scholarly journals Urbanization effect on sunshine duration during global dimming and brightening periods in China

2016 ◽  
Author(s):  
Yawen Wang ◽  
Martin Wild ◽  
Arturo Sanchez-Lorenzo ◽  
Yonghui Yang ◽  
Veronica Manara ◽  
...  
Keyword(s):  
Air Pollution ◽  
Rural Areas ◽  
Average Rate ◽  
Sunshine Duration ◽  
Regional Scale ◽  
Urbanization Effect ◽  
Surface Solar Radiation ◽  
Decadal Variations ◽  
Global Dimming ◽  
Urban And Rural Areas

Abstract. There is an ongoing debate on whether the observed decadal variations in surface solar radiation, known as "dimming and brightening", are a global or just local phenomenon. We investigated this issue using a comprehensive set of long-term sunshine duration records from China, which experienced a rapid growth in urbanization during past decades. 172 pairs of urban and nearby rural stations were analyzed over the period 1960–1989 ("dimming phase") and 1990–2013 ("brightening phase"). There is a large overlap in urban and rural sunshine duration trends for both dimming (≈ 86 %) and brightening (≈ 84 %) phases. This indicates that rather than urban dimming or rural brightening, the global dimming and brightening phenomena are more of national/regional scale in China. In the dimming phase, sunshine duration significantly declined in both urban and rural areas at an average rate of −0.20 h d−1 decade−1 and −0.14 h d−1 decade−1 respectively, i.e. rural dimming has been around two-thirds of urban dimming. This ratio generally increases from a minimum of 0.39 to a maximum of 0.87 with increasing indices of urbanization, reaching saturation when the urbanization level exceeds 50 %, or the urban population exceeds 20 million persons, or the population density becomes higher than 250 person km−2. Urbanization can be treated as a useful indicator for anthropogenic air pollution in studying pollution-driven changes in sunshine duration during the dimming phase when pollution control and monitoring were largely absent. After the transition into the brightening phase, the increasing number of environment-related laws and regulations as well as investments in the abatement of environmental pollution might have helped in counteracting air pollutants generated during the urbanization process. Therefore, in the brightening phase, urbanization no longer simply indicates an increase in air pollution and its effect on sunshine duration becomes insignificant. In conclusion, urbanization can give a general indication of pollution-driven sunshine dimming until pollution regulations become effective.

scholarly journals Urbanization effect on trends in sunshine duration in China

2017 ◽  
Vol 35 (4) ◽  
pp. 839-851 ◽  
Author(s):  
Yawen Wang ◽  
Martin Wild ◽  
Arturo Sanchez-Lorenzo ◽  
Veronica Manara
Keyword(s):  
Rural Areas ◽  
Urban Areas ◽  
Large Scale ◽  
Sunshine Duration ◽  
Regional Scale ◽  
Urbanization Effect ◽  
Surface Solar Radiation ◽  
Urbanization Level ◽  
Decadal Variations

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.

scholarly journals Is global dimming and brightening in Japan limited to urban areas?

2016 ◽  
Author(s):  
Katsumasa Tanaka ◽  
Atsumu Ohmura ◽  
Doris Folini ◽  
Martin Wild ◽  
Nozomu Ohkawara
Keyword(s):  
Solar Radiation ◽  
Rural Areas ◽  
Urban Areas ◽  
Large Scale ◽  
Temporal Trends ◽  
Surface Radiation ◽  
Surface Solar Radiation ◽  
Decadal Time Scale ◽  
Global Dimming ◽  
Urban And Rural Areas

Abstract. Observations worldwide indicate secular trends of all-sky surface solar radiation on decadal time scale, termed global dimming and brightening. Accordingly, the observed surface radiation in Japan generally shows a strong decline till the end of the 1980s and then a recovery toward around 2000. Because a substantial number of measurement stations are located within or proximate 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 had 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 finding suggests that global dimming and brightening in Japan occurred on a large scale, independently of urbanization.

scholarly journals Is global dimming and brightening in Japan limited to urban areas?

