scholarly journals Understanding the impact of recent advances in isoprene photooxidation on simulations of regional air quality

2012 ◽  
Vol 12 (10) ◽  
pp. 27173-27218 ◽  
Author(s):  
Y. Xie ◽  
F. Paulot ◽  
W. P. L. Carter ◽  
C. G. Nolte ◽  
D. J. Luecken ◽  
...  
Keyword(s):  
Air Quality ◽  
Dry Deposition ◽  
Deposition Velocity ◽  
Chemical Mechanism ◽  
Recent Advances ◽  
Dry Deposition Velocity ◽  
Isoprene Nitrates ◽  
Isoprene Oxidation ◽  
Oxidation Chemistry ◽  
The Impact

Abstract. The CMAQ model in combination with observations for INTEX-NA/ICARTT 2004 are used to evaluate recent advances in isoprene oxidation chemistry and provide constraints on isoprene nitrate yields, isoprene nitrate lifetimes, and NOx recycling rates. We incorporate recent advances in isoprene oxidation chemistry into the SAPRC-07 chemical mechanism within the US EPA Community Multiscale Air Quality (CMAQ) model. The results show improved model performance for a range of species compared against aircraft observations from the INTEX-NA/ICARTT 2004 field campaign. We further investigate the key processes in isoprene nitrate chemistry and evaluate the impact of uncertainties in the isoprene nitrate yield, NOx (NOx = NO + NO2) recycling efficiency, dry deposition velocity, and RO2 + HO2 reaction rates. We focus our examination in the Southeastern United States, which is impacted by both abundant isoprene emissions and high levels of anthropogenic pollutants. We find that NOx concentrations increase by 4–9% as a result of reduced removal by isoprene nitrate chemistry. O3 increases by 2 ppbv as a result of changes in NOx. OH concentrations increase by 30%, which can be primarily attributed to greater HOx production. We find that the model can capture observed total alkyl and multifunctional nitrates (∑ANs) and their relationship with O3, by assuming either an isoprene nitrate yield of 6% and daytime lifetime of 6 h or a yield of 12% and lifetime of 4 h. Uncertainties in the isoprene nitrates can impact ozone production by 10% and OH concentrations by 6%. The uncertainties in NOx recycling efficiency appear to have larger effects than uncertainties in isoprene nitrate yield and dry deposition velocity. Further progress depends on improved understanding of isoprene oxidation pathways, the rate of NOx recycling from isoprene nitrates, and the fate of the secondary, tertiary, and further oxidation products of isoprene.

scholarly journals Understanding the impact of recent advances in isoprene photooxidation on simulations of regional air quality

2013 ◽  
Vol 13 (16) ◽  
pp. 8439-8455 ◽  
Author(s):  
Y. Xie ◽  
F. Paulot ◽  
W. P. L. Carter ◽  
C. G. Nolte ◽  
D. J. Luecken ◽  
...  
Keyword(s):  
United States ◽  
Air Quality ◽  
Dry Deposition ◽  
Deposition Velocity ◽  
Recent Advances ◽  
Dry Deposition Velocity ◽  
Isoprene Nitrates ◽  
Isoprene Oxidation ◽  
Oxidation Chemistry ◽  
The Impact

Abstract. The CMAQ (Community Multiscale Air Quality) us model in combination with observations for INTEX-NA/ICARTT (Intercontinental Chemical Transport Experiment–North America/International Consortium for Atmospheric Research on Transport and Transformation) 2004 are used to evaluate recent advances in isoprene oxidation chemistry and provide constraints on isoprene nitrate yields, isoprene nitrate lifetimes, and NOx recycling rates. We incorporate recent advances in isoprene oxidation chemistry into the SAPRC-07 chemical mechanism within the US EPA (United States Environmental Protection Agency) CMAQ model. The results show improved model performance for a range of species compared against aircraft observations from the INTEX-NA/ICARTT 2004 field campaign. We further investigate the key processes in isoprene nitrate chemistry and evaluate the impact of uncertainties in the isoprene nitrate yield, NOx (NOx = NO + NO2) recycling efficiency, dry deposition velocity, and RO2 + HO2 reaction rates. We focus our examination on the southeastern United States, which is impacted by both abundant isoprene emissions and high levels of anthropogenic pollutants. We find that NOx concentrations increase by 4–9% as a result of reduced removal by isoprene nitrate chemistry. O3 increases by 2 ppbv as a result of changes in NOx. OH concentrations increase by 30%, which can be primarily attributed to greater HOx production. We find that the model can capture observed total alkyl and multifunctional nitrates (∑ANs) and their relationship with O3 by assuming either an isoprene nitrate yield of 6% and daytime lifetime of 6 hours or a yield of 12% and lifetime of 4 h. Uncertainties in the isoprene nitrates can impact ozone production by 10% and OH concentrations by 6%. The uncertainties in NOx recycling efficiency appear to have larger effects than uncertainties in isoprene nitrate yield and dry deposition velocity. Further progress depends on improved understanding of isoprene oxidation pathways, the rate of NOx recycling from isoprene nitrates, and the fate of the secondary, tertiary, and further oxidation products of isoprene.

