Fast Thermal Radiative Transfer Model Distribution

RTSPEC is a rapid plane-parallel unpolarized radiative transfer model for calculating upwelling radiance spectra from a thermally emitting atmosphere. It implements the Deeter and Evans (1998) hybrid Eddington approximation/single scattering approximate radiative transfer solution. It assumes that the only scattering portion of the atmosphere is a multiple layer cloud. The calculated spectrum is averaged with a rectangular or triangular bandpass or convolved using a rectangular, triangular, or sinc^2 FFT window, to produce the output spectrum. Multiple spectral segments or channels may be output.

The model is written in a variant of Fortran77 and comes with a Unix example script and sample input files.

Download the compressed tar distribution.
The README file shows the contents of the distribution.
The RTSPEC source file contains documentation of the model.


What's New

February 5, 2001
Bug fix: Very rarely the Eddington and Hybrid single layer solution routines (EDDSCATRT and SEDDSCATRT) would give bad (e.g. negative radiances) due to the Planck slope parameter (beta) being close to the Eddington eigenvalue (lambda). The check for this was not implemented correctly.
Changes were also made to the spectrum convolution routine.

December 15, 1999
Significant bug fix: downwelling radiances for mu<1 were in error due to incorrect linear Planck function integration across a layer. This could even affect upwelling radiances slightly by reflection of downwelling flux.

June 1, 1999
Major upgrade by Aaron Evans, including:

  1. Upward viewing geometry
  2. Added surface reflection
  3. Double sideband simulation
  4. Convolution with sinc or sinc squared
  5. More modular code

A paper describing the Eddington, single scattering, and hybrid methods has been published in the Journal of Quantitative Spectroscopy and Radiative Transfer:
Deeter, M. N. and K. F. Evans, 1998: A hybrid Eddington-single scattering radiative transfer model for computing radiances from thermally emitting atmospheres. J. Quant. Spectosc. Radiat. Transfer, 60, 635-648.
It is available here as a compressed Postscript file.


Last modified: July 9, 2001

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