scholarly journals Relative effects of open biomass and crop straw burning on haze formation over central and eastern China: modelling study driven by constrained emissions

2019 ◽  
Author(s):  
Khalid Mehmood ◽  
Yujie Wu ◽  
Liqiang Wang ◽  
Shaocai Yu ◽  
Pengfei Li ◽  
...  
Keyword(s):  
High Pressure ◽  
Transport Model ◽  
Eastern China ◽  
Chemical Transport ◽  
Ambient Air ◽  
Attractive Alternative ◽  
Pressure System ◽  
Crop Straw ◽  
Satellite Retrievals ◽  
Straw Burning

Abstract. Open biomass burning (OBB) has large potential in triggering local and regional severe haze with elevated fine particulate matter (PM2.5) concentrations and could thus deteriorate ambient air quality and threaten human health. Open crop straw burning (OCSB), as a critical part of OBB, emits abundant gaseous and particulate pollutants, especially in fields with intensive agriculture, such as central and eastern China (CEC). However, there are high uncertainties in current OCSB and other types of OBB emissions that could drive chemical transport models (CTMs) to fail to evaluate their respective impacts on haze formations accurately. Satellite retrievals provide an attractive alternative that can be used to simultaneously quantify emissions of OCSB and other types of OBB, such as the Fire INventory from NCAR version 1.5 (FINNv1.5), which yet generally underestimate their magnitudes due to unresolved small fires. In this study, we selected June in 2014 as our study period, which exhibited a complete evolution process of OBB (from June 1 to 19) over CEC. During this period, OBB was dominated by OCSB in terms of the number of fire hotspot and associated emissions (74 ~ 94 %), most of which were located at Henan and Anhui (> 60 %) with intensive enhancements from June 5 to 14 (> 80 %). It is found that OCSB presented a generally strong spatiotemporal correlation with regional haze over the central part of CEC (Henan, Anhui, Hubei, and Hunan), while other types of OBB emissions had certain influences on Jiangxi, Zhejiang, and Fujian. Based on these analyses, we established a constraining method that integrates ground PM2.5 measurements with a state-of-art fully coupled regional meteorological and chemical transport model (the two-way coupled WRF-CMAQ) in order to derive optimal OBB emissions based on FINNv1.5. It is demonstrated that these emissions could allow the model to reproduce meteorological and chemical fields over CEC during the study period, whereas original FINNv1.5 underestimated OBB emissions by 2 ~ 7 times, depending on specific spatiotemporal scales. The results show that OBB had substantial impacts on surface PM2.5 concentrations over CEC. Most of OBB contributions were dominated by OCSB, especially in Henan, Anhui, Hubei, and Hunan, while other types of OBB emissions also exerted certain influence in Jiangxi, Zhejiang, and Fujian. With the concentration-weighted trajectory (CWT) method, potential OCSB sources leading to severe haze in Henan, Anhui, Hubei, and Hunan were pinpointed. The results illustrated that the OCSB emissions in Henan and Anhui can cause haze not only locally but also regionally through regional transport. Combining with meteorological analyses, we can find that surface weather patterns played a cardinal role in reshaping spatial and temporal characteristics of PM2.5 concentrations. Stationary high-pressure systems over CEC enhanced local PM2.5 concentrations in Henan and Anhui. Then, with the evolution of meteorological patterns, Hubei and Hunan in the low-pressure system were forced to receive the pollution from areas (i.e., Henan and Anhui) enveloped in the high-pressure system. These results highlight that policymakers should strictly undertake interprovincial joint enforcement actions to prohibit irregular OBB, especially OCSB over CEC. By comparison, the constrained OBB emissions can, to a large extent, not only supplement insufficient estimations derived from satellite retrievals but also reduce overestimations of bottom-up methods.