scholarly journals Importance of Dry Deposition Parameterization Choice in Global Simulations of Surface Ozone

2019 ◽  
Author(s):  
Anthony Y. H. Wong ◽  
Jeffrey A. Geddes ◽  
Amos P. K. Tai ◽  
Sam J. Silva
Keyword(s):  
Land Cover ◽  
Dry Deposition ◽  
Transport Model ◽  
Surface Ozone ◽  
Deposition Velocity ◽  
Chemical Transport Model ◽  
Area Index ◽  
Ozone Sensitivity ◽  
Dry Deposition Velocity ◽  
The Impact

Abstract. Dry deposition is the second largest sink of tropospheric ozone. Increasing evidence has shown that ozone dry deposition actively links meteorology and hydrology with ozone air quality. However, there is little systematic investigation on the performance of different ozone dry deposition parameterizations at the global scale, and how parameterization choice can impact surface ozone simulations. Here we present the results of the first global, multi-decade modelling and evaluation of ozone dry deposition velocity (vd) using multiple ozone dry deposition parameterizations. We use consistent assimilated meteorology and satellite-derived leaf area index (LAI) to simulate vd over 1982–2011 driven by four sets of ozone dry deposition parametrization that are representative of the current approaches of global ozone dry deposition modelling, such that the differences in simulated vd are entirely due to differences in deposition model structures. In addition, we use the surface ozone sensitivity to vd predicted by a chemical transport model to estimate the impact of mean and variability of ozone dry deposition velocity on surface ozone. Our estimated vd from four different parameterizations are evaluated against field observations, and while performance varies considerably by land cover types, our results suggest that none of the parameterizations are universally better than the others. Discrepancy in simulated mean vd among the parameterizations is estimated to cause 2 to 5 ppbv of discrepancy in surface ozone in the Northern Hemisphere (NH) and up to 8 ppbv in tropical rainforest in July, and up to 8 ppbv in tropical rainforests and seasonally dry tropical forests in Indochina in December. Parameterization-specific biases based on individual land cover type and hydroclimate are found to be the two main drivers of such discrepancies. We find statistically significant trends in the multiannual time series of simulated July daytime vd in all parameterizations, driven by warming and drying (southern Amazonia, southern African savannah and Mongolia) or greening (high latitudes). The trends in July daytime vd is estimated to be 1 % yr−1 and leads to up to 3 ppbv of surface ozone changes over 1982–2011. The interannual coefficient of variation (CV) of July daytime mean vd in NH is found to be 5 %–15 %, with spatial distribution that varies with the dry deposition parameterization. Our sensitivity simulations suggest this can contribute between 0.5 to 2 ppbv to interannual variability (IAV) in surface ozone, but all models tend to underestimate interannual CV when compared to long-term ozone flux observations. We also find that IAV in some dry deposition parameterizations are more sensitive to LAI while others are more sensitive to climate. Comparisons with other published estimates of the IAV of background ozone confirm that ozone dry deposition can be an important part of natural surface ozone variability. Our results demonstrate the importance of ozone dry deposition parameterization choice on surface ozone modelling, and the impact of IAV of vd on surface ozone, thus making a strong case for further measurement, evaluation and model-data integration of ozone dry deposition on different spatiotemporal scales.

