TBSCAT is a subroutine, callable from Fortran or Matlab, which computes top-of-atmosphere microwave brightness temperatures for an atmosphere defined by profiles of temperature, water-vapor density, non-precipitating cloud-liquid water density, and densities of four types of precipitation (rain, snow, graupel, and ice), all specified as functions of pressure by the calling program.  The calling program also supplies the equivalent-melted-size distributions for each type of precipitation particle and an "icefactor" for each of the three frozen types, which specifies the volume fraction of ice (as opposed to air) within the particles.  The ice dielectric constant of Hufford (1991) and dielectric mixing formulas (raisin-pudding model) of Shivola (1989) and Karkkainen et al. (2001) are used to calculate the dielectric constant of the frozen particles.  TBSCAT computes Mie scattering and extinction for spherical particles and includes absorption by the atmospheric gases oxygen, water vapor and nitrogen as well as by the cloud liquid water.  The equation of radiative transfer is solved by the method of Rosenkranz (2002).  Although the solution method can handle non-specular surface scattering, at present the code only implements specular reflection at the surface; two reflection coefficients are specified by the calling program, usually for vertical and horizontal polarization.  The number of radiation streams and their angles of propagation from zenith are also specified by the calling program.  Planar stratification of the atmosphere is assumed, which implies azimuthal symmetry of emitted brightness temperature.  Contact pwr@mit.edu to obtain a copy of the code.

References

Hufford, G., Int. J. IR & MM Waves 12, 677-682 (1991).

Karkkainen, K., A. Shivola, and K. Nikoskinen, IEEE Trans. Geosci. Remote. Sens 39, 1013-1018 (2001).

Rosenkranz, P. W., IEEE Trans. Geosci. Remote. Sens. 40, 1889-1892 (2002).

Shivola, A., IEEE Trans. Geosci. Remote. Sens. 27, 403-415 (1989).