Relative effects of open biomass and crop straw burning on haze formation over central and eastern China: modelling study driven by constrained emissions

2020 ◽  
Author(s):  
Pengfei Li ◽  
Shaocai Yu ◽  
Yujie Wu ◽  
khalid Mehmood ◽  
Liqiang Wang ◽  
...  
Keyword(s):  
High Pressure ◽  
Transport Model ◽  
Eastern China ◽  
Chemical Transport ◽  
Ambient Air ◽  
Chemical Transport Model ◽  
Pressure System ◽  
Crop Straw ◽  
Satellite Retrievals ◽  
Straw Burning

<p><span>Open biomass burning (OBB) has large potential in triggering local and regional severe haze with elevated fine particulate matter (PM<sub>2.5</sub>) concentrations and could thus deteriorate ambient air quality and threaten human health. Open crop straw burning (OCSB), as a critical part of OBB, emits abundant gaseous and particulate pollutants, especially in fields with intensive agriculture, such as central and eastern China (CEC).  However, uncertainties in current OCSB and other types of OBB emissions in </span><span>chemical transport models (CTMs) lead to inaccuracies in evaluating their impacts on haze formations. Satellite retrievals provide </span><span>an alternative that can be used to simultaneously quantify emissions of </span><span>OCSB and other types of OBB, such as </span><span>the Fire INventory from NCAR version 1.5 (FINNv1.5), which, nevertheless, generally underestimate their magnitudes due to unresolved small fires. In this study, we selected June in 2014 as our study period, which exhibited a complete evolution process of OBB (from June 1 to 19) over CEC. During this period, OBB was dominated by OCSB in terms of the number of fire hotspot and associated emissions, most of which were located at Henan and Anhui with intensive enhancements from June 5 to 14. OCSB generally exhibits spatiotemporal correlation with regional haze over the central part of CEC (Henan, Anhui, Hubei, and Hunan), while other types of OBB emissions had influences on Jiangxi, Zhejiang, and Fujian. Based on these analyses, we establish a constraining method that integrates </span><span>ground-level PM<sub>2.5</sub> measurements with </span><span>a state-of-art fully coupled regional meteorological and chemical transport model (the two-way coupled WRF-CMAQ) in order to derive optimal OBB emissions based on FINNv1.5. It is demonstrated that these emissions allow the model to reproduce meteorological and chemical fields over CEC during the study period, whereas the original FINNv1.5 underestimated OBB emissions by 2 ~ 7 times, depending on specific spatiotemporal scales. The results show that OBB had substantial impacts on surface PM<sub>2.5</sub> concentrations over CEC. Most of the OBB contributions were dominated by OCSB, especially in Henan, Anhui, Hubei, and Hunan, while other types of OBB emissions also exerted influence in Jiangxi, Zhejiang, and Fujian. With the </span><span>concentration-weighted trajectory (CWT) method, potential OCSB sources leading to severe haze in Henan, Anhui, Hubei, and Hunan were pinpointed. The results show that the OCSB emissions in Henan and Anhui can cause haze not only locally but also regionally through regional transport. </span><span>Combining with meteorological analyses, we can find that surface weather patterns played a cardinal role in reshaping spatial and temporal characteristics of PM<sub>2.5</sub> concentrations. Stationary high-pressure systems over CEC enhanced local PM<sub>2.5</sub> concentrations in Henan and Anhui. Then, with the evolution of meteorological patterns, Hubei and Hunan in the low-pressure system were impacted by areas enveloped in the high-pressure system. These results suggest that policymakers should strictly undertake interprovincial joint enforcement actions to prohibit irregular OBB, especially OCSB over CEC. Constrained OBB emissions can, to a large extent, supplement estimations derived from satellite retrievals as well as reduce overestimates of bottom-up methods.</span></p>

scholarly journals Relative effects of open biomass burning and open crop straw burning on haze formation over central and eastern China: modeling study driven by constrained emissions

