scholarly journals Using a New Top‐Down Constrained Emissions Inventory to Attribute the Previously Unknown Source of Extreme Aerosol Loadings Observed Annually in the Monsoon Asia Free Troposphere

2021 ◽  
Author(s):  
Shuo Wang ◽  
Jason Blake Cohen ◽  
Weizhi Deng ◽  
Kai Qin ◽  
Jianping Guo
Keyword(s):  
Free Troposphere ◽  
Top Down ◽  
Emissions Inventory ◽  
Monsoon Asia ◽  
Unknown Source

scholarly journals A top-down assessment using OMI NO2 suggests an underestimate in the NOx emissions inventory in Seoul, South Korea during KORUS-AQ

2018 ◽  
Author(s):  
Daniel L. Goldberg ◽  
Pablo E. Saide ◽  
Lok N. Lamsal ◽  
Benjamin de Foy ◽  
Zifeng Lu ◽  
...  
Keyword(s):  
South Korea ◽  
Emission Rate ◽  
Model Simulation ◽  
Nox Emission ◽  
Metropolitan Region ◽  
Nox Emissions ◽  
Top Down ◽  
Bottom Up ◽  
Field Campaign ◽  
Emissions Inventory

Abstract. In this work, we investigate the NOx emissions inventory in Seoul, South Korea using a regional NASA Ozone Monitoring Instrument (OMI) NO2 product. We first develop a regional OMI NO2 product by re-calculating the air mass factors using a high-resolution (4 × 4 km2) WRF-Chem model simulation, which better captures the NO2 shape profiles in urban regions. We then apply a model-derived spatial averaging kernel to further downscale the retrieval and account for the sub-pixel variability. These two modifications yield OMI NO2 values in the regional product that are 1.37 larger in the Seoul metropolitan region and > 2 times larger near large industrial sources. These two modifications also yield an OMI NO2 product that is in better agreement with the Pandora NO2 spectrometer measurements acquired during the Korea U.S.-Air Quality (KORUS-AQ) field campaign. NOx emissions are then derived for the Seoul metropolitan area during the KORUS-AQ field campaign using a top-down approach with the standard and regional NASA OMI NO2 products. We first apply the top-down approach to a model simulation to ensure that the method is appropriate: the WRF-Chem simulation utilizing the bottom-up emission inventory yields a NOx emission rate of 227 ± 94 kton/yr, while the bottom-up inventory itself yields a NOx emission rate of 198 kton/yr. Using the top-down approach on the regional OM NO2 product, we derive the NOx emissions rate from Seoul to be 484 ± 201 kton/yr, and a 353 ± 146 kton/yr NOx emissions rate using the standard NASA OMI NO2 product. This suggests an underestimate of 53 % and 36 % using the regional and standard NASA OMI NO2 products respectively. To supplement this finding, we compare the NO2 simulated by WRF-Chem to observations of the same quantity acquired by aircraft and find a model underestimate. When NOx emissions in the WRF-Chem model are doubled, there is better agreement with KORUS-AQ aircraft observations. Although the current work is focused on South Korea using OMI, the methodology developed in this work can be applied to other world regions using TROPOMI and future satellite datasets (e.g., GEMS and TEMPO) to produce high-quality region-specific top-down NOx emission estimates.

scholarly journals Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data

2009 ◽  
Vol 9 (17) ◽  
pp. 6305-6317 ◽  
Author(s):  
M. Zavala ◽  
S. C. Herndon ◽  
E. C. Wood ◽  
T. B. Onasch ◽  
W. B. Knighton ◽  
...  
Keyword(s):  
Measurement Techniques ◽  
Early Morning ◽  
Emission Factors ◽  
Top Down ◽  
Bottom Up ◽  
Emissions Inventory ◽  
Mobile Sources ◽  
Mobile Emissions ◽  
The City ◽  
Road Emission

