Air Quality and Climate Change, Topic 3 of the Model Inter-Comparison Study for Asia Phase III (MICS-Asia III), Part II: aerosol radiative effects and aerosol feedbacks

Abstract. Topic 3 of the Model Inter-Comparison Study for Asia (MICS-Asia) Phase III examines how online coupled air quality models perform in simulating wintertime haze events in the North China Plain region and evaluates the importance of aerosol radiative feedbacks. This paper discusses the estimates of aerosol radiative forcing, aerosol feedbacks, and possible causes for the differences among the participating models. Over the Beijing–Tianjin–Hebei (BTH) region, the ensemble mean of estimated aerosol direct radiative forcing (ADRF) at the top of atmosphere, inside the atmosphere, and at the surface are −1.1, 7.7, and −8.8 W m−2 during January 2010, respectively. Subdivisions of direct and indirect aerosol radiative forcing confirm the dominant role of direct forcing. During severe haze days (17–19 January 2010), the averaged reduction in near-surface temperature for the BTH region can reach 0.3–1.6 ∘C. The responses of wind speeds at 10 m (WS10) inferred from different models show consistent declines in eastern China. For the BTH region, aerosol–radiation feedback-induced daytime changes in PM2.5 concentrations during severe haze days range from 6.0 to 12.9 µg m−3 (<6 %). Sensitivity simulations indicate the important effect of aerosol mixing states on the estimates of ADRF and aerosol feedbacks. Besides, black carbon (BC) exhibits a large contribution to atmospheric heating and feedbacks although it accounts for a small share of mass concentration of PM2.5.

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Air Quality and Climate Change, Topic 3 of the Model Inter-Comparison Study for Asia Phase III (MICS-Asia III), Part I: overview and model evaluation

10.5194/acp-2017-731 ◽

2017 ◽

Cited By ~ 1

Author(s):

Meng Gao ◽

Zhiwei Han ◽

Zirui Liu ◽

Meng Li ◽

Jinyuan Xin ◽

...

Keyword(s):

Air Quality ◽

Model Evaluation ◽

Air Pollutants ◽

North China ◽

Correlation Coefficients ◽

Phase Iii ◽

Comparison Study ◽

Model Ensemble ◽

Near Surface ◽

Ensemble Mean

Abstract. Topic 3 of the Model Inter-Comparison Study for Asia (MICS-Asia) Phase III examines how online coupled air quality models perform in simulating high aerosol pollution in the North China Plain region during wintertime haze events and evaluates the importance of aerosol radiative and microphysical feedbacks. A comprehensive overview of the MICS-ASIA III Topic 3 study design, including descriptions of participating models and model inputs, the experimental designs, and results of model evaluation, are presented. Two winter months (January 2010 and January 2013) were selected as study periods, when severe haze occurred in North China. Simulations were designed to evaluate radiative and microphysical feedbacks, together and separately, relative to simulations without feedbacks. Six modeling groups from China, Korea and the United States submitted results from seven applications of online coupled chemistry-meteorology models. Results are compared to meteorology and air quality measurements, including the Campaign on Atmospheric Aerosol Research Network of China (CARE-China) network, and the Acid Deposition Monitoring Network in East Asia (EANET). The analysis focuses on model evaluations and aerosol effects on meteorology and air quality, and potentially other interesting topics, such as the impacts of model resolutions on aerosol-radiation-weather interactions. The model evaluations for January 2010 show that current online-coupled meteorology-chemistry model can generally well reproduced meteorological features and variations of major air pollutants, including aerosol concentrations. The correlation coefficients between multi-model ensemble mean and observed near-surface temperature, water vapor mixing ratio and wind speeds can reach as high as 0.99, 0.99 and 0.98. The correlation coefficients between multi-model ensemble mean and the CARE-China observed near-surface air pollutants range from 0.51 to 0.94 (0.51 for ozone and 0.94 for PM2.5). However, large discrepancies exist between simulated aerosol chemical compositions from different models, which is due to different parameterizations of chemical reactions. The coefficient of variation (standard deviation divided by average) can reach above 1.3 for sulfate in Beijing, and above 1.6 for nitrate and organic aerosol in coastal regions, indicating these compositions are less consistent from different models. During clean periods, simulated Aerosol Optical Depths (AOD) from different models are consistent, but peak values differ during severe haze event, which can be explained by the differences in simulated inorganic aerosol concentrations and the hygroscopic growth efficiency (affected by varied RH). These results provide some brief senses of how current online-coupled meteorology-chemistry models reproduce severe haze events, and some directions for future model improvements.