2020 ◽  
Vol 20 (4) ◽  
pp. 2419-2443 ◽  
Author(s):  
Khalid Mehmood ◽  
Yujie Wu ◽  
Liqiang Wang ◽  
Shaocai Yu ◽  
Pengfei Li ◽  
...  
Keyword(s):  
High Pressure ◽  
Biomass Burning ◽  
Eastern China ◽  
Chemical Transport ◽  
Ambient Air ◽  
Eastern Coast ◽  
Pressure System ◽  
Crop Straw ◽  
Satellite Retrievals ◽  
Straw Burning

Abstract. Open biomass burning (OBB) has a high potential to trigger local and regional severe haze with elevated fine particulate matter (PM2.5) concentrations and could thus deteriorate ambient air quality and threaten human health. Open crop straw burning (OCSB), as a critical part of OBB, emits abundant gaseous and particulate pollutants, especially in fields with intensive agriculture, such as in central and eastern China (CEC). This region includes nine provinces, i.e., Hubei, Anhui, Henan, Hunan, Jiangxi, Shandong, Jiangsu, Shanghai, and Fujian. The first four ones are located inland, while the others are on the eastern coast. However, uncertainties in current OCSB and other types of OBB emissions in chemical transport models (CTMs) lead to inaccuracies in evaluating their impacts on haze formations. Satellite retrievals provide an alternative that can be used to simultaneously quantify emissions of OCSB and other types of OBB, such as the Fire INventory from NCAR version 1.5 (FINNv1.5), which, nevertheless, generally underestimates their magnitudes due to unresolved small fires. In this study, we selected June 2014 as our study period, which exhibited a complete evolution process of OBB (from 1 to 19 June) over CEC. During this period, OBB was dominated by OCSB in terms of the number of fire hotspots and associated emissions (74 %–94 %), most of which were located at Henan and Anhui (> 60 %) with intensive enhancements from 5 to 14 June (> 80 %). OCSB generally exhibits a spatiotemporal correlation with regional haze over the central part of CEC (Henan, Anhui, Hubei, and Hunan), while other types of OBB emissions had influences on Jiangxi, Zhejiang, and Fujian. Based on these analyses, we establish a constraining method that integrates ground-level PM2.5 measurements with a state-of-art fully coupled regional meteorological and chemical transport model (the two-way coupled WRF-CMAQ) in order to derive optimal OBB emissions based on FINNv1.5. It is demonstrated that these emissions allow the model to reproduce meteorological and chemical fields over CEC during the study period, whereas the original FINNv1.5 underestimated OBB emissions by 2–7 times, depending on specific spatiotemporal scales. The results show that OBB had substantial impacts on surface PM2.5 concentrations over CEC. Most of the OBB contributions were dominated by OCSB, especially in Henan, Anhui, Hubei, and Hunan, while other types of OBB emissions also exerted an influence in Jiangxi, Zhejiang, and Fujian. With the concentration-weighted trajectory (CWT) method, potential OCSB sources leading to severe haze in Henan, Anhui, Hubei, and Hunan were pinpointed. The results show that the OCSB emissions in Henan and Anhui can cause haze not only locally but also regionally through regional transport. Combining with meteorological analyses, we can find that surface weather patterns played a cardinal role in reshaping spatial and temporal characteristics of PM2.5 concentrations. Stationary high-pressure systems over CEC enhanced local PM2.5 concentrations in Henan and Anhui. Then, with the evolution of meteorological patterns, Hubei and Hunan in the low-pressure system were impacted by areas (i.e., Henan and Anhui) enveloped in the high-pressure system. These results suggest that policymakers should strictly undertake interprovincial joint enforcement actions to prohibit irregular OBB, especially OCSB over CEC. Constrained OBB emissions can, to a large extent, supplement estimations derived from satellite retrievals as well as reduce overestimates of bottom-up methods.

scholarly journals Seasonal and spatial variability of surface ozone over China: contributions from background and domestic pollution