Abstract. Mobile emissions represent a significant fraction of the total anthropogenic emissions burden in the Mexico City Metropolitan Area (MCMA) and, therefore, it is crucial to use top-down techniques informed by on-road exhaust measurements to evaluate and improve traditional bottom-up official emissions inventory (EI) for the city. We present the measurements of on-road fleet-average emission factors obtained using the Aerodyne mobile laboratory in the MCMA in March 2006 as part of the MILAGRO/MCMA-2006 field campaign. A comparison of our on-road emission measurements with those obtained in 2003 using essentially the same measurement techniques and analysis methods indicates that, in the three year span, NO emission factors remain within the measured variability ranges whereas emission factors of aldehydes and aromatics species were reduced for all sampled driving conditions. We use a top-down fuel-based approach to evaluate the mobile emissions from the gasoline fleet estimated in the bottom-up official 2006 MCMA mobile sources. Within the range of measurement uncertainties, we found probable slight overpredictions of mean EI estimates on the order of 20–28% for CO and 14–20% for NO. However, we identify a probable EI discrepancy of VOC mobile emissions between 1.4 and 1.9; although estimated benzene and toluene mobile emissions in the inventory seem to be well within the uncertainties of the corresponding emissions estimates. Aldehydes mobile emissions in the inventory, however, seem to be underpredicted by factors of 3 for HCHO and 2 for CH3CHO. Our on-road measurement-based estimate of annual emissions of organic mass from PM1 particles suggests a severe underprediction (larger than a factor of 4) of PM2.5 mobile emissions in the inventory. Analyses of ambient CO, NOx and CO/NOx concentration trends in the MCMA indicate that the early morning ambient CO/NOx ratio has decreased at a rate of about 1.9 ppm/ppm/year over the last two decades due to reductions in CO levels rather than by NOx. These trends, together with the analysis of fuel sales and fleet size, suggest that the relative contribution of diesel vehicles to overall NOx levels has increased over time in the city. Despite the impressive increase in the size of the vehicle fleet between 2000 and 2006, the early morning ambient concentrations of CO and NOx have not increased accordingly, probably due to the reported low removal rates of older vehicles, which do not have emissions control technologies, and partially due to the much lower emissions from newer gasoline vehicles. This indicates that an emission-based air quality improvement strategy targeting large reductions of emissions from mobile sources should be directed towards a significant increase of the removal rate of older, highly-polluting, vehicles.

scholarly journals A review on top-down and bottom-up approach for air pollution studies

2018 ◽  
Vol 7 (2) ◽  
pp. 52-60
Author(s):  
Francis Olawale Abulude ◽  
Moez Bahloul ◽  
Smart Olubayode ◽  
Ebenezer Alaba Adeoya
Keyword(s):  
Air Pollution ◽  
Source Apportionment ◽  
Pollution Control ◽  
Dispersion Modelling ◽  
Top Down ◽  
Bottom Up ◽  
Emissions Inventory ◽  
Global Problem ◽  
Sources Of Pollution

AbstractIt is a well-known fa ct that pollution is a global problem and mus t be holis ticall y ta ckled. In doing this, a dequa te knowledge of the sources of pollution is i mporta nt; therefore, the ai m of this paper is to review source a pportionment wi th reference to top-down and bottom-up methods . In this paper, dispersion modelling, emissions inventory and sa mpling methods are dis cussed. Also, anal yti cal methods invol ved in top -down source apportionment a re mentioned. The two techniques are needed to evalua te pollutants and their sources . Based on these two approa ches , pollution control s tra tegy is developed and decisions can be made on deci ding the ri ght approach to sol ve or reduce the pollution problems .

scholarly journals Exploiting satellite measurements to reduce uncertainties in UK bottom-up NO<sub>x</sub> emission estimates

2021 ◽  
Author(s):  
Richard J. Pope ◽  
Rebecca Kelly ◽  
Eloise A. Marais ◽  
Ailish M. Graham ◽  
Chris Wilson ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Spatiotemporal Variability ◽  
Nox Emissions ◽  
Ozone Monitoring Instrument ◽  
Top Down ◽  
Bottom Up ◽  
Emissions Inventory ◽  
Monitoring Instrument ◽  
Hazardous Pollutants ◽  
The Uk