scholarly journals Importance of dry deposition parameterization choice in global simulations of surface ozone

2019 ◽  
Vol 19 (22) ◽  
pp. 14365-14385 ◽  
Author(s):  
Anthony Y. H. Wong ◽  
Jeffrey A. Geddes ◽  
Amos P. K. Tai ◽  
Sam J. Silva
Keyword(s):  
Land Cover ◽  
Dry Deposition ◽  
Transport Model ◽  
Surface Ozone ◽  
Deposition Velocity ◽  
Tropical Rainforests ◽  
Area Index ◽  
Ozone Sensitivity ◽  
Dry Deposition Velocity ◽  
The Impact

Abstract. Dry deposition is a major sink of tropospheric ozone. Increasing evidence has shown that ozone dry deposition actively links meteorology and hydrology with ozone air quality. However, there is little systematic investigation on the performance of different ozone dry deposition parameterizations at the global scale and how parameterization choice can impact surface ozone simulations. Here, we present the results of the first global, multidecadal modelling and evaluation of ozone dry deposition velocity (vd) using multiple ozone dry deposition parameterizations. We model ozone dry deposition velocities over 1982–2011 using four ozone dry deposition parameterizations that are representative of current approaches in global ozone dry deposition modelling. We use consistent assimilated meteorology, land cover, and satellite-derived leaf area index (LAI) across all four, such that the differences in simulated vd are entirely due to differences in deposition model structures or assumptions about how land types are treated in each. In addition, we use the surface ozone sensitivity to vd predicted by a chemical transport model to estimate the impact of mean and variability of ozone dry deposition velocity on surface ozone. Our estimated vd values from four different parameterizations are evaluated against field observations, and while performance varies considerably by land cover types, our results suggest that none of the parameterizations are universally better than the others. Discrepancy in simulated mean vd among the parameterizations is estimated to cause 2 to 5 ppbv of discrepancy in surface ozone in the Northern Hemisphere (NH) and up to 8 ppbv in tropical rainforests in July, and up to 8 ppbv in tropical rainforests and seasonally dry tropical forests in Indochina in December. Parameterization-specific biases based on individual land cover type and hydroclimate are found to be the two main drivers of such discrepancies. We find statistically significant trends in the multiannual time series of simulated July daytime vd in all parameterizations, driven by warming and drying (southern Amazonia, southern African savannah, and Mongolia) or greening (high latitudes). The trend in July daytime vd is estimated to be 1 % yr−1 and leads to up to 3 ppbv of surface ozone changes over 1982–2011. The interannual coefficient of variation (CV) of July daytime mean vd in NH is found to be 5 %–15 %, with spatial distribution that varies with the dry deposition parameterization. Our sensitivity simulations suggest this can contribute between 0.5 to 2 ppbv to interannual variability (IAV) in surface ozone, but all models tend to underestimate interannual CV when compared to long-term ozone flux observations. We also find that IAV in some dry deposition parameterizations is more sensitive to LAI, while in others it is more sensitive to climate. Comparisons with other published estimates of the IAV of background ozone confirm that ozone dry deposition can be an important part of natural surface ozone variability. Our results demonstrate the importance of ozone dry deposition parameterization choice on surface ozone modelling and the impact of IAV of vd on surface ozone, thus making a strong case for further measurement, evaluation, and model–data integration of ozone dry deposition on different spatiotemporal scales.

To what extent does the environmental magnetism technique acts as a way of assessing the uptake of atmospheric particles by plants?

2021 ◽  
Author(s):  
Sarah Letaïef ◽  
Pierre Camps ◽  
Thierry Poidras ◽  
Patrick Nicol ◽  
Delphine Bosch ◽  
...  
Keyword(s):  
Air Quality ◽  
Endemic Species ◽  
Fine Particles ◽  
Magnetic Measurements ◽  
Deposition Velocity ◽  
Environmental Magnetism ◽  
Air Pollutant ◽  
Atmospheric Pollutants ◽  
Area Index ◽  
The Impact

