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The AIRS scanning ultraviolet photometer aboard the Polar Bear satellite was launched in late 1986. It was designed to obtain UV images with high spatial and wavelength resolution at several emission lines simultaneously. The objective of the program is to geometrically and photometrically calibrate the data. The processing is designed to provide kilometer-scaled images that can be projected upon various coordinate systems. These tools afford studies of the spatial and temporal variability of airglow and aurora. Each data-stream from a pass is converted to a 240 x 240 image representing 5000 x 5000km records of intensity. The major progress during the report period has been modification and development of programs to accomplish the following: 1) A Chapman function correction to the solar flux dependence of the intensity, resulting with a successful daytime fit of power unity of above variable to pixel brightness. 2) Separation of night-glow domain to ordinary and continuous (24 hr) night regions. 3) Projection of images onto dipole & corrected geomagnetic coordinate systems. 4) Comparison of auroral arcs with known auroral oval and initiation of a UV oval from input images. Keywords: Aurora; Ultraviolet; Image processing; Airglow. (jhd)

Journal of Research of the National Bureau of Standards

The primary goal of the proposed research was to use images from the Ultraviolet Imager (UVI) as remote monitors of changes in the ratio of thermospheric O to N2 at high latitudes in response to geomagnetic disturbances. The principal project tasks were to select UVI image data, develop and extend modeling/analysis tools, and, finally, correlate observed changes with geomagnetic activity. In particular, it was necessary to model the average expected dayglow surface to isolate changes from storms. Note that this research differs significantly from previous efforts in that the 'quiet-time' dayglow surface is modeled from first principles rather than being developed empirically from observations. This technique should thus be more generally applicable to observations from other missions.

The primary goal of the proposed research was to use images from the Ultraviolet Imager (UVI) as remote monitors of changes in the ratio of thermospheric O to N2 at high latitudes in response to geomagnetic disturbances. The principal project tasks were to select UVI image data, develop and extend modeling/analysis tools, and, finally, correlate observed changes with geomagnetic activity. In particular, it was necessary to model the average expected dayglow surface to isolate changes from storms. Note that this research differs significantly from previous efforts in that the 'quiet-time' dayglow surface is modeled from first principles rather than being developed empirically from observations. This technique should thus be more generally applicable to observations from other missions.

The aeronomy group at the University of Pittsburgh is actively engaged in a series of coordinated satellite, sounding rocket, and laboratory studies designed to expand and clarify knowledge of the physics and chemistry of planetary atmospheres. Three major discoveries have been made that will lead ultimately to a complete and dramatic revision of our ideas on the ionospheres of Mars, Venus, and the Earth and on the origin of their vacuum ultraviolet airglows. The results have already suggested a new generation of ionosphere studies which probably can be carried out best by laser heterodyning techniques. Laboratory studies have also identified, for the first time, the physical mechanism responsible for the remarkable nitric oxide buildup observed in some auroral arcs. This development is an important break-through in auroral physics, and has military ramifications of considerable interest to the Department of Defense. This work may also shed some light on related NO and atomic nitrogen problems in the mesosphere.

The aeronomy group at the University of Pittsburgh is actively engaged in a series of coordinated satellite, sounding rocket, and laboratory studies designed to expand and clarify knowledge of the physics and chemistry of planetary atmospheres. Three major discoveries have been made that will lead ultimately to a complete and dramatic revision of our ideas on the ionospheres of Mars, Venus, and the Earth and on the origin of their vacuum ultraviolet airglows. The results have already suggested a new generation of ionosphere studies which probably can be carried out best by laser heterodyning techniques. Laboratory studies have also identified, for the first time, the physical mechanism responsible for the remarkable nitric oxide buildup observed in some auroral arcs. This development is an important break-through in auroral physics, and has military ramifications of considerable interest to the Department of Defense. This work may also shed some light on related NO and atomic nitrogen problems in the mesosphere.

