Temporal Characteristics and Potential Sources of Black Carbon in Megacity Shanghai, China

Wei, Chong; Wang, M. H.; Fu, Qingyan; Dai, Cheng; Huang, Ruifang; Bao, Quan

doi:10.1029/2019jd031827

Cited by 35 publications

(24 citation statements)

References 66 publications

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“…From the figure, one can also conclude that the number of larger LRs within the PBL followed a decreasing trend with the passage of observation time, alluding to gradually reduced emissions of absorbing aerosols in Shanghai. The reduction was in good agreement with the reductions of BC and particulate matter (PM) concentrations caused by a series of energy-saving and emission-reduction measures such as the Shanghai Clean Air Action Plan (2018-2022) implemented by the Shanghai government in recent years (Wei et al, 2020).…”

Section: Temporal Variations In Lrsupporting

confidence: 66%

“…As an active remote-sensing instrument, the elastic scattering lidar can obtain vertical distribution information of aerosols; however, it is necessary to assume an aerosol extinction-to-backscattering ratio (i.e., lidar ratio, LR) in the retrieval process (Fernald, 1984;Welton et al, 2001), which can result in significant errors for the extinction coefficient, followed by aerosol optical depth (AOD). To our knowledge, the LRs at 355, 532, and 1064 nm are usually assumed to be 50 sr in China (Fan et al, 2018; Published by Copernicus Publications on behalf of the European Geosciences Union.…”

Section: Introductionmentioning

confidence: 99%

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Long-term variation in aerosol lidar ratio in Shanghai based on Raman lidar measurements

Liu

Chen

et al. 2021

Atmos. Chem. Phys.

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Abstract. Accurate lidar ratio (LR) and better understanding of its variation characteristics can not only improve the retrieval accuracy of parameters from elastic lidar, but also play an important role in assessing the impacts of aerosols on climate. Using the observational data of a Raman lidar in Shanghai from 2017 to 2019, LRs at 355 nm were retrieved and their variations and influence factors were analyzed. Within the height range of 0.5–5 km, about 90 % of the LRs were distributed in 10–80 sr with an average value of 41.0 ± 22.5 sr, and the LR decreased with the increase in height. The volume depolarization ratio (δ) was positively correlated with LR, and it also decreased with the increase in height, indicating that the vertical distribution of particle shape was one of the influence factors of the variations in LR with height. LR had a strong dependence on the original source of air masses. Affected by the aerosols transported from the northwest, the average LR was the largest, 44.2 ± 24.7 sr, accompanied by the most irregular particle shape. The vertical distribution of LR was affected by atmospheric turbidity, with the greater gradient of LR under clean conditions. The LR above 1 km could be more than 80 sr, when Shanghai was affected by biomass burning aerosols.

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Section: Temporal Variations In Lrsupporting

confidence: 66%

Section: Introductionmentioning

confidence: 99%

Long-term variation in aerosol lidar ratio in Shanghai based on Raman lidar measurements

Liu

Chen

et al. 2021

Atmos. Chem. Phys.

View full text Add to dashboard Cite

show abstract

“…From this figure, one can also conclude that the number of larger LR within the PBL followed a decreasing trend with the passage of observation time, alluding to a gradually reduced emission of absorbing aerosols in Shanghai. This reduction was in good agreement with the reductions of BC and particulate matter (PM) concentrations caused by a series of energy-saving and emission-reduction measures such as the Shanghai Clean Air Action Plan (2018-2022) implemented by the Shanghai government in recent years(Wei et al, 2020).…”

supporting

confidence: 74%

Study on variations in lidar ratios for Shanghai based on Raman lidar

Liu

Chen

et al. 2020

Preprint

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Abstract. Accurate Lidar ratios (LR) and better understanding of their variation characteristics can not only improve the retrieval accuracy of parameters from elastic lidar, but also play an important role in assessing the impacts of aerosols on the climate. Using the observational data of Raman lidar in Shanghai from 2017 to 2019, the LR at 355 nm were retrieved and their variations and influencing factors were analyzed. Within the height range of 0.5 km–5 km, about 90 % of the LR were distributed in 10 sr–80 sr with an average value of 41.0 ± 22.5 sr, and the LR decreased with the increase of height. The volume depolarization ratios (δ) were positively correlated with LR, and they also decreased with the increase of height, indicating that the vertical distribution of particle shape was one of the influencing factors of the variations of LR with height. LR had a strong dependence on the original source of the air masses. Affected by the aerosol transported from northwest of Shanghai, the average LR was the largest, 44.2 ± 24.7 sr, accompanied by the most irregular particle shape. The vertical distributions of LR were affected by the atmospheric turbidity, with the greater gradient of LR under the clean conditions. The LR above 1 km could be more than 80 sr, when Shanghai was affected by the biomass burning aerosols.

