Abstract:Biogenic volatile organic compounds (BVOC) play an important role in global environmental chemistry and climate. In the present work, biogenic emissions from China in 2017 were estimated based on the Model of Emissions of Gases and Aerosols from Nature (MEGAN). The effects of BVOC emissions on ozone and secondary organic aerosol (SOA) formation were
“…According to the studies of Su et al (2017), Zheng et al (2019) and Wu et al (2019), it can be deduced that NO x has been significantly reduced by about 60%, at least 2 times the reduction of VOCs in Hangzhou. The influence of stringent emission control measures on VOCs is not as immediate an effect as that on NO x , which is associated with the fact that there was a large amount of biogenic VOC emission in Hangzhou and surrounding regions (Liu et al, 2018;Wu et al, 2020). In fact, the average temperature during the study period is as high as around 31 • C (Fig.…”
Section: Discussionmentioning
confidence: 93%
“…Hangzhou, the capital of Zhejiang Province, is located in the center of the Yangtze River Delta, which is one of the most developed areas in China. Resulting from local emissions (Wu et al, 2014;Hu et al, 2015) and transboundary transport of aerosol and trace gases (Liu et al, 2015;Ni et al, 2018;Zhang et al, 2018), air pollution in Hangzhou has become serious in recent years. In 2016, Hangzhou hosted the G20 (Group of 20 Finance Ministers and Central Bank Governors) summit from 4 to 6 September.…”
Abstract. Serious urban ozone (O3) pollution was observed during the campaign of
2016 G20 summit in Hangzhou, China, while other pollutants had been
significantly reduced by the short-term emission control measures. To
understand the underlying mechanism, the Weather Research Forecast with
Chemistry (WRF-Chem) model is used to investigate the spatial and temporal
O3 variations in Hangzhou from 24 August to 6 September 2016. The
model is first successfully evaluated and validated for local and regional
meteorological and chemical parameters by using the ground and upper-air
level observed data. High ozone concentrations, temporally during most of the daytime emission control period and spatially from the surface to the
top of the planetary boundary layer, are captured in Hangzhou and even the
whole Yangtze River Delta region. Various atmospheric processes are further analyzed to
determine the influential factors of local ozone formation through the
integrated process rate method. Interesting horizontal and vertical
advection circulations of O3 are observed during several short
periods, and the effects of these processes are nearly canceled out. As a
result, ozone pollution is mainly attributed to the local photochemical
reactions that are not obviously influenced by the emission reduction
measures. The ratio of reduction of Volatile Organic Compounds (VOCs) to
that of NOx is a critical parameter that needs to be carefully considered for future alleviation of ozone formation. In addition, the vertical diffusion from the upper-air background O3 also plays an important role in shaping the surface ozone concentration. These results provide insight into urban O3 formation in Hangzhou and support the Model Intercomparison Study Asia Phase III (MICS-Asia Phase III).
“…According to the studies of Su et al (2017), Zheng et al (2019) and Wu et al (2019), it can be deduced that NO x has been significantly reduced by about 60%, at least 2 times the reduction of VOCs in Hangzhou. The influence of stringent emission control measures on VOCs is not as immediate an effect as that on NO x , which is associated with the fact that there was a large amount of biogenic VOC emission in Hangzhou and surrounding regions (Liu et al, 2018;Wu et al, 2020). In fact, the average temperature during the study period is as high as around 31 • C (Fig.…”
Section: Discussionmentioning
confidence: 93%
“…Hangzhou, the capital of Zhejiang Province, is located in the center of the Yangtze River Delta, which is one of the most developed areas in China. Resulting from local emissions (Wu et al, 2014;Hu et al, 2015) and transboundary transport of aerosol and trace gases (Liu et al, 2015;Ni et al, 2018;Zhang et al, 2018), air pollution in Hangzhou has become serious in recent years. In 2016, Hangzhou hosted the G20 (Group of 20 Finance Ministers and Central Bank Governors) summit from 4 to 6 September.…”
Abstract. Serious urban ozone (O3) pollution was observed during the campaign of
2016 G20 summit in Hangzhou, China, while other pollutants had been
significantly reduced by the short-term emission control measures. To
understand the underlying mechanism, the Weather Research Forecast with
Chemistry (WRF-Chem) model is used to investigate the spatial and temporal
O3 variations in Hangzhou from 24 August to 6 September 2016. The
model is first successfully evaluated and validated for local and regional
meteorological and chemical parameters by using the ground and upper-air
level observed data. High ozone concentrations, temporally during most of the daytime emission control period and spatially from the surface to the
top of the planetary boundary layer, are captured in Hangzhou and even the
whole Yangtze River Delta region. Various atmospheric processes are further analyzed to
determine the influential factors of local ozone formation through the
integrated process rate method. Interesting horizontal and vertical
advection circulations of O3 are observed during several short
periods, and the effects of these processes are nearly canceled out. As a
result, ozone pollution is mainly attributed to the local photochemical
reactions that are not obviously influenced by the emission reduction
measures. The ratio of reduction of Volatile Organic Compounds (VOCs) to
that of NOx is a critical parameter that needs to be carefully considered for future alleviation of ozone formation. In addition, the vertical diffusion from the upper-air background O3 also plays an important role in shaping the surface ozone concentration. These results provide insight into urban O3 formation in Hangzhou and support the Model Intercomparison Study Asia Phase III (MICS-Asia Phase III).
