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Platform perturbations in above-water radiometry
Stanford B Hooker1, Giuseppe Zibordi
1Laboratory for Hydrospheric Processes, Greenbelt, Maryland 20771, USA. stan@ardbeg.gsfc.nasa.gov
Applied Optics
|February 25, 2005
Summary
Above-water spectral measurements from offshore towers show that platform reflections cause errors. These errors decrease with distance, becoming negligible beyond the tower
Area of Science:
- Ocean optics
- Remote sensing
- Radiometry
Background:
- Above-water spectral measurements are crucial for ocean color remote sensing.
- Offshore platforms can introduce errors due to superstructure reflections.
- Understanding these errors is vital for accurate water-leaving radiance determination.
Purpose of the Study:
- To quantify the impact of offshore platform proximity on above-water spectral measurements.
- To assess the accuracy of water-leaving radiance determinations under varying distances from a platform.
- To evaluate methods for correcting superstructure reflection errors.
Main Methods:
- Comparison of above-water and in-water spectral measurements.
- Parameterization of measurement proximity using distance (x) relative to tower height (H).
- Development of a diagnostic variable to quantify superstructure reflections.
Main Results:
- Measurement uncertainty is highest near the platform (x/H << 1).
- Platform perturbations decrease significantly as distance (x/H) increases.
- In the far field (x > H), platform perturbation is negligible.
Conclusions:
- Above-water measurements are reliable in the far field (x > H).
- A 5% absolute accuracy objective for remote sensing can be achieved beyond the near-field effects.
- The study provides a framework for understanding and mitigating platform-induced errors in oceanographic measurements.