Atmospheric Ultraviolet Radiance Integrated Code (AURIC): theory, software architecture, inputs, and selected results

The Atmospheric Ultraviolet Radiance Integrated Code (AURIC) is a software package developed under the sponsorship of the Air Force Phillips Laboratory/Geophysics Directorate (PL/GP) for upper atmospheric radiance modeling from the far ultraviolet to the near infrared. It effectively extends the PL/GP code MODTRAN for calculating atmospheric transmittance and radiance (IR and Rayleigh + aerosol scattering of sunlight) to altitudes above 100 km and wavelengths down to 1050 Angstrom. The science content of the airglow and upper atmospheric composition codes is presented in this paper. The development has focused on the re-engineering of research codes according to modern software standards and on critical reviews of input parameters (cross sections, rate coefficients, molecular band constants, etc.). In addition to describing the structure and operation of AURIC, detailed, quantitative descriptions are given of the calculation of photoelectron fluxes, the chemistry associated with dayglow and nightglow, and the generation of spectral radiances; Numerous tables are presented of electron impact cross sections and rate coefficients along with associated bibliographies. Results include photoelectron fluxes, volume emission rates, limb profiles of selected emission features, spectral radiances, and densities of ionic and neutral species. To document validation activities, many of the results are compared with published rocket and satellite data showing good overall agreement with the measurements. The airglow modeling capabilities of AURIC make it a powerful tool for characterizing optical backgrounds at thermospheric heights, for developing remote sensing algorithms, for simulating data from rocket and satellite optical instrumentation, and for conducting science investigations (sensitivity studies and data analyses). (C) 1999 Elsevier Science Ltd. All rights reserved.