Abstract. Nitrogen oxides (NOx, NO+NO2) are potent air pollutants which directly impact on human health and which aid the formation of other hazardous pollutants such as ozone (O3) and particulate matter. In this study, we use satellite tropospheric column nitrogen dioxide (TCNO2) data to evaluate the spatiotemporal variability and magnitude of the United Kingdom (UK) bottom-up National Atmospheric Emissions Inventory (NAEI) NOx emissions. Although emissions and TCNO2 represent different quantities, for UK city sources we find a spatial correlation of ~0.5 between the NAEI NOx emissions and TCNO2 from the high-spatial-resolution TROPOspheric Monitoring Instrument (TROPOMI), suggesting a good spatial distribution of emission sources in the inventory. Between 2005 and 2015, the NAEI total UK NOx emissions and long-term TCNO2 record from the Ozone Monitoring Instrument (OMI), averaged over England, show decreasing trends of 4.4 % and 2.2 %, respectively. Top-down NOx emissions were derived in this study by applying a simple mass balance approach to TROPOMI observed downwind NO2 plumes from city sources. Overall, these top-down estimates were consistent with the NAEI, but for larger cities such as London and Manchester the inventory is significantly (> 25 %) less than the top-down emissions. This NAEI NOx emission underestimate is supported by comparing simulations from the GEOS-Chem atmospheric chemistry model, driven by the NAEI emissions, with satellite and surface NO2 observations over the UK. This yields substantial model negative biases, providing further evidence to demonstrate that the NAEI may be underestimating NOx emissions in London and Manchester.

scholarly journals Evaluation of mobile emissions contributions to Mexico City's emissions inventory using on-road and cross-road emission measurements and ambient data

2009 ◽  
Vol 9 (2) ◽  
pp. 6363-6395 ◽  
Author(s):  
M. Zavala ◽  
S. C. Herndon ◽  
E. C. Wood ◽  
T. B. Onasch ◽  
W. B. Knighton ◽  
...  
Keyword(s):  
Early Morning ◽  
Emission Factors ◽  
Top Down ◽  
Bottom Up ◽  
Emissions Inventory ◽  
Mobile Sources ◽  
Mobile Emissions ◽  
Concentration Changes ◽  
The City ◽  
Road Emission

Abstract. Mobile emissions represent a significant fraction of the total anthropogenic emissions burden in the Mexico City Metropolitan Area (MCMA) and, therefore, it is crucial to use top-down techniques informed by on-road exhaust measurements to evaluate and improve traditional bottom-up official emissions inventory (EI) for the city. We present the measurements of on-road fleet-average emission factors obtained using the Aerodyne mobile laboratory in the MCMA in March 2006 as part of the MILAGRO/MCMA-2006 field campaign. A comparison of our on-road emission measurements with those obtained in 2003 using essentially the same measurement techniques and analysis methods indicates that, in the three year span, NO emission factors remain within the measured variability ranges whereas emission factors of aldehydes and aromatics species were reduced for all sampled driving conditions. We use a top-down fuel-based approach to evaluate the mobile emissions from the gasoline fleet estimated in the bottom-up official 2006 MCMA mobile sources. Within the range of measurement uncertainties, we found probable slight overpredictions of mean EI estimates on the order of 20–28% for CO and 14–20% for NO. However, we identify a probable EI underprediction of VOC mobile emissions between 1.4 and 1.9; although estimated benzene and toluene mobile emissions in the inventory seem to be well within the uncertainties of the corresponding emissions estimates. Aldehydes mobile emissions in the inventory, however, seem to be under predicted by factors of 3 for HCHO and 2 for CH3CHO. Our on-road measurement based estimate of annual emissions of organic mass from PM1 particles suggests a severe underprediction (larger than a factor of 4) of PM2.5 mobile emissions in the inventory. Analyses of ambient CO, NOx and CO/NOx concentration trends in the MCMA indicate that the early morning ambient CO/NOx ratio has decreased at a rate of about 1.9 ppm/ppm/year over the last two decades and that the decrease has been driven by reductions in CO levels rather than by NOx concentration changes, suggesting that the relative contribution of diesel vehicles to overall NOx levels has increased over time in the city. Despite the impressive increases in the size of the vehicle fleet between 2000 and 2006, the early morning ambient concentrations of CO and NOx have not increased accordingly, probably due to the reported low removal rates of older vehicles, which do not have emissions control technologies, and partially due to the much lower emissions from newer gasoline vehicles. This indicates that an emission-based air quality control strategy targeting large reductions of emissions from mobile sources should be directed towards a significant increase of the removal rate of older, highly-polluting, vehicles.