The principal instruments and facilities are described with special emphasis on new construction or modifications. This equipment includes two high dispersion grating spectrographs, two types of patrol spectrographs, ground- based, aircraft borne and balloon-borne infrared spectrometers, a scanning spectrometer for the visible and ultra violet regions with memory unit, two types of photometer for the study of twilight alkali emissions, a Michelson interferometer for the near infrared region and a temperature-measuring photometer for the measuring of auroral rotational temperatures. Also described are facilities for producing specialized interference filters, a source for the Vegard-Kaplan bands, intensity standards for absolute brightness measurements of aurora and a system for obtaining all-sky photographs through interference filters. There is also a brief description of two rocket borne photometers which are under development. Twilight airglow and dayglow measurements, observations of auroral emissions, of the night airglow and of auroral temperatures are discussed. A study is described of the possibility of measuring atmospheric temperatures using the vibrational ratios of N(2) bands. New quantitative measurements of the Vegard-Kaplan bands in the second positive bands of N(2) with the photo electric scanning spectrometer and memory are described.

The data base on column intensity and spatial-temporal irregularity structure of 2 1/2 - 7 micrometers infrared auroral airglow radiations is reviewed, and models of occurrence of sky background clutter in sensor fields are specified. Probabilities and geographic location of auroral particle fluxes, energy conversion efficiencies and relaxation times after excitation, chemiluminescence and fluorescence spectrums of the important radiating species N0, C02, N2 and N0+ (at approx 10/cm resolution), characteristic power spectral densities of the fluctuations in input, and methods of calculating sight paths through the upper-atmospheric layers are compiled for use in the auroral model. The statistical auroral oval defined by a geomagnetic field-disturbance index and magnetic time is taken as the location of occurrence of excitation by incoming electron fluxes (the effect of the proton component is found to be negligible). Hardness of the electron's energy distribution is shown to have important effects on the noise spectrums and the requirements for information about flux structure. Intensities of both flows depend critically on sight path length through the emitting atmospheric layers. As the average variation of hydroxyl zenith radiance is small, it limb brightness is a sharp maximum at readily-determined intercept latitudes-longitudes.

The data base on column intensity and spatial-temporal irregularity structure of 2 1/2 - 7 micrometers infrared auroral airglow radiations is reviewed, and models of occurrence of sky background clutter in sensor fields are specified. Probabilities and geographic location of auroral particle fluxes, energy conversion efficiencies and relaxation times after excitation, chemiluminescence and fluorescence spectrums of the important radiating species N0, C02, N2 and N0+ (at approx 10/cm resolution), characteristic power spectral densities of the fluctuations in input, and methods of calculating sight paths through the upper-atmospheric layers are compiled for use in the auroral model. The statistical auroral oval defined by a geomagnetic field-disturbance index and magnetic time is taken as the location of occurrence of excitation by incoming electron fluxes (the effect of the proton component is found to be negligible). Hardness of the electron's energy distribution is shown to have important effects on the noise spectrums and the requirements for information about flux structure. Intensities of both flows depend critically on sight path length through the emitting atmospheric layers. As the average variation of hydroxyl zenith radiance is small, it limb brightness is a sharp maximum at readily-determined intercept latitudes-longitudes.

Results obtained by rocket-borne optical spectrometry are presented. Composition measurements and auroral studies are reported. The production of N (D-2) atoms by photo-absorption processes, and by electron impact excitation of N2 are discussed along with vibrationally excited CO2(+) ions in planetary atmospheres.

In late 1986, AFGL launched the Polar BEAR satellite, which was designed for UV imagery of the northern pole region. The AIRS scanning ultraviolet photometer aboard the satellite provides images of day and night auroral structures of unprecedented spectral and spatial resolution at 2 working spectral windows simultaneously. It is necessary to apply geometric and photometric corrections to the image in order to enhance and map it onto the ionosphere. Furthermore, satellite attitude corrections are imperative to assure that image coordinates are properly rotated to the real-time body reference system. To the best knowledge of the authors, this project is the first one to fully include geometric and photometric corrections to VUV images of the ionosphere. (aw)