scholarly journals The HNO<sub>3</sub> forming branch of the HO<sub>2</sub> + NO reaction: pre-industrial-to-present trends in atmospheric species and radiative forcings

2011 ◽  
Vol 11 (5) ◽  
pp. 14801-14835 ◽  
Author(s):  
O. A. Søvde ◽  
C. R. Hoyle ◽  
G. Myhre ◽  
I. S. A. Isaksen
Keyword(s):  
Radiative Forcing ◽  
Transport Model ◽  
Three Dimensional ◽  
Branching Ratio ◽  
Pressure Effects ◽  
Atmospheric Composition ◽  
Chemistry Transport Model ◽  
Radiative Forcings ◽  
Atmospheric Species ◽  
Temperature And Pressure Effects

Abstract. Recent laboratory measurements have shown the existence of a HNO3 forming branch of the HO2 + NO reaction. This reaction is the main source of atmospheric O3, through the subsequent photolysis of NO2, as well as being a major source of OH. The branching of the reaction to HNO3 reduces the formation of these species significantly, affecting O3 abundances, climate and the oxidation capacity of the troposphere. The Oslo CTM2, a three-dimensional chemistry transport model, is used to calculate atmospheric composition and trends with and without the new reaction branch. Results for the present day atmosphere, when both temperature and pressure effects on the branching ratio are accounted for, show an increase of the global, annual mean methane lifetime by 10.9 %, resulting from a 14.1 % reduction in the global, annual mean OH concentration. Comparisons with measurements show that including the new branch improves the modelled O3, but that it is not possible to conclude whether the NOy distribution improves. We model an approximately 11 % reduction in the tropical tropospheric O3 increase since pre-industrial times, as well as an 8 % decrease in the trend of OH concentration, when the new branch is accounted for. The radiative forcing due to changes in O3 over the industrial era was calculated as 0.33 W m−2, reducing to 0.26 W m−2 with the new reaction branch. These results are significant, and it is important that this reaction branching is confirmed by other laboratory groups.

scholarly journals The HNO<sub>3</sub> forming branch of the HO<sub>2</sub> + NO reaction: pre-industrial-to-present trends in atmospheric species and radiative forcings

2011 ◽  
Vol 11 (17) ◽  
pp. 8929-8943 ◽  
Author(s):  
O. A. Søvde ◽  
C. R. Hoyle ◽  
G. Myhre ◽  
I. S. A. Isaksen
Keyword(s):  
Radiative Forcing ◽  
Transport Model ◽  
Three Dimensional ◽  
Branching Ratio ◽  
Pressure Effects ◽  
Atmospheric Composition ◽  
Radiative Forcings ◽  
Atmospheric Species ◽  
Tropospheric O3 ◽  
The Tropics

Abstract. Recent laboratory measurements have shown the existence of a HNO3 forming branch of the HO2 + NO reaction. This reaction is the main source of tropospheric O3, through the subsequent photolysis of NO2, as well as being a major source of OH. The branching of the reaction to HNO3 reduces the formation of these species significantly, affecting O3 abundances, radiative forcing and the oxidation capacity of the troposphere. The Oslo CTM2, a three-dimensional chemistry transport model, is used to calculate atmospheric composition and trends with and without the new reaction branch. Results for the present day atmosphere, when both temperature and pressure effects on the branching ratio are accounted for, show an 11 % reduction in the calculated tropospheric burden of O3, with the main contribution from the tropics. An increase of the global, annual mean methane lifetime by 10.9 %, resulting from a 14.1 % reduction in the global, annual mean OH concentration is also found. Comparisons with measurements show that including the new branch improves the modelled O3 in the Oslo CTM2, but that it is not possible to conclude whether the NOy distribution improves. We model an approximately 11 % reduction in the tropical tropospheric O3 increase since pre-industrial times, and a 4 % reduction of the increase in total tropospheric burden. Also, an 8 % decrease in the trend of OH concentrations is calculated, when the new branch is accounted for. The radiative forcing due to changes in O3 over the industrial era was calculated as 0.33 W m−2, reducing to 0.26 W m−2 with the new reaction branch. These results are significant, and it is important that this reaction branching is confirmed by other laboratory groups.

