Influence of in-cloud oxidation of organic compounds on tropospheric ozone

2021 ◽  
Author(s):  
Simon Rosanka ◽  
Rolf Sander ◽  
Bruno Franco ◽  
Catherine Wespes ◽  
Andreas Wahner ◽  
...  
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Aqueous Phase ◽  
Phase Transfer ◽  
Sulfur Oxidation ◽  
Box Model ◽  
Atmospheric Models ◽  
Model Studies ◽  
Phase Chemistry ◽  
The Impact

<p>Large parts of the troposphere are affected by clouds, whose aqueous-phase chemistry differs significantly from gas-phase chemistry. Box-model studies have demonstrated that clouds influence the tropospheric oxidation capacity. However, most global atmospheric models do not represent this chemistry reasonably well and are largely limited to sulfur oxidation. Therefore, we have developed the Jülich Aqueous-phase Mechanism of Organic Chemistry (JAMOC), making a detailed in-cloud oxidation model of oxygenated volatile organic compounds (OVOCs) readily available for box as well as for regional and global simulations that are affordable with modern supercomputers. JAMOC includes the phase transfer of species containing up to ten carbon atoms, and the aqueous-phase reactions of a selection of species containing up to four carbon atoms, e.g., ethanol, acetaldehyde, glyoxal. The impact of in-cloud chemistry on tropospheric composition is assessed on a regional and global scale by performing a combination of box-model studies using the Chemistry As A Boxmodel Application (CAABA) and the global atmospheric model ECHAM/MESSy (EMAC). These models are capable to represent the described processes explicitly and integrate the corresponding ODE system with a Rosenbrock solver. </p><p>Overall, the explicit in-cloud oxidation leads to a reduction of predicted OVOCs levels. By comparing EMAC's prediction of methanol abundance to spaceborne retrievals from the Infrared Atmospheric Sounding Interferometer (IASI), a reduction in EMAC's overestimation is observed in the tropics. Further, the in-cloud OVOC oxidation shifts the hydroperoxyl radicals (HO<sub>2</sub>) production from the gas- to the aqueous-phase. As a result, the in-cloud destruction (scavenging) of ozone (O<sub>3</sub>) by the superoxide anion (O<sub>2</sub><sup>-</sup>) is enhanced and accompanied by a reduction in both sources and sinks of tropospheric O<sub>3</sub> in the gas phase. By considering only the in-cloud sulfur oxidation by O<sub>3</sub>, about 13 Tg a<sup>-1</sup> of O<sub>3</sub> are scavenged, which increases to 336 Tg a<sup>-1</sup> when JAMOC is used. With the full oxidation scheme, the highest O<sub>3</sub> reduction of 12 % is predicted in the upper troposphere/lower stratosphere (UTLS). Based on the IASI O<sub>3</sub> retrievals, it is demonstrated that these changes in the free troposphere significantly reduce the modelled tropospheric O<sub>3</sub> columns, which are known to be generally overestimated by global atmospheric models. Finally, the relevance of aqueous-phase oxidation of organics for ozone in hazy polluted regions will be presented.  </p>

The Impact of the Aqueous Phase Chemistry of HNO4 on Gas Phase Tropospheric Chemistry

2001 ◽  
Vol 32 ◽  
pp. 269-270
Author(s):  
J.E. WILLIAMS ◽  
F.J. DENTENER ◽  
A.R. van den BERG
Keyword(s):  
Gas Phase ◽  
Aqueous Phase ◽  
Tropospheric Chemistry ◽  
Phase Chemistry ◽  
The Impact

scholarly journals Development of a protocol for the auto-generation of explicit aqueous-phase oxidation schemes of organic compounds

2019 ◽  
Vol 19 (14) ◽  
pp. 9209-9239 ◽  
Author(s):  
Peter Bräuer ◽  
Camille Mouchel-Vallon ◽  
Andreas Tilgner ◽  
Anke Mutzel ◽  
Olaf Böge ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Aqueous Phase ◽  
Rate Constants ◽  
Particle Growth ◽  
Chemical Mechanism ◽  
Estimation Methods ◽  
Radical Reactivity ◽  
Chemical Complexity ◽  
Model Studies ◽  
Phase Chemistry

