scholarly journals A black carbon peak and its sources in the free troposphere of Beijing induced by cyclone lifting and transport from central China

2021 ◽  
Vol 21 (20) ◽  
pp. 15555-15567
Author(s):  
Zhenbin Wang ◽  
Bin Zhu ◽  
Hanqing Kang ◽  
Wen Lu ◽  
Shuqi Yan ◽  
...  
Keyword(s):  
Black Carbon ◽  
Air Pollutants ◽  
Process Analysis ◽  
Central China ◽  
Atmospheric Environment ◽  
Upward Movement ◽  
Free Troposphere ◽  
Regional Sources ◽  
Vertical Distributions ◽  
Weak Pressure Gradient

Abstract. Observations suggest that the vertical distributions of air pollutants, such as black carbon (BC), present as various types depending on the emission sources and meteorological diffusion conditions. However, the formation process and source appointment of some special BC profiles are not fully understood. In this paper, by using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) with a BC-tagging technique, we investigate the formation mechanism and regional sources of a BC peak in the free troposphere observed by an aircraft flight in Beijing (BJ) on 5 May 2018. The results show that the contribution rate of the Beijing–Tianjin–Hebei (BTH) region to the surface BC of BJ exceeded 80 % in this case. Local sources dominated BC in BJ from the surface to approximately 700 m (78.5 %), while the BC peak in the free troposphere (∼4000 m) was almost entirely imported from external sources (99.8 %). Combining BC tracking and process analysis, we find that horizontal advection (HADV) and vertical advection (VADV) processes played an important role in the convergent and upward movement and the transport of BC. The BC originating from the surface in central provinces, including Shanxi (SX), Henan (HN), and Hebei (HB), had been uplifted through a cyclone system 16 h previously, was transported to a height of approximately 3000 m above BJ, and was then lifted by the VADV process to approximately 4000 m. At the surface, BJ and its surroundings were under the control of a weak pressure gradient, leading to the accumulation of BC within the boundary layer. Our results indicate that cyclone systems can quickly lift air pollutants, such as BC, up to the free troposphere, as well as extend their lifetimes and further affect the regional atmospheric environment and climate.

scholarly journals A black carbon peak in the free troposphere of Beijing induced by cyclone lifting and transport from Central China

2021 ◽  
Author(s):  
Zhenbin Wang ◽  
Bin Zhu ◽  
Hanqing Kang ◽  
Wen Lu ◽  
Shuqi Yan ◽  
...  
Keyword(s):  
Black Carbon ◽  
Air Pollutants ◽  
Process Analysis ◽  
Central China ◽  
Atmospheric Environment ◽  
Upward Movement ◽  
Free Troposphere ◽  
Regional Sources ◽  
Vertical Distributions ◽  
Weak Pressure Gradient

Abstract. Observations suggest that the vertical distributions of air pollutants, such as black carbon (BC), present as various types depending on the emission sources and meteorological diffusion conditions. However, the formation process and source appointment of some special BC profiles are not fully understood. In this paper, by using the Weather Research and Forecasting model coupled with chemistry (WRF-Chem) with a BC-tagging technique, we investigate the formation mechanism and regional sources of a BC peak in the free troposphere observed by aircraft flight in Beijing (BJ) on May 5th, 2018. The results show that the contribution rate of the Beijing-Tianjin-Hebei (BTH) region to the surface BC of BJ exceeded 80 % in this case. Local sources dominated BC in BJ from the surface to approximately 700 m (78.5 %), while the BC peak in the free troposphere (~4000 m) was almost entirely imported from external sources (99.8 %). Combining BC tracking and process analysis, we find that horizontal advection (HADV) and vertical advection (VADV) processes played an important role in the convergent and upward movement and the transport of BC. The BC originating from the surface in central provinces, including Shanxi (SX), Henan (HN) and Hebei (HB), was uplifted through a cyclone system 16 hours previously, transported to a height of approximately 3000 m above BJ, and then lifted by the VADV process to approximately 4000 m. At the surface, BJ and its surroundings were under the control of a weak pressure gradient, leading to the accumulation of BC within the boundary layer. Our results indicate that cyclone systems can quickly lift air pollutants, such as BC, up to the free troposphere, as well as extend their lifetimes and further affect the regional atmospheric environment and climate.

scholarly journals Meteorological effects on PM<sub>2.5</sub> change over a receptor region in regional transport of air pollutants: observational study of recent year emission reduction in central China