scholarly journals Key drivers of ozone change and its radiative forcing over the 21st century

2018 ◽  
Vol 18 (9) ◽  
pp. 6121-6139 ◽  
Author(s):  
Fernando Iglesias-Suarez ◽  
Douglas E. Kinnison ◽  
Alexandru Rap ◽  
Amanda C. Maycock ◽  
Oliver Wild ◽  
...  
Keyword(s):  
Climate Change ◽  
21St Century ◽  
Radiative Forcing ◽  
Climate Model ◽  
Stratospheric Ozone ◽  
Atmospheric Composition ◽  
Climate Conditions ◽  
Radiative Balance ◽  
Radiative Forcings ◽  
Year 2000

Abstract. Over the 21st century changes in both tropospheric and stratospheric ozone are likely to have important consequences for the Earth's radiative balance. In this study, we investigate the radiative forcing from future ozone changes using the Community Earth System Model (CESM1), with the Whole Atmosphere Community Climate Model (WACCM), and including fully coupled radiation and chemistry schemes. Using year 2100 conditions from the Representative Concentration Pathway 8.5 (RCP8.5) scenario, we quantify the individual contributions to ozone radiative forcing of (1) climate change, (2) reduced concentrations of ozone depleting substances (ODSs), and (3) methane increases. We calculate future ozone radiative forcings and their standard error (SE; associated with inter-annual variability of ozone) relative to year 2000 of (1) 33 ± 104 m Wm−2, (2) 163 ± 109 m Wm−2, and (3) 238 ± 113 m Wm−2 due to climate change, ODSs, and methane, respectively. Our best estimate of net ozone forcing in this set of simulations is 430 ± 130 m Wm−2 relative to year 2000 and 760 ± 230 m Wm−2 relative to year 1750, with the 95 % confidence interval given by ±30 %. We find that the overall long-term tropospheric ozone forcing from methane chemistry–climate feedbacks related to OH and methane lifetime is relatively small (46 m Wm−2). Ozone radiative forcing associated with climate change and stratospheric ozone recovery are robust with regard to background climate conditions, even though the ozone response is sensitive to both changes in atmospheric composition and climate. Changes in stratospheric-produced ozone account for ∼ 50 % of the overall radiative forcing for the 2000–2100 period in this set of simulations, highlighting the key role of the stratosphere in determining future ozone radiative forcing.

scholarly journals Assimilation of surface NO<sub>2</sub> and O<sub>3</sub> observations into the SILAM chemistry transport model

2015 ◽  
Vol 8 (2) ◽  
pp. 191-203 ◽  
Author(s):  
J. Vira ◽  
M. Sofiev
Keyword(s):  
Transport Model ◽  
Time Of Day ◽  
Covariance Matrices ◽  
Atmospheric Composition ◽  
Integrated Modelling ◽  
Daily Maximum ◽  
Observation Error ◽  
Data Set ◽  
Chemistry Transport Model ◽  
Error Covariance

Abstract. This paper describes the assimilation of trace gas observations into the chemistry transport model SILAM (System for Integrated modeLling of Atmospheric coMposition) using the 3D-Var method. Assimilation results for the year 2012 are presented for the prominent photochemical pollutants ozone (O3) and nitrogen dioxide (NO2). Both species are covered by the AirBase observation database, which provides the observational data set used in this study. Attention was paid to the background and observation error covariance matrices, which were obtained primarily by the iterative application of a posteriori diagnostics. The diagnostics were computed separately for 2 months representing summer and winter conditions, and further disaggregated by time of day. This enabled the derivation of background and observation error covariance definitions, which included both seasonal and diurnal variation. The consistency of the obtained covariance matrices was verified using χ2 diagnostics. The analysis scores were computed for a control set of observation stations withheld from assimilation. Compared to a free-running model simulation, the correlation coefficient for daily maximum values was improved from 0.8 to 0.9 for O3 and from 0.53 to 0.63 for NO2.

