scholarly journals The impact of traffic emissions on atmospheric ozone and OH: results from QUANTIFY

2009 ◽  
Vol 9 (9) ◽  
pp. 3113-3136 ◽  
Author(s):  
P. Hoor ◽  
J. Borken-Kleefeld ◽  
D. Caro ◽  
O. Dessens ◽  
O. Endresen ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Lower Troposphere ◽  
Local Maximum ◽  
Traffic Emissions ◽  
Transport Sector ◽  
Maximum Effect ◽  
Ship Emissions ◽  
Emission Data ◽  
Global Emission ◽  
The Impact

Abstract. To estimate the impact of emissions by road, aircraft and ship traffic on ozone and OH in the present-day atmosphere six different atmospheric chemistry models have been used. Based on newly developed global emission inventories for road, ship and aircraft emission data sets each model performed sensitivity simulations reducing the emissions of each transport sector by 5%. The model results indicate that on global annual average lower tropospheric ozone responds most sensitive to ship emissions (50.6%±10.9% of the total traffic induced perturbation), followed by road (36.7%±9.3%) and aircraft exhausts (12.7%±2.9%), respectively. In the northern upper troposphere between 200–300 hPa at 30–60° N the maximum impact from road and ship are 93% and 73% of the maximum effect of aircraft, respectively. The latter is 0.185 ppbv for ozone (for the 5% case) or 3.69 ppbv when scaling to 100%. On the global average the impact of road even dominates in the UTLS-region. The sensitivity of ozone formation per NOx molecule emitted is highest for aircraft exhausts. The local maximum effect of the summed traffic emissions on the ozone column predicted by the models is 0.2 DU and occurs over the northern subtropical Atlantic extending to central Europe. Below 800 hPa both ozone and OH respond most sensitively to ship emissions in the marine lower troposphere over the Atlantic. Based on the 5% perturbation the effect on ozone can exceed 0.6% close to the marine surface (global zonal mean) which is 80% of the total traffic induced ozone perturbation. In the southern hemisphere ship emissions contribute relatively strongly to the total ozone perturbation by 60%–80% throughout the year. Methane lifetime changes against OH are affected strongest by ship emissions up to 0.21 (± 0.05)%, followed by road (0.08 (±0.01)%) and air traffic (0.05 (± 0.02)%). Based on the full scale ozone and methane perturbations positive radiative forcings were calculated for road emissions (7.3±6.2 mWm−2) and for aviation (2.9±2.3 mWm−2). Ship induced methane lifetime changes dominate over the ozone forcing and therefore lead to a net negative forcing (−25.5±13.2 mWm−2).

scholarly journals Future impact of traffic emissions on atmospheric ozone and OH based on two scenarios

2012 ◽  
Vol 12 (8) ◽  
pp. 20975-21012
Author(s):  
Ø. Hodnebrog ◽  
T. K. Berntsen ◽  
O. Dessens ◽  
M. Gauss ◽  
V. Grewe ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Radiative Forcing ◽  
Road Traffic ◽  
North Atlantic Ocean ◽  
Lower Troposphere ◽  
Traffic Emissions ◽  
Transport Sector ◽  
Atmospheric Ozone ◽  
The Future ◽  
The Impact