<p>Numerous studies have already shown the possibility of tracing the sources, the<br>compositions, and the concentration of atmospheric pollutants deposited on plant<br>leaves. In environmental geochemistry, inter-element and isotope ratios from<br>chemical element assays have been used for these purposes. Alternatively,<br>environmental magnetism represents a quick and inexpensive asset that is<br>increasingly used as a relative indicator for concentrations of air pollutant on bio<br>accumulator surfaces such as plants. However, a fundamental issue is still pending:<br>Do plants in urban areas represent a sink for fine particles that is sufficiently effective<br>to improve air quality? This is a very topical issue because some studies have shown<br>that the foliage can trap fine particles by different dry deposition processes, while<br>other studies based on CFD models indicate that plant hedges in cities can hinder<br>the atmospheric dispersion of pollutants and therefore increase pollution at the level of<br>emission sources such as traffic. To date, no consensus was made because several<br>factors not necessary well known must be taken into account, such as, PM<br>concentration and size, prevailing wind, surface structures, epicuticular wax, to<br>mention just a few examples. A first step toward the understanding of the impact of<br>urban greens on air quality is the precise determination of the deposition velocity (Vd)<br>parameter. This latter is specific for each species and it is most of the time<br>underestimated in modeling-based studies by taking standard values.<br>In that perspective, we built a wind tunnel (6 m long, 86 cm wide and 86 cm high) to<br>perform analogical experiments on different endemic species. All parameters are<br>controlled, i.e, the wind speed, the nature and the injection time of pollutants (Gasoline<br>or Diesel exhausts, brakes or tires dust, etc…). We can provide the PM concentrations<br>upwind and downwind of natural reconstituted hedges by two dustmeters (LOACs -<br>MétéoModem). Beforehand, parameters such as the hedge resistance (%) or the leaf<br>area index (LAI) have been estimated for each studied specie to allow comparability<br>between plants removal potential. The interest would ultimately combine PM<br>concentration measured by size bins from the LOACs with magnetic measurements<br>(ARM, IRM100mT, IRM300mT and SIRM) of plant leaves. The idea is to check whether it<br>would be possible to precisely determine in situ the dust removal rate by urban greens<br>with environmental magnetism measurements. Up to now, we have carried out on<br>different endemic species such as Elaeagnus x ebbingei leaves and Mediterranean<br>pine needles, the results of which will be presented.</p>

scholarly journals Impacts of future land use and land cover change on mid-21<sup>st</sup>-century surface ozone air quality: Distinguishing between the biogeophysical and biogeochemical effects

2019 ◽  
Author(s):  
Lang Wang ◽  
Amos P. K. Tai ◽  
Chi-Yung Tam ◽  
Mehliyar Sadiq ◽  
Peng Wang ◽  
...  
Keyword(s):  
Land Use ◽  
Air Quality ◽  
Land Cover ◽  
Dry Deposition ◽  
Surface Ozone ◽  
Boreal Summer ◽  
Ozone Pollution ◽  
Lulc Change ◽  
Lulc Changes ◽  
The Impact

Abstract. Surface ozone (O3) is an important air pollutant and greenhouse gas. Land use and land cover (LULC) is one of the critical factors influencing ozone, in addition to anthropogenic emissions and climate. LULC change can on the one hand affect ozone biogeochemically, i.e., via dry deposition and biogenic emissions of volatile organic compounds (VOCs). LULC change can on the other hand alter regional- to large-scale climate through modifying albedo and evapotranspiration, which can lead to changes in surface temperature, hydrometeorology and atmospheric circulation that can ultimately impact ozone biogeophysically over local and remote areas. Such biogeophysical effects of LULC on ozone are largely understudied. This study investigates the individual and combined biogeophysical and biogeochemical effects of LULC on ozone, and explicitly examines the critical pathway for how LULC change impacts ozone pollution. A global coupled atmosphere–chemistry–land model is driven by projected LULC changes from the present day (2000) to future (2050) under RCP4.5 and RCP8.5 scenarios, focusing on the boreal summer. Results reveal that when considering biogeochemical effects only, surface ozone is predicted to have slight changes by up to 2 ppbv maximum in some areas due to LULC changes. It is primarily driven by changes in isoprene emission and dry deposition counteracting each other in shaping ozone. In contrast, when considering the integrated effect of LULC, ozone is more substantially altered by up to 6 ppbv over several regions, reflecting the importance of biogeophysical effects on ozone changes. Furthermore, large areas of these ozone changes are found over the regions without LULC changes where the biogeophysical effect is the only pathway for such changes. The mechanism is likely that LULC change induces a regional circulation response, in particular the formation of anomalous stationary high-pressure systems, shifting of moisture transport, and near-surface warming over the middle-to-high northern latitudes in boreal summer, owing to associated changes in albedo and surface energy budget. Such temperature changes then alter ozone substantially. We conclude that the biogeophysical effect of LULC is an important pathway for the influence of LULC change on ozone air quality over both local and remote regions, even in locations without significant LULC changes. Overlooking the impact of biogeophysical effect may cause evident underestimation of the impacts of LULC change on ozone pollution.