scholarly journals CHIMERE-2017: from urban to hemispheric chemistry-transport modeling

2017 ◽  
Vol 10 (6) ◽  
pp. 2397-2423 ◽  
Author(s):  
Sylvain Mailler ◽  
Laurent Menut ◽  
Dmitry Khvorostyanov ◽  
Myrto Valari ◽  
Florian Couvidat ◽  
...  
Keyword(s):  
Transport Model ◽  
Model Simulation ◽  
Point Of View ◽  
Atmospheric Composition ◽  
Test Case ◽  
Polar Regions ◽  
Chemistry Transport Model ◽  
Computational Point ◽  
Improve Model ◽  
Code Complexity

Abstract. CHIMERE is a chemistry-transport model designed for regional atmospheric composition. It can be used at a variety of scales from local to continental domains. However, due to the model design and its historical use as a regional model, major limitations had remained, hampering its use at hemispheric scale, due to the coordinate system used for transport as well as to missing processes that are important in regions outside Europe. Most of these limitations have been removed in the CHIMERE-2017 version, allowing its use in any region of the world and at any scale, from the scale of a single urban area up to hemispheric scale, with or without polar regions included. Other important improvements have been made in the treatment of the physical processes affecting aerosols and the emissions of mineral dust. From a computational point of view, the parallelization strategy of the model has also been updated in order to improve model numerical performance and reduce the code complexity. The present article describes all these changes. Statistical scores for a model simulation over continental Europe are presented, and a simulation of the circumpolar transport of volcanic ash plume from the Puyehue volcanic eruption in June 2011 in Chile provides a test case for the new model version at hemispheric scale.

scholarly journals Technical Note: A new SIze REsolved Aerosol Model (SIREAM)

2007 ◽  
Vol 7 (6) ◽  
pp. 1537-1547 ◽  
Author(s):  
E. Debry ◽  
K. Fahey ◽  
K. Sartelet ◽  
B. Sportisse ◽  
M. Tombette
Keyword(s):  
Size Distribution ◽  
Transport Model ◽  
Three Dimensional ◽  
Technical Note ◽  
Aerosol Size Distribution ◽  
Short Paper ◽  
Chemistry Transport Model ◽  
Dynamical Mass ◽  
Aerosol Model ◽  
Transfer Method

Abstract. We briefly present in this short paper a new SIze REsolved Aerosol Model (SIREAM) which simulates the evolution of atmospheric aerosol by solving the General Dynamic Equation (GDE). SIREAM segregates the aerosol size distribution into sections and solves the GDE by splitting coagulation and condensation/evaporation-nucleation. A quasi-stationary sectional approach is used to describe the size distribution change due to condensation/evaporation, and a hybrid equilibrium/dynamical mass-transfer method has been developed to lower the computational burden. SIREAM uses the same physical parameterizations as those used in the Modal Aerosol Model, MAM Sartelet et al. (2006). It is hosted in the modeling system Polyphemus Mallet et al., 2007, but can be linked to any other three-dimensional Chemistry-Transport Model.

scholarly journals Technical Note: A new SIze REsolved Aerosol Model (SIREAM)

2006 ◽  
Vol 6 (6) ◽  
pp. 11845-11875 ◽  
Author(s):  
E. Debry ◽  
K. Fahey ◽  
K. Sartelet ◽  
B. Sportisse ◽  
M. Tombette
Keyword(s):  
Size Distribution ◽  
Atmospheric Aerosol ◽  
Transport Model ◽  
Three Dimensional ◽  
Technical Note ◽  
Aerosol Size Distribution ◽  
Short Paper ◽  
Chemistry Transport Model ◽  
Aerosol Model ◽  
General Dynamic

