Dear Colleagues, Christmas is around the corner - only five months to go! And as usual for this time of the year we send a Newsletter announcing a new version of libRadtran. Attached to this eMail is the 15th libRadtran Newsletter. The main issue of this Newsletter is to announce the new release libRadtran-2.0-beta We decided to jump from 1.7 to 2.0-beta because the uvspec input file syntax has changed in order to make it more logical and hopefully easier to understand. A translate script is available to convert old input files to the new syntax. The main new feature is the absorption parameterization REPTRAN which replaces the old LOWTRAN parameterization (see below for more details). REPTRAN is based on the most recent HITRAN molecular absorption data. 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! Best wishes, Claudia Emde, Arve Kylling, Josef Gasteiger, Robert Buras and Bernhard Mayer. /*---------------------------------------------------------------- * libRadtran Newsletter No. 15 * * July 24, 2014 * * Bernhard Mayer (bernhard.mayer_at_lmu.de) * Claudia Emde (claudia.emde_at_lmu.de) * Robert Buras (robert_at_buras.eu) * Arve Kylling (arve.kylling_at_gmail.com) * Jonas Kylling (joirkyl_at_gmail.com) * Josef Gasteiger (josef.gasteiger_at_lmu.de) * Bettina Richter (bettirichter_at_googlemail.com) * * ### More info: http://www.libradtran.org ### *----------------------------------------------------------------*/ The main issue of this Newsletter is to announce the new release libRadtran-2.0-beta which will be remembered as the Summer Holidays Release (SHR). As always the new release includes several new features, bug fixes, and most probable several new bugs. Please help us to find and fix them! *** Major changes: * A new absorption parameterization called REPTRAN has been included. Three resolutions (fine: 1 cm^-1, medium: 5 cm^-1 , and coarse: 15 cm^-1) are available for the solar and the thermal spectral ranges. In addition, specifically optimized band parameterizations have been developed for a number of satellite instruments (ADEOS, ALOS, EarthCARE, Envisat, ERS, Landsat, MSG, PARASOL, Proba, Sentinel, Seosat, and SPOT) which are not only more accurate than calculations based on the previous LOWTRAN parameterization but also more efficient since less solver calls are needed. In some spectral regions the uncertainty was reduced by a factor of 10. The parameterization is based on a weighted mean over representative wavelengths. For more details please read the newly published paper: J. Gasteiger, C. Emde, B. Mayer, R. Buras, S.A. Buehler, O. Lemke, Representative wavelengths absorption parameterization applied to satellite channels and spectral bands, J. Quant. Spectrosc. Radiat. Transfer, 148, 99-115 You may download it for free at http://authors.elsevier.com/a/1PP3m564R-TEQ until September 10th, 2014. * The syntax of the input file has changed quite a bit. You might find this annoying in the beginning but you may also notice that the option names are now more logical. At least for new libRadtran users, learning the syntax should be easier as before. You can simply convert your old input files to the new syntax using a Python script src_py/translate.py: python src_py/translate.py old.inp > new.inp * New ice optical properties by Bryan Baum have been added. The bulk optical properties are based on single scattering properties of severely roughened ice crystals and they are available for the full spectral region from 0.2 to 100 microns. Reference: Baum, B. A., P. Yang, A. J. Heymsfield, A. Bansemer, A. Merrelli, C. Schmitt, and C. Wang: Ice cloud bulk single-scattering property models with the full phase matrix at wavelengths from 0.2 to 100 ?m., J. Quant. Spectrosc. Radiat. Transfer, 146, 123-139 * Several new examples and plotting facilities have been added to the GUI. Try "python GUI.py" in the GUI directory! * In order to simplify the installation of libRadtran for Windows users we have generated a virtual Linux machine (for VirtualBox) with libRadtran installed. The virtual machine and instructions how to run it are available from the libRadtran homepage. *** Bug fixes: * Radiances calculated with disort were inaccurate (up to a few %) for some directions when only one viewing zenith angle (umu) or only one viewing azimuth angle (phi) was specified. The reason for this was that a Fourier series expansion was cut off too early. * Polarized radiances in MYSTIC were inaccurate (<1%) when variance reduction method VROOM was enabled. The error became visible when several "profiles" with very different types of phase functions were included. * The sign of the Stokes components U and V for polarized ocean surface reflection (bpdf_tsang) has been corrected. It was wrong due to different coordinate systems used in MYSTIC and in the code by Mishchenko which is applied to calculate the reflectance matrix. * The aerosol_haze option did not work in versions 1.6 and 1.7. * Numerous other minor bug fixes and code improvements.