determining incidence and reflected angles from a selected warmest pixel;
- and
- determining downwelling infrared flux in the wavebands and at the incidence angle and utilizing determination of downwelling infrared flux to provide a corrected calculation of true sea surface temperature.
The method of 1 further comprising determining a desired high angle downwelling flux from lower elevation angle observation.
A method for accurate measurement of physical temperature of sea surface skin comprising the steps of:
- calibrating a passive noncontact infrared thermal 8 to 14 micron band multi-pixel camera capable of capturing a plurality of pixels in each captured image of its field of view to express thermal blackbody temperature of each of the pixels;
- directing the field of view of the camera to the sea surface at a known incidence angle and capturing an image or images thereof, wherein the camera field of view pixel width is a fraction of a degree thus spanning only a few millimeters of the sea surface, and sending data indicative thereof to a processor;
- utilizing angle of a viewed wave surface in each pixel, view angle of the infrared camera onto the wave surface in each pixel, and angle of the reflected view of the sky in each pixel to determine the flux emitted from the sea surface and reflected sky flux in each pixel at the processor;
- and
- obtaining corrected sea surface skin temperature at the processor by separating the values of emitted flux from the first several microns of the sea surface skin and values of variable flux from sky reflected from the wave surface angles in the field of view of the camera in a selected pixel and processing accordingly.
Dependencies are inferred from the claim text.