Abstract. We briefly present in this short paper a new SIze REsolved Aerosol Model (SIREAM) which simulates the evolution of atmospheric aerosol by solving the General Dynamic Equation (GDE). SIREAM segregates the aerosol size distribution into sections and solves the GDE by splitting coagulation and condensation/evaporation. A moving sectional approach is used to describe the size distribution change due to condensation/evaporation and a hybrid method has been developed to lower the computational burden. SIREAM uses the same physical parameterizations as those used in the Modal Aerosol Model, MAM sartelet05development. It is hosted in the modeling system POLYPHEMUS (Mallet et al., 2006) but can be linked to any other three-dimensional Chemistry-Transport Model.

scholarly journals Description and evaluation of a detailed gas-phase chemistry scheme in the TM5-MP global chemistry transport model (r112)

2020 ◽  
Author(s):  
Stelios Myriokefalitakis ◽  
Nikos Daskalakis ◽  
Angelos Gkouvousis ◽  
Andreas Hilboll ◽  
Twan van Noije ◽  
...  
Keyword(s):  
Gas Phase ◽  
Transport Model ◽  
Vertical Mixing ◽  
Three Dimensional ◽  
Chemical Mechanism ◽  
Aerosol Formation ◽  
Chemistry Transport Model ◽  
Mixing Ratios ◽  
Time Requirements ◽  
Phase Chemistry

Abstract. This work documents and evaluates the tropospheric gas-phase chemical mechanism MOGUNTIA in the three-dimensional chemistry transport model TM5-MP. Compared to the modified CB05 chemical mechanism previously used in the model, the MOGUNTIA includes a detailed representation of the light hydrocarbons (C1-C4) and isoprene, along with a simplified chemistry representation of terpenes and aromatics. Another feature implemented in TM5-MP for this work is the use of the Rosenbrock solver in the chemistry code, which can replace the classical Euler Backward Integration method of the model. Global budgets of ozone (O3), carbon monoxide (CO), hydroxyl radicals (OH), nitrogen oxides (NOX) and volatile organic compounds (VOCs) are here analyzed and their mixing ratios are compared with a series of surface, aircraft and satellite observations for the year 2006. Both mechanisms appear to be able to represent satisfactorily observed mixing ratios of important trace gases, with the MOGUNTIA chemistry configuration yielding lower biases compared to measurements in most of the cases. However, the two chemical mechanisms fail to reproduce the observed mixing ratios of light VOCs, indicating insufficient primary emission source strengths, too weak vertical mixing in the boundary layer, and/or a low bias in the secondary contribution of C2-C3 organics via VOC atmospheric oxidation. Relative computational memory and time requirements of the different model configurations are also compared and discussed. Overall, compared to other chemistry schemes in use in global CTMs, the MOGUNTIA scheme simulates a large suite of oxygenated VOCs that are observed in the atmosphere at significant levels and are involved in aerosol formation, expanding, thus, the applications of TM5-MP.

scholarly journals Measurements and modelling of atmospheric pollution over the Paris area: an overview of the ESQUIF Project

2000 ◽  
Vol 18 (11) ◽  
pp. 1467-1481 ◽  
Author(s):  
L. Menut ◽  
R. Vautard ◽  
C. Flamant ◽  
C. Abonnel ◽  
M. Beekmann ◽  
...  
Keyword(s):  
Transport Model ◽  
Numerical Models ◽  
Atmospheric Composition ◽  
Mesoscale Meteorology ◽  
Chemistry Transport Model ◽  
Elevated Ozone ◽  
Composition And Structure ◽  
Paris Area ◽  
Set Up ◽  
Pollution Events