Abstract. The future impact of traffic emissions on atmospheric ozone and OH has been investigated separately for the three sectors AIRcraft, maritime SHIPping and ROAD traffic. To reduce uncertainties we present results from an ensemble of six different atmospheric chemistry models, each simulating the atmospheric chemical composition in a possible high emission scenario (A1B), and with emissions from each transport sector reduced by 5% to estimate sensitivities. Our results are compared with optimistic future emission scenarios (B1 and B1 ACARE), presented in a companion paper, and with the recent past (year 2000). Present-day activity indicates that anthropogenic emissions so far evolve closer to A1B than the B1 scenario. As a response to expected changes in emissions, AIR and SHIP will have increased impacts on atmospheric O3 and OH in the future while the impact of ROAD traffic will decrease substantially as a result of technological improvements. In 2050, maximum aircraft-induced O3 occurs near 80° N in the UTLS region and could reach 9 ppbv in the zonal mean during summer. Emissions from ship traffic have their largest O3 impact in the maritime boundary layer with a maximum of 6 ppbv over the North Atlantic Ocean during summer in 2050. The O3 impact of road traffic emissions in the lower troposphere peaks at 3 ppbv over the Arabian Peninsula, much lower than the impact in 2000. Radiative Forcing (RF) calculations show that the net effect of AIR, SHIP and ROAD combined will change from a~marginal cooling of −0.38 ± 13 mW m−2 in 2000 to a relatively strong cooling of −32 ± 8.9 (B1) or −31 ± 20 mW m−2 (A1B) in 2050, when taking into account RF due to changes in O3, CH4 and CH4-induced O3. This is caused both by the enhanced negative net RF from SHIP, which will change from −20 ± 5.4 mW m−2 in 2000 to −31 ± 4.8 (B1) or −40 ± 11 mW m−2 (A1B) in 2050, and from reduced O3 warming from ROAD, which is likely to turn from a positive net RF of 13 ± 7.9 mW m−2 in 2000 to a slightly negative net RF of −2.9 ± 1.7 (B1) or −3.3 ± 3.8 (A1B) mW m−2 in the middle of this century. The negative net RF from ROAD is temporary and induced by the strong decline in ROAD emissions prior to 2050, which only affects the methane cooling term due to the longer lifetime of CH4 compared to O3. The O3 RF from AIR in 2050 is strongly dependent on scenario and ranges from 19 ± 6.8 (B1 ACARE) to 62 ± 13.6 mW m−2 (A1B). There is also a considerable span in the net RF from AIR in 2050, ranging from −0.54 ± 4.6 (B1 ACARE) to 12 ± 11 (A1B) mW m−2 compared to 6.5 ± 2.1 mW m−2 in 2000.

scholarly journals Future impact of traffic emissions on atmospheric ozone and OH based on two scenarios

2012 ◽  
Vol 12 (24) ◽  
pp. 12211-12225 ◽  
Author(s):  
Ø. Hodnebrog ◽  
T. K. Berntsen ◽  
O. Dessens ◽  
M. Gauss ◽  
V. Grewe ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Radiative Forcing ◽  
Road Traffic ◽  
North Atlantic Ocean ◽  
Lower Troposphere ◽  
Traffic Emissions ◽  
Transport Sector ◽  
Atmospheric Ozone ◽  
The Future ◽  
The Impact

Abstract. The future impact of traffic emissions on atmospheric ozone and OH has been investigated separately for the three sectors AIRcraft, maritime SHIPping and ROAD traffic. To reduce uncertainties we present results from an ensemble of six different atmospheric chemistry models, each simulating the atmospheric chemical composition in a possible high emission scenario (A1B), and with emissions from each transport sector reduced by 5% to estimate sensitivities. Our results are compared with optimistic future emission scenarios (B1 and B1 ACARE), presented in a companion paper, and with the recent past (year 2000). Present-day activity indicates that anthropogenic emissions so far evolve closer to A1B than the B1 scenario. As a response to expected changes in emissions, AIR and SHIP will have increased impacts on atmospheric O3 and OH in the future while the impact of ROAD traffic will decrease substantially as a result of technological improvements. In 2050, maximum aircraft-induced O3 occurs near 80° N in the UTLS region and could reach 9 ppbv in the zonal mean during summer. Emissions from ship traffic have their largest O3 impact in the maritime boundary layer with a maximum of 6 ppbv over the North Atlantic Ocean during summer in 2050. The O3 impact of road traffic emissions in the lower troposphere peaks at 3 ppbv over the Arabian Peninsula, much lower than the impact in 2000. Radiative forcing (RF) calculations show that the net effect of AIR, SHIP and ROAD combined will change from a marginal cooling of −0.44 ± 13 mW m−2 in 2000 to a relatively strong cooling of −32 ± 9.3 (B1) or −32 ± 18 mW m−2 (A1B) in 2050, when taking into account RF due to changes in O3, CH4 and CH4-induced O3. This is caused both by the enhanced negative net RF from SHIP, which will change from −19 ± 5.3 mW m−2 in 2000 to −31 ± 4.8 (B1) or −40 ± 9 mW m−2 (A1B) in 2050, and from reduced O3 warming from ROAD, which is likely to turn from a positive net RF of 12 ± 8.5 mW m−2 in 2000 to a slightly negative net RF of −3.1 ± 2.2 (B1) or −3.1 ± 3.4 (A1B) mW m−2 in the middle of this century. The negative net RF from ROAD is temporary and induced by the strong decline in ROAD emissions prior to 2050, which only affects the methane cooling term due to the longer lifetime of CH4 compared to O3. The O3 RF from AIR in 2050 is strongly dependent on scenario and ranges from 19 ± 6.8 (B1 ACARE) to 61 ± 14 mW m−2 (A1B). There is also a considerable span in the net RF from AIR in 2050, ranging from −0.54 ± 4.6 (B1 ACARE) to 12 ± 11 (A1B) mW m−2 compared to 6.6 ± 2.2 mW m−2 in 2000.

