title: Worldwide variations in artificial skyglow.
abstract: Despite constituting a widespread and significant environmental change, understanding of artificial nighttime skyglow is extremely limited. Until now, published monitoring studies have been local or regional in scope, and typically of short duration. In this first major international compilation of monitoring data we answer several key questions about skyglow properties. Skyglow is observed to vary over four orders of magnitude, a range hundreds of times larger than was the case before artificial light. Nearly all of the study sites were polluted by artificial light. A non-linear relationship is observed between the sky brightness on clear and overcast nights, with a change in behavior near the rural to urban landuse transition. Overcast skies ranged from a third darker to almost 18 times brighter than clear. Clear sky radiances estimated by the World Atlas of Artificial Night Sky Brightness were found to be overestimated by ~25%; our dataset will play an important role in the calibration and ground truthing of future skyglow models. Most of the brightly lit sites darkened as the night progressed, typically by ~5% per hour. The great variation in skyglow radiance observed from site-to-site and with changing meteorological conditions underlines the need for a long-term international monitoring program.
authors: 1] Leibniz-Institute for Freshwater Ecology and Inland Fisheries [2] Institute for Space Sciences, Freie Universität Berlin, Berlin, Germany [3] Deutsches GeoForschungsZentrum Potsdam, Potsdam, Germany.
authors: Christopher C M
authors: CC
authors: Kyba
authors: Institut für Umweltphysik, Universität Bremen, Bremen, Germany.
authors: Kai Pong
authors: KP
authors: Tong
authors: Environment and Sustainability Institute, University of Exeter, Penryn, UK.
authors: Jonathan
authors: J
authors: Bennie
authors: Morehead State University, Morehead, USA.
authors: Ignacio
authors: I
authors: Birriel
authors: Morehead State University, Morehead, USA.
authors: Jennifer J
authors: JJ
authors: Birriel
authors: The Heights Observatory, Adelaide.
authors: Andrew
authors: A
authors: Cool
authors: Unaffiliated Citizen Scientist.
authors: Arne
authors: A
authors: Danielsen
authors: Environment and Sustainability Institute, University of Exeter, Penryn, UK.
authors: Thomas W
authors: TW
authors: Davies
authors: National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
authors: Peter N den
authors: PN
authors: Outer
authors: Unaffiliated Citizen Scientist.
authors: William
authors: W
authors: Edwards
authors: Unaffiliated Citizen Scientist.
authors: Rainer
authors: R
authors: Ehlert
authors: Light Pollution Science and Technology Institute (ISTIL), Thiene, Italy.
authors: Fabio
authors: F
authors: Falchi
authors: Institute for Space Sciences, Freie Universität Berlin, Berlin, Germany.
authors: Jürgen
authors: J
authors: Fischer
authors: Attivarti.org, Torniella, Italy.
authors: Andrea
authors: A
authors: Giacomelli
authors: Attivarti.org, Torniella, Italy.
authors: Francesco
authors: F
authors: Giubbilini
authors: National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
authors: Marty
authors: M
authors: Haaima
authors: Landesamt für Umwelt, Gesundheit und Verbraucherschutz Brandenburg, Germany.
authors: Claudia
authors: C
authors: Hesse
authors: Institut für Umweltphysik, Universität Bremen, Bremen, Germany.
authors: Georg
authors: G
authors: Heygster
authors: Leibniz-Institute for Freshwater Ecology and Inland Fisheries.
authors: Franz
authors: F
authors: Hölker
authors: Environment and Sustainability Institute, University of Exeter, Penryn, UK.
authors: Richard
authors: R
authors: Inger
authors: 1] National Optical Astronomy Observatory, Tucson, USA [2] Utah State University, Logan, USA.
authors: Linsey J
authors: LJ
authors: Jensen
authors: Leibniz-Institute for Freshwater Ecology and Inland Fisheries.
authors: Helga U
authors: HU
authors: Kuechly
authors: Unaffiliated Citizen Scientist.
authors: John
authors: J
authors: Kuehn
authors: Rothney Astrophysical Observatory, University of Calgary, Calgary, Canada.
authors: Phil
authors: P
authors: Langill
authors: National Institute for Public Health and the Environment, Bilthoven, The Netherlands.
authors: Dorien E
authors: DE
authors: Lolkema
authors: Department of Physics, University of Alberta, Edmonton, Canada.
authors: Matthew
authors: M
authors: Nagy
authors: Departamento de Astrofísica y Ciencias de la Atmósfera, Universidad Complutense de Madrid, Madrid, Spain.
authors: Miguel
authors: M
authors: Nievas
authors: Faculty of Business Administration, Toyo University, Tokyo, Japan.
authors: Nobuaki
authors: N
authors: Ochi
authors: Leibniz-Institut für Astrophysik Potsdam (AIP), Potsdam, Germany.
authors: Emil
authors: E
authors: Popow
authors: Institut für Astrophysik, Vienna, Austria.
authors: Thomas
authors: T
authors: Posch
authors: Institut für Astrophysik, Vienna, Austria.
authors: Johannes
authors: J
authors: Puschnig
authors: Institute for Space Sciences, Freie Universität Berlin, Berlin, Germany.
authors: Thomas
authors: T
authors: Ruhtz
authors: Sotto le Stelle, Utrecht, The Netherlands.
authors: Wim
authors: W
authors: Schmidt
authors: Leibniz-Institut für Astrophysik Potsdam (AIP), Potsdam, Germany.
authors: Robert
authors: R
authors: Schwarz
authors: Leibniz-Institut für Astrophysik Potsdam (AIP), Potsdam, Germany.
authors: Axel
authors: A
authors: Schwope
authors: Lumineux Consult, Arnhem, The Netherlands.
authors: Henk
authors: H
authors: Spoelstra
authors: Unihedron, Grimsby, Canada.
authors: Anthony
authors: A
authors: Tekatch
authors: Winer Observatory, Sonoita, USA.
authors: Mark
authors: M
authors: Trueblood
authors: National Optical Astronomy Observatory, Tucson, USA.
authors: Constance E
authors: CE
authors: Walker
authors: Leibniz-Institut für Astrophysik Potsdam (AIP), Potsdam, Germany.
authors: Michael
authors: M
authors: Weber
authors: Department of Physics and Astronomy, McMaster University, Hamilton, Canada.
authors: Douglas L
authors: DL
authors: Welch
authors: Departamento de Astrofísica y Ciencias de la Atmósfera, Universidad Complutense de Madrid, Madrid, Spain.
authors: Jaime
authors: J
authors: Zamorano
authors: Environment and Sustainability Institute, University of Exeter, Penryn, UK.
authors: Kevin J
authors: KJ
authors: Gaston