Recent updates to the atmospheric aerosol modelling of the ECMWF IFS in support to CAMS

2021 ◽  
Author(s):  
Samuel Remy ◽  
Zak Kipling ◽  
Vincent Huijnen ◽  
Johannes Flemming ◽  
Swen Metzger ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dry Deposition ◽  
Wet Deposition ◽  
Deposition Velocity ◽  
Surface Concentration ◽  
Atmospheric Composition ◽  
Small Scale ◽  
Skill Scores ◽  
Simulated Surface ◽  
The Impact

&lt;p&gt;The Integrated Forecasting System (IFS) of ECMWF is used within the Copernicus Atmosphere Monitoring Service (CAMS) to provide global analyses and forecasts of atmospheric composition, including aerosols as well as reactive trace gases and greenhouse gases.&lt;/p&gt;&lt;p&gt;The aerosol model of the IFS, IFS-AER, is a simple sectional-bulk scheme that forecasts seven species: &amp;#160;dust, sea-salt, black carbon, organic matter, sulfate, and &amp;#160;since July 2019, nitrate and ammonium. &amp;#160;The main developments that have been recently carried out, tested and are now contemplated for implementation in the next operational version (known as cycle 48r1) are presented here.&lt;/p&gt;&lt;p&gt;The dry deposition velocities are computed as a function of roughness length, particle size and surface friction velocity, while wet deposition depends mainly on the precipitation fluxes. The parameterizations of both dry and wet deposition have been upgraded with more recent schemes, which have been shown to improve the simulated deposition fluxes for several aerosol species. The impact of this upgrade on the skill scores of simulated aerosol optical depth (AOD) and surface particulate matter concentrations against a range of observations is very positive.&lt;/p&gt;&lt;p&gt;The simulated surface concentration of nitrate and ammonium are frequently strongly overestimated over Europe and the &amp;#160;United States in the current version of the IFS. Nitrate, ammonium, and their precursors nitric acid and ammonia, were evaluated against a range of ground and remote data and it was found that the recently-implemented gas-particle partitioning scheme is too efficient in producing nitrate and ammonium particles.&lt;/p&gt;&lt;p&gt;A series of small-scale changes, such as adjusting nitrate dry deposition velocity, direct particulate sulphate emission, and limiting nitrate/ammonium production by the concentration of mineral cations, have been implemented and shown to be effective in improving the simulated surface concentration of &amp;#160;nitrate and ammonium.&lt;/p&gt;&lt;p&gt;The representation of secondary organic aerosol (SOA) in the IFS has been overhauled with the introduction of a new SOA species, distinct from primary organic matter, with anthropogenic and biogenic components. The implementation of this new species leads to a significant improvement of the simulated surface concentration of organic carbon. An evaluation of simulated SOA concentrations at the surface against climatological values derived from observations using Positive Matrix Factorisation (PMF) techniques also shows a reasonable agreement.&lt;/p&gt;

Determining PM2.5 dry deposition velocity on plant leaves: An indirect experimental method

2019 ◽  
Vol 46 ◽  
pp. 126467 ◽  
Author(s):  
Shan Yin ◽  
Xuyi Zhang ◽  
Annie Yu ◽  
Ningxiao Sun ◽  
Junyao Lyu ◽  
...  
Keyword(s):  
Experimental Method ◽  
Dry Deposition ◽  
Deposition Velocity ◽  
Plant Leaves ◽  
Dry Deposition Velocity
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