scholarly journals The impact of traffic emissions on atmospheric ozone and OH: results from QUANTIFY

2008 ◽  
Vol 8 (5) ◽  
pp. 18219-18266 ◽  
Author(s):  
P. Hoor ◽  
J. Borken-Kleefeld ◽  
D. Caro ◽  
O. Dessens ◽  
O. Endresen ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Southern Hemisphere ◽  
Total Ozone ◽  
Traffic Emissions ◽  
Maximum Effect ◽  
Ship Emissions ◽  
Aircraft Emissions ◽  
Upper Troposphere ◽  
Ship Traffic ◽  
The Impact

Abstract. To estimate the impact of emissions by road, aircraft and ship traffic on ozone and OH of the present-day atmosphere seven different atmospheric chemistry models simulated the atmospheric composition of the year 2003. Based on newly developed global emission inventories for road, maritime and aircraft emission data sets each model performed a series of five simulations: A base scenario using the full set of emissions, three sensitivity studies with each individual sector of transport reduced by 5% and one simulation with all traffic related emissions reduced by 5%. The approach minimizes non-linearities in atmospheric chemical effects and are later scaled to 100%. The global annual mean impact of ship emissions on ozone in the boundary layer leads to an increase of ozone of 1.2%, followed by road (0.87%) and aircraft emissions (0.3%). In the upper troposphere between 200–300 hPa both road and ship traffic affect ozone by 1.1%, whereas aircraft emissions contribute 0.9%. However, the sensitivity of ozone formation per NOx molecule emitted is highest for aircraft exhausts. The local maximum effect of the summed traffic emissions on the ozone column predicted by the models is 4.0 DU and occurs over the northern subtropical Atlantic. The impact of traffic emissions on total ozone in the Southern Hemisphere is approximately half of the northern hemispheric perturbation. Below 800 hPa both ozone and OH respond most sensitively to ship emissions in the marine boundary layer over the Atlantic, where the effect can exceed 10% (zonal mean) which is 80% of the total traffic induced ozone perturbation. In the Southern Hemisphere ship emissions contribute relatively strongly to the total ozone perturbation by 60%–80% throughout the year (equivalent to 1–1.5 ppbv). Road emissions have the strongest impact on ozone in the continental boundary layer and the free troposphere in summer. They also affect the upper troposphere particularly during northern summer associated with strong convection in mid latitudes. Ozone perturbations due to road traffic show the strongest seasonal cycle in the northern troposphere, and can even change sign in the continental boundary layer during winter. The OH concentration in the boundary layer is most strongly affected by ship emissions, which has a significant influence on the lifetime of many trace gases including methane. Methane lifetime changes due to ship emissions amount to 4.1%, followed by road (1.6%) and air traffic (1.0%).

scholarly journals Multi-model study of mercury dispersion in the atmosphere: Vertical distribution of mercury species

2016 ◽  
Author(s):  
Johannes Bieser ◽  
Franz Slemr ◽  
Jesse Ambrose ◽  
Carl Brenninkmeijer ◽  
Steve Brooks ◽  
...  
Keyword(s):  
Vertical Distribution ◽  
Atmospheric Chemistry ◽  
Lower Troposphere ◽  
Elemental Mercury ◽  
Mercury Species ◽  
Substantial Impact ◽  
Model Studies ◽  
Model Study ◽  
The Impact ◽  
The Vertical Distribution

Abstract. Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model inter-comparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground based observations of mercury concentration and deposition, here we investigate the vertical distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on inter-continental flights. The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including inter-hemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury (RM) patterns depending on altitude. High RM concentrations in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parametrizations in the chemistry transport models also proved to have a substantial impact on model results.

scholarly journals On the impact of future climate change on tropopause folds and tropospheric ozone

2019 ◽  
Vol 19 (22) ◽  
pp. 14387-14401 ◽  
Author(s):  
Dimitris Akritidis ◽  
Andrea Pozzer ◽  
Prodromos Zanis
Keyword(s):  
Atmospheric Chemistry ◽  
Tropospheric Ozone ◽  
Eastern Mediterranean ◽  
Stratospheric Ozone ◽  
Lower Troposphere ◽  
Future Climate Change ◽  
Identification Algorithm ◽  
The Future ◽  
Projected Changes ◽  
The Impact

