Dear Colleagues, you receive this eMail because you are either a user of the radiative transfer package libRadtran or because we think that you might be interested in this information. Should you not be interested in receiving further information, please let us know. Attached to this eMail is the 9th libRadtran Newsletter. The main issue of this Newsletter is to announce the new version, *** libRadtran 1.4 *** which includes some bug fixes and several improvements compared to version 1.3. And now, we wish you all a Merry Christmas and a happy and successful new year! Bernhard Mayer, Ulrich Hamann, Claudia Emde, and Arve Kylling. ------------------------------------------------------------------ Dr. Bernhard Mayer Bernhard.Mayer_at_dlr.de Deutsches Zentrum fuer Luft- und Raumfahrt (DLR) Institut fuer Physik der Atmosphaere, Oberpfaffenhofen, D-82234 Wessling, Germany. Phone: +49 8153 282568, Fax: +49 8153 281841, Homepage: http://www.bmayer.de ------------------------------------------------------------------ /*---------------------------------------------------------------- * libRadtran Newsletter No. 9 * * December 24, 2008 * * Bernhard Mayer (bernhard.mayer_at_dlr.de) * Ulrich Hamann (ulrich.hamann_at_dlr.de) * Claudia Emde (claudia.emde_at_dlr.de) * Arve Kylling (arve.kylling_at_helse-sunnmore.no) * * ### More info: http://www.libradtran.org ### *----------------------------------------------------------------*/ Dear libRadtran users, merry Christmas and a good start into the New Year! In a good tradition, now for the 7th time in a row, a new libRadtran version is released as a Christmas gift. Below you will find a rather detailed list of new options and bug fixes. But before that I want to point out a few highlights: * In March 2008 we started an exciting project funded by ESA: ESASLight is a 2-years project (March 2008 - March 2010) aiming at the development of a comprehensive radiative transfer package to support ESA's present and future satellite missions. libRadtran was selected as the starting point of this development. In that line, we started on fully implementing polarization and Raman scattering into libRadtran. Also, user-friendliness and documentation will be further improved. * The libRadtran homepage was redesigned in fall. We added a user area where anybody who has an interesting application or knows some tips and tricks may add a section. So far, nobody was brave enough to do so except Bernhard Mayer and Arve Kylling. Don't be shy! * The number of "Publications that used libRadtran" (http://www.libradtran.org/publications.html) has increased to 141. If you published a paper which uses libRadtran, please let us know! Most of these papers will be discovered by SCOPUS, but I only add those which I can access electronically from my Desktop. This includes AGU, AMS, OSA, ELSEVIER and of course all electronic reprints you send me. And now for the changes of version 1.4 compared to 1.3: *** Major changes: * The first major change you will find out quickly when you try to do the first calculation with libRadtran 1.4: The directory structure has been changed to a standard Linux/Unix structure. In particular, we have - src: source of all tools - libsrc_c: source code of the libRadtran C library libRadtran_c.a - libsrc_f: source code of the libRadtran Fortran library libRadtran_f.a - bin: executables The rest (in partcular the data directory) hasn't changed. With this new directory structure finally "make install" works as well. You don't need "make install" to run uvspec but you may use it to install uvspec in the standard Unix directory tree /usr/bin/, /usr/include, /usr/share, ... (or whatever path you specify in configure --prefix ...) Should you have created 1000 scripts for your calculations with uvspec you may now use your free time over Christmas to change "tools/uvspec" to "bin/uvspec" in each of those ;-) * Several changes to the treatment of optical properties of water and in particular ice clouds: PLEASE READ CAREFULLY IF YOU USED ICE CLOUDS IN LIBRADTRAN BEFORE because some important changes were done which not only make the treatment of ice clouds more consistent but affect the uvspec output: that is, version 1.4 will give different numbers than 1.3 if the input is not changed accordingly. This is one of the rare occasions were the model output for a given input file produced by the new uvspec version differs significantly from the output of the old version - as you know we usually try to avoid that except in case of bugs: - Different parameterizations are available for ice clouds, including Fu, Key, Yang, Baum. The authors of the different parameterizations used different definitions (e.g. of the effective radius) and