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Assessing the formation and evolution mechanisms of severe haze pollution in Beijing−Tianjin−Hebei region by using process analysis

10.5194/acp-2019-245 ◽

2019 ◽

Cited By ~ 1

Author(s):

Lei Chen ◽

Jia Zhu ◽

Hong Liao ◽

Yi Gao ◽

Yulu Qiu ◽

...

Keyword(s):

Radiative Forcing ◽

Process Analysis ◽

Vertical Mixing ◽

Mixing Process ◽

Aerosol Chemistry ◽

Near Surface ◽

Aerosol Radiative Forcing ◽

Local Emission ◽

Aerosol Radiative ◽

Pm2.5 Concentration

Abstract. Fine–particle pollution associated with haze threatens human health, especially in the North China Plain, where extremely high PM2.5 concentrations were frequently observed during winter. In this study, the WRF–Chem model coupled with an improved integrated process analysis scheme was used to investigate the formation and evolution mechanisms of a haze event happened over Beijing–Tianjin–Hebei (BTH) in December 2015, including examining the contributions of local emission and outside transport to the absolute PM2.5 concentration in BTH, and the contributions of each detailed physical or chemical process to the variations in the PM2.5 concentration. The influence mechanisms of aerosol radiative forcing (including aerosol direct and indirect effects) were also examined by using the process analysis. During the aerosol accumulation stage (December 20–22, Stage_1), the average near–surface PM2.5 concentration in BTH was 250.0 µg m−3, which was contributed by local emission of 42.3 % and outside transport of 36.6 %. During the aerosol dispersion stage (December 23–27, Stage_2), the average concentration of PM2.5 was 107.9 µg m−3. The contribution of local emission increased to 50.9 %, while the contribution of outside transport decreased to 24.3 %. The 24–h change (23:00LST minus 00:00LST) in the near–surface PM2.5 concentration was +50.4 µg m−3 during Stage_1 and −41.5 µg m−3 during Stage_2. Contributions of aerosol chemistry process and vertical mixing process to the 24–h change were +43.8 (+17.9) µg m−3 and −161.6 (−221.6) µg m−3 for Stage_1 (Stage_2), respectively. Small differences in contributions from other processes were found between Stage_1 and Stage_2, such as advection process, cloud chemistry process, and so on. Therefore, the PM2.5 increase over BTH during haze formation stage (Stage_1) was mainly attributed to strong production by aerosol chemistry process and weak removal by vertical mixing process. When aerosol radiative feedback was considered, the 24–h PM2.5 increase was enhanced by 9.6 µg m−3 during Stage_1, which could be mainly attributed to the contributions of vertical mixing process (+39.8 µg m−3), advection process (−38.6 µg m−3) and aerosol chemistry process (+5.1 µg m−3). The restrained vertical mixing could be the primary reason for the enhancement in near–surface PM2.5 increase when aerosol radiative forcing was considered.

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Air quality and climate change, Topic 3 of the Model Inter-Comparison Study for Asia Phase III (MICS-Asia III) – Part 1: Overview and model evaluation

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-4859-2018 ◽

2018 ◽

Vol 18 (7) ◽

pp. 4859-4884 ◽

Cited By ~ 23

Author(s):

Meng Gao ◽

Zhiwei Han ◽

Zirui Liu ◽

Meng Li ◽

Jinyuan Xin ◽

...

Keyword(s):

Air Quality ◽

Model Evaluation ◽

The United States ◽

Chemical Mechanism ◽

Research Network ◽

Phase Iii ◽

Chemical Compositions ◽

Comparison Study ◽

Near Surface ◽

Ensemble Mean

Abstract. Topic 3 of the Model Inter-Comparison Study for Asia (MICS-Asia) Phase III examines how online coupled air quality models perform in simulating high aerosol pollution in the North China Plain region during wintertime haze events and evaluates the importance of aerosol radiative and microphysical feedbacks. A comprehensive overview of the MICS-Asia III Topic 3 study design, including descriptions of participating models and model inputs, the experimental designs, and results of model evaluation, are presented. Six modeling groups from China, Korea and the United States submitted results from seven applications of online coupled chemistry–meteorology models. Results are compared to meteorology and air quality measurements, including data from the Campaign on Atmospheric Aerosol Research Network of China (CARE-China) and the Acid Deposition Monitoring Network in East Asia (EANET). The correlation coefficients between the multi-model ensemble mean and the CARE-China observed near-surface air pollutants range from 0.51 to 0.94 (0.51 for ozone and 0.94 for PM2.5) for January 2010. However, large discrepancies exist between simulated aerosol chemical compositions from different models. The coefficient of variation (SD divided by the mean) can reach above 1.3 for sulfate in Beijing and above 1.6 for nitrate and organic aerosols in coastal regions, indicating that these compositions are less consistent from different models. During clean periods, simulated aerosol optical depths (AODs) from different models are similar, but peak values differ during severe haze events, which can be explained by the differences in simulated inorganic aerosol concentrations and the hygroscopic growth efficiency (affected by varied relative humidity). These differences in composition and AOD suggest that future models can be improved by including new heterogeneous or aqueous pathways for sulfate and nitrate formation under hazy conditions, a secondary organic aerosol (SOA) formation chemical mechanism with new volatile organic compound (VOCs) precursors, yield data and approaches, and a more detailed evaluation of the dependence of aerosol optical properties on size distribution and mixing state. It was also found that using the ensemble mean of the models produced the best prediction skill. While this has been shown for other conditions (for example, the prediction of high-ozone events in the US (McKeen et al., 2005)), this is to our knowledge the first time it has been shown for heavy haze events.