Abstract. Using a transient simulation for the period 1960–2100 with the state-of-the-art ECHAM5/MESSy Atmospheric Chemistry (EMAC) global model and a tropopause fold identification algorithm, we explore the future projected changes in tropopause folds, stratosphere-to-troposphere transport (STT) of ozone, and tropospheric ozone under the RCP6.0 scenario. Statistically significant changes in tropopause fold frequencies from 1970–1999 to 2070–2099 are identified in both hemispheres, regionally exceeding 3 %, and are associated with the projected changes in the position and intensity of the subtropical jet streams. A strengthening of ozone STT is projected for the future in both hemispheres, with an induced increase in transported stratospheric ozone tracer throughout the whole troposphere, reaching up to 10 nmol mol−1 in the upper troposphere, 8 nmol mol−1 in the middle troposphere, and 3 nmol mol−1 near the surface. Notably, the regions exhibiting the largest changes of ozone STT at 400 hPa coincide with those with the highest fold frequency changes, highlighting the role of the tropopause folding mechanism in STT processes under a changing climate. For both the eastern Mediterranean and Middle East (EMME) and Afghanistan (AFG) regions, which are known as hotspots of fold activity and ozone STT during the summer period, the year-to-year variability of middle-tropospheric ozone with stratospheric origin is largely explained by the short-term variations in ozone at 150 hPa and tropopause fold frequency. Finally, ozone in the lower troposphere is projected to decrease under the RCP6.0 scenario during MAM (March, April, and May) and JJA (June, July, and August) in the Northern Hemisphere and during DJF (December, January, and February) in the Southern Hemisphere, due to the decline of ozone precursor emissions and the enhanced ozone loss from higher water vapour abundances, while in the rest of the troposphere ozone shows a remarkable increase owing mainly to the STT strengthening and the stratospheric ozone recovery.

scholarly journals Multi-model study of mercury dispersion in the atmosphere: vertical and interhemispheric distribution of mercury species

2017 ◽  
Vol 17 (11) ◽  
pp. 6925-6955 ◽  
Author(s):  
Johannes Bieser ◽  
Franz Slemr ◽  
Jesse Ambrose ◽  
Carl Brenninkmeijer ◽  
Steve Brooks ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Lower Troposphere ◽  
Elemental Mercury ◽  
Mercury Species ◽  
Substantial Impact ◽  
Model Studies ◽  
Model Study ◽  
High Concentrations ◽  
Intercomparison Study ◽  
The Impact

Abstract. Atmospheric chemistry and transport of mercury play a key role in the global mercury cycle. However, there are still considerable knowledge gaps concerning the fate of mercury in the atmosphere. This is the second part of a model intercomparison study investigating the impact of atmospheric chemistry and emissions on mercury in the atmosphere. While the first study focused on ground-based observations of mercury concentration and deposition, here we investigate the vertical and interhemispheric distribution and speciation of mercury from the planetary boundary layer to the lower stratosphere. So far, there have been few model studies investigating the vertical distribution of mercury, mostly focusing on single aircraft campaigns. Here, we present a first comprehensive analysis based on various aircraft observations in Europe, North America, and on intercontinental flights. The investigated models proved to be able to reproduce the distribution of total and elemental mercury concentrations in the troposphere including interhemispheric trends. One key aspect of the study is the investigation of mercury oxidation in the troposphere. We found that different chemistry schemes were better at reproducing observed oxidized mercury patterns depending on altitude. High concentrations of oxidized mercury in the upper troposphere could be reproduced with oxidation by bromine while elevated concentrations in the lower troposphere were better reproduced by OH and ozone chemistry. However, the results were not always conclusive as the physical and chemical parameterizations in the chemistry transport models also proved to have a substantial impact on model results.

scholarly journals The global impact of the transport sectors on atmospheric aerosol: simulations for year 2000 emissions

2013 ◽  
Vol 13 (19) ◽  
pp. 9939-9970 ◽  
Author(s):  
M. Righi ◽  
J. Hendricks ◽  
R. Sausen
Keyword(s):  
Size Distribution ◽  
Atmospheric Chemistry ◽  
Particle Number ◽  
Climate Model ◽  
Climate Impacts ◽  
Transport Sector ◽  
Intergovernmental Panel ◽  
Data Set ◽  
Surface Level ◽  
The Impact

