Multi-Pixel Infrared Camera for Sea Surface Temperature Correction
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Solution Overview
Problem
Current sea surface temperature measurement systems are inaccurate due to their inability to effectively correct for downwelling flux and sky reflection, leading to significant biases and errors in temperature readings, especially at varying incidence angles, which are crucial for precise weather and climate modeling.
Innovation Solution
A compact, automatic, multi-pixel infrared camera system that captures images with a narrow field of view, allowing for precise correction of sky flux reflection and determination of true sea surface temperature by using Fresnel equations to account for incidence and reflection angles, thereby isolating the emitted flux from the sea surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pixel noncontact thermometer is used to measure sea surface temperature, then the device complexity is reduced, but the measurement precision deteriorates due to large field of view containing multiple wave slopes and variable sea temperature emission
Solution Approach 1:
The patent divides the measurement task into multiple pixels, where each pixel measures a specific wave slope angle. This segmentation allows the system to capture temperature data from different incidence angles simultaneously, enabling precise correction of sky reflection effects while maintaining manageable device complexity through parallel measurement channels.
Solution Approach 2:
The patent adds the dimension of angular resolution by measuring temperature at multiple incidence angles across the field of view. This dimensional expansion from single-point to multi-angle measurement enables the system to separate sea surface emission from sky reflection components, significantly improving measurement precision without excessive complexity increase.
2Area of stationary object
If satellite observations with wide footprint are used, then the area coverage is improved, but the measurement precision deteriorates due to large variation in sea slope and unknown sea state bias
Solution Approach 1:
The patent applies local quality analysis by examining temperature measurements at different local incidence angles within the satellite footprint. Each pixel provides localized temperature data that can be corrected for local sea slope effects, allowing the system to maintain precision across the wide area coverage by treating each local region with angle-specific correction.
Solution Approach 2:
The patent changes the measurement parameter from single-temperature reading to multi-angle temperature distribution. By measuring temperature as a function of incidence angle across the wide footprint, the system can identify and correct for sea state variations, maintaining measurement precision while achieving broad area coverage.
3Difficulty of detecting and measuring
If measurements are taken at higher incidence angles, then the sensitivity to sea surface emission is improved, but the measurement precision deteriorates due to increased sky reflection contribution
Solution Approach 1:
The patent implements feedback by using the multi-pixel angular temperature distribution to calculate and subtract the sky reflection component. The system measures temperatures at multiple angles, uses Fresnel equations to model the expected reflection contribution, and iteratively corrects the sea surface temperature measurement, improving precision while maintaining sensitivity to emission.
Solution Approach 2:
The patent converts the harmful effect of sky reflection into a beneficial measurement tool. By measuring at multiple incidence angles where reflection varies predictably according to Fresnel equations, the system can actually determine the reflection component and subtract it, turning the previously problematic reflection into a source of information that improves measurement precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate sea surface temperature measurements with an error margin of about 0.3°C, significantly improving the precision of remote sensing and weather forecasting by minimizing contamination from sky reflections.
Implementation Method 1
The amplitude of the upwelling flux emitted by the sea is a strong function of incidence angle
Implementation Method 2
The downwelling flux from the sky contributes to this upwelling measurement as a function if incidence and reflection angles in accord with the Fresnel equations
Data Source
AI summary
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.