2021 ◽  
Author(s):  
Xiaoyun Sun ◽  
Tianliang Zhao ◽  
Yongqing Bai ◽  
Shaofei Kong ◽  
Huang Zheng ◽  
...  
Keyword(s):  
Air Pollution ◽  
Air Pollutants ◽  
Emission Reduction ◽  
Central China ◽  
Atmospheric Environment ◽  
Anthropogenic Emissions ◽  
Short Term ◽  
Regional Transport ◽  
Conversion Efficiencies

Abstract. As an important issue in atmospheric environment, the contributions of anthropogenic emissions and meteorological conditions to air pollution have been few assessed over the receptor region in regional transport of air pollutants. In this study on observations of environment and meteorology over 2015–2019, the Kolmogorov–Zurbenko (KZ) filter was performed to decompose the PM2.5 variations into multi-time scale components over the Twain-Hu Basin (THB), a receptor region in regional transport of air pollutants in central China, where the short-term, seasonal and long-term components accounted for respectively 47.5 %, 41.4 % and 3.7 % to daily PM2.5 changes. The short-term and seasonal components dominated the day-to-day PM2.5 variations with long-term component determining the change trend of PM2.5 concentrations over recent years. The emission- and meteorology-related long-term PM2.5 components over the THB were identified. The meteorological contribution to PM2.5 declining trend presented the distinct spatial pattern over the THB with northern positive rates up to 61.92 % and southern negative rates down to −24.93 %. The opposite effects of meteorology on PM2.5 pollution could accelerate and offset the effects of emission reductions in the northern and southern THB, which is attributed to the upwind diffusion and downward accumulation of air pollutants over the receptor region in regional PM2.5 transport. It is noteworthy that the increasing conversion efficiencies of SO2 and NO2 to sulfate and nitrate for secondary PM2.5 could offset the effects of PM2.5 emission reduction on air pollution in the THB during recent years, revealing the enhancing contribution of gaseous precursor emissions to PM2.5 concentrations with controlling anthropogenic emissions of PM2.5 and the gaseous precursors over the receptor region in regional transport of air pollutants.

scholarly journals Nocturnal Boundary Layer Evolution and Its Impacts on the Vertical Distributions of Pollutant Particulate Matter

Atmosphere ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 610
Author(s):  
Yu Shi ◽  
Lei Liu ◽  
Fei Hu ◽  
Guangqiang Fan ◽  
Juntao Huo
Keyword(s):  
Boundary Layer ◽  
Nitrate Concentration ◽  
Inversion Layer ◽  
Mixing Layer ◽  
Early Morning ◽  
Nocturnal Boundary Layer ◽  
Atmospheric Environment ◽  
Considerable Proportion ◽  
Surface Inversion ◽  
Vertical Distributions

To investigate the evolution of the nocturnal boundary layer (NBL) and its impacts on the vertical distributions of pollutant particulates, a combination of in situ observations from a large tethered balloon, remote sensing instruments (aerosol lidar and Doppler wind lidar) and an atmospheric environment-monitoring vehicle were utilized. The observation site was approximately 100 km southwest of Beijing, the capital of China. Results show that a considerable proportion of pollutant particulates were still suspended in the residual layer (RL) (e.g., the nitrate concentration reached 30 μg m−3) after sunset. The NBL height calculated by the aerosol lidar was closer to the top of the RL before midnight because of the pollutants stored aloft in the RL and the shallow surface inversion layer; after midnight, the NBL height was more consistent with the top of the surface inversion layer. As the convective mixing layer gradually became established after sunrise the following day, the pollutants stored in the nocturnal RL of the preceding night were entrained downward into the mixing layer. The early morning PM2.5 concentration near 700 m in the RL on 20 December decreased by 83% compared with the concentration at 13:34 on 20 December at the same height. The nitrate concentration also decreased significantly in the RL, and the mixing down of nitrate from the RL could contribute about 37% to the nitrate in the mixing layer. Turbulence activities still existed in the RL with the bulk Richardson number (Rb) below the threshold value. The corresponding increase in PM2.5 was likely to be correlated with the weak turbulence in the RL in the early morning.

scholarly journals The importance of Asia as a source of black carbon to the European Arctic during springtime 2013

2015 ◽  
Vol 15 (20) ◽  
pp. 11537-11555 ◽  
Author(s):  
D. Liu ◽  
B. Quennehen ◽  
E. Darbyshire ◽  
J. D. Allan ◽  
P. I. Williams ◽  
...  
Keyword(s):  
Black Carbon ◽  
Arctic Sea Ice ◽  
Anthropogenic Sources ◽  
The Arctic ◽  
Geometric Standard Deviation ◽  
Free Troposphere ◽  
Aerosol Composition ◽  
Upper Troposphere ◽  
European Arctic ◽  
Mean Concentration

