Precipitating Auroral Electron Flux Characteristics Based on UV Data Obtained by the AIRS Experiment Onboard the Polar BEAR Satellite
Abstract
The AIRS instrument on satellite Polar BEAR is the first to obtain narrow band UV images for more than one band at a time. This provides the opportunity to do serious quantitative analysis of the data in terms of composition and the energy sources producing the emission (aurora and dayglow). Analysis of auroral imaging data from two passes will be presented. On one of these, simultaneous images were obtained at 1356 A (OI 1356 A plus N sub 2 LBH), 1596 A (LBH), and 3914 A (N sub 2(+) 1N). On the other, the observed bands were centered at 1304 A (OI 1304 A), 1544 A (LBH), and 3914 A. Variations in data ratios among the three bands for either pass exceeded a factor of three over the portion of the auroral oval seen within the images. The possible causes of these variations are changes in the hardness of the precipitating particle spectrum (here the particles are assumed to be electrons), changes in the abundance of O relative to N sub 2, changes in the albedo at 3914 A, and statistical fluctuations where signals were low. To interpret the data, yields (Rayleighs/ (erg cm(-2)s(-1))) and yield ratios appropriate to the band centers and their widths were calculated versus hardness of the precipitating electron spectrum. The calculations used MSIS model atmospheres with O density scalings of 1.0 and 0.5. The input parameters were appropriate to the times at which the data were collected to the regions observed. Incident electron spectra were characterized by modified Gaussian and Maxwellian energy distributions defined in terms of characteristic energy E sub o (in keV) and energy flux Q (in ergs cm(-2)s(-1)).
Document Details
- Document Type
- Technical Report
- Publication Date
- Mar 01, 1992
- Accession Number
- ADA260015
Entities
People
- D. J. Strickland
- R. J. Cox