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
Received: 01 Jul 2016 – Discussion started: 04 Aug 2016
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.
Revised: 17 Oct 2016 – Accepted: 24 Oct 2016 – Published: 11 Nov 2016
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, doi:10.5194/acp-16-13969-2016, 2016.