Accession Number:

ADA275207

Title:

SHARC, A Model for Calculating Atmospheric and Infrared Radiation Under Non-Equilibrium Conditions

Descriptive Note:

Technical rept.

Corporate Author:

PHILLIPS LAB HANSCOM AFB MA

Report Date:

1994-01-24

Pagination or Media Count:

18.0

Abstract:

A new computer model, SHARC, has been developed by the Air Force for calculating high-altitude atmospheric IR radiance and transmittance spectra with a resolution of better than 1cm. Comprehensive coverage of the 2 to 40 microns 250cm to 5,000cm wavelength region is provided for arbitrary lines of sight in the 50-300 km altitude regime. SHARC accounts for the deviation from local thermodynamic equilibrium LTE in vibrational state populations by explicitly modeling the detailed production, loss, and energy transfer process among the important molecular vibrational states. The calculated vibrational populations are found to be similar to those obtained from other non-LTE codes. The radiation transport algorithm is based on a single-line equivalent width approximation along with a statistical correction for line overlap. This approach is reasonably accurate for most applications and is roughly two orders of magnitude faster than the traditional LBL methods which explicitly integrate over individual line shapes. In addition to quiescent atmospheric processes, this model calculates the auroral production and excitation of CO2, NO, and NO in localized regions of the atmosphere. Illustrative comparisons of SHARC predictions to other models and to data from the CIRRIS, SPIRE and FWI field experiments are presented. Non-local thermodynamic equilibrium, Infrared radiation, Computer code, Vibrational and rotational levels, Limb radiance.

Subject Categories:

  • Atmospheric Physics
  • Meteorology
  • Computer Programming and Software
  • Optics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE