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. Should you know of anybody who might be interested in libRadtran and whose name is not on the distribution list, please let us also know as well. Attached to this eMail is the sixth libRadtran Newsletter. The main issue of this Newsletter is to announce the new version, *** libRadtran 1.1-beta *** which includes some bug fixes and several improvements compared to version 1.01 And now, we wish you all a happy and successful new year! Bernhard Mayer 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. 6 * * December 24, 2005 * * Bernhard Mayer (bernhard.mayer_at_dlr.de) * Arve Kylling (arve.kylling_at_helse-sunnmore.no) * * ### More info: http://www.libradtran.org ### *----------------------------------------------------------------*/ Welcome to the sixth libRadtran Newsletter! Dear libRadtran users, it is Christmas again and hence time for an update! First, I am glad to inform you that a new developer joined the team: Ulrich Hamann, who started working on his PhD thesis at DLR in April 2005, was bold enough to have a closer look at the source code and soon became deeply involved in libRadtran development. Have a look at the libRadtran web page to learn about his experiences! Another important event was the publication of the libRadtran paper in ACP in summer 2005. Please get a copy (it's freely available) if you haven't yet! Quite a few things have changed in 2005, see below! We felt that the model is ready for a release, although we might want some more testing - hence we call the version a "beta version", although we haven't encountered any problems so far! Actually, the model output changed a bit in the gas absorption bands as we removed some inconsistencies in the assumption of the variation of trace gas profiles within a model layer, see below. And now for the changes from version 1.01 to 1.1-beta: *** Bug fixes: * Fixed a bug with Rayleigh depolarisation: For "rayleigh_crs nicolet" a depolarisation of -999 was used accidentally which led to a completely wrong second moment of the phase function and hence a wrong diffuse radiation. * Small bug: The extinction coefficient was still calculated as 1/km / g/m3 water, not as 1/km / cm3/m3 as stated in the manual. Removed RHOH2O from the calculation. The difference is a factor of 1/0.998 in the extinction coefficient, but only if a size distribuition was specified. Thanks Tobias Zinner! * Small change in the documentation: sdisort (double precision version) can actually be used for clouds. * When converting the Fortran 90 routines of the Fu and Liou code to Fortran 77, vf90 replaced the symbols (from fl_radparams.inc) by their actual values. Hence, any change in vl_radparams.inc had NO effect on the source code in fl_misc_subs.f etc. -> Segmentation Fault Fixed that. * Small fix to UVTools.pm: zenith angle calculation was not possible for t>24h. Thanks to Ola Engelsen! * Fixed a segfault detected by Manfred Wendisch which occurred when a vertical redistribution was required and a the moments of the phase function were defined (e.g. if one used "wc_properties mie" for a wc_file the levels of which do not conincide with those in atmosphere_file) *** New options: * Added new option output_user to define the columns desired for output. Available options are wavelength, zout; edir, eglo, edn, eup; fdir, fglo, fdn, fup; uavgdir, uavgglo, uavgdn, uavgup; albedo. This is a first step towards "making the uvspec output user-configurable". * Added option ic_cloudcover, equivalent to wc_cloudcover. If only one is specified, only this one is handled as IPA while the other one is considered plane-paraÂllel. If both are specified, the cloud fractions must be equal. * New parameters for the RPV BRDF in disort2: - rpv_scale, to scale the complete BRDF; that way the albedo can be adjusted; rpv_scale can also be defined wavelength-dependent, as a 4th parameter in rpv_file - rpv_sigma, rpv_t1, rpv_t2; to parameterize snow according to Deguenther and Meerkoetter (2000); no wavelength dependence possible Snow BRDF needs more checking; the impact of the parameters sigma, t1, t2 is nearly negligible when the values from Deguenther and Meerkoetter (2000) are used. * Better handling of RPV BRDF in disort2: disort2 checks if BDREF gives an albedo between 0 and 1, for 100 equally spaced umu0's; this test was copied to the BDREF function and is applied whenever one of the input paranmeters toBDREF has changed; very often, the albedo exceeds 1 for low incidence angles (small mu); this is captured now by determining the largest angle for which a reasonable albedo is determined and to replace the BRDF for smaller mu's with that for the last reasonable mu. * tools/addlevel now accepts more than 1 level to be added simultaneously *** Smaller changes: * More consistent treatment of atmospheric profiles: air density is interpolated logarithmically, temperature linearely. The mixing ratio of all trace gases are interpolated linearely now, except for ozone and NO2 where the number concentrations are interpolated linearely. This behaviour can be controlled by the user with z_interpolate, see documentation. This is true for vertical redistribution as well as for the calculation of layer properties. * Relaxed additional atmosphere input files: dens_file's don't need to cover the whole atmosphere anymore; only the z-range covered by the dens_file's is used to over-write the atmosphere_file; above and below this z-range the original values (from atmosphere_file) are kept. * Added some more examples and removed several of the "serious differences" by improving the existing examples; most of the "serious differences" during "make check" were caused by numerical noise. * Now also applying user-defined asymmetry parameter (wc/ic_scale_gg and wc/ic_set_gg) to mie files (defined by wc/ic_properties mie); please note that this may result in a weird scattering phase function. * Added the ECHAM4 parameterization for water and ice clouds. Use only for comparison with ECHAM4 because the wavelength grid is really crude. See Roeckner et al, 1996, MPI report 218. * Small change to Errpack2: Alle error messages and warning are now going to stderr (Fortran Unit 0). * disort and disort2 did not work for some solar zenith angles, e.g. 60 degrees. Added fix for the "SETDIS--beam angle=computational angle": In tools/sza.c it is checked if the condition for the Error is satisfied (using the code from DISORT.f, DISORT2.f). If yes, then the solar zenith angle is changed slightly. The condition is fulfilled if the relative difference between umu0 and cmu is smaller than 1e-4. If this is the case, umu0 is set to (1 - 1.1e-4) * cmu or (1 + 1.1e-4) * cmu - whichever is closer. Tested for SZA 60 degrees. Fix is only invoked for disort and disort2. * "chekin--vertical temperature step may be too large ..." is now only printed once (more than once does not make sense). * Altitudes in case of "output heating" are now also output in increasing order The latest version is available at http://www.libradtran.org, as usual. And now, have fun! Bernhard Mayer (bernhard.mayer_at_dlr.de) Ulrich Hamann (ulrich.hamann_at_dlr.de) Arve Kylling (arve.kylling_at_helse-sunnmore.no)