Abstract. We use the EMAC (ECHAM/MESSy Atmospheric Chemistry) global model with the aerosol module MADE (Modal Aerosol Dynamics model for Europe, adapted for global applications) to quantify the impact of transport emissions (land transport, shipping and aviation) on the global aerosol. We consider a present-day (2000) scenario according to the CMIP5 (Climate Model Intercomparison Project Phase 5) emission data set developed in support of the IPCC (Intergovernmental Panel on Climate Change) Fifth Assessment Report. The model takes into account particle mass and number emissions: The latter are derived from mass emissions under different assumptions on the size distribution of particles emitted by the three transport sectors. Additional sensitivity experiments are performed to quantify the effects of the uncertainties behind such assumptions. The model simulations show that the impact of the transport sectors closely matches the emission patterns. Land transport is the most important source of black carbon (BC) pollution in the USA, Europe and the Arabian Peninsula, contributing up to 60–70% of the total surface-level BC concentration in these regions. Shipping contributes about 40–60% of the total aerosol sulfate surface-level concentration along the most-traveled routes of the northern Atlantic and northern Pacific oceans, with a significant impact (~ 10–20%) along the coastlines. Aviation mostly affects aerosol number, contributing about 30–40% of the particle number concentration in the northern midlatitudes' upper troposphere (7–12 km), although significant effects are also simulated at the ground, due to the emissions from landing and take-off cycles. The transport-induced perturbations to the particle number concentrations are very sensitive to the assumptions on the size distribution of emitted particles, with the largest uncertainties (about one order of magnitude) obtained for the land transport sector. The simulated climate impacts, due to aerosol direct and indirect effects, are strongest for the shipping sector, in the range of −222.0 to −153.3 mW m−2, as a consequence of the large impact of sulfate aerosol on low marine clouds and their optical properties.

scholarly journals The global impact of the transport sectors on atmospheric aerosol in 2030 – Part 2: Aviation

2016 ◽  
Vol 16 (7) ◽  
pp. 4481-4495 ◽  
Author(s):  
Mattia Righi ◽  
Johannes Hendricks ◽  
Robert Sausen
Keyword(s):  
Atmospheric Chemistry ◽  
Atmospheric Aerosol ◽  
Radiative Forcing ◽  
Particle Number ◽  
Number Concentration ◽  
Radiation Budget ◽  
Transport Sector ◽  
Particle Number Concentration ◽  
Year 2000 ◽  
The Impact

Abstract. We use the EMAC (ECHAM/MESSy Atmospheric Chemistry) global climate–chemistry model coupled to the aerosol module MADE (Modal Aerosol Dynamics model for Europe, adapted for global applications) to simulate the impact of aviation emissions on global atmospheric aerosol and climate in 2030. Emissions of short-lived gas and aerosol species follow the four Representative Concentration Pathways (RCPs) designed in support of the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. We compare our findings with the results of a previous study with the same model configuration focusing on year 2000 emissions. We also characterize the aviation results in the context of the other transport sectors presented in a companion paper. In spite of a relevant increase in aviation traffic volume and resulting emissions of aerosol (black carbon) and aerosol precursor species (nitrogen oxides and sulfur dioxide), the aviation effect on particle mass concentration in 2030 remains quite negligible (on the order of a few ng m−3), about 1 order of magnitude less than the increase in concentration due to other emission sources. Due to the relatively small size of the aviation-induced aerosol, however, the increase in particle number concentration is significant in all scenarios (about 1000 cm−3), mostly affecting the northern mid-latitudes at typical flight altitudes (7–12 km). This largely contributes to the overall change in particle number concentration between 2000 and 2030, which also results in significant climate effects due to aerosol–cloud interactions. Aviation is the only transport sector for which a larger impact on the Earth's radiation budget is simulated in the future: the aviation-induced radiative forcing in 2030 is more than doubled with respect to the year 2000 value of −15 mW m−2 in all scenarios, with a maximum value of −63 mW m−2 simulated for RCP2.6.

