SHDOM: Overview
Spherical Harmonic Discrete Ordinate Method
for 3D Atmospheric Radiative Transfer
This program computes unpolarized monochromatic or spectral band
radiative transfer in a one, two, or three-dimensional medium for either
collimated solar and/or thermal emission sources of radiation. The
properties of the medium can be specified completely generally, i.e. the
extinction, single scattering albedo, Legendre coefficients of the
scattering phase function, and temperature for the particular wavelength
or spectral band may be specified at each input grid point. SHDOM is
superior to Monte Carlo radiative transfer methods when many radiative
quantities are desired, e.g. the radiance field across the domain top or
the 3D distribution of heating. Radiances at any angle, hemispheric
fluxes, net fluxes, mean radiances, and net flux convergence (related to
heating rates) may be output anywhere in the domain. For highly peaked
phase functions the delta-M method may be chosen, in which case the
radiance is computed with an untruncated phase function single
scattering correction. A correlated k-distribution approach is used for
the integration over a spectral band. There may be uniform or spatially
variable Lambertian reflection and emission from the ground surface.
Several types of bidirectional reflection distribution functions (BRDF)
for the surface are implemented, and more may be added easily. SHDOM
may be run on a single processor or on multiple processors (e.g. an SMP
machine or a cluster) using the Message Passing Interface (MPI).