WinDOAS

The experience of BIRA-IASB in the development and the improvement of DOAS algorithms goes back in the early nineties with the atmospheric research activities using ground-based UV-Visible DOAS spectrometers aiming at the long-term monitoring minor components involved in the catalytic destruction of the ozone layer or the anthropogenic pollution.

WinDOAS is the result of more than 18 years of expertise in DOAS retrieval from ground-based and satellites measurements. It combines some powerful DOAS tools and a friendly user interface. The retrieval results have been validated extensively through different campaigns.

The program has known a success story : first developed for DOAS activities at BIRA-IASB, it is now used worldwide and for many different DOAS applications (ground-based, satellites, balloons, long-path…).

Last update on 21 April 2009

Be careful : WinDOAS is only supported by Windows operating system. Because of the new cross-platform QDOAS user interface is intended to replace it, no new development will be operated on WinDOAS anymore and it is recommended to move to QDOAS now. Because the user interface and the engine of QDOAS are similar to WinDOAS ones, WinDOAS users should move easily to QDOAS.

The user interface

• Friendly user interface with projects and analysis windows organized in trees;
  
• Organization of options for projects and analysis windows in different tab pages;
  
• Possibility to display the result of the fit;
  
• Step by step, possibility to move easily in the file;
  
• Possibility to zoom in graphs;
  
• Possibility to disable the user interface and to load the program from the command line;
• Support different spectra file formats (SAOZ, MFC, GOME, SCIA, ...)
  
• According to the format of files, some specific implementations to manage files; possibility to include folders;
  
• Output fully configurable.
  

Main DOAS features

• Decomposition of the DOAS equation into a linear and a non linear least-squares fitting problems;
  
• Possibility to define several spectral fitting windows;
  
• Shift and squeeze for any spectral item;
  
• Possibility to fix the concentration of any species;
  
• Possibility to filter spectra and cross sections;
  
• Possibility to correct for an instrumental offset;
  
• Polynomial until order 5 to fit the continuous part;
  
• Differential cross sections (using orthogonalisation or high-pass filtering);
  
• Automatic selection of the reference spectrum;
• Characterization of the wavelength calibration and the slit function of the instrument using a NLLS fitting approach where the measured intensities are fitted to a high-resolution solar spectrum degraded to the resolution of the instrument; several analytical slit function supported.
  
• Cross sections can be convoluted using the information retrieved at the previous step;
  
• Powerful convolution tool (standard convolution and I0-corrected, different supported line shapes, possibility to account for a wavelength dependence of the resolution);
  
• Ring/Undersampling tools;
  

Documentation

WinDOAS Software user manual, February 2001

The latest version of the WinDOAS online help and the S/W user manual is a little bit out of date but as WinDOAS tends to be replaced by QDOAS, no S/W user manual will be issued anymore.

Download and technical support

To download the latest version of WinDOAS (last update on April 2009) or for technical support, please, contact Caroline FAYT or Michel VAN ROOZENDAEL.