Abstract. This paper presents a new CAPRAM–GECKO-A protocol for mechanism auto-generation of aqueous-phase organic processes. For the development, kinetic data in the literature were reviewed and a database with 464 aqueous-phase reactions of the hydroxyl radical with organic compounds and 130 nitrate radical reactions with organic compounds has been compiled and evaluated. Five different methods to predict aqueous-phase rate constants have been evaluated with the help of the kinetics database: gas–aqueous phase correlations, homologous series of various compound classes, radical reactivity comparisons, Evans–Polanyi-type correlations, and structure–activity relationships (SARs). The quality of these prediction methods was tested as well as their suitability for automated mechanism construction. Based on this evaluation, SARs form the basis of the new CAPRAM–GECKO-A protocol. Evans–Polanyi-type correlations have been advanced to consider all available H atoms in a molecule besides the H atoms with only the weakest bond dissociation enthalpies (BDEs). The improved Evans–Polanyi-type correlations are used to predict rate constants for aqueous-phase NO3 and organic compounds reactions. Extensive tests have been performed on essential parameters and on highly uncertain parameters with limited experimental data. These sensitivity studies led to further improvements in the new CAPRAM–GECKO-A protocol but also showed current limitations. Biggest uncertainties were observed in uptake processes and the estimation of Henry's law coefficients as well as radical chemistry, in particular the degradation of alkoxy radicals. Previous estimation methods showed several deficits, which impacted particle growth. For further evaluation, a 1,3,5-trimethylbenzene oxidation experiment has been performed in the aerosol chamber “Leipziger Aerosolkammer” (LEAK) at high relative humidity conditions and compared to a multiphase mechanism using the Master Chemical Mechanism (MCMv3.2) in the gas phase and using a methylglyoxal oxidation scheme of about 600 reactions generated with the new CAPRAM–GECKO-A protocol in the aqueous phase. While it was difficult to evaluate single particle constituents due to concentrations close to the detection limits of the instruments applied, the model studies showed the importance of aqueous-phase chemistry in respect to secondary organic aerosol (SOA) formation and particle growth. The new protocol forms the basis for further CAPRAM mechanism development towards a new version 4.0. Moreover, it can be used as a supplementary tool for aerosol chambers to design and analyse experiments of chemical complexity and help to understand them on a molecular level.

scholarly journals Oxidation of low-molecular-weight organic compounds in cloud droplets: development of the Jülich Aqueous-phase Mechanism of Organic Chemistry (JAMOC) in CAABA/MECCA (version 4.5.0)

2021 ◽  
Vol 14 (6) ◽  
pp. 4103-4115
Author(s):  
Simon Rosanka ◽  
Rolf Sander ◽  
Andreas Wahner ◽  
Domenico Taraborrelli
Keyword(s):  
Organic Chemistry ◽  
Gas Phase ◽  
Organic Compounds ◽  
Aqueous Phase ◽  
Phase Transfer ◽  
Cloud Droplets ◽  
Physico Chemical ◽  
Oxygenated Volatile Organic Compounds ◽  
Chemical Scheme ◽  
Selection Of Species

Abstract. The Jülich Aqueous-phase Mechanism of Organic Chemistry (JAMOC) is developed and implemented in the Module Efficiently Calculating the Chemistry of the Atmosphere (MECCA; version 4.5.0). JAMOC is an explicit in-cloud oxidation scheme for oxygenated volatile organic compounds (OVOCs), suitable for global model applications. It is based on a subset of the comprehensive Cloud Explicit Physico-chemical Scheme (CLEPS; version 1.0). The phase transfer of species containing up to 10 carbon atoms is included, and a selection of species containing up to 4 carbon atoms reacts in the aqueous phase. In addition, the following main advances are implemented: (1) simulating hydration and dehydration explicitly; (2) taking oligomerisation of formaldehyde, glyoxal, and methylglyoxal into account; (3) adding further photolysis reactions; and (4) considering gas-phase oxidation of new outgassed species. The implementation of JAMOC in MECCA makes a detailed in-cloud OVOC oxidation model readily available for box as well as for regional and global simulations that are affordable with modern supercomputing facilities. The new mechanism is tested inside the box model Chemistry As A Boxmodel Application (CAABA), yielding reduced gas-phase concentrations of most oxidants and OVOCs except for the nitrogen oxides.

scholarly journals Oxidation of low-molecular weight organic compounds in cloud droplets: development of the JAMOC chemical mechanism in CAABA/MECCA (version 4.5.0gmdd)