2010 ◽  
Vol 10 (11) ◽  
pp. 27853-27891 ◽  
Author(s):  
Y. Wang ◽  
Y. Zhang ◽  
J. Hao ◽  
M. Luo
Keyword(s):  
Yangtze River ◽  
Transport Model ◽  
Surface Ozone ◽  
Eastern China ◽  
Chemical Transport ◽  
Anthropogenic Emissions ◽  
Spatial Gradient ◽  
Chemical Transport Model ◽  
Significant Drop ◽  
Background Ozone

Abstract. Both observations and a 3-D chemical transport model suggest that surface ozone over populated eastern China features a significant drop in mid-summer and that the peak month differs by latitude and region. Source-receptor analysis is used to quantify the contributions of background ozone and Chinese anthropogenic emissions on this variability. Annual mean background ozone over China shows a spatial gradient from 55 ppbv in the northwest to 20 ppbv in the southeast, corresponding with changes in topography and ozone lifetime. Anthropogenic background (annual mean of 12.6 ppbv) shows distinct troughs in the summer and peaks in the spring. On the monthly-mean basis, Chinese pollution ozone (CPO) has a peak of 20–25 ppbv in June north of the Yangtze River and in October south of it, which explains the peaks of surface ozone in these months. The mid-summer drop in ozone over eastern China is driven by the decrease of background ozone (−15 ppbv). Tagged simulations suggest that this decrease is driven by reduced transport from Europe and North America, whereas ozone from Southeast Asia and Pacific Ocean exhibits a maximum in the summer over eastern China. This contrast in seasonality provides clear evidence that the seasonal switch in monsoonal wind patterns plays a significant role in determining the seasonality of background ozone over China.

scholarly journals Investigating the importance of sub-grid particle formation in point source plumes over eastern China using IAP-AACM v1.0 with a sub-grid parameterization

2021 ◽  
Vol 14 (7) ◽  
pp. 4411-4428
Author(s):  
Ying Wei ◽  
Xueshun Chen ◽  
Huansheng Chen ◽  
Yele Sun ◽  
Wenyi Yang ◽  
...  
Keyword(s):  
Point Source ◽  
Transport Model ◽  
Aerosol Particles ◽  
Eastern China ◽  
Regional Scale ◽  
Chemical Transport ◽  
Particle Formation ◽  
Point Sources ◽  
Formation Processes ◽  
New Particle Formation

Abstract. The influence of sub-grid particle formation (SGPF) in point source plumes on aerosol particles over eastern China was firstly illustrated by implementing an SGPF scheme into a global–regional nested chemical transport model with an aerosol microphysics module. The key parameter in the scheme was optimized based on the observations in eastern China. With the parameterization of SGPF, the spatial heterogeneity and diurnal variation in particle formation processes in sub-grid scale were well resolved. The SGPF scheme can significantly improve the model performance in simulating aerosol components and new particle formation processes at typical sites influenced by point sources. The comparison with observations at Beijing, Wuhan and Nanjing showed that the normal mean bias (NMB) of sulfate and ammonium could be reduced by 23 %–27 % and 12 %–14 %, respectively. When wind fields are well reproduced, the correlation of sulfate between simulation and observation can be increased by 0.13 in Nanjing. Considering the diurnal cycle of new particle formation, the SGPF scheme can greatly reduce the overestimation of particle number concentration in nucleation and Aitken mode at night caused by fixed-fraction parameterization of SGPF. On the regional scale, downwind areas of point source experienced an increase in sulfate concentration of 25 %–50 %. The results of this study indicate the significant effects of SGPF on aerosol particles over areas with the point source and the necessity of a reasonable representation of SGPF processes in chemical transport models.

scholarly journals Characterizing model errors in chemical transport modelling of methane: Using GOSAT XCH<sub>4</sub> data with weak constraint four-dimensional variational data assimilation

