Accession Number : ADA136434

Title :   An Investigation of Methods for Computing Long Path Atmospheric Transmittance.

Descriptive Note : Technical rept.,

Corporate Author : AEROSPACE CORP EL SEGUNDO CA CHEMISTRY AND PHYSICS LAB

Personal Author(s) : Johnson,B R

PDF Url : ADA136434

Report Date : 01 Dec 1983

Pagination or Media Count : 61

Abstract : The reliability of the statistical band model for long path length, low transmittance conditions is investigated by a comparing the band model with precise line by line calculations. Two test systems are utilized; a system of H2O adsorbers and a system of computer generated line parameters. It is found that the statistical band model is fairly reliable for calculating band transmittance in the range T 0.1, but for transmittance less than this, it is not reliable and can be in error by several orders of magnitude. An explanation for this behavior is offered. In the second part of this investigation, a new nonstatistical method based on a simple approximation of the k-distribution function is developed. It is compared with precise line by line calculations and is found to be very reliable for all transmittance conditions. (Author)

Descriptors :   *Atmospheric attenuation, *Optical analysis, *Statistical analysis, Line spectra, Infrared spectra, Radiation attenuation, Water, Carbon dioxide, Paths, Mathematical models, Energy bands, Approximation(Mathematics), K band, Monte Carlo method, Band spectra, Distribution functions

Subject Categories : Atmospheric Physics
      Statistics and Probability
      Optics

Distribution Statement : APPROVED FOR PUBLIC RELEASE