2020 ◽  
Author(s):  
Simon Rosanka ◽  
Rolf Sander ◽  
Andreas Wahner ◽  
Domenico Taraborrelli
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Aqueous Phase ◽  
Phase Transfer ◽  
Chemical Mechanism ◽  
Cloud Droplets ◽  
Physico Chemical ◽  
Chemical Scheme ◽  
Selection Of Species ◽  
Bug Fixes

Abstract. The Jülich Aqueous-phase Mechanism of Organic Chemistry (JAMOC) is developed and implemented in the Module Efficiently Calculating the Chemistry of the Atmosphere (MECCA, version 4.5.0gmdd1). JAMOC is an explicit in-cloud oxidation scheme for oxygenated volatile organic compounds (OVOCs), suitable for global model applications. It is based on a subset of the comprehensive CLoud Explicit Physico-chemical Scheme (CLEPS, version 1.0). The phase transfer of species containing up to ten carbon atoms is included, and a selection of species containing up to four carbon atoms reacts in the aqueous-phase. In addition, the following main advances are implemented: (1) simulating hydration and dehydration explicitly, (2) taking oligomerisation of formaldehyde, glyoxal and methylglyoxal into account, (3) adding further photolysis reactions, and (4) considering gas-phase oxidation of new outgassed species. The implementation of JAMOC in MECCA makes a detailed in-cloud OVOC oxidation model readily available for box as well as for regional and global simulations that are affordable with modern supercomputing facilities. The new mechanism is tested inside the box-model Chemistry As A Boxmodel Application (CAABA), yielding reduced gas-phase concentrations of most oxidants and OVOCs except for the nitrogen oxides. 1 The name of this version indicates that it is used for the interactive discussion in GMDD. If necessary, bug fixes can still be made. We plan to release the final version CAABA/MECCA-4.5.0 together with the final paper in GMD.

scholarly journals Development of a protocol for the auto-generation of explicit aqueous-phase oxidation schemes of organic compounds

2019 ◽  
Author(s):  
Peter Bräuer ◽  
Camille Mouchel-Vallon ◽  
Andreas Tilgner ◽  
Anke Mutzel ◽  
Olaf Böge ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Aqueous Phase ◽  
Rate Constants ◽  
Particle Growth ◽  
Estimation Methods ◽  
Radical Reactivity ◽  
Chemical Complexity ◽  
Model Studies ◽  
Aerosol Chamber ◽  
Phase Chemistry

Abstract. This paper presents a new CAPRAM/GECKO-A protocol for mechanism auto-generation of aqueous-phase organic mechanisms. For the development, kinetic data in the literature was reviewed and a database with 464 aqueous-phase reactions of the hydroxyl radical with organic compounds and 130 nitrate radical reactions with organic compounds has been compiled and evaluated. Five different methods to predict aqueous-phase rate constants have been evaluated with the help of the kinetics database: gas-aqueous correlations, homologous series of various compound classes, radical reactivity comparisons, Evans-Polanyi-type correlations, and structure-activity relationships (SARs). The quality of these prediction methods was tested as well as their suitability for automated mechanism construction. Based on this evaluation, SARs form the basis of the new CAPRAM/GECKO-A protocol. Evans-Polanyi-type correlations have been advanced to consider all available H-atoms in a molecule besides the H-atoms with only the weakest bond dissociation enthalpy (BDE). The improved Evans-Polanyi-type correlations are used to predict rate constants for aqueous-phase NO3 + organic compounds reactions. Extensive tests have been performed on essential parameters and highly uncertain parameters with limited experimental data. These sensitivity studies led to further improvements in the new CAPRAM/GECKO-A protocol, but also showed current limitations. Biggest uncertainties were observed in uptake processes and the estimation of Henry's Law coefficients as well as radical chemistry, in particular the degradation of alkoxy radicals. Previous estimation methods showed several deficits, which impacted particle growth. For further evaluation, a mesitylene oxidation experiment has been performed at the aerosol chamber LEAK at high relative humidity conditions and compared to a multiphase mechanism using the MCMv3.2 in the gas phase and a methylglyoxal oxidation scheme of about 600 reactions generated with the new CAPRAM/GECKO-A protocol in the aqueous phase. While it was difficult to evaluate single particle constituents due to concentrations close to the detection limits of the instruments applied, the model studies showed the importance of aqueous-phase chemistry in respect to SOA formation and particle growth. The new protocol forms the basis for further CAPRAM mechanism development towards a new version 4.0. Moreover, it can be used as supplementary tool for aerosol chambers to design and analyse experiments of chemical complexity and help understanding them on a molecular level.

