The best source of information about atmospheric kinetics is the so-called Master Chemical Mechanism (MCM) developed at the University of Leeds. The following is a link to MCM through the NCAR site

https://www.ncas.ac.uk/en/air-quality-projects/76-master-chemical-mechanism

I strongly recommend getting acquainted with the MCM before you begin a specific study of atmospheric chemistry.

Thank you for the reply. Maybe, I am missing something, but as far as I know, by the MCM we can know the kinetic information of the individual elementary reactions. However, the atmospheric reactions work in tandem. Then how is the MCM going to help us without having kinetic modeling studies that are missing presently.

As far as the air pollution studies are concern, without having such kinetic studies, there may be misunderstanding between transport of the pollutants and kinetics of the reactions during the interpretation of the modeling results. Therefore, the main focus of the discussion is that how the modelers can come to conclude between them without having kinetic studies.

Not surprisingly, the atmospheric kinetics is a very complex topic. By suggesting to consult the master chemical mechanism I only share my past experiences when the MCM was the best and authoritative source of information during the development of atmospheric chemistry models. I certainly agree with you comments; we definitely need an active program of research in atmospheric kinetics.

The historical perspective of this subject is summarized in the recent article: “100 Years of Progress in Gas-Phase Atmospheric Chemistry Research”

https://journals.ametsoc.org/doi/full/10.1175/AMSMONOGRAPHS-D-18-0008.1

For the description of a new research maybe the conferences and the recent reviews such as

https://pubs.rsc.org/en/content/articlelanding/2012/cs/c2cs35070j#!divAbstract

can give you a better description of the future trends.

There is the full textbook of Pitts and Pitts

Chemistry of the Upper and Lower Atmosphere

1st Edition Authors: Barbara Finlayson-Pitts James Pitts, Jr.

eBook ISBN: 9780080529073

Hardcover ISBN: 9780122570605

and here a sort of summary

https://pdfs.semanticscholar.org/5ac7/b76f70fadd621fb6d394c416cbb666d4fd1a.pdf

Thank you, Harry ten Brink. This book covers almost everything about atmospheric chemistry. However, atmospheric kinetic modeling studies with the present reaction mechanisms are not available in the book and in the latest literature as well.

There is a lot of material on the elementary reactions and their kinetic behavior, but there is a little understanding on the kinetics on the overall mechanisms (I mean atmospheric kinetic behavior). All I am saying is that during course of time, few reactions turn on depending on the concentration and type of the reactants, radiation, temperature, and even pressure. However, because of the change in these inputs, the other reactions in the atmosphere may turn on by turning of the previous reaction reactions. Therefore, we have to have clear understanding of the system through diligent and vast amount of kinetic studies, instead of depending too much on the models, which create usually ambiguity while analysing the model results. At present, the modeling studies available in the literature can't distinguish between the meteorology and chemistry effects on the air pollution due to the lack of the overall understanding of the atmospheric chemical kinetic behavior.

Perhaps the article by Kohse-Höinghaus et al. (2018): “Kinetics in the real world: Linking molecules, processes, and systems” can be used as a partial answer to the original question (the paper is in the RG system and you can request a copy).

Kishore

Please provide examples

Of course every organic molecule has its own reaction path but in that way the total system becomes too complex

And a question from my side is what exactly do you want or need and for what

Dear Janusz Pudykiewicz , The abstract of the suggested paper looks quite related to the discussion. I have just requested for the fulltext.

Thank you.

Dear Harry ten Brink,

I understand that the system becomes too complex. However, we have to drive the mathematical/numerical models, not the other way around. The present complex chemistry models are driving us and our research because of lack of understanding of the working of it.

I want to recommend to understand the system through mechanism reduction and controlled atmosphere experiments using simple chemistry box models before making loose conclusions in the coupled meteorology-chemistry modeling experiments. However, I am not against operational air quality forecasting using the coupled models.

Kishore

This is very vague to me

How could the chemistry be decoupled?

