Improvement of aerosol optical depth retrieval using visibility data in China during the past 50 years

Wu, Jian; Luo, Junming; Zhang, Liya; Xia, Lei; Zhao, Deming; Tang, Jianping

doi:10.1002/2014jd021550

Cited by 54 publications

(39 citation statements)

References 58 publications

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“…Lu et al (2010) [1973][1974][1975][1976][1977][1978][1979][1980] period, and southern China shows an even faster impairment (2.9 % yr −1 ) than the north (1.2 % yr −1 ). For the next 2 decades the 1/Vis increase slows down in both the south and the north, in accordance with other investigations using Vis and SSR data Luo et al, 2001;Wu et al, 2014). The south exhibits a slower (0.2 % yr −1 ) and less significant (p > 0.3) increase than the north (0.5-0.6 % yr −1 ).…”

Section: Trend Evaluationsupporting

confidence: 91%

“…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 Evaluationsupporting

confidence: 91%

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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“…This procedure has been used to obtain decadal time series of the aerosol optical thickness over the Netherlands and China (Boers et al, 2015;Wu et al, 2014). We examined the European Centre for Medium-Range Weather Forecasts reanalysis (ERA-Interim) data (Dee et al, 2011) for changes in the planetary boundary layer depth.…”

Section: Retrieval Of Aerosol Optical Thicknessmentioning

confidence: 99%

“…Apart from occasional sun photometer records (Ruckstuhl et al (2008), data on aerosol are often unavailable. However, recent studies by Wu et al (2014) and Boers et al (2015) have shown that it is possible to retrieve useful aerosol optical thickness data from surface visibility records. The principal idea behind both studies is almost 50 years old (Eltermann, 1970;Kriebel, 1978;Peterson and Fee, 1981; revived by the work of Wang et al, 2009) and asserts that clear-sky optical thickness is most often caused by aerosols residing in the planetary boundary layer, which can be characterized by the optical extinction at 550 nm.…”

Section: Introductionmentioning

confidence: 99%

Impact of aerosols and clouds on decadal trends in all-sky solar radiation over the Netherlands (1966–2015)

2017

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Abstract.A 50-year hourly data set of global shortwave radiation, cloudiness and visibility over the Netherlands was used to quantify the contribution of aerosols and clouds to the trend in yearly-averaged all-sky radiation (1.81 ± 1.07 W m −2 decade −1 ). Yearly-averaged clearsky and cloud-base radiation data show large year-to-year fluctuations caused by yearly changes in the occurrence of clear and cloudy periods and cannot be used for trend analysis. Therefore, proxy clear-sky and cloud-base radiations were computed. In a proxy analysis hourly radiation data falling within a fractional cloudiness value are fitted by monotonic increasing functions of solar zenith angle and summed over all zenith angles occurring in a single year to produce an average. Stable trends can then be computed from the proxy radiation data. A functional expression is derived whereby the trend in proxy all-sky radiation is a linear combination of trends in fractional cloudiness, proxy clearsky radiation and proxy cloud-base radiation. Trends (per decade) in fractional cloudiness, proxy clear-sky and proxy cloud-base radiation were, respectively, 0.0097 ± 0.0062, 2.78 ± 0.50 and 3.43 ± 1.17 W m −2 . To add up to the allsky radiation the three trends have weight factors, namely the difference between the mean cloud-base and clear-sky radiation, the clear-sky fraction and the fractional cloudiness, respectively. Our analysis clearly demonstrates that all three components contribute significantly to the observed trend in all-sky radiation. Radiative transfer calculations using the aerosol optical thickness derived from visibility observations indicate that aerosol-radiation interaction (ARI) is a strong candidate to explain the upward trend in the clear-sky radiation. Aerosol-cloud interaction (ACI) may have some impact on cloud-base radiation, but it is suggested that decadal changes in cloud thickness and synoptic-scale changes in cloud amount also play an important role.

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“…The result indicated that there was one upward trend pre-2008 (0.0003) and one downward trend post-2008 (−0.0005) for AOD in China during 2000-2015. The AOD values were higher in spring (0.410) than that in summer (0.370), autumn (0.260), and winter (0.340). Wu et al [31] analyzed the spatial and temporal variations of AOD values during 1960-2009 using the Multiangle Imaging Spectroradiometer (MISR) AOD records and meteorological measurements. The results showed that the AOD values over mainland China exhibited an increasing trend (0.004 year −1 ) during reconstructed the AOD values during 1993-2012 throughout China using a broadband extinction model, which showed good agreements with AERONET AOD values with RRMSE, MAE, and R of 0.101, 0.029, and 0.848, respectively.…”

Section: Introductionmentioning

confidence: 99%

Characteristic and Driving Factors of Aerosol Optical Depth over Mainland China during 1980–2017

et al. 2018

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Abstract:Since the reform and opening up of China, the increasing aerosol emissions have posted great challenges to the country's climate change and human health. The aerosol optical depth (AOD) is one of the main physical indicators quantifying the atmospheric turbidity and air pollution. In this study, 38-years (1980-2017) of spatial and temporal variations of AOD in China were analyzed using AOD records derived from MODIS atmosphere products and the MERRA-2 dataset. The results showed that the annual mean AOD values throughout China have gone through an increasing, but fluctuating, trend, especially in 1982 and in 1992 due to two volcano eruptions; the AOD values experienced a dramatically increasing period during 2000-2007 with the rapid economic development and "population explosions" in China/after 2008, the AOD values gradually decreased from 0.297 (2008) to 0.257 (2017). The AOD values in China were generally higher in spring than that in other seasons. The Sichuan Basin has always been an area with high AOD values owing to the strong human activity and the basin topography (hindering aerosol diffusions in the air). In contrast, the Qinghai Tibet Plateau has always been an area with low AOD values due to low aerosol emissions and clear sky conditions there. The trend analysis of AOD values during 1980-2017 in China indicated that the significant increasing trend was mainly observed in Southeastern China. By contrast, the AOD values in the northernmost of China showed a significant decreasing trend. Then, the contributions (AODP) of the AOD for black carbon aerosol (BCAOD), dust aerosol (DUAOD), organic carbon aerosol (OCAOD), sea salt aerosol (SSAOD), and SO 4 aerosol (SO 4 AOD) to the total AOD values were calculated. The results showed that DUAOD (25.43%) and SO 4 AOD (49.51%) were found to be the main driving factors for the spatial and temporal variations of AOD values. Finally, the effects of anthropogenic aerosol emissions, socioeconomic factors, and land-use and land coverage changes on AOD were analyzed. The GDP, population density, and passenger traffic volume were found to be the main socioeconomic drivers for AOD distributions. Relatively larger AOD values were mainly found in urban land and land covered by water, while lower AOD values were found in grassland and permanent glacier areas.

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Improvement of aerosol optical depth retrieval using visibility data in China during the past 50 years

Cited by 54 publications

References 58 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 aerosols and clouds on decadal trends in all-sky solar radiation over the Netherlands (1966–2015)

Characteristic and Driving Factors of Aerosol Optical Depth over Mainland China during 1980–2017

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