Impacts of acidity on multiphase chemistry in aqueous particles and clouds

2020 ◽  
Author(s):  
Thomas Schaefer ◽  
Andreas Tilgner ◽  
Havala O. T. Pye ◽  
V. Faye McNeill ◽  
Hartmut Herrmann
Keyword(s):  
Organic Compounds ◽  
Aqueous Phase ◽  
Carbonyl Compounds ◽  
Kinetic Data ◽  
The Other ◽  
Aerosol Composition ◽  
Other Hand ◽  
Wide Range ◽  
Phase Chemistry ◽  
The Impact

<p>The acidity of aqueous atmospheric solutions is a key parameter driving both partitioning of semi-volatile acidic or basic trace gases and their linked aqueous-phase chemistry. On the other hand, acidity of atmospheric aqueous phases, e.g. deliquesced aerosol particles, cloud and fog droplets, is conversely affected by aqueous-phase chemistry processes. Those feedbacks in acidity and chemistry have crucial implications for the (i) tropospheric lifetime of air pollutants, hence air quality and atmospheric aerosol composition, (ii) deposition input into other terrestrial and oceanic ecosystems, (iii) the visibility, (iv) climate and (v) human health. Due to their fundamental role, atmospheric research has gained substantial progress in the understanding in feedbacks of acidity and multiphase chemistry. In the present study, the current state of knowledge on the acidity-multiphase chemistry feedbacks has been summarized. From a wide range of topics, two selected issues focusing on impacts of acidity (i) on the hydration of organic carbonyl compounds and (ii) multiphase chemistry of dissociating organic compounds in aqueous particles and clouds will be presented.</p><p>Hydration processes are typically known to be acid- or base-catalyzed. Thus, the acidity of an aqueous solution can affect the hydration and all other processes linked to it. This comprehensive literature study revealed that the hydration of simple aldehydes and ketones as well as dicarbonyls is less affected by acidity. However, for multifunctional carbonyl compounds such as pyruvic acid, the hydration equilibrium constant of the carbonyl group is strongly influenced by the electronic effects of the adjacent group. The hydration of carbonyl groups in compounds that also contain pH sensitive moieties, such as α-oxocarboxylic acids, is highly influenced by the acidity of the surrounding environment. However, this acidity effect is often not considered in multiphase models.</p><p>Furthermore, oxidation reactions of dissociating organic compounds can be affected by acidity. To examine the effect of acidity on the chemical processing of dissociating organic compounds, kinetic data for their oxidation by OH, NO<sub>3</sub> and O<sub>3</sub> have been newly compiled in the present study. Kinetic reactivity data of both protonated and deprotonated organic compounds together with their reactivity ratio  have been investigated to identify possible acidity effects. The present study showed that, for OH reactions, the impact of acidity on the chemical kinetics is often quite small and only important for some specific compounds. On the other hand, for NO<sub>3</sub> reaction, particularly under cloud conditions, acidity can substantially affect the chemical NO<sub>3</sub>-initiated processing of organic compounds. Less acidic conditions will enhance the degradation of dissociating compounds via NO<sub>3</sub> because of more rapid oxidation and possibility of additional ETR pathway. Furthermore, the present O<sub>3</sub> kinetic data analyses have demonstrated the role of acidity for ozonolysis processes, especially for phenolic compounds. Overall, the present study summarizes atmospheric implications and needs for future investigations, particularly with respect to changing aerosol and cloud acidity conditions in the future.</p>

scholarly journals CLEPS 1.0: A new protocol for cloud aqueous phase oxidation of VOC mechanisms

2017 ◽  
Vol 10 (3) ◽  
pp. 1339-1362 ◽  
Author(s):  
Camille Mouchel-Vallon ◽  
Laurent Deguillaume ◽  
Anne Monod ◽  
Hélène Perroux ◽  
Clémence Rose ◽  
...  
Keyword(s):  
Gas Phase ◽  
Organic Compounds ◽  
Aqueous Phase ◽  
Water Soluble ◽  
Transfer Scheme ◽  
Chemical Complexity ◽  
Global Rate ◽  
Physico Chemical ◽  
Chemical Scheme ◽  
Phase Chemistry