2016 ◽  
Vol 16 (21) ◽  
pp. 13969-14001 ◽  
Author(s):  
Katsumasa Tanaka ◽  
Atsumu Ohmura ◽  
Doris Folini ◽  
Martin Wild ◽  
Nozomu Ohkawara
Keyword(s):  
Solar Radiation ◽  
Rural Areas ◽  
Urban Areas ◽  
Large Scale ◽  
Temporal Trends ◽  
Surface Radiation ◽  
Surface Solar Radiation ◽  
Decadal Time Scale ◽  
Global Dimming ◽  
Urban And Rural Areas

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.

scholarly journals Measurements of ozone and its precursors in Beijing during summertime: impact of urban plumes on ozone pollution in downwind rural areas

2011 ◽  
Vol 11 (6) ◽  
pp. 17337-17373 ◽  
Author(s):  
J. Xu ◽  
J. Z. Ma ◽  
X. L. Zhang ◽  
X. B. Xu ◽  
X. F. Xu ◽  
...  
Keyword(s):  
Rural Areas ◽  
Surface Ozone ◽  
Regional Scale ◽  
Rural Site ◽  
Traffic Density ◽  
Prevailing Wind ◽  
Ozone Pollution ◽  
Rural Sites ◽  
Urban And Rural Areas ◽  
Urban Plumes

Abstract. Sea-land and mount-valley circulations are the dominant mesoscale synoptic systems affecting the Beijing area during summertime. Under the influence of these two circulations, the prevailing wind is southwesterly from afternoon to midnight, and then changes to northeasterly till forenoon. In this study, surface ozone (O3), carbon monoxide (CO), nitric oxide (NO), nitrogen dioxide (NO2), nitrogen oxide (NOx) and non-methane hydrocarbons (NMHCs) were measured at four sites located along the route of prevailing wind, including two upwind urban sites (Fengtai (FT) and Baolian (BL)), an upwind suburban site (Shunyi (SY)) and a downwind rural site (Shangdianzi (SDZ)) during 20 June–16 September 2007. The purpose is to improve our understanding of ozone photochemistry in urban and rural areas of Beijing and the influence of urban plumes on ozone pollution in downwind rural areas. It is found that ozone pollution was synchronism in the urban and rural areas of Beijing, coinciding with the regional-scale synoptic processes. Due to the high traffic density and local emissions, the average levels of reactive gases NOx and NMHCs at the non-rural sites were much higher than those at SDZ. The level of long-lived gas CO at SDZ was comparable to and slightly lower than it was at other sites. The daily-averaged ozone concentration at SDZ was much higher than at other sites due to weak titration. Ranking by OH loss rate coefficient (LOH), alkenes played a dominant role in total NMHCs reactivity at both urban and rural sites during the experiment, accounting for 48.6 % and 52.1 % of total LOH, respectively. The NMHCs data were also used to estimate the ozone potential formation (OFP) in Beijing. The leading contributors to ozone formation were aromatics at both urban and rural sites during the experiment, which accounts for 55.5 % and 49.4 % of total OFP, respectively. The ozone peak values are found to lag behind one site after another along the route of prevailing wind from SW to NE. Intersection analyses of trace gases reveal that polluted air masses arriving at SDZ were more aged with both higher O3 and Ox concentrations than those at BL. The results indicate that urban plume can transport not only O3 but its precursors, the latter leading more photochemical O3 production when being mixed with background atmosphere in the downwind rural area.

scholarly journals A New Estimation of Urbanization’s Contribution to the Warming Trend in China

2015 ◽  
Vol 28 (22) ◽  
pp. 8923-8938 ◽  
Author(s):  
Fang Wang ◽  
Quansheng Ge ◽  
Shaowu Wang ◽  
Qingxiang Li ◽  
Philip D. Jones
Keyword(s):  
Climate Warming ◽  
Rural Areas ◽  
Urban Areas ◽  
Warming Trend ◽  
Heat Island ◽  
Urban Station ◽  
Urbanization Effect ◽  
Urban Heat ◽  
Urban And Rural Areas ◽  
Urban Effects

Abstract The extent to which an urbanization effect has contributed to climate warming is under debate in China. Some previous studies have shown that the urban heat island (UHI) contribution to national warming was substantial (10%–40%). However, by considering the spatial scale of urbanization effects, this study indicates that the UHI contribution is negligible (less than 1%). Urban areas constitute only 0.7% of the whole of China. According to the proportions of urban and rural areas used in this study, the weighted urban and rural temperature averages reduced the estimated total warming trend and also reduced the estimated urban effects. Conversely, if all stations were arithmetically averaged, that is, without weighting, the total warming trend and urban effects will be overestimated as in previous studies because there are more urban stations than rural stations in China. Moreover, the urban station proportion (68%) is much higher than the urban area proportion (0.7%).

scholarly journals Indoor air pollution and health of children in biomass fuel-using households of Bangladesh: comparison between urban and rural areas

2011 ◽  
Vol 16 (6) ◽  
pp. 375-383 ◽  
Author(s):  
Md. Khalequzzaman ◽  
Michihiro Kamijima ◽  
Kiyoshi Sakai ◽  
Takeshi Ebara ◽  
Bilqis Amin Hoque ◽  
...  
Keyword(s):  
Air Pollution ◽  
Indoor Air ◽  
Rural Areas ◽  
Indoor Air Pollution ◽  
Biomass Fuel ◽  
Urban And Rural Areas

scholarly journals Global dimming and urbanization: did stronger negative SSR trends collocate with regions of population growth?