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Analysis of Aerosol Radiative Forcing over Beijing under Different Air Quality Conditions Using Ground-Based Sun-Photometers between 2013 and 2015

Remote Sensing ◽

10.3390/rs8060510 ◽

2016 ◽

Vol 8 (6) ◽

pp. 510 ◽

Cited By ~ 4

Author(s):

Wei Chen ◽

Lei Yan ◽

Nan Ding ◽

Mengdie Xie ◽

Ming Lu ◽

...

Keyword(s):

Air Quality ◽

Radiative Forcing ◽

Aerosol Radiative Forcing ◽

Aerosol Radiative

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Biases of aerosol simulation in the AerChemMIP models over China and impact of emission uncertainties

10.5194/egusphere-egu21-1689 ◽

2021 ◽

Author(s):

Tianyi Fan ◽

Xiaohong Liu ◽

Chenglai Wu ◽

Yi Gao ◽

Qiang Zhang ◽

...

Keyword(s):

Radiative Forcing ◽

Emission Inventory ◽

Climate Models ◽

Eastern China ◽

Western China ◽

Monsoon Circulation ◽

Emission Data ◽

Aerosol Radiative Forcing ◽

The Impact ◽

Aerosol Radiative

<p>&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160;&#160; Biases of aerosol simulation by models participating the Aerosol and Chemistry Model Intercomparison Project (AerChemMIP) were identified over China. Although the yearly trend of simulated aerosol optical depth (AOD) agrees with the MODIS satellite retrievals for the country-wide averages, this agreement is an offset between the underestimation of AOD over eastern China and the overestimation of AOD over western China. The AODs were underestimated over the Northeastern China Plain and the North China Plain all year along and overestimated over Sichuan Basin in the winter. These model biases were persistent over multiple years from 2002 to 2015. We attempt to evaluate the impact of emission uncertainties on model simulated aerosol properties and aerosol radiative forcing by comparing the simulations by the Community Earth System Model version 2 (CESM2) with the default inventory developed by the Community Emission Data System (CEDS) and with a country-level inventory (Multi-resolution Emission Inventory for China, MEIC). It turns out that the differences between simulations with the two emission inventories are much smaller than the differences between simulations and observations. Low-bias of precursor gases (e.g., SO<sub>2</sub>), too strong convergence of wind field, too strong dilution and transport by summer monsoon circulation, too much wet scavenging by precipitation, and too weak aerosol swelling due to low-biased relative humidity are suggested to be responsible for the biased AOD in eastern China. This indicates that the influence of emission inventory uncertainties on aerosol radiative forcing can be overwhelmed by influences of biased meteorology and aerosol processes. Therefore, it is necessary for climate models to perform reasonably well in the dynamical, physical and chemical processes in order to estimate the aerosol radiative forcing.&#160;&#160;&#160;</p>

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Differences in Sulfate Aerosol Radiative Forcing between the Daytime and Nighttime over East Asia Using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) Model

Atmosphere ◽

10.3390/atmos9110441 ◽

2018 ◽

Vol 9 (11) ◽

pp. 441 ◽

Cited By ~ 1

Author(s):

Hongyue Zhang ◽

Siyu Chen ◽

Nanxuan Jiang ◽

Xin Wang ◽

Xiaorui Zhang ◽

...

Keyword(s):

Climate Change ◽

East Asia ◽

Radiative Forcing ◽

Eastern China ◽

Sulfate Aerosol ◽

Weather Research And Forecasting ◽

Forecasting Model ◽

Sulfate Aerosols ◽

Aerosol Radiative Forcing ◽

Aerosol Radiative

The effect of aerosols is an important indicator of climate change. Sulfate aerosols, as the major scattering aerosols, which have attracted more and more attention in recent years. The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) were utilized to investigate the spatial distribution of sulfate aerosols and their radiative forcing characteristics over East Asia in 2010. Results showed that sulfate aerosols were mainly distributed over eastern China (24–43° N, 101–126° E), especially in the Sichuan Basin. The concentration of sulfate aerosols decreased with increasing altitude over East Asia. It also exhibited obvious seasonal variations, where the largest range of sulfate aerosol concentrations was found in summer, with a maximum of 2.4 μg kg−1 over eastern China. Although sulfate aerosol concentrations varied slightly during day and night, there was still a significantly difference in the sulfate aerosol radiative forcing. Specifically, the magnitude of the direct radiative forcing induced by sulfate aerosols at the surface was approximately −3.02 W m−2 in the daytime, while that was +0.24 W m−2 in the nighttime. This asymmetric change that was caused by the radiative forcing of sulfate aerosols between day and night would have significant impacts on climate change at the regional scale.