Abstract. Black carbon aerosol (BC) deposited to the Arctic sea ice or present in the free troposphere can significantly affect the Earth's radiation budget at high latitudes yet the BC burden in these regions and the regional source contributions are poorly constrained. Aircraft measurements of aerosol composition in the European Arctic were conducted during the Aerosol–Cloud Coupling And Climate Interactions in the Arctic (ACCACIA) campaign in March 2013. Pollutant plumes were encountered throughout the lower to upper Arctic troposphere featuring enhancements in CO and aerosol mass loadings, which were chemically speciated into BC and non-refractory sulphate and organic matter. FLEXPART-WRF simulations have been performed to evaluate the likely contribution to the pollutants from regional ground sources. By combining up-to-date anthropogenic and open fire biomass burning (OBB) inventories, we have been able to compare the contributions made to the observed pollution layers from the sources of eastern/northern Asia (AS), Europe (EU) and North America (NA). Over 90 % of the contribution to the BC was shown to arise from non-OBB anthropogenic sources. AS sources were found to be the major contributor to the BC burden, increasing background BC loadings by a factor of 3–5 to 100.8 ± 48.4 ng sm−3 (in standard air m3 at 273.15 K and 1013.25 mbar) and 55.8 ± 22.4 ng sm−3 in the middle and upper troposphere respectively. AS plumes close to the tropopause (about 7.5–8 km) were also observed, with BC concentrations ranging from 55 to 73 ng sm−3, which will potentially have a significant radiative impact. EU sources influenced the middle troposphere with a BC mean concentration of 70.8 ± 39.1 ng sm−3 but made a minor contribution to the upper troposphere due to the relatively high latitude of the source region. The contribution of NA was shown to be much lower at all altitudes with BC mean concentration of 20 ng sm−3. The BC transported to the Arctic is mixed with a non-BC volume fraction representing between 90–95 % of the mass, and has a relatively uniform core size distribution with mass median diameter 190–210 nm and geometric standard deviation σg = 1.55–1.65 and this varied little across all source regions. It is estimated that 60–95 % of BC is scavenged between emission and receptor based on BC / ΔCO comparisons between source inventories and measurement. We show that during the springtime of 2013, the anthropogenic pollution particularly from sources in Asia, contributed significantly to BC across the European Arctic free troposphere. In contrast to previous studies, the contribution from open wildfires was minimal. Given that Asian pollution is likely to continue to rise over the coming years, it is likely that the radiative forcing in the Arctic will also continue to increase.

scholarly journals What Factors Drive Air Pollutants in China? An Analysis from the Perspective of Regional Difference Using a Combined Method of Production Decomposition Analysis and Logarithmic Mean Divisia Index

2019 ◽  
Vol 11 (17) ◽  
pp. 4650 ◽  
Author(s):  
Xu ◽  
Miao ◽  
Li ◽  
Zhou ◽  
Ma ◽  
...  
Keyword(s):  
Air Pollutants ◽  
Emission Reduction ◽  
Northeast China ◽  
Decomposition Analysis ◽  
Inhibitory Effect ◽  
Central China ◽  
Substitution Effects ◽  
Logarithmic Mean ◽  
Energy Substitution ◽  
Technology Improvement

Air pollution in China attracts the world’s attention, so it is important to study its driving factors for air pollutants. The combined Production Decomposition Analysis and Logarithmic Mean Divisia Index (PDA–LMDI) model is applied to construct a regional contribution index in this study to explore the regional differences in factors affecting sulfur dioxide (SO2), nitrogen oxides (NOx), and particulate matter with diameter not greater than 2.5 µm (PM2.5) from 2005 to 2015 in China. The regional emission coefficient had a great inhibitory effect, which reduced SO2, NOx, and PM2.5 by 25,364.9, 10,449.3, and 11,295.3 kilotons (kt) from 2005 to 2015, respectively. For this inhibitory effect, the degree to emission reduction was great for North and East China, followed by South and Central China, and small for Southwest. Northwest. and Northeast China. The regional technical efficiency, technology improvement, capital-energy substitution and labor-energy substitution effects each reduced SO2, NOx, and PM2.5 by about 3500, 3100, and 1500 kt from 2005 to 2015, respectively. For the regional technical efficiency and technology improvement effects, the degree to emission reduction was great in East and Central China, and small in South Northwest and Northeast China. For the regional capital- and labor-energy substitution effects, the degree of emission reduction was great for North East and Central China, and small for Northwest and South China. The regional output proportion effect increased SO2, NOx, and PM2.5 by 1211.2, 320.1, and 277.8 kt from 2005 to 2015, respectively. The national economic growth had a relatively great promoting effect and increased SO2, NOx, and PM2.5 by 26,445.5, 23,827.5, and 11,925.5 kt from 2005 to 2015, respectively. Each region should formulate relevant policies and measures for emission reduction according to local conditions.