2015 ◽  
Vol 15 (21) ◽  
pp. 31133-31151
Author(s):  
A. Imamovic ◽  
K. Tanaka ◽  
D. Folini ◽  
M. Wild
Keyword(s):  
Urban Areas ◽  
Correlation Coefficients ◽  
Population Based ◽  
Anthropogenic Aerosols ◽  
Urbanization Effect ◽  
Surface Solar Radiation ◽  
Significance Level ◽  
High Data ◽  
Global Dimming ◽  
The 1960S

Abstract. Global dimming refers to the decrease in surface solar radiation (SSR) observed from the 1960s to the 1980s at different measurement sites all around the world. It is under debate whether anthropogenic aerosols emitted from urban areas close to the measurement sites are mainly responsible for the dimming. In order to assess this urbanization impact on SSR, we use spatially explicit population density data of 0.08° resolution to construct population indices (PI) at 157 high data quality sites. Our study extends previous population-based studies by incorporating distance-weighting as a simple aerosol diffusion model. We measured urbanization in the surrounding of a site as the PI change form 1960 to 1990 and found no negative correlation with the corresponding SSR trends from 1964 to 1989 for the 92 sites in Europe and Japan. For the 39 sites in China the correlation coefficients are significant at the 5 % level and reach around −0.35, while for the 26 remaining Asian, mostly Russian sites the correlation coefficients reach around −0.55 at the 1 % significance level. Results are similar, when the absolute levels of PIs are taken as an indicator for urbanization. Our findings call into question the existence of an urbanization effect for the sites in Europe and Japan, while such an effect cannot be ruled out for the sites in Asia, especially in Russia.

Air pollution and cause-specific mortality: A comparative study of urban and rural areas in China

Chemosphere ◽  
2021 ◽  
Vol 262 ◽  
pp. 127884 ◽  
Author(s):  
Shuang Zhao ◽  
Shiliang Liu ◽  
Xiaoyun Hou ◽  
Yongxiu Sun ◽  
Robert Beazley
Keyword(s):  
Air Pollution ◽  
Comparative Study ◽  
Rural Areas ◽  
Specific Mortality ◽  
Urban And Rural Areas

scholarly journals Decadal variations in estimated surface solar radiation over Switzerland since the late 19th century

2012 ◽  
Vol 12 (4) ◽  
pp. 10815-10843 ◽  
Author(s):  
A. Sanchez-Lorenzo ◽  
M. Wild
Keyword(s):  
Solar Radiation ◽  
20Th Century ◽  
Decadal Variability ◽  
Sunshine Duration ◽  
Strong Increase ◽  
Surface Solar Radiation ◽  
Clear Sky ◽  
Decadal Variations ◽  
Flux Measurements ◽  
The 1950S

Abstract. Our knowledge on trends in surface solar radiation (SSR) involves uncertainties due to the scarcity of long-term time series of SSR, especially with records before the second half of the 20th century. Here we study the trends of all-sky SSR from 1885 to 2010 in Switzerland, which have been estimated using a homogenous dataset of sunshine duration series. This variable is shown to be a useful proxy data of all-sky SSR, which can help to solve some of the current open issues in the dimming/brightening phenomenon. Unlike the second half of the 20th century that is characterized also in Switzerland by a dimming from the 1950s to the 1980s and a subsequent brightening, all-sky SSR has been fairly stable with little variations in the first half of the 20th century. Cloud cover changes seem to explain the major part of the decadal variability observed in all-sky SSR, at least until the 1970s; at this point, a discrepancy in the sign of the trend is visible in the series. Finally, an attempt to estimate SSR series for clear-sky conditions, based also on sunshine duration records since the 1930s, has been made for the first time. The mean clear-sky SSR series shows no relevant changes between the 1930s to the 1950s, then a decrease from 1960s to 1970s, and ends with a strong increase from the 1980s up to the present. During the last three decades the estimated clear-sky SSR trends reported in this study are in line with previous findings over Switzerland based on direct radiative flux measurements. Equally, the clear signal of the El Chichón and Pinatubo volcanic eruption visible in the estimated clear-sky SRR records further demonstrates its potential to infer aerosol-induced radiation changes from sunshine duration observations.

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