Everyone who has done smog-chamber studies with reactive species and aerosol (as we have) is aware of wall effects interfering

Also: what is the use of testing all existing organic substances in gas and aerosol phase and more problematic what should be the oxidant and how to follow all of the follow-up reactions and products

Dear Harry ten Brink ,

What do you say about smog-chamber experiments? They are also decoupled experiments (as you said wall effects: no transport and incorrect deposition), but they are quite useful in proposing reaction mechanisms (I have to remind here that they are small part of the atmospheric chemistry but still useful) and for the estimation of the kinetic information of the elementary reactions.

I really agree with you on the vague part of decoupling of the chemistry; however, having no knowledge on the mechanistic of the chemical mechanisms used in the research studies goes from bad to worse.

Do you really suggest the research community to run the coupled models without knowing how they are working inside? During early years of my PhD, my advisor commented on my coupled model results. The comment goes like this "Anybody can run the models and get the results if one has computers and technical knowledge". That's why I mentioned in the previous comment that the operational air quality forecasting with the coupled models is okay as the technical skills are enough there.

I still do not see what your aim is

There are thousands of reactions and even those that are basic in describing the formation of major pollutants via oxidation are not understood

Examples

nitric acid, sulphate

the way to approach is comparing the results of a full model with measured concentrations over a very long period.

On the other hand I remember from the early seventies that the concentration of the OH radical in the atmosphere was measured

Modellers directly commented that at such a high concentration was incompatible with the lifetime of toluene deduced from the transport distance from sources

The measuring method for OH was reevaluated and a large error was found

This shows that modelling also works the other way round

Dear Harry ten Brink ,

How did the modelers directly commented that at such a high concentration was incompatible with the lifetime of toluene deduced from the transport distance from sources? With the model running experience or with the atmospheric kinetic behavior?

I would like to ask you one scenario of atmospheric reactions. For example, your hypothetical tropospheric chamber (no transport and deposition) has both NO and Acetone along with N2 and O2 under tropospheric radiation. Could you please guess what kind of trajectory of the concentration of PAN takes place and why? If you do kinetic modeling through mechanism reduction, you will find a beautiful peaks and valleys and those represent the forward and backward reactions due to equilibriums shifts by the change in reactants and products that go on to other reactions. If you don't do kinetic modeling studies, you never know what happens in the atmosphere.

Above is a small example and we need several hundreds of such studies to learn about the atmospheric kinetic behavior.

Finally, I accept that there are still gaps in the oxidations in the atmosphere because of lack of knowledge on emissions and their interactions. But, the first things first. The science has already been messed up by dumping of thousands of reactions without proper add-on kind of studies. So, my recommendation is to understand it through kinetic studies while others take on their different paths.

Dear Kishore Ragi

Inventing of the artificial chemistry is definitely to be avoided if we want our models to have any relation to the real atmosphere. This problem was discussed by Heymann (2010): Lumping, testing, tuning: The invention of an artificial chemistry in atmospheric transport modeling (Studies in History and Philosophy of Science Part B: Studies in History and Philosophy of Modern Physics)

The paper was published in the special issue dedicated to modeling and simulation in the atmospheric and climate sciences and the text is available on request in the RG system.

Considering the complexity of the problem it is indeed very wise to perform first the detailed kinetic studies (both theoretical and experimental) followed by the rational compression of the chemical mechanism. In this area I would like to suggest Sportisse (2000): Reduction of Chemical Kinetics in Air Pollution Modeling., J. Comp. Physics, Vol 164, issue 2, p 354–376

https://www.sciencedirect.com/science/article/pii/S0021999100966014

The reality of chemical modeling is that some atmospheric chemistry models still use the outdated lumping methods. It is indeed an excellent idea to revisit these problems.

Acetone is an example of a molecule with a rather low concentration in the atmosphere. What would be the reason to study its reactions then?

and what time frame are you thinking of for the sequential reactions? seconds minutes hours?