2019 ◽  
Author(s):  
Ilya Stanevich ◽  
Dylan B. A. Jones ◽  
Kimberly Strong ◽  
Martin Keller ◽  
Daven K. Henze ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Transport Model ◽  
Eastern China ◽  
Chemical Transport ◽  
Model Fit ◽  
Model Errors ◽  
Time Step ◽  
Transport Modelling ◽  
Strong Constraint ◽  
The Tropics

Abstract. We examined biases in the global GEOS-Chem chemical transport model for the period of February–May 2010 using weak constraint (WC) four-dimensional variational (4D-Var) data assimilation and dry-air mole fractions of CH4 (XCH4) from the Greenhouse gases Observing SATellite (GOSAT). The ability of the observations and the WC 4D-Var method to mitigate model errors in CH4 concentrations was first investigated in a set of observing system simulation experiments (OSSEs). We then assimilated the GOSAT XCH4 retrievals and found that they were capable of differentiating the vertical distribution of model errors and of removing a significant portion of biases in the modelled CH4 state. In the WC 4D-Var assimilation, corrections were added to the modeled CH4 state at each model time step to account for model errors and improve the model fit to the assimilated observations. Compared to the conventional strong constraint (SC) 4D-Var assimilation, the WC method was able to significantly improve the model fit to independent observations. Examination of the WC state corrections suggested that a significant source of the model errors was associated with discrepancies in the model CH4 in the stratosphere. The WC state corrections also suggested that the model vertical transport in the troposphere at mid- and high-latitudes is too weak. The problem was traced back to biases in the uplift of CH4 over the source regions in eastern China and North America. In the tropics, the WC assimilation pointed to the possibility of biased CH4 outflow from the African continent to the Atlantic in the mid-troposphere. The WC assimilation in this region would greatly benefit from glint observations over the ocean to provide additional constraints on the vertical structure of the model errors in the tropics. We also compared the WC assimilation at the 4° × 5° and 2° × 2.5° horizontal resolutions and found that the WC corrections to mitigate the model errors were significantly larger at 4° × 5° than at 2° × 2.5° resolution, indicating the presence of resolution-dependent model errors. Our results illustrate the potential utility of the WC 4D-Var approach for characterizing model errors. However, a major limitation of this approach is the need to better characterize the specified model error covariance in the assimilation scheme.

scholarly journals Characterizing model errors in chemical transport modeling of methane: using GOSAT XCH<sub>4</sub> data with weak-constraint four-dimensional variational data assimilation

2021 ◽  
Vol 21 (12) ◽  
pp. 9545-9572
Author(s):  
Ilya Stanevich ◽  
Dylan B. A. Jones ◽  
Kimberly Strong ◽  
Martin Keller ◽  
Daven K. Henze ◽  
...  
Keyword(s):  
Data Assimilation ◽  
Vertical Structure ◽  
Transport Model ◽  
Eastern China ◽  
Chemical Transport ◽  
Model Fit ◽  
Model Errors ◽  
Time Step ◽  
Strong Constraint ◽  
The Tropics

Abstract. We examined biases in the global GEOS-Chem chemical transport model for the period of February–May 2010 using weak-constraint (WC) four-dimensional variational (4D-Var) data assimilation and dry-air mole fractions of CH4 (XCH4) from the Greenhouse gases Observing SATellite (GOSAT). The ability of the observations and the WC 4D-Var method to mitigate model errors in CH4 concentrations was first investigated in a set of observing system simulation experiments (OSSEs). We then assimilated the GOSAT XCH4 retrievals and found that they were capable of providing information on the vertical structure of model errors and of removing a significant portion of biases in the modeled CH4 state. In the WC 4D-Var assimilation, corrections were added to the modeled CH4 state at each model time step to account for model errors and improve the model fit to the assimilated observations. Compared to the conventional strong-constraint (SC) 4D-Var assimilation, the WC method was able to significantly improve the model fit to independent observations. Examination of the WC state corrections suggested that a significant source of model errors was associated with discrepancies in the model CH4 in the stratosphere. The WC state corrections also suggested that the model vertical transport in the troposphere at middle and high latitudes is too weak. The problem was traced back to biases in the uplift of CH4 over the source regions in eastern China and North America. In the tropics, the WC assimilation pointed to the possibility of biased CH4 outflow from the African continent to the Atlantic in the mid-troposphere. The WC assimilation in this region would greatly benefit from glint observations over the ocean to provide additional constraints on the vertical structure of the model errors in the tropics. We also compared the WC assimilation at 4∘ × 5∘ and 2∘ × 2.5∘ horizontal resolutions and found that the WC corrections to mitigate the model errors were significantly larger at 4∘ × 5∘ than at 2∘ × 2.5∘ resolution, indicating the presence of resolution-dependent model errors. Our results illustrate the potential utility of the WC 4D-Var approach for characterizing model errors. However, a major limitation of this approach is the need to better characterize the specified model error covariance in the assimilation scheme.

