AtChem on-line project

Outline

We run the AtChem code as a web service, thus making the MCM simulation of atmosphere chemistry phenomena accessible to other members of the EUROCHAMP group.

Curent version

Run AtChem on-line

New in version 1.5:

• Option to alter O2 and N2 concentrations - see help page for furhter details.

New in version 1.4:

• Evolution of the concentration is plotted for several species.
• Output is less verbose.

New in version 1.3:

• Generic rates can be defined in the mechanism file.
• Number of photolysis rates can vary (was hard-coded 35).
• Photolysis constants can be provided in a file with extension “.const” (see below).
• Extension “.config” is no longer accepted for photolysis rates – please use “.rates”.
• RO2 sum is saved in file envVar.output.
• Output is less verbose.
• Header of photolysis rates output file is fixed.
• Instantaneous rates are output at correct intervals.

Warning! Instead of photolysisRates.config you should now provide either photolysisRates.rates (format unchanged) or photolysisRates.const with J/L/N columns (number/rate/name).

You can still use the previous version: v.1.4

Sample data

• allfiles: a large set of data, containing all input files
• simplest: dataset describing reaction A - > C with rate coefficient 1e-4

Source code

The core code is written by Chris Martin in Fortran 90 and uses an open-source library CVODE, providing rapid solvers of ODE systems. The Python wrapper, written by Kasia Borońska, takes care of converting the input data, running the simulation on the server and displaying links to zipped output files. You can download a current version of AtChem from https://atchem.leeds.ac.uk/sources.

Documentation

Using the on-line version is straightforward. User uploads the mechanism file (in FACSIMILE format), initial concentrations file and, optionally, some configuration files, set environment variables and model parameters. It is also possible to enter the job name and a short description. After pressing "submit", the simulation will be run on the server and links to input and output files will be displayed, along with a unique job ID.

People involved

• Kasia Borońska
• Peter Jimack
• Mike Pilling
• Andrew Rickard
• Monica Vázquez Moreno
• David Waller
• Jennifer Young