Engineering topics

Creutzberg, F.

Publications and source records attributed to Creutzberg, F..

9 records

NASA NTRS1998

Auroral Boundaries: Comparison Between UV Images, In Situ Precipitation, and Groundbased Optical Observations

The location of poleward and equatorward boundaries are used as diagnostics of substorm phase and energy storage in the magnetosphere. Boundaries are estimated from groundbased observations (all sky imagers, meridian scanning photometers, and magnetometers), from in situ particle observations, and from spacebased global auroral observations. Each observational technique has relative advantages. Based on recent studies, different observing techniques can give differing boundary locations. Understanding any differences in the boundaries from each observing technique is important when using the data as a diagnostic for the magnetosphere. In this study, FUV auroral images from the POLAR Ultraviolet Imager are used to estimate auroral boundaries. These boundaries are then compared with similar boundaries derived from DMSP in situ particle precipitation observations and from groundbased meridian scanning photometers. The goal is to see how well the boundaries from these three dissimilar observations correlate, to estimate dependences on instrumental capabilities, i.e. imager resolution, and to serve as a potential first step to derive an algorithm for finding oval boundaries from groundbased optical data.

Germany, G. A.↗

NASA NTRS1998

Auroral Boundaries: Comparison Between UV Images, In Situ Precipitation, and Groundbased Optical Observations

The location of poleward and equatorward boundaries are used as diagnostics of substorm phase and energy storage in the magnetosphere. Boundaries are estimated from groundbased observations (all sky imagers, meridian scanning photometers, and magnetometers), from in situ particle observations, and from spacebased global auroral observations. Each observational technique has relative advantages. However, recent studies suggest caution when comparing boundaries derived from different methods. in the study, FUV auroral images from the POLAR Ultraviolet Imager are used to estimate auroral boundaries. These boundaries are then compared with similar boundaries derived from DMSP in situ particle precipitation observations and from groundbased meridian scanning photometers. The goal is to see how well the boundaries from these three dissimilar observations correlate, to estimate dependencies on instrumental capabilities, i.e. imager resolution, and to serve as a potential first step to derive an algorithm for finding oval boundaries from groundbased optical data.

Germany, G. A.↗

NASA NTRS1993

Proton aurora and substorm intensifications

Ground based measurements from the CANOPUS array of meridian scanning photometers and precipitating ion and electron data from the DMSP F9 satellite show that the electron arc which brightens to initiate substorm intensifications is formed within a region of intense proton precipitation that is well equatorward (approximately four to six degrees) of the nightside open-closed field line boundary. The precipitating protons are from a population that is energized via earthward convection from the magnetotail into the dipolar region of the magnetosphere and may play an important role in the formation of the electron arcs leading to substorm intensifications on dipole-like field lines.

Samson, J. C.↗

NASA NTRS1992

Proton aurora and substorm intensifications

Ground based measurements from the CANOPUS array of meridian scanning photometers and precipitating ion and electron data from the DMSP F9 satellite show that the electron arc which brightens to initiate substorms intensifications is formed within a region of intense proton precipitation that is well equatorward (about 4-6 deg) of the nightside open-closed field line boundary. The precipitating protons are from a population that is energized via Earthward convection from the magnetotail into the dipolar region of the magnetosphere and may play an important role in the formation of the electron arcs leading to substorm intensifications on dipolelike field lines.

Samson, J. C.↗

NASA NTRS1991

The Aries auroral modelling campaign - Characterization and modelling of an evening auroral arc observed from a rocket and a ground-based line of meridian scanners

A summary of the Aries experiments and results is presented with specific attention given to the tomographic analysis developed from ground-based photometric data. The instrumentation includes particle detectors, rocket photometers, plasma probes, and 1-deg meridian scanning photometers, and an all-sky TV system. The geophysical conditions during the observations are described including the auroral features and wavelengths, rocket trajectories, and the effectiveness of particle measurements. The tomographic inversion is explained with examples of rocket-photometer height data and contrasted with ground-based photometric data. The modeling techniques used to derive height profiles are described and indirectly compared to measured auroral intensities and intensity ratios. An enhancement of atomic oxygen is inferred from discrepancies with previous studies which confirm the difference between observed intensity ratios and modeled results.

Jones, A. V.↗

NASA NTRS1988

The photons payload, G-494: A learning experience

PHOTONS (Photometric Thermospheric Oxygen Nightglow Study) is an optical remote sensing payload developed for Get Away Special (GAS) flight by the National Research Council of Canada. The device is extremely sensitive and is suitable for making measurements of low intensity, aeronomically generated atmospheric emissions in the nadir and the limb and of Shuttle ram glow. The unit uses a sealed canister and UV transmitting viewing ports. During the flight of STS 61-C, PHOTONS received one hour of operation and aeronomic observations were made. Good diagnostic data were obtained and the science part of the experiment malfunctioned. Post flight inspection revealed that the payload was in perfect working order except for total failure of the photomultiplier detectors. The experiment and the payload are described and the flight results are discussed along with the cause of the malfunctions. It is shown that enough was learned from the flight diagnostic data and about the cause of the malfunction to conclude that the engineering flight was successful and that subsequent flight of the PHOTONS payload will be productive.

Harris, F. R.↗

NASA NTRS1987

Low altitude transverse ion acceleration - Auroral morphology and in-situ plasma observations

Detailed plasma and field measurements acquired from a recent sounding rocket within regions of transverse ion acceleration near 500 km altitude during a large auroral substorm at Churchill (Canada) are described. Data from simultaneous ground-based observations of the optical auroral morphology are presented as well. Ionospheric ions were energized to about 300 eV, perpendicular to the local geomagnetic field to within about 1-2 deg. The results are suggestive of parametric decay of large-amplitude lower hybrid waves into H(+) Bernstein waves, resulting in the transverse ion acceleration.

Yau, A. W.↗

NASA NTRS1985

Waterhole auroral arc modification experiments Electrodynamic response

The Waterhole series of experiments, which tested current theories of the electrodynamic structure of auroral arcs, is discussed. In these experiments, the current-carrying capability of the ionospheric plasma was modified by the explosive release of a large number of reactive molecules in the ionospheric F region, with the net effect of reducing the local plasma density over spatial scales comparable to the auroral forms. The response of the aurora to this perturbation was monitored directly by plasma diagnostic instruments on the rocket carrying the explosive release and indirectly from the ground by various photometric and imaging devices. Model predictions of the perturbation induced by the two releases are summarized, and the rocket-borne and ground-based instrumentation is described. Results from both flights are summarized, and a theoretical model is presented which relates the differences in observed response to the topological relationship between the releases and the auroral form.

Whalen, B. A.↗

NASA NTRS1976

Rocket and ground-based measurements of the dayside magnetospheric cleft from Cape Parry, N.W.T.

On Dec. 6, 1974, a Black Brant VD rocket was launched from Cape Parry, N.W.T., into the dayside magnetospheric cleft. The prime launch criterion was the detection of 6300-A emission by two ground-based scanning photometers, but support was provided by two ionosondes. The payload passed through a narrow region of soft electron precipitation, a broader region of enhanced electron densities, and a similarly broad region of O I 5577-A and 6300-A emission. At apogee (236 km), the payload had not penetrated into the 5200-A emission, which had a very sharp equatorward boundary and extended far into the polar cap, presumably as a result of antisunward convection.

Shepherd, G. G.↗