Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 13969-14001, 2016
https://doi.org/10.5194/acp-16-13969-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
11 Nov 2016
Is global dimming and brightening in Japan limited to urban areas?
Katsumasa Tanaka1,2, Atsumu Ohmura2, Doris Folini2, Martin Wild2, and Nozomu Ohkawara3 1Center for Global Environmental Research, National Institute for Environmental Studies (NIES), Tsukuba, Japan
2Institute for Atmospheric and Climate Science, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
3Global Environment and Marine Department, Japan Meteorological Agency (JMA), Tokyo, Japan
Abstract. Worldwide observations indicate secular trends of all-sky surface solar radiation on a decadal time scale, termed global dimming and brightening. Accordingly, the observed surface radiation in Japan generally shows a strong decline until the end of the 1980s and then a recovery until around 2000. Because a substantial number of measurement stations are located within or close to populated areas, one may speculate that the observed trends are strongly influenced by local air pollution and are thus not of large-scale significance. This hypothesis poses a serious question as to what regional extent the global dimming and brightening are significant: are the global dimming and brightening truly global phenomena, or regional, or even only local? Our study focused on 14 meteorological observatories that measured all-sky surface solar radiation, zenith transmittance, and maximum transmittance. On the basis of municipality population time series, historical land use maps, recent satellite images, and actual site visits, we concluded that eight stations have been significantly influenced by urbanization, with the remaining six stations being left pristine. Between the urban and rural areas, no marked differences were identified in the temporal trends of the aforementioned meteorological parameters. Our findings suggest that global dimming and brightening in Japan occurred on a large scale, independently of urbanization.

Citation: Tanaka, K., Ohmura, A., Folini, D., Wild, M., and Ohkawara, N.: Is global dimming and brightening in Japan limited to urban areas?, Atmos. Chem. Phys., 16, 13969-14001, https://doi.org/10.5194/acp-16-13969-2016, 2016.
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Short summary
Surface solar radiation observed in Japan generally shows a strong decline until the end of the 1980s and then a recovery up until around 2000. A substantial number of measurement stations are located close to populated areas and are speculated to have been influenced by air pollution. However, data obtained at 14 meteorological observatories suggest that the large decadal variations in surface solar radiation occur on a large scale and not limited to urban areas.
Surface solar radiation observed in Japan generally shows a strong decline until the end of the...
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