scholarly journals Life-Areas and How to Estimate Greenhouse Gas Emission Footprints

2021 ◽  
pp. 37-52
Author(s):  
Markus Hadler ◽  
Beate Klösch ◽  
Stephan Schwarzinger ◽  
Markus Schweighart ◽  
Rebecca Wardana ◽  
...  
Keyword(s):  
Greenhouse Gas ◽  
Greenhouse Gas Emission ◽  
Individual Behavior ◽  
Level Of Detail ◽  
Top Down ◽  
Trade Off ◽  
Emissions Inventory ◽  
Trade Offs ◽  
Survey Results ◽  
In The Beginning

AbstractTo enjoy a fulfilling life, a person needs six fundamental life requirements to be met. These six requirements or “life-areas” are housing, mobility, consumption of goods (e.g., clothing), diet, other activities (entertainment), and information. In the beginning of this chapter, a top-down estimate of Austrian consumption-based emissions in each life-area is presented. These are organized into segments that may be easily reduced by changing individual behavior and those segments that are fundamental aspects of our society. The remainder of this chapter discusses how to estimate the greenhouse gas (GHG) output. There is a trade-off between accuracy and level of detail, and the need to combine bottom-up survey results with the top-down national emissions inventory. How these trade-offs may be handled is demonstrated using a practical example.

scholarly journals Observations of Methane Emissions from California Dairies from Ground and Space: New Top-Down Constraints at Regional Scales

2020 ◽  
Author(s):  
Manvendra K. Dubey ◽  
Sajjan Heerah ◽  
Isis Frausto-Vicencio ◽  
Seongeun Jeong ◽  
Marc Fischer ◽  
...  
Keyword(s):  
Field Measurements ◽  
High Signal ◽  
Mitigation Policy ◽  
Top Down ◽  
Emissions Inventory ◽  
Precision Level ◽  
Methane Fluxes ◽  
Field Campaigns ◽  
Change Mitigation

&lt;p&gt;California has made reducing methane (CH&lt;sub&gt;4&lt;/sub&gt;) from its dairy industry, which accounts for nearly 50% of its inventoried CH&lt;sub&gt;4&amp;#160;&lt;/sub&gt;emissions, a key part of its climate change mitigation plan. However, in situ atmospheric measurement-based estimates suggest that the state-wide dairy source may be underestimated by up to a factor of 2. &amp;#160;Furthermore, emissions at the local scales important to mitigation policy (10&amp;#8217;s km) are very uncertain. Ground based measurements of atmospheric column averaged methane concentrations (XCH&lt;sub&gt;4&lt;/sub&gt;) can provide useful constraints on local to regional methane fluxes. Additionally, the high spatial and temporal resolution XCH&lt;sub&gt;4&amp;#160;&lt;/sub&gt;observations by the space-based TROPOMI and GOSAT instruments provide an excellent opportunity to measure CH&lt;sub&gt;4&lt;/sub&gt;&amp;#160;fluxes at these scales. We report field measurements of XCH&lt;sub&gt;4&lt;/sub&gt; gradients across the dairy intensive region (500 dairies, 330 Gg/yr CH4 emissions inventory) in the San Joaquin Valley (SJV) using two EM27/SUN solar spectrometers. With our EM27&amp;#8217;s we observed several days of sustained downwind-upwind XCH&lt;sub&gt;4&lt;/sub&gt; enhancements of over 40 ppb, placing these signals well above TROPOMI and GOSAT&amp;#8217;s precision level and among the highest reported XCH&lt;sub&gt;4&amp;#160;&lt;/sub&gt;enhancements. We compare TROPOMI and GOSAT spatial XCH&lt;sub&gt;4&amp;#160;&lt;/sub&gt;enhancements to our EM27 data to validate it in an area of high signal and to demonstrate its utility for observing localized sources. We also use GOSAT and TROPOMI&amp;#8217;s data to characterize the wider SJV&amp;#8217;s CH&lt;sub&gt;4&lt;/sub&gt; sources and to fill in temporal gaps between our field campaigns. Finally, we perform inverse optimizations using WRF-STILT simulations demonstrating that top-down observationally constrained dairy emissions are a factor of 2 larger than reported inventories. &amp;#160;This work illustrates how ground and space-based measurements can complement each other to improve our understanding of CH&lt;sub&gt;4&lt;/sub&gt;&amp;#160;sources at scales relevant to mitigation policy.&lt;/p&gt;

