AtChem Online

Master Chemical Mechanism simulation online

Not logged in. (log in)


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

Current version

Run AtChem online

Version 2.1 (2022-12)

Version 2.0

Version 1.5

Version 1.4

Version 1.3

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).

Sample data

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 this link.


Using the online 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