Thermospheric O/N2 Based on DE-1 FUV Dayglow Imaging Data

Work performed during the second half of Year 1 of the contract is summarized. The primary objective of the work is to derive global dayside thermospheric oxygen concentrations from DE-1 far ultraviolet imaging data which we are considering under both magnetically quiet and disturbed times. Work to date has been more qualitative in producing maps showing intensity variations beyond those that can be explained by changes in solar zenith angle (SZA) and look angle across an image (Craven et al., 1995; Meier et al., 1994; Gladstone, 1994). In meeting our primary objective, four tasks have been addressed during the reporting period: (1) Investigating the uniqueness of the relationship between the dayglow emission seen using DE-1's 123 filter (dominated by OI 130.4 nm emission) and the column abundance of O relative to N2 referenced to an N2 depth of 10(exp 17) cm(exp 2); (2) Completion of the algorithm for rapid conversion of DE-1 disk dayglow measurements to O/N2 values; (3) Applying the algorithm to a simulation in which a model DE image was constructed using TIGCM atmospheres. The retrieved image of O/N2 was compared to TIGCM O/N2 obtained by integrations of the TIGCM densities; and (4) Applying the algorithm to selected DE-1 data