
Open access
Date
2017Type
- Journal Article
Abstract
There is an ongoing debate on whether the observed decadal variations in surface solar radiation, known as "dimming" and "brightening" periods, are a large-scale or solely local phenomenon. We investigated this issue using long-term sunshine duration records from China, which experienced a rapid increase in urbanization during the past decades. Over the period 1960–2013, 172 pairs of urban and nearby rural stations were analyzed. Urban and rural sunshine duration trends show similar spatial patterns during a dimming phase (1960–1989) and a subsequent period during which trends were leveling off (1990–2013). This indicates that rather than local effects, the trends in sunshine duration are on more of a national or regional scale in China. Nevertheless, in the dimming phase, the declining rate of sunshine duration in rural areas is around two-thirds of that in urban areas. The ratio of rural to urban dimming generally increases from a minimum of 0.39 to a maximum of 0.87 with increasing indices of urbanization calculated based on the year 2013. It reaches a maximum when the urbanization level exceeds 50 %, the urban population exceeds 20 million, or the population density becomes higher than 250 person km−2. After the transition into the leveling-off period, sunshine duration trends are no longer significantly affected by urbanization. Meanwhile, the number of laws and regulations related to air pollution and investment in pollution treatment have been increasing in China. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000191685Publication status
publishedExternal links
Journal / series
Annales GeophysicaeVolume
Pages / Article No.
Publisher
CopernicusSubject
Meteorology and atmospheric dynamics (climatology; radiative processes)Organisational unit
03360 - Schär, Christoph (emeritus) / Schär, Christoph (emeritus)
Funding
135395 - Towards an improved understanding of the Global Energy Balance: absorption of solar radiation (SNF)
159938 - Towards an improved understanding of the Global Energy Balance: temporal variation of solar radiation in the climate system (SNF)
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