Abstract. A new detailed aqueous phase mechanism named the Cloud Explicit Physico-chemical Scheme (CLEPS 1.0) is proposed to describe the oxidation of water soluble organic compounds resulting from isoprene oxidation. It is based on structure activity relationships (SARs) which provide global rate constants together with branching ratios for HO⋅ abstraction and addition on atmospheric organic compounds. The GROMHE SAR allows the evaluation of Henry's law constants for undocumented organic compounds. This new aqueous phase mechanism is coupled with the MCM v3.3.1 gas phase mechanism through a mass transfer scheme between gas phase and aqueous phase. The resulting multiphase mechanism has then been implemented in a model based on the Dynamically Simple Model for Atmospheric Chemical Complexity (DSMACC) using the Kinetic PreProcessor (KPP) that can serve to analyze data from cloud chamber experiments and field campaigns. The simulation of permanent cloud under low-NOx conditions describes the formation of oxidized monoacids and diacids in the aqueous phase as well as a significant influence on the gas phase chemistry and composition and shows that the aqueous phase reactivity leads to an efficient fragmentation and functionalization of organic compounds.

scholarly journals Application of random forest regression to the calculation of gas-phase chemistry within the GEOS-Chem chemistry model v10

2019 ◽  
Vol 12 (3) ◽  
pp. 1209-1225 ◽  
Author(s):  
Christoph A. Keller ◽  
Mat J. Evans
Keyword(s):  
Machine Learning ◽  
Random Forest ◽  
Gas Phase ◽  
Atmospheric Chemistry ◽  
Random Forest Regression ◽  
Data Set ◽  
Gas Phase Chemistry ◽  
Chemical Conditions ◽  
Phase Chemistry ◽  
The Impact

Abstract. Atmospheric chemistry models are a central tool to study the impact of chemical constituents on the environment, vegetation and human health. These models are numerically intense, and previous attempts to reduce the numerical cost of chemistry solvers have not delivered transformative change. We show here the potential of a machine learning (in this case random forest regression) replacement for the gas-phase chemistry in atmospheric chemistry transport models. Our training data consist of 1 month (July 2013) of output of chemical conditions together with the model physical state, produced from the GEOS-Chem chemistry model v10. From this data set we train random forest regression models to predict the concentration of each transported species after the integrator, based on the physical and chemical conditions before the integrator. The choice of prediction type has a strong impact on the skill of the regression model. We find best results from predicting the change in concentration for long-lived species and the absolute concentration for short-lived species. We also find improvements from a simple implementation of chemical families (NOx = NO + NO2). We then implement the trained random forest predictors back into GEOS-Chem to replace the numerical integrator. The machine-learning-driven GEOS-Chem model compares well to the standard simulation. For ozone (O3), errors from using the random forests (compared to the reference simulation) grow slowly and after 5 days the normalized mean bias (NMB), root mean square error (RMSE) and R2 are 4.2 %, 35 % and 0.9, respectively; after 30 days the errors increase to 13 %, 67 % and 0.75, respectively. The biases become largest in remote areas such as the tropical Pacific where errors in the chemistry can accumulate with little balancing influence from emissions or deposition. Over polluted regions the model error is less than 10 % and has significant fidelity in following the time series of the full model. Modelled NOx shows similar features, with the most significant errors occurring in remote locations far from recent emissions. For other species such as inorganic bromine species and short-lived nitrogen species, errors become large, with NMB, RMSE and R2 reaching >2100 % >400 % and <0.1, respectively. This proof-of-concept implementation takes 1.8 times more time than the direct integration of the differential equations, but optimization and software engineering should allow substantial increases in speed. We discuss potential improvements in the implementation, some of its advantages from both a software and hardware perspective, its limitations, and its applicability to operational air quality activities.

Oxidation of substituted aromatic hydrocarbons in the tropospheric aqueous phase: kinetic mechanism development and modelling

2018 ◽  
Vol 20 (16) ◽  
pp. 10960-10977 ◽  
Author(s):  
Erik H. Hoffmann ◽  
Andreas Tilgner ◽  
Ralf Wolke ◽  
Olaf Böge ◽  
Arno Walter ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Aromatic Hydrocarbons ◽  
Aromatic Compounds ◽  
Kinetic Data ◽  
Kinetic Mechanism ◽  
Detailed Model ◽  
Model Studies ◽  
Phase Chemistry

An aqueous-phase chemistry mechanism for the oxidation of aromatic compounds in the atmosphere is developed based on available kinetic data. Detailed model studies successfully describe the oxidation and functionalization of monoaromatic compounds in the atmosphere.

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