The effects of anthropogenic heat fluxes on regional meteorology and air quality in typical city clusters of China

2020 ◽  
Author(s):  
Min Xie ◽  
Tijian Wang ◽  
Jie Shi ◽  
Mengmeng Li ◽  
Da Gao ◽  
...  
Keyword(s):  
Air Quality ◽  
Wind Speed ◽  
Significant Role ◽  
Air Pollutants ◽  
Heat Fluxes ◽  
Anthropogenic Heat ◽  
Atmospheric Environment ◽  
Urban Meteorology ◽  
Ozone Concentrations ◽  
Chemical Effects

&lt;p&gt;Anthropogenic heat (AH) can affect regional meteorology and air quality. The spatial distributions of AH fluxes in the typical city clusters of China are estimated. Moreover, in order to study their impacts on regional atmospheric environment, these heat fluxes are incorporated into the modified WRF/Chem with the seasonal and the diurnal variation. The modeling results show that AH fluxes over YRD and PRD have been growing in recent years. The high values of AH can reach 113.5 W/m&lt;sup&gt;2&lt;/sup&gt; in YRD and 60 W/m&lt;sup&gt;2&lt;/sup&gt; in PRD, respectively. AH fluxes can significantly change the urban meteorology. In YRD, 2-m air temperature (T&lt;sub&gt;2&lt;/sub&gt;) increases by 1.6 &amp;#176;&amp;#1057; in January and 1.4&amp;#176;&amp;#1057; in July, the planetary boundary layer height (PBLH) rises up by 140m in January and 160m in July, and 10-m wind speed (W&lt;sub&gt;10&lt;/sub&gt;) is intensified by 0.7 m/s in January and 0.5 m/s in July. More moisture can be transported to higher levels, and increase the accumulative precipitation by 15-30% in July of YRD. In PRD, T&lt;sub&gt;2&lt;/sub&gt; rises up by 1.1&amp;#176;&amp;#1057; in January and over 0.5&amp;#176;&amp;#1057; in July, the PBLH increases by 120m in January and 90m in July, W&lt;sub&gt;10&lt;/sub&gt; is enhanced over 0.35 m/s in January and 0.3 m/s in July, and the accumulative precipitation is intensified by 20-40% in July. These changes in meteorology can influence the distribution of air pollutants as well. Due to the increase of PBLH, surface wind speed and upward movement, the concentrations of primary air pollutants decrease near surface and increase at the upper layers over the cities. Chemical effects can play a significant role in ozone changes over the urban areas of YRD, so ozone concentrations increase at surface and decrease at the upper layers. In PRD cities, however, the chemical effects play a significant role in ozone changes in winter, while the vertical movement can be the dominant effect in summer. Thus, ozone concentrations in big cities increase in January, but decrease at the lower layers and increase at the upper layers in July. In all, AH fluxes should not be ignored in urban meteorology and air quality assessments.&lt;/p&gt;

Diurnal concentrations of black carbon and some other air pollutants in Ljubljana, Slovenia

1993 ◽  
Vol 27 (8) ◽  
pp. 1347-1350 ◽  
Author(s):  
M. Bizjak ◽  
R. Cigler ◽  
A.D.A. Hansen ◽  
V. Hudnik
Keyword(s):  
Black Carbon ◽  
Air Pollutants

Study of Effects of Long-Range Transport of Air Pollutants on the Atmospheric Environment

2014 ◽  
Vol 955-959 ◽  
pp. 1341-1345 ◽  
Author(s):  
Xia Zhang ◽  
Liang Tian ◽  
Xian Sun ◽  
Chuang Ye Jiang
Keyword(s):  
Air Quality ◽  
Long Range ◽  
Air Pollutants ◽  
Concentration Field ◽  
Atmospheric Environment ◽  
Shanxi Province ◽  
Long Range Transport ◽  
Flux Method ◽  
Range Transport ◽  
Pollutants Transport

Based on meteorological field output by MM5 mesoscale meteorological model and concentration field output by CALPUFF air quality model, “flux method” was applied to study effects of long-range transport of air pollutants on the atmospheric environment, in which micro-element method was used to solve the process of air pollutants transport in long-range of three-dimensional space. This method was first applied in studying a construction project’s impact on air quality in Guanzhong region of Shanxi Province. The results shows that the deviation of flux method is less which the value is 16 percent, and among all year around, the pollutants transport the more flux to the ENE and WSW directions of the project compared to other directions. Additional, the flux of fall and winter is more than it of spring and summer, and the project has a more severe influence of atmospheric environment in Xi’an city than it of Weinan city.

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