All-sky imaging: a simple, versatile system for atmospheric research
| Autor: | Axel Kreuter, Michael Schwarzmann, Matthias Zangerl, Mario Blumthaler |
|---|---|
| Rok vydání: | 2013 |
| Předmět: |
Atmospheric physics
Computer science business.industry Materials Science (miscellaneous) Cloud cover media_common.quotation_subject Irradiance Polarimetry Image processing Polarizer Polarization (waves) Industrial and Manufacturing Engineering law.invention Spectroradiometer Optics Sky law Radiance Business and International Management business Ultraviolet radiation Astrophysics::Galaxy Astrophysics Remote sensing media_common |
| Zdroj: | Applied optics. 48(6) |
| ISSN: | 1559-128X |
| Popis: | A simple and inexpensive fully automated all-sky imaging system based on a commercial digital camera with a fish-eye lens and a rotating polarizer is presented. The system is characterized and two examples of applications in atmospheric physics are given: polarization maps and cloud detection. All-sky polarization maps are obtained by acquiring images at different polarizer angles and computing Stokes vectors. The polarization in the principal plane, a vertical cut through the sky containing the Sun, is compared to measurements of a well-characterized spectroradiometer with polarized radiance optics to validate the method. The images are further used for automated cloud detection using a simple color-ratio algorithm. The resulting cloud cover is validated against synoptic cloud observations. A Sun coverage parameter is introduced that shows, in combination with the total cloud cover, useful correlation with UV irradiance. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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