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Review of 'Air Quality and Climate Change, Topic 3 of the Model Inter-Comparison Study for Asia Phase III (MICS-Asia III), Part II: aerosol radiative effects and aerosol feedbacks' by Meng Gao et al.

10.5194/acp-2019-719-rc2 ◽

2019 ◽

Author(s):

Anonymous

Keyword(s):

Climate Change ◽

Air Quality ◽

Phase Iii ◽

Comparison Study ◽

Radiative Effects ◽

Aerosol Radiative Effects ◽

Aerosol Radiative

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Method to calculate the aerosol asymmetry factor based on measurements from the humidified nephelometer system

10.5194/acp-2017-1148 ◽

2018 ◽

Author(s):

Gang Zhao ◽

Chunsheng Zhao ◽

Ye Kuang ◽

Yuxuan Bian ◽

Jiangchuan Tao ◽

...

Keyword(s):

Radiative Forcing ◽

Field Measurements ◽

Mie Scattering ◽

Asymmetry Factor ◽

Hygroscopic Growth ◽

Aerosol Radiative Forcing ◽

The North ◽

Ambient Relative Humidity ◽

Wide Range ◽

Aerosol Radiative

Abstract. The aerosol asymmetry factor (g) is one of the most important factors for assessing direct aerosol radiative forcing. So far, few studies have focused on the measurements and parameterization of g. The characteristics of g are studied based on field measurements over the North China Plain by using the Mie scattering theory. The results show that calculated g values can vary over a wide range (between 0.54 and 0.67). When ambient relative humidity (RH) reaches 90 %, g is significantly enhanced by a factor of 1.2 due to aerosol hygroscopic growth. Direct aerosol radiative forcing can be reduced by 40 % when g increases by 20 %. For the first time, a novel method to calculate g based on measurements from the humidified nephelometer system is proposed. This method can constrain the uncertainty of g within 2 % for dry aerosol populations and 4 % for ambient aerosols, taking into account aerosol hygroscopic growth. Sensitivity studies show that ambient RH and aerosol hygroscopicity are the most important factors that influence the accuracy of predicting g.

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Source attribution of black carbon and its direct radiative forcing in China

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-4319-2017 ◽

2017 ◽

Vol 17 (6) ◽

pp. 4319-4336 ◽

Cited By ~ 36

Author(s):

Yang Yang ◽

Hailong Wang ◽

Steven J. Smith ◽

Po-Lun Ma ◽

Philip J. Rasch

Keyword(s):

Air Quality ◽

East Asia ◽

Black Carbon ◽

Radiative Forcing ◽

North China ◽

Eastern China ◽

Coupled Model ◽

Near Surface ◽

Direct Radiative Forcing ◽

Local Emissions

Abstract. The source attributions for mass concentration, haze formation, transport and direct radiative forcing of black carbon (BC) in various regions of China are quantified in this study using the Community Earth System Model (CESM) with a source-tagging technique. Anthropogenic emissions are from the Community Emissions Data System that is newly developed for the Coupled Model Intercomparison Project Phase 6 (CMIP6). Over north China where the air quality is often poor, about 90 % of near-surface BC concentration is contributed by local emissions. Overall, 35 % of BC concentration over south China in winter can be attributed to emissions from north China, and 19 % comes from sources outside China in spring. For other regions in China, BC is largely contributed from nonlocal sources. We further investigated potential factors that contribute to the poor air quality in China. During polluted days, a net inflow of BC transported from nonlocal source regions associated with anomalous winds plays an important role in increasing local BC concentrations. BC-containing particles emitted from East Asia can also be transported across the Pacific. Our model results show that emissions from inside and outside China are equally important for the BC outflow from East Asia, while emissions from China account for 8 % of BC concentration and 29 % in column burden in the western United States in spring. Radiative forcing estimates show that 65 % of the annual mean BC direct radiative forcing (2.2 W m−2) in China results from local emissions, and the remaining 35 % is contributed by emissions outside of China. Efficiency analysis shows that a reduction in BC emissions over eastern China could have a greater benefit for the regional air quality in China, especially in the winter haze season.

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