Lunar skylight polarization signal polluted by urban lighting

On clear moonlit nights, a band of highly polarized light stretches across the sky at a 90 degree angle from the moon, and it was recently demonstrated that nocturnal organisms are able to navigate based on it. Urban skyglow is believed to be almost unpolarized, and is therefore expected to dilute t...

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Bibliographic Details
Published in:Journal of Geophysical Research: Atmospheres 2011-12, Vol.116 (D24), p.n/a
Main Authors: Kyba, C. C. M., Ruhtz, T., Fischer, J., Hölker, F.
Format: Article
Language:English
Subjects:
aeroecology
Air pollution
Atmosphere
Atmospheric sciences
Climate change
Earth
Earth sciences
Earth, ocean, space
ecological light pollution
Exact sciences and technology
Geobiology
Geophysics
Light pollution
Moon
moonlight
nocturnal navigation
Planets
Polarization
polarized light
Remote sensing
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Summary:On clear moonlit nights, a band of highly polarized light stretches across the sky at a 90 degree angle from the moon, and it was recently demonstrated that nocturnal organisms are able to navigate based on it. Urban skyglow is believed to be almost unpolarized, and is therefore expected to dilute this unique partially linearly polarized signal. We found that urban skyglow has a greater than expected degree of linear polarization (p = 8.6 ± 0.3%), and confirmed that its presence diminishes the natural lunar polarization signal. We also observed that the degree of linear polarization can be reduced as the moon rises, due to the misalignment between the polarization angles of the skyglow and scattered moonlight. Under near ideal observing conditions, we found that the lunar polarization signal was clearly visible (p = 29.2 ± 0.8%) at a site with minimal light pollution 28 km from Berlin's center, but was reduced (p = 11.3 ± 0.3%) within the city itself. Daytime measurements indicate that without skyglow pwould likely be in excess of 50%. These results indicate that nocturnal animal navigation systems based on perceiving polarized scattered moonlight likely fail to operate properly in highly light‐polluted areas, and that future light pollution models must take polarization into account. Key Points Urban skyglow pollutes the lunar skylight polarization signal Nocturnal animal polarization‐based navigation will fail in lit urban areas Urban skyglow is more polarized than previously predicted
ISSN:0148-0227
2169-897X
2156-2202
2169-8996
DOI:10.1029/2011JD016698