Band Model Calculation of Atmospheric Transmittance for Hot Gas Line Emission Sources. Account of Doppler Broadening
Abstract
The effective transmittances along a slant path from the source altitude to space at a zenith angle of 75 deg are computed and averaged over three wide bandpasses in the 2.7 micrometer spectral region. Statistical band model calculations are performed for the assumption that the emission-absorption lines have a Lorentz, Doppler, or Voigt profile. Inhomogeneities inherent in treating the line of sight through the and the hot gas source as a single, highly inhomogeneous optical path are accounted for by using either the Curtis- Godson, the Lindquist-Simmons, or the two-path derivative approximation. The latter is derived herein and is shown to be superior to the Lindquist-Simmons approximation in treating radiative transfer calculations for the Doppler or Voigt line shape. With line shape properly accounted for, the results still indicate a large difference between the effective atmospheric transmittance and the atmospheric transmittance appropriate for continuum emission. This large difference can result only from the high degree of line correlation that exists between the hot H2O/CO2 emission spectrum and the cool H2O/CO2 atmospheric absorption spectrum.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 30, 1975
- Accession Number
- ADA013719
Entities
People
- Stephen J. Young
Organizations
- The Aerospace Corporation