Abstract. The "Étude et Simulation de la QUalité de l'air en Ile de France" (ESQUIF) project is the first integrated project dedicated to the study of the processes leading to air pollution events over the Paris area. The project was carried out over two years (summer 1998 to winter 2000) to document all types of meteorological conditions favourable to air quality degradation, and in particular to photo oxydant formation. The goals of ESQUIF are (1) to improve our understanding of the relevant chemical and dynamical processes and, in turn, improve their parametrizations in numerical models, and (2) to improve and validate existing models dedicated to pollution analysis, scenarios and/or forecasting, by establishing a comprehensive and thorough database. We present the rationale of the ESQUIF project and we describe the experimental set-up. We also report on the first experiments which took place during the summer of 1998 involving surface networks, and remote sensing instruments as well as several aircraft. Focusing on three days of August 1998, the relative contributions of long-range transported and locally-produced ozone to the elevated ozone concentrations observed during this period are discussed and chemistry-transport model preliminary results on this period are compared to measurements.Key words: Atmospheric composition and structure (pollution – urban and regional; troposphere – composition and chemistry) – Meteorology and atmospheric dynamics (mesoscale meteorology)

Air pollution and cloud-interaction over Europe in 1985 and today

2020 ◽  
Author(s):  
Roland Schrödner ◽  
Christa Genz ◽  
Bernd Heinold ◽  
Holger Baars ◽  
Silvia Henning ◽  
...  
Keyword(s):  
Radiative Forcing ◽  
Transport Model ◽  
Cloud Droplet ◽  
Forecast Model ◽  
Sensitivity Study ◽  
High Definition ◽  
Chemistry Transport Model ◽  
Meteorological Model ◽  
Cloud Properties ◽  
Aerosol Mass

&lt;p&gt;Aerosol concentrations over Europe and Germany were simulated for the years 1985 and 2013 using the aerosol-chemistry transport model COSMO-MUSCAT. The aerosol fields from the two simulations were used in a high-resolution meteorological model for a sensitivity study on cloud properties. The modelled aerosol and cloud variables were compared to a variety of available observations, including satellites, remote sensing and in-situ observations. Finally, the radiative forcing of the aerosol could be estimated from the different sensitivity simulations.&lt;/p&gt;&lt;p&gt;Due to reduction of emissions the ambient aerosol mass and number in Europe was strongly decreased since the 1980s. Hence, today&amp;#8217;s number of particles in the CCN size range is smaller. The HD(CP)&lt;sup&gt;2&lt;/sup&gt; (High Definition Clouds and Precipitation for Climate Prediction) project amongst others aimed at analysing the effect of the emission reduction on cloud properties.&lt;/p&gt;&lt;p&gt;As a pre-requiste, the aerosol mass, number, and composition over Germany were simulated for 1985 and 2013 using the regional chemistry-transport-model COSMO-MUSCAT. The EDGAR emission inventory was used for both years.&lt;/p&gt;&lt;p&gt;The model results were compared to observations from the two HD(CP)&lt;sup&gt;2&lt;/sup&gt; campaigns that took place in 2013 (HOPE, HOPE-Melpitz) as well as the AVHRR aerosol optical thickness product, which is available from 1981 onwards. Despite the fact, that emissions of the 1980s are very uncertain, the modelled AOD is in good agreement with observations. The modelled mean CCN number concentration in 1985 is a factor of 2-4 higher than in 2013.&lt;/p&gt;&lt;p&gt;Within HD(CP)&lt;sup&gt;2&lt;/sup&gt;, the ICON weather forecast model was applied in a configuration allowing for large-eddy simulations. In these simulations, the time-varying CCN fields for the year 1985 and 2013 calculated with COSMO-MUSCAT were used as input for ICON-LEM. In the present-day simulation, the cloud droplet number agrees with observations, whereas the perturbed (1985) simulation does not with droplet numbers about twice as high as in 2013. Also, for other cloud variables systematic changes between the two scenarios were observed.&lt;/p&gt;

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