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“…We verity the trend in modeled BC concentrations using the measurements in three typical sites located in East China and western Japan. The long-term observational records of BC concentrations in Beijing and Shanghai present clear decreasing trends over the recent decade (Xia et al, 2020;Wei et al, 2020). The annual mean surface BC decreases from 8.5 μg m −3 in 2008 to 3.5 μg m −3 in 2016 in Beijing, and from about 4.0 μg m −3 to 2.2 μg m −3 in Shanghai.…”

Section: Changes In the Burdens Of Sulfate And Bc Massmentioning

confidence: 97%

The positive radiative forcing by the substantial SO<sub>2</sub> emission reductions is counteracted by decreased BC concentrations in China over the recent decade

Liu¹,

Matsui²

2020

Preprint

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Abstract. Anthropogenic emissions in China play an important role in altering global radiation budget. Over the recent decade, the clean-air options in China result in substantial reductions in anthropogenic emissions, especially sulfur dioxide (SO2), and improved air quality. However, the associated changes in aerosol climate effects are poorly understood. In this study, we use an advanced global climate model integrated with latest anthropogenic emission inventory to estimate the changes in the aerosol radiative forcings by the emission variation in China between 2008 and 2016. First, our simulations exhibit decreases of 46 % and 25 % for the annual mean surface-level sulfate and black carbon (BC) mass concentrations in East China, respectively, which is the key region subject to stringent emission control options. The decreasing tendency of aerosol optical depth and aerosol absorption optical depth retrieved by satellites is also captured by the model for the period. We find that the resultant net radiative forcing by the changes in the BC and SO2 emissions is −0.04 W m−2 in East China. The substantial reductions in SO2 emissions diminish the scattering effects of sulfate and lead to an overall change of +0.17 W m−2 for the annual mean all-sky shortwave aerosol direct radiative forcing at the top of the atmosphere and +0.13 W m−2 for aerosol-induced cloud radiative forcing. In the meantime, the reduction in BC emissions induces a negative BC radiative forcing of −0.34 W m−2. By accounting for the joint effect of BC and SO2 emissions, our results demonstrate that the positive radiative forcing by the SO2 emission reductions is counteracted by the decrease of BC in China over the recent decade. While the local radiative forcing is small due to the counteracted effects of SO2 and BC emissions, it is relatively larger (+0.16 W m−2) over the north Pacific remote regions for this period, primarily contributed by the reductions in sulfate particles and their effects on cloud properties. With a comprehensive future emission scenario for 2030 and 2050 developed by the recent study, we predict that the strictest environmental policies will induce the change of aerosol radiative forcings of +0.55 and +1.23 W m−2 over East China between 2016–2030 and 2016–2050, respectively. Targeted emission control policies are desirable to improve air quality and mitigate climate change in the future.

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Temporal Characteristics and Potential Sources of Black Carbon in Megacity Shanghai, China

Cited by 35 publications

References 66 publications

Long-term variation in aerosol lidar ratio in Shanghai based on Raman lidar measurements

Long-term variation in aerosol lidar ratio in Shanghai based on Raman lidar measurements

Study on variations in lidar ratios for Shanghai based on Raman lidar

The positive radiative forcing by the substantial SO<sub>2</sub> emission reductions is counteracted by decreased BC concentrations in China over the recent decade

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Temporal Characteristics and Potential Sources of Black Carbon in Megacity Shanghai, China

Cited by 35 publications

References 66 publications

Long-term variation in aerosol lidar ratio in Shanghai based on Raman lidar measurements

Long-term variation in aerosol lidar ratio in Shanghai based on Raman lidar measurements

Study on variations in lidar ratios for Shanghai based on Raman lidar

The positive radiative forcing by the substantial SO&lt;sub&gt;2&lt;/sub&gt; emission reductions is counteracted by decreased BC concentrations in China over the recent decade

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The positive radiative forcing by the substantial SO<sub>2</sub> emission reductions is counteracted by decreased BC concentrations in China over the recent decade