Minutes of final meeting, 17 March 2010, ESTEC Noordwijk, 9:00 - 15:00


  • Marc Bouvet (MB), ESA-ESTEC
  • Bernhard Mayer (BM), LMU
  • Jerome Caron (JC), ESA-ESTEC
  • Claudia Isola (CI), ESA-ESTEC
  • Fabrizio Ramoino (FR), ESA-ESTEC
  • Ines Fuente (IF), ESA-ESTEC
  • Nicolas Floury (NF), ESA-ESTEC
  • Michael Eisinger (ME), ESA-ESTEC
  • ? , ESA-ESTEC
  • Franz Schreier (FS), DLR
  • Arve Kylling (AK), Alesund
  • Claudia Emde (CE), LMU


  1. General presentation of the project
  2. Progress since last PM (Software, Documentation)
  3. Discussion of next steps


General presentation of project

As an introduction BM gave a presentation about the usefulness of a project like ESASLight for both ESA and the developers. Before ESASLight the libRadtran toolbox has been developed mostly without dedicated funding. The ESASLight study considerably speeded up libRadtran development. To include polarization and Raman scattering would not have been possible without ESASLight since key personnel (AK, CE) who did the development, would have had to work on other tasks. The graphical user's interface would certainly not have been developed without the ESASLight study.

CE presented an overview of the project and summarized the individual tasks that have been completed. The focus was on results of the newly implemented algorithms. JC asked if it was still possible to use the ASCII input files in addition to the GUI. The former are urgently needed for batch processing. The answer was of course “yes”; the GUI provides only a user-friendly interface to generate these input files. JC asked whether a Windows executable could be made available. For the GUI this is possible; to run the full radiative transfer model in batch mode, however, CYGWIN will always be required because it provides the appropriate framework for libRadtran. Once CYGWIN is installed properly, the installation of libRadtran via 'configure' and 'make' is straightforward so that an executable was not considered to be neccessary. A general discussion about whether it would be possible to simplify the installation process followed. It was agreed that the emphasis should be to provide platform-independent software. It is not possible without considerable efforts to provide a “1-click-install” for libRadtran without giving up the philosophy of platform independence.

AK gave an overview of the libRadtran radiative transfer toolbox and presented the GUI. ME asked about the memory requirements of libRadtran. This question has no definite answer since memory requirements depend very much on the application. Anything from a few MB up to several GB may be needed. For most applications memory issues should not be a problem nowadays. The possibility of looping over input parameters was discussed. AK/CE answered that a variety of tools is available (shell scripts, Perl, Excel, …) to automatically generate input files and there is no need to re-invent the wheel. A loop over one parameter is in principle possible but in general the user wants nested loops with dependent parameters. This may not be easily implemented in a general framework. Examples for such scripts should be put on the ESASLight webpage, e.g. in user area. JC also suggested to put a progress bar in the GUI to be able to estimate the computation time of a calculation. AK said that in most cases it is not possible to calculate the computation time in advance, hence a progress bar can unfortunately not be included.

FS presented user-friendly Python tools for line-by-line calculations which can be used to compute the molecular optical thicknesses of all layers. This is the input that is required for high spectral reolution radiative transfer simulations using uvspec. It is not clear which HITRAN version is the best. The line-by-line program by FS does not include continua so far, this is one of the next steps for the further development.

Progress since PM7

Action items 2-6 have been closed. Action item 1 (“Fix GUI problems”) was discussed in the later presentation by AK.

BM gave a summary of the features of the new libRadtran release that has been delivered to ESA (libRadtran2.0-esa). In addition to the public version libRadtran-1.5-beta which is freely available from www.libradtran.org, libRadtran-2.0-esa includes the 3D model MYSTIC (including new variance reduction, polarization, spherical geometry …). Most of the developments in ESASLight are Open Source with exception of the 3D radiative transfer code which (the files mystic.c and vroom.c) should be put under the “Source Code Software Licence under Confidentiality Terms” (Appendix 6 of draft contract). With this license agreement, the code can be used inside ESA and can be sub-licensed to groups for specific tasks. MB will ask ESA administration to prepare the license agreement that will be signed by ESA and by BM.

AK gave a demonstration of the GUI with focus on changes since PM7. Nearly all of the many points raised by MB at PM7 have been addressed and solved. The name “uvspec” has not been changed because uvspec has been well known under this name for more than 15 years. Instead, the documentation was changed so that it is absolutely clear now that “uvspec” is the main tool in libRadtran and that it covers the full spectral range from the UV to the thermal IR. The following issues are to be included in a future project:

  • include units in plots
  • replace LOWTRAN with better k-distribution
  • include headers in output files if requested

AK emphasized that user feedback is very important in order to improve the GUI.

AK showed how examples can be added to the GUI. It was agreed that more ESA specific examples (simulations of satellite measurements for various instruments) should be included.


The documentation has been completely re-written. CE briefly went through the new user's guide and pointed out what has been changed. MB commented that the documentation has improved a lot and that it is now much better structured. He asked whether the Py4CATS documentation should be included into the libRadtran user's guide. Py4CATS, including documentation, will be available as a separate tool from the libRadtran webpage. MB also suggested to include an example of a reflectance calculation (e.g. SCIAMACHY) into the user's guide.

The final documents were briefly discussed. MB said that the final report, the executive summary, and the abstract are o.k. Only some minor updates are required (author list needs to be completed, some typos need to be fixed).

Action items

  1. license agreement for MYSTIC (MB)
  2. update final documents (CE)
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