This tar file contains two polarized plane-parallel radiative transfermodels written by Frank Evans at Colorado State University and the University of Colorado.  The first is rt3 which is for randomly orientedparticles (isotropic media) and includes solar and thermal sources ofradiation.  The second is rt4 which is for horizontally orientedparticles (azimuthally symmetric media), but does only thermal sources. The rt3 model is described in K. F. Evans and G. L. Stephens, 1991: "A New Polarized Atmospheric Radiative Transfer Model", J. Quant. Spectrosc. Radiat. Transfer, v. 46, no. 5, pp. 413-423, 1991.The rt4 model is briefly described in Evans, K. F., and G. L. Stephens, 1995: "Microwave radiative transfer through clouds composed of realistically shaped ice crystals. Part II: Remote Sensing of Ice Clouds",J. Atmos. Sci., v. 52, 2058-2072.   This latest version of rt3 and rt4 allows the radiances at any level inthe input medium to be output. The output format has been changed tothat the actual radiance is output for a specified number of azimuthangles, instead of outputting the Fourier series.  The radiances may nowbe output as V and H polarization and/or brightness temperatures (thePlanck function is always used internally now).    Delta-M scalingmay be specified for rt3.The models are written in a variant of Fortran 77 which allows longsubroutine and variable names and the use of ENDDO in DO loops.  Thearrays are currently setup for a radiance vector length of 64 (e.g. 16angles, 4 Stokes parameters).  See the beginning  of rt3.f andradtran3.f or rt4.f and radtran4.f for documentation on using theprograms.The following is a list of the files:  rt3.f         main program, contains documentation at beginning  radtran3.f    RADTRAN subroutine with documentation at beginning  radscat3.f    subroutines  radintg3.f        "  radutil3.f        "  radmat.f          "  rt4.f         main program, contains documentation at beginning  radtran4.f    RADTRANO subroutine with documentation at beginning  radscat4.f    subroutines  radintg4.f        "  radutil4.f        "  scatcnv.f     program to convert scattering files from rt3 format                   (Legendre series in scattering angle) to rt4 format.  runmietest    Unix script to test rt3 with the Mie example from the paper.  runtesta      Unix script for a more general test of rt3.  runtestr      Unix script that does a test of rt4 with spherical raindrops.  runtestc      Unix script for a test of rt4 using oriented ice columns.If you use these models I would appreciate you sending me e-mail tellingme about it.  Comments and suggestions are welcome.    Frank Evans           July 3, 1996    Program in Atmospheric an Oceanic Sciences    University of Colorado, Boulder    evans@nit.colorado.edu     (303) 492-4994