some applied delta-scaling while others did not. E.g. Fu et al. used a different definition of the effective radius than Key et al. and they delta-scaled their optical properties while Key et al. did not. The philosophy of libRadtran was to implement each parameterization as close to the original publication as possible. For that reason, we used different definitions of the effective radius for each parameterization and applied delta-scaling or not depending on the parameterization. As long as you define your ice cloud by its ice water content and effective radius this is fine. Once the optical thickness is specified e.g. with ic_set_tau, however, things are quite different. This was explained in detail in the user manual and in the libRadtran publication, Figure 9. From version 1.4 on, all parameterizations are treated consistently. Hence you may define an optical thickness now irrespective of the chosen parameterization and will get comparable results for the different parameterizations. In particular, all user-defined optical properties (optical thickness, asymmetry parameter, ...) are not delta-scaled and the effective radius definition follows key/yang/baum. The Fu et al. (1996) effective radius is converted analytically to this definition, see also option ic_fu_reff. - In versions before 1.4 cloud microphysical properties (defined in wc_file/ic_file) were considered level properties. If you wanted to define a layer property (which is probably the most common approach to define a cloud, and in particular a sharp cloud top and bottom) you needed to say wc_layer/ic_layer. As probably 99% of the input files contained "wc_layer/ic_layer" we decided to make this the default. To get the old behaviour, use wc_level! * Polarization with the polRadtran solver is now more or less fully implemented. polRadtran was included several years ago, but did not work for an atmosphere including aerosols or clouds, and even for a Rayleigh atmosphere we were not sure if the result was correct. For that reason, simply forget everything you knew about polarization in libRadtran prior to version 1.4 and check the manual how it works now. Polarized calculations may now include molecules, aerosol particles, water and ice clouds (of course only if the respective optical properties include polarization-dependent single-scattering properties or if you provide your own ones). For that purpose, the Mie tool has been upgraded as well. * The OPAC database (Optical Properties of Aerosols and Clouds, http://www.lrz-muenchen.de/~uh234an/www/radaer/opac.html) was included to allow defining a user-defined mixture of aerosol types. Usage is very simple: See the documentation of aerosol_species_file and aerosol_species_library. You need to download the OPAC data set separately from the libRadtran download page. * We tried to make the self-check a bit more robust and hope that users won't get 1000 serious errors anymore. See also the section about serious errors in the FAQ at http://www.libradtran.org! * Several new output_user options have been added, see the manual for a complete list. ** Smaller changes: * For the calculation of heating rates with "heating_rate local", two extra layers are introduced above and below each layer to be calculated. This is computationally expensive and might change in future. * "zout CPT" sets the output altitude to the cold-point tropopause * We often mentioned that in order to speed up disort and other solvers for your particular application you might adjust the constants in libsrc_f/DISORT.MXD and recompile. A new option "optimize_fortran" was added which helps in that process as it tells you which minimum settings are needed for this particular input file. * Fixed a bug in aerosol_scale_tau which was already introduced in 2002. * Three new "no" options: ic_no_scattering, wc_no_scattering, aerosol_no_scattering, in order to turn off scattering by ice clouds, water clouds, or aerosols seperately. * Slightly improved optical property files for the Baum et al. parameterization. * Now it is explicitely forbidden to over-write the asymmetry parameter if an explicit water cloud / ice cloud / aerosol phase function was defined via its Legendre moments (it does not make sense anyway). * Added the delta-scaling factor to the verbose output * radiance to brightness temperature conversion for the "brightness" option did not converge in some cases. Fixed that (or at least made this much less likely) The latest version is available at http://www.libradtran.org, as usual. And now, have fun! Bernhard Mayer (bernhard.mayer_at_dlr.de) Claudia Emde (claudia.emde_at_dlr.de) Ulrich Hamann (ulrich.hamann_at_dlr.de) Arve Kylling (arve.kylling_at_helse-sunnmore.no)