• k-distributions are obtained directly from a line-by-line radiative transfer code, LBLRTM , which has been extensively validated against observations, principally at the ARM SGP site
• fluxes and cooling  rates can be calculated over sixteen bands contiguous bands in the longwave (10-3250 cm^-1)
• modeled molecular absorbers are:  water vapor, carbon dioxide, ozone, nitrous oxide, methane, oxygen, nitrogen and halocarbons.
• fluxes calculated by RRTM agree with those computed by LBLRTM within 1.0 W/m2 at all levels, and the computed cooling rates agree to within 0.1 K/day in the troposphere and 0.3 K/day in the stratosphere.
• water clouds:
  • The optical properties of water clouds are calculated for each spectral band from the Hu and Stamnes parameterization.  The optical depth,  single-scattering albedo, and asymmetry parameter are parameterized as a function of cloud equivalent radius and liquid water path.  Reference: Hu, Y. X., and K. Stamnes, An accurate parameterization of the radiative properties of water clouds suitable for use in climate models.  J. Climate, Vol. 6, 728-742, 1993.
• ice clouds:
  • The optical properties of ice clouds are calculated for each spectral band from the ice particle parameterization from Fu, Yang, and Sun (J. Climate, Vol 11, 1998, pp. 2223 - 2237).

An accelerated version of RRTM v3.0 for use in GCMs is in preparation.

A release note will be sent to the user community when this version is available.