Trends of visibility on sunny days in China in the recent 50 years

Wu, Jian; Fu, Chaoying; Zhang, Liya; Tang, Jianping

doi:10.1016/j.atmosenv.2012.03.037

Cited by 71 publications

(52 citation statements)

References 15 publications

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“…A prominent feature in the trends over China is more heterogeneity in the spatial distribution compared to the trend maps over the US and Europe. This could be a result of asynchronous economic development, as several studies reported "lagging" of Vis impairment in rural sites (from ∼ 1990s) compared to urban sites (from ∼ 1960s) in China (Quan et al, 2011;Wu et al, 2012). The overall increasing trend in 1/Vis reverses in the last period of 2006-2013, when most stations in southern China and many in northern China show a statistically significant decreasing trend of 1/Vis.…”

Section: Trend Evaluationmentioning

confidence: 76%

“…Historical Vis data from more than 3000 stations have been applied to characterize decadal trends in global aerosol optical depth (AOD) from 1973 to 2007 (Wang et al, 2009). Regional trend studies of Vis were also conducted for populated areas e.g., the US (Husar et al, 1981;Schichtel et al, 2001), Europe (Vautard et al, 2009) and China (Che et al, 2007;Chen and Wang, 2015;Lin et al, 2014;Wu et al, 2012Wu et al, , 2014, and the inferred trends were usually attributed to changes in anthropogenic emission. Another study employing Vis over desert regions (Mahowald et al, 2007) found an association of Vis with meteorology factors such as drought index (based on precipitation and temperature) and surface wind speeds.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation and application of multi-decadal visibility data for trend analysis of atmospheric haze

Martin

Boys

et al. 2016

Atmos. Chem. Phys.

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Abstract. There are few multi-decadal observations of atmospheric aerosols worldwide. This study applies global hourly visibility (Vis) observations at more than 3000 stations to investigate historical trends in atmospheric haze over 1945-1996 for the US, and over 1973-2013 for Europe and eastern Asia. A comprehensive data screening and processing framework is developed and applied to minimize uncertainties and construct monthly statistics of inverse visibility (1/Vis). This data processing includes removal of relatively clean cases with high uncertainty, and change point detection to identify and separate methodological discontinuities such as the introduction of instrumentation. Although the relation between 1/Vis and atmospheric extinction coefficient (b ext ) varies across different stations, spatially coherent trends of the screened 1/Vis data exhibit consistency with the temporal evolution of collocated aerosol measurements, including the b ext trend of −2.4 % yr −1 (95 % CI: −3.7, −1.1 % yr −1 ) vs. 1/Vis trend of −1.6 % yr −1 (95 % CI: −2.4, −0.8 % yr −1 ) over the US for 1989-1996, and the fine aerosol mass (PM 2.5 ) trend of −5.8 % yr −1 (95 % CI: −7.8, 1973-2008 (r ∼ 0.9). Consistent "reversal points" from increasing to decreasing in SO 2 emission data are also captured by the regional 1/Vis time series (e.g., late 1970s for the eastern US, early 1980s for western Europe, late 1980s for eastern Europe, and mid 2000s for China). The consistency of 1/Vis trends with other in situ measurements and emission data demonstrates promise in applying these quality assured 1/Vis data for historical air quality studies.

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Section: Trend Evaluationmentioning

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Evaluation and application of multi-decadal visibility data for trend analysis of atmospheric haze

Martin

Boys

et al. 2016

Atmos. Chem. Phys.

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“…Alpert and Kishcha (2008) had shown that solar dimming was observed over only a limited part of the total land area and was restricted to highly populated sites dominated by anthropogenic aerosol emissions and that urban areas received less solar radiation than rural areas. Wu et al (2012) reported decreasing trends in visibility at most stations in China in recent 50 years and visibility in large cities is lower than small cities. Significantly increased aerosol concentrations by pollutant emission in eastern China for the last few decades have been reported (e.g., Qian et al 2009b) and have been suggested to be responsible for the observed reduction in global solar radiation (Qian et al 2007).…”

Section: Discussionmentioning

confidence: 99%

Impact of land use/land cover change on changes in surface solar radiation in eastern China since the reform and opening up

Qian

2014

Theor Appl Climatol

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Observational evidence of the impacts of land use/land cover change (LULCC) on changes in surface solar radiation (SSR) in eastern China (EC) during 1979-2008 are identified by using diurnal temperature range as a proxy of SSR and by using observation minus reanalysis approach to disentangle these effects. For the period 1979-2008, the impact of LULCC is shown as a reduction in SSR in most stations in EC, whereas SSR in the reanalysis data has increased at nearly every location. The competition of the dimming effect of LULCC with the brightening effect in the reanalysis results in an observed dipole pattern of SSR with slightly decreasing (increasing) trends in most stations north (south) of the Yangtze River and statistically significant decreasing trends in central EC. In terms of EC area mean, this competition has resulted in a slightly dimming trend in the observed SSR during 1979-2008, although a transition from an apparent dimming to a general leveling off near 1990 is identified. For the period 1990-2008, LULCC has significantly reduced SSR in central EC and southern China. This dimming effect of LULCC competes with the apparent brightening effect in the reanalysis to result in the general leveling off in the observed SSR in terms of EC area mean and a sandwich spatial pattern in the observed SSR in EC where parts of central EC show significant dimming. The impact of LULCC on the changes in SSR may be through both biogeophysical and biogeochemical processes.

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“…Six Chinese megacities have suffered from continuously decreasing visibilities in the past 30 years (Chang et al, 2009). Overall, visibilities on clear days decreased significantly during the period 1960-1990 over all of China; trends thereafter, however, have not been consistent (Wu et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

The distribution and trends of fog and haze in the North China Plain over the past 30 years

Yang

et al. 2014

Atmos. Chem. Phys.

183

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Abstract. Frequent low visibility, haze and fog events were found in the North China Plain (NCP). Data throughout the NCP during the past 30 years were examined to determine the horizontal distribution and decadal trends of low visibility, haze and fog events. The impact of meteorological factors such as wind and relative humidity (RH) on those events was investigated. Results reveal distinct distributions of haze and fog days, due to their different formation mechanisms. Low visibility, haze and fog days all display increasing trends of before 1995, a steady stage during the period 1995-2003 and a drastically drop thereafter. All three events occurred most frequently during the heating season. Benefiting from emission control measures, haze and fog both show decreasing trends in winter during the past 3 decades, while summertime haze displays continuous increasing trends. The distribution of wind speed and wind direction as well as the topography within the NCP has determinative impacts on the distribution of haze and fog. Weakened south-easterly winds in the southern part of the NCP have resulted in high pollutant concentrations and frequent haze events along the foot of the Taihang Mountains. The orographically generated boundary layer wind convergence line in the central area of the southern NCP is responsible for the frequent fog events in this region. Wind speed has been decreasing throughout the entire southern NCP, resulting in more stable atmospheric conditions and weaker dispersion abilities, calling for harder efforts to control emissions to prevent haze events. Haze events are strongly influenced by the ambient RH. RH values associated with haze days are evidently increasing, suggesting that an increasing fraction of haze events are caused by the hygroscopic growth of aerosols, rather than simply by high aerosol loadings.

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Trends of visibility on sunny days in China in the recent 50 years

Cited by 71 publications

References 15 publications

Evaluation and application of multi-decadal visibility data for trend analysis of atmospheric haze

Evaluation and application of multi-decadal visibility data for trend analysis of atmospheric haze

Impact of land use/land cover change on changes in surface solar radiation in eastern China since the reform and opening up

The distribution and trends of fog and haze in the North China Plain over the past 30 years

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