Quantifying burning efficiency in Megacities using NO2/CO ratio from the Tropospheric Monitoring Instrument (TROPOMI)

2020 ◽  
Author(s):  
Srijana Lama ◽  
Sander Houweling ◽  
Folkert Boersma ◽  
Ilse Aben ◽  
Hugo Denier van der Gon ◽  
...  
Keyword(s):  
Air Quality ◽  
Los Angeles ◽  
Atmospheric Chemistry ◽  
European Space Agency ◽  
Monitoring Network ◽  
Emission Factors ◽  
Rapid Urbanization ◽  
Global Emission ◽  
The Impact ◽  
Emission Ratios

<p>Economic development and rapid urbanization have increased the consumption of fossil fuel in megacities degrading the local air quality. Burning efficiency is a major factor determining the impact of fuel burning on the environment. It varies with environmental conditions and influences the ratio at which pollutants are emitted, as expressed by the emission factor. Emission factors are an important source of uncertainty in global emission inventories.</p><p>To improve the quantification of burning efficiency and emission factors, this study investigates co-located NO<sub>2</sub> and CO satellite retrievals from TROPOMI over the megacities of Tehran, Mexico City, Cairo, Riyadh, Lahore and Los Angeles. The TROPOMI instrument was successfully launched by the European Space Agency on 13 October, 2017. It measures atmospheric trace gases with daily coverage and a spatial resolution of 7x7 km<sup>2</sup>. At this resolution, TROPOMI detects hotspots of CO and NO<sub>2</sub> pollution over megacities in single satellite overpasses. The Upwind Background and Plume rotation methods are applied to quantify and evaluate TROPOMI derived ∆NO<sub>2</sub>/∆CO ratios. TROPOMI derived ∆NO<sub>2</sub>/∆CO ratios show a strong correlation (r = 0.85 and 0.7) with emission ratios from the Emission Database for Global Atmospheric Research (EDGAR v4.3.2) and Monitoring Atmospheric Chemistry and Climate and CityZen (MACCity) 2018, with the highest ratio for Riyadh and lowest for Lahore. Inventory-derived emission ratios are larger than TROPOMI-derived total column ratios by 60 to 80%. As we will show, this can largely be explained by the limited lifetime of NO<sub>2</sub> and the different vertical sensitivity of the TROPOMI NO<sub>2 </sub>and CO column retrievals. Taking this into account, TROPOMI retrieved emission ratios are generally within 10 to 25% of MACCity. However, larger differences, up to 80%, are found with EDGAR. For Los Angeles, both inventories overestimate NO2/CO ratios compared with TROPOMI. Validation using the air quality monitoring network of Los Angeles supports the lower ∆NO<sub>2</sub>/∆CO ratios inferred from TROPOMI, indicating that burning efficiencies in Los Angeles are indeed poorer than indicated by the inventories.</p><p><strong> </strong></p>

scholarly journals Accounting for non-linear chemistry of ship plumes in the GEOS-Chem global chemistry transport model

2011 ◽  
Vol 11 (22) ◽  
pp. 11707-11722 ◽  
Author(s):  
G. C. M. Vinken ◽  
K. F. Boersma ◽  
D. J. Jacob ◽  
E. W. Meijer
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Lower Troposphere ◽  
Secondary Compounds ◽  
Computationally Efficient ◽  
Ship Emissions ◽  
The North ◽  
Non Linear ◽  
Marine Areas ◽  
Improved Model

Abstract. We present a computationally efficient approach to account for the non-linear chemistry occurring during the dispersion of ship exhaust plumes in a global 3-D model of atmospheric chemistry (GEOS-Chem). We use a plume-in-grid formulation where ship emissions age chemically for 5 h before being released in the global model grid. Besides reducing the original ship NOx emissions in GEOS-Chem, our approach also releases the secondary compounds ozone and HNO3, produced during the 5 h after the original emissions, into the model. We applied our improved method and also the widely used "instant dilution" approach to a 1-yr GEOS-Chem simulation of global tropospheric ozone-NOx-VOC-aerosol chemistry. We also ran simulations with the standard model (emitting 10 molecules O3 and 1 molecule HNO3 per ship NOx molecule), and a model without any ship emissions at all. The model without any ship emissions simulates up to 0.1 ppbv (or 50%) lower NOx concentrations over the North Atlantic in July than our improved GEOS-Chem model. "Instant dilution" overestimates NOx concentrations by 0.1 ppbv (50%) and ozone by 3–5 ppbv (10–25%), compared to our improved model over this region. These conclusions are supported by comparing simulated and observed NOx and ozone concentrations in the lower troposphere over the Pacific Ocean. The comparisons show that the improved GEOS-Chem model simulates NOx concentrations in between the instant dilution model and the model without ship emissions, which results in lower O3 concentrations than the instant dilution model. The relative differences in simulated NOx and ozone between our improved approach and instant dilution are smallest over strongly polluted seas (e.g. North Sea), suggesting that accounting for in-plume chemistry is most relevant for pristine marine areas.

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