scholarly journals A top-down assessment using OMI NO<sub>2</sub> suggests an underestimate in the NO<sub><i>x</i></sub> emissions inventory in Seoul, South Korea, during KORUS-AQ

2019 ◽  
Vol 19 (3) ◽  
pp. 1801-1818 ◽  
Author(s):  
Daniel L. Goldberg ◽  
Pablo E. Saide ◽  
Lok N. Lamsal ◽  
Benjamin de Foy ◽  
Zifeng Lu ◽  
...  
Keyword(s):  
South Korea ◽  
Metropolitan Area ◽  
Model Simulation ◽  
Nox Emissions ◽  
Top Down ◽  
Bottom Up ◽  
Air Mass ◽  
Field Campaign ◽  
Emissions Inventory ◽  
Seoul Metropolitan Area

Abstract. In this work, we investigate the NOx emissions inventory in Seoul, South Korea, using a regional ozone monitoring instrument (OMI) NO2 product derived from the standard NASA product. We first develop a regional OMI NO2 product by recalculating the air mass factors using a high-resolution (4 km × 4 km) WRF-Chem model simulation, which better captures the NO2 profile shapes in urban regions. We then apply a model-derived spatial averaging kernel to further downscale the retrieval and account for the subpixel variability. These two modifications yield OMI NO2 values in the regional product that are 1.37 times larger in the Seoul metropolitan region and >2 times larger near substantial point sources. These two modifications also yield an OMI NO2 product that is in better agreement with the Pandora NO2 spectrometer measurements acquired during the South Korea–United States Air Quality (KORUS-AQ) field campaign. NOx emissions are then derived for the Seoul metropolitan area during the KORUS-AQ field campaign using a top-down approach with the standard and regional NASA OMI NO2 products. We first apply the top-down approach to a model simulation to ensure that the method is appropriate: the WRF-Chem simulation utilizing the bottom-up emissions inventory yields a NOx emissions rate of 227±94 kt yr−1, while the bottom-up inventory itself within a 40 km radius of Seoul yields a NOx emissions rate of 198 kt yr−1. Using the top-down approach on the regional OMI NO2 product, we derive the NOx emissions rate from Seoul to be 484±201 kt yr−1, and a 353±146 kt yr−1 NOx emissions rate using the standard NASA OMI NO2 product. This suggests an underestimate of 53 % and 36 % in the bottom-up inventory using the regional and standard NASA OMI NO2 products respectively. To supplement this finding, we compare the NO2 and NOy simulated by WRF-Chem to observations of the same quantity acquired by aircraft and find a model underestimate. When NOx emissions in the WRF-Chem model are increased by a factor of 2.13 in the Seoul metropolitan area, there is better agreement with KORUS-AQ aircraft observations and the recalculated OMI NO2 tropospheric columns. Finally, we show that by using a WRF-Chem simulation with an updated emissions inventory to recalculate the air mass factor (AMF), there are small differences (∼8 %) in OMI NO2 compared to using the original WRF-Chem simulation to derive the AMF. This suggests that changes in model resolution have a larger effect on the AMF calculation than modifications to the South Korean emissions inventory. Although the current work is focused on South Korea using OMI, the methodology developed in this work can be applied to other world regions using TROPOMI and future satellite datasets (e.g., GEMS and TEMPO) to produce high-quality region-specific top-down NOx emissions estimates.

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