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Author Barentine, J.C.; Walker, C.E.; Kocifaj, M.; Kundracik, F.; Juan, A.; Kanemoto, J.; Monrad, C.K.
Title Skyglow Changes Over Tucson, Arizona, Resulting From A Municipal LED Street Lighting Conversion Type Journal Article
Year 2018 Publication Journal of Quantitative Spectroscopy and Radiative Transfer Abbreviated Journal Journal of Quantitative Spectroscopy and Radiative Transfer
Volume 212 Issue Pages 10-23
Keywords Skyglow; Tucson; Arizona; LED; modeling; radiative transfer; LED
Abstract The transition from earlier lighting technologies to white light-emitting diodes (LEDs) is a significant change in the use of artificial light at night. LEDs emit considerably more short-wavelength light into the environment than earlier technologies on a per-lumen basis. Radiative transfer models predict increased skyglow over cities transitioning to LED unless the total lumen output of new lighting systems is reduced. The City of Tucson, Arizona (U.S.), recently converted its municipal street lighting system from a mixture of fully shielded high- and low-pressure sodium (HPS/LPS) luminaires to fully shielded 3000 K white LED luminaires. The lighting design intended to minimize increases to skyglow in order to protect the sites of nearby astronomical observatories without compromising public safety. This involved the migration of over 445 million fully shielded HPS/LPS lumens to roughly 142 million fully shielded 3000 K white LED lumens and an expected concomitant reduction in the amount of visual skyglow over Tucson. SkyGlow Simulator models predict skyglow decreases on the order of 10-20% depending on whether fully shielded or partly shielded lights are in use. We tested this prediction using visual night sky brightness estimates and luminance-calibrated, panchromatic all-sky imagery at 15 locations in and near the city. Data were obtained in 2014, before the LED conversion began, and in mid-2017 after approximately 95% of  ~18,000 luminaires was converted. Skyglow differed marginally, and in all cases with valid data changed by  <±20%. Over the same period, the city’s upward-directed optical radiance detected from Earth orbit decreased by approximately 7%. While these results are not conclusive, they suggest that LED conversions paired with dimming can reduce skyglow over cities.
Address International Dark-Sky Association, 3223 N 1st Ave, Tucson, AZ, 85719 USA; john(at)darksky.org
Corporate Author Thesis
Publisher Elsevier Place of Publication Editor
Language English Summary Language English Original Title
Series Editor Series Title Abbreviated Series Title
Series Volume Series Issue Edition
ISSN 0022-4073 ISBN (up) Medium
Area Expedition Conference
Notes Approved no
Call Number IDA @ john @ Serial 1819
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