Method for Fusing Observational Data and Chemical Transport Model Simulations To Estimate Spatiotemporally Resolved Ambient Air Pollution

2016 ◽  
Vol 50 (7) ◽  
pp. 3695-3705 ◽  
Author(s):  
Mariel D. Friberg ◽  
Xinxin Zhai ◽  
Heather A. Holmes ◽  
Howard H. Chang ◽  
Matthew J. Strickland ◽  
...  
Keyword(s):  
Air Pollution ◽  
Observational Data ◽  
Transport Model ◽  
Chemical Transport ◽  
Ambient Air ◽  
Ambient Air Pollution ◽  
Chemical Transport Model ◽  
Model Simulations

scholarly journals Global high-resolution simulations of tropospheric nitrogen dioxide using CHASER V4.0

2017 ◽  
Author(s):  
Takashi Sekiya ◽  
Kazuyuki Miyazaki ◽  
Koji Ogochi ◽  
Kengo Sudo ◽  
Masayuki Takigawa
Keyword(s):  
High Resolution ◽  
Nitrogen Dioxide ◽  
San Francisco ◽  
Biomass Burning ◽  
Transport Model ◽  
Eastern China ◽  
Small Scale ◽  
Aircraft Observations ◽  
Satellite Retrievals ◽  
Ozone Monitoring

Abstract. We evaluate global tropospheric nitrogen dioxide (NO2) simulations using the CHASER V4.0 global chemical transport model (CTM) at horizontal resolutions ranging from 0.56° to 2.8°. Model evaluation was conducted using satellite tropospheric NO2 retrievals from the Ozone Monitoring Instrument (OMI) and the Global Ozone Monitoring Experiment-2 (GOME-2), and aircraft observations from the 2014 Front Range Air Pollution and Photochemistry Experiment (FRAPPÉ). Agreement against satellite retrievals improved greatly at 0.56° and 1.1° resolutions (compared to 2.8° resolution) over polluted and biomass burning regions. A resolution of 0.56° was necessary to improve model performance over areas with strong local sources, with mean bias reductions of 67 % over Beijing, 62 % over Tokyo, and 73 % over San Francisco in summer. Validation using aircraft observations indicated that high-resolution simulations reduced negative NO2 biases below 700 hPa over the Denver metropolitan area. These improvements in high-resolution simulations were attributable to (1) closer spatial representativeness between simulations and observations and (2) better representation of large-scale concentration fields (i.e., at 2.8°) through consideration of small-scale processes. Model evaluations conducted at 0.5°- and 2.8°-bin grids indicated that the contributions of both these processes were comparable over most polluted regions, whereas the latter effect (2) made a larger contribution (of up to 90 %) over eastern China and biomass burning areas. The evaluations presented in this paper demonstrate the potential of using a high-resolution global CTM for studying megacity-scale air pollutants across the entire globe, potentially also contributing to global satellite retrievals and chemical data assimilation.

Sign in / Sign up

Export Citation Format

Share Document