“…Globally, most of the SOC formation is due to the ozone induced oxidation of monoterpenes like α-pinene, β-pinene and limonene ( Watne et al, 2017 ). Recently Wu et al (2020) have shown that 70% of SOC is formed from the BVOCs in China. Fig.…”
The present study has been conducted to investigate the relative changes of carbonaceous aerosols (CA) over a high altitude Himalayan atmosphere with and without (very low) anthropogenic emissions. Measurements of atmospheric organic (OC) and elemental carbon (EC) were conducted during the lockdown period (April 2020) due to global COVID 19 outbreak and compared with the normal period (April 2019). The interesting, unexpected and surprising observation is that OC, EC and the total CA (TCA) during the lockdown (OC: 12.1 ± 5.5 μg m
−3
; EC: 2.2 ± 1.1 μg m
−3
; TCA: 21.5 ± 10 μg m
−3
) were higher than the normal period (OC: 7.04 ± 2.2 μg m
−3
; EC: 1.9 ± 0.7 μg m
−3
; TCA: 13.2 ± 4.1 μg m
−3
). The higher values for OC/EC ratio too was observed during the lockdown (5.7 ± 0.9) compared to the normal period (4.2 ± 1.1). Much higher surface O
3
during the lockdown (due to very low NO) could better promote the formation of secondary OC (SOC) through the photochemical oxidation of biogenic volatile organic compounds (BVOCs) emitted from Himalayan coniferous forest cover. SOC during the lockdown (7.6 ± 3.5 μg m
−3
) was double of that in normal period (3.8 ± 1.4 μg m
−3
). Regression analysis between SOC and O
3
showed that with the same amount of increase in O
3
, the SOC formation increased to a larger extent when anthropogenic emissions were very low and biogenic emissions dominate (lockdown) compared to when anthropogenic emissions were high (normal). Concentration weighted trajectory (CWT) analysis showed that the anthropogenic activities over Nepal and forest fire over north-east India were the major long-distant sources of the CA over Darjeeling during the normal period. On the other hand, during lockdown, the major source regions of CA over Darjeeling were regional/local. The findings of the study indicate the immense importance of Himalayan biosphere as a major source of organic carbon.
“…Biogenic volatile organic compounds (BVOCs) emitted by plants are important in emission and air pollution research, as they are significant contributors of secondary air pollutants, including ozone and secondary fine particles [20][21][22].…”
Section: Biogenic Emissions: the Megan Modelmentioning
A bottom-up emissions inventory is one of the most important data sets needed to understand air quality (AQ) and climate change (CC). Several emission inventories have been developed for Asia, including Transport and Chemical Evolution over the Pacific (TRACE-P), Regional Emission Inventory in Asia (REAS), and Inter-Continental Chemical Transport Experiment (INTEX) and, while these have been used successfully for many international studies, they have limitations including restricted amounts of information on pollutant types and low levels of transparency with respect to the polluting sectors or fuel types involved. To address these shortcomings, we developed: (1) a base-year, bottom-up anthropogenic emissions inventory for Asia, using the most current parameters and international frameworks (i.e., the Greenhouse gas—Air pollution INteractions and Synergies (GAINS) model); and (2) a base-year, natural emissions inventory for biogenic and biomass burning. For (1), we focused mainly on China, South Korea, and Japan; however, we also covered emission inventories for other regions in Asia using data covering recent energy/industry statistics, emission factors, and control technology penetration. The emissions inventory (Comprehensive Regional Emissions inventory for Atmospheric Transport Experiment (CREATE)) covers 54 fuel classes, 201 subsectors, and 13 pollutants, namely SO2, NOx, CO, non-methane volatile organic compounds (NMVOC), NH3, OC, BC, PM10, PM2.5, CO2, CH4, N2O, and Hg. For the base-year natural emissions inventory, the Model of Emissions of Gases and Aerosols from Nature (MEGAN) and BlueSky-Asia frameworks were used to estimate biogenic and biomass burning emissions, respectively. Since the CREATE emission inventory was designed/developed using international climate change/air quality (CC/AQ) assessment frameworks, such as GAINS, and has been fully connected with the most comprehensive emissions modeling systems—such as the US Environmental Protection Agency (EPA) Chemical Manufacturing Area Source (CMAS) system—it can be used to support various climate and AQ integrated modeling studies, both now and in the future.
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