Visible Airglow Experiment data analysis

The Visible Airglow Experiment (VAE) was designed to provide detailed profiles of the distribution of excited states of atoms and molecules in the upper atmosphere. The studies supported during the funding period (1983 - 1989) have made significant contributions in the area of thermospheric aeronomy, and the progress during the first four years of this period has been reviewed by Hays et al. (1988). The investigations carried out have resulted in more than 20 publications, and these are summarized

High resolution Doppler lidar

A high resolution lidar system was implemented to measure winds in the lower atmosphere. The wind speed along the line of sight was determined by measuring the Doppler shift of the aerosol backscattered laser signal. The system in its present configuration is stable, and behaves as indicated by theoretical simulations. This system was built to demonstrate the capabilities of the detector system as a prototype for a spaceborne lidar. The detector system investigated consisted of a plane Fabry-Perot etalon, and a 12-ring anode detector. This system is generically similar to the Fabry-Perot interferometer developed for passive wind measurements on board the Dynamics Explorer satellite. That this detector system performs well in a lidar configuration was demonstrated

Atmospheric scattering effects on ground-based Fabry-Perot measurements of thermospheric winds: An inversion technique

The theoretical development of a technique to recover velocities measured with a Fabry-Perot interferometer in the presence of scattered light is presented. Simulations are carried out which show that the inversion is effective in recovering actual velocities, especially in instances when the observed brightness is dominated by scattered light.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25593/1/0000137.pd

Optical effects of spacecraft-environment interaction Spectrometric observations of the DE-2 satellite

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76678/1/AIAA-25728-876.pd

Mesospheric 5577A green line and atmospheric motions--Atmosphere explorer satellite observations

Photometric measurements of the 5577A O(1S) green line mesospheric emission obtained by the Visible Airglow Experiment (VAE) on board the Atmosphere Explorer (AE) satellite have been analyzed. The inverted volume emission rate profiles showed a peak at approximately 96-97 km with a half-width of ~8 km. The diurnal variation of the intensity indicates the presence of a wave component with 10 ~ 12 h period, probably of solar semi-diurnal tide. Shorter time scale variations due to the presence of travelling waves were also observed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26532/1/0000071.pd

Optical effects of spacecraft-environment interaction Spectrometric observations by the DE-B satellite

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76162/1/AIAA-1983-2657-139.pd

Thin discs, thick dwarfs and the effects of stellar feedback

We investigate the role of stellar mass in shaping the intrinsic thickness of galaxy discs by determining the probability distribution of apparent axis ratios (b/a) for two different samples that probe the faint end of the galaxy luminosity function. We find that the b/a distribution has a characteristic 'U-shape' and identify a limiting mass M_* ~ 2x10^9 M_sun below which low-mass galaxies start to be systematically thicker. This tendency holds for very faint (M_B ~ -8) dwarfs in the Local Volume, which are essentially spheroidal systems. We argue that galaxy shape is the result of the complex interplay between mass, specific angular momentum and stellar feedback effects. Thus, the increasing importance of turbulent motions in lower mass galaxies leads to the formation of thicker systems, a result supported by the latest hydrodynamical simulations of dwarf galaxy formation and other theoretical expectations. We discuss several implications of this finding, including the formation of bars in faint galaxies, the deprojection of HI line profiles and simulations of environmental effects on the dwarf galaxy population.Comment: 6 pages, 2 figures. Accepted for publication in MNRAS Letter

Non-thermal O(1D) produced by dissociative recombination of O2+: A theoretical model and observational results

Thermal and non-thermal O(1D) number density profiles are calculated. The two populations are assumed to be coupled by a thermalization cross-section which determines the loss and production in the non-thermal and thermal populations, respectively. The sources, sinks and transport of the two populations are used to model volume emission rate profiles at 6300 A. The 6300 A brightness measured by the Visible Airglow Experiment is then used to establish the presence of the non-thermal population and to determine the thermalization cross-section.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24250/1/0000513.pd

Line shape of the non-thermal 6300 A O(1D) emission

The line shape of the non-thermal O(1D) 6300 A emission is calculated using the two population model of Schmitt, Abreu and Hays (Planet. Space Sci. 29, 1095, 1981). The calculated line shapes simulate observations made from a space platform at different zenith angles and altitudes. The non-thermal line shapes observed at zenith angles other than the local vertical have been obtained by using the Addition theorem for spherical harmonics of a Legendre polynomial expansion of the non-thermal population distribution function.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/24001/1/0000250.pd

The High Resolution Doppler Imager (HRDI) on the Upper Atmosphere Research Satellite

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76425/1/AIAA-1993-123-305.pd