Minutes of phone conference, 17 June 2009, 10:00 - 11:15


  • Marc Bouvet (MB), ESA
  • Claudia Emde (CE), DLR
  • Bernhard Mayer (BM), DLR
  • Arve Kylling (AK), Ă…lesund


  1. Discussion of Tasks 3, 4, 5
  2. General issues


Discussion of Task 3, Algorithm development
  1. Raman scattering - WP3100, status: ongoing
    The issue regarding Raman scattering in cloudy cases has partly been solved. The decrease of the filling-in factor when a cloud is included is still too large.
  2. Tools to generate single scattering properties by aspherical particles, WP3220, status: ongoing
    Two methods have been tested, DDSCAT and the T-matrix code by Mishchenko. The webpage http://www.t-matrix.de/ includes many tools. It was briefly discussed whether such tools should be included in the libRadtran package. MB said it would be preferable to have pre-calculated data rather than a tool which users should use to calculate their own optical properties. CE suggested to calculate some example data files within ESASLight using the T-matrix method. It was agreed that the topic of aspherical particles should be on the recommendation list for the future evolution of the libRadtran package.
  3. Database for Single Scattering Properties - WP3230, status: ongoing
    This work package is pending because the restructuring of DISORT is not yet finished. The data base for water clouds will be finished by end of September.
  4. Extension of surface properties - WP3300, status ongoing
    There are only two small open issues. One is to check whether polarization can be included in Cox and Munk, this has not yet been done. The other is to generate an effective surface albedo from BRDFs which had been suggested in the proposal. Since this function should be easy to implement it will be done within ESASLight (probably not for the intermediate but for the final version).
  5. Representation of aerosols - WP3400, status: closed
    An action item from MTR was to include standard aerosol mixtures which has been done.
  6. Development of graphical tools - WP3510, status ongoing
    More options and plotting utilities have been included. The framework has now been tested under UNIX/Linux, Windows and Mac environments. Work on automatic generation of the GUI has been started.
  7. Refraction - WP3530, status: ongoing
    Refraction has been implemented in MYSTIC. The results look reasonable but are not yet quantitatively validated. A function to compute the wavelength dependent refractive index of air has been included in libRadtran.
  8. DISORT improvements - WP3540, status ongoing
    Modification of 2nd order intensity correction implemented and validated. This work package can be closed soon. The DISORT instability, which occurs in rare cases, will be addressed in the future (should be included in the recommendation list).
  9. Line-by-line interface - WP3560. status: ongoing
    According to F. Schreier from IMF(DLR), the MIRART interface will be available by the end of September.
Discussion of Task 4, Verification
  1. Raman scattering
    Verification will be done once the code development is finished.
  2. Polarization
    Several parts from the verification plan have been done: the comparison with Coulson benchmark data, testing the reciprocity principle for realistic atmospheres, intercomparison between different solvers (DISORT, MYSTIC, polradtran), and several efficiency tests. Some more comparisons to measurements will be done. Furthermore a model intercomparison study initialized by A. Kokhanowsky is ongoing. Also 3D test calculations for a simple step cloud are currently performed.
  3. Work on the test suite has started. This is a bigger project which can not be completed within this study (another topic for the recommendation list).
Discussion of Task 5, Documentation
  1. The user guide is continuously updated.
  2. A draft of the technical note (D13) has been prepared by AK. It includes some theoretical background: a short derivation of the radiative transfer equation and an overview of the capabilities/approximations/limitations of the various solvers of libRadtran .
  3. Writing of the final ATBSs started, to be finished by end of December as planned.
Review of action items

A1: Check possibility of including polarization in Cox and Munk (still open) .

A2: Include standard aerosol mixtures (closed) .

  • No new action items.
Other issues

MB announced that there would be a continuation of the activity and suggested that we should already start to think about what we would recommend for the future evolution of the libRadtran package.

Date of PM6

As planned, PM6 will take place on the 18th of September in Ă…lesund. AK will organize this meeting.

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