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Physical and Biophysical Chemistry Division (I)


Number: 1999-037-2-100

Title: Evaluated kinetic data for atmospheric chemistry

Task Group
: R.A. Cox

Members: M. Amman, R. Atkinson, J.N. Crowley, R.F. Hampson, R.G. Hynes, M.E. Jenkin, M. J. Rossi, and J. Troe, and T.J. Wallington

Completion Date: 2007 - project completed

Remarks: see project 2007-001-2-100 for continuation

Continuation and expension of 141/3/89
The primary objective of this project is to enhance the accessibility and availability of the evaluated kinetic database, which has been assembled by the IUPAC Subcommittee for Gas Kinetic Data evaluation for Atmospheric Chemistry, by placing the material on an interactive site on the www. A second objective is to develop and implement a scheme for updating the material on the website.

The IUPAC Subcommittee (formally the CODATA Task Group on Chemical Kinetics) was originally tasked to produce an evaluation of the existing chemical kinetics data in 1977, in response to the need to provide an internationally judged data set for modelling the depletion of atmospheric ozone due to man made pollutants. Since that time the Subcommittee has continued to expand and update the evaluations to aid modelling of a wide range of issues involving Atmospheric Chemistry. The evaluations have been published in a series of nine peer reviewed articles in J. Phys. Chem. Ref. Data. These articles contain two elements: Firstly a summary table which contains a list of recommended rate parameters giving the best available values for rate coefficients for use in models representing atmospheric chemistry explicitly as a system of elementary chemical reactions: Secondly each reaction is discussed in a separate data sheet, in which the key experimental data are summarised and the basis of the recommendation together with its uncertainty is given. These data sheets provide details which are of interest to atmospheric modellers and experimental scientists conducting investigations of kinetics and mechanisms of atmospheric reactions, and chemical kinetics generally.
In order to further publicize the accessibility of this web-based material to the scientific community, the evaluation is also being published as a series of journal articles in Atmospheric Chemistry and Physics.

In 1998 the IUPAC Subcommittee created a website at the Centre for Atmospheric Science in the Department of Chemistry, University of Cambridge, UK, (http://www.iupac-kinetic.ch.cam.ac.uk). This site has attracted very significant interest since its creation, and has now been expanded, and a mirror site has been created at the IUPAC HQ website in N. Carolina, US. Currently there are approximately 2000 connections to the website per week and over 300 subscriptions to the web mailing list for announcements.

The main purpose of the ongoing IUPAC project is to extend the content of the website to include the remaining datasheets for the 600 gas phase reactions, the photochemical reactions (absorption cross sections, quantum yields), and heterogeneous reactions (kinetic uptake coefficients for atmospheric gases on a range of surfaces), for which the data have been evaluated since the first publication by the Group in 1980. In addition to expansion, the website is continually being modified to give improved access, including a simple search facility and implemented hyperlinks between the summary table and the data sheets.

The database covers over 600 reactions relevant to the chemistry of the stratosphere and the troposphere. The data sheets are grouped in a series of categories which include:

  1. Gas phase and photolysis reactions of Ox, HOx, NOx and SOx species.
  2. Gas-Phase and photolysis reactions of organic species (including reactions with HOx, NO3 and halogen radicals.
  3. Reactions of organic peroxy radicals, organic alkoxy radicals and other organic radicals with oxygen.
  4. Gas Phase and photolysis reactions of inorganic FOx, ClOx, BrOx and IOx species.
  5. Gas Phase and photolysis reactions of organic halogen species.
  6. Uptake coefficients for non-reactive and reactive heterogeneous processes.

In the future the efforts of laboratory kineticists will continue to provide new data in response to new scientific and societal issues in the field of Atmospheric Chemistry. The IUPAC Group is seeking a more effective way of updating and extending the portfolio of recommended rate coefficients, which will be necessary to maintain an effective and ongoing communication between laboratory scientists and atmospheric modellers.

This project was presented at a poster session at the IUPAC Congress/GA July 2005
>view pdf - 544KB<

and also at the IUPAC Congress/GA August 2007
>view pdf - 747KB<

The establishment of web-based material allows for the first time the opportunity of near continuous update of the evaluation. The development and implementation of protocols for the updating of the evaluation, both web-based and archived hard copy will also be carried out.

> Publications listing (including latest supplements)
> Subcommittee Homepage

For an overview, see Chem Int. (Tools of the Trade series) Vol. 29 No. 1, Jan-Feb 2007 > full text


> Dec 2007 report update (pdf file - 2.6MB)

Project completed > see project 2007-001-2-100 for continuation

Last Update: 18 December 2007

<project announcement published in Chem. Int. 24(1) 2002>


Questions or Comments about this Project
Please contact the Coordinator

Page last modified 18 December 2007.
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