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Nagy, A. F.

Publications and source records attributed to Nagy, A. F..

At least 127 records · Page 7
All sourcesNASA NTRSDOE OSTI
NASA NTRS1974

Cyclonic disturbances and their consequences in the thermosphere

We draw attention to the possible existence of cyclonic type of disturbances in the thermosphere which are created by localized energy sources in the vicinity of the nightside (and possibly the dayside) auroral oval. Due to the Coriolis force and the character of F-region ion motions, cyclonic disturbance cells of limited extent (3000 to 5000 km) may appear in conjunction with auroral substorms or more prolonged geomagnetic activity. Owing to prevailing thermospheric winds, these disturbances can be expected to drift equatorwards to midlatitude regions. The disturbance zone can be characterized in terms of a cyclonic wind pattern and significant changes in thermospheric neutral gas composition. This latter effect results in decreased plasma densities in the F-region for the lifetime of the disturbance.

Banks, P. M.↗
NASA NTRS1974

Is the red arc a good indicator of ionosphere-magnetosphere conditions

Weak red arcs were observed on the two consecutive nights of July 12-13 and July 13-14, 1969, at Richland, Washington, whereas no red arcs were detectable on the nights preceding and following the observations. Satellite (Ogo 6) data of electron temperature and density, low-frequency ac electric field, and suprathermal electron flux corresponding to the conjugate region of Richland show no significant variations during these days. The data show elevated electron temperatures and enhanced low-frequency ac noise levels at the expected red arc position in the neighborhood of the density trough, as indicated by previous observations. The data appear to indicate that the optical criterion of red arc occurrence would lead to the conclusion of significantly different ionosphere-magnetosphere conditions during these four nights, whereas the more detailed in situ data show that the conditions were very similar.

Nagy, A. F.↗
NASA NTRS1974

Theory of photoelectron production, transport and energy loss

Current understanding of the theory of ionospheric photoelectron production, transport and energy loss is summarized. The various approaches used in the theoretical calculations of photoelectron fluxes appear to be self consistent and sound; improved values for a number of input parameters are needed now in order to achieve significant improvements and more confidence in the results. The major remaining problem in the present day theory of photoelectron transport and energy loss is centered around the calculations of photoelectron transit through the protonosphere.

Nagy, A. F.↗
NASA NTRS1973

The effect of conjugate photoelectron impact ionization on the pre-dawn ionosphere

The measured photoelectron fluxes are used to show that ionization by photoelectrons is not sufficiently large to affect significantly the nighttime ionosphere. The measured downward photoelectron flux used in the calculations is shown in a table. This flux was measured on December 9, 1971 at an altitude of 1400 km, when the local zenith angle was 159 deg and the conjugate zenith angle was 85.2 deg.

Nagy, A. F.↗
NASA NTRS1973

Thermalization and transport of photoelectrons - A comparison of theoretical approaches.

Three methods of studying ionospheric photoelectron thermalization, in which transport effects are evaluated in different ways, are outlined and compared. One method uses a diffusion equation formulation, the second proceeds from a two-stream approximation to the general particle transfer equation, and the third employs a Monte Carlo technique to simulate electron paths. The methods are compared by applying them to identically prepared models. The methods are in close agreement for altitudes in the region of local energy loss, but higher altitudes reveal a discrepancy of as much as a factor of 2 in the net flux of photoelectrons. The discrepancy is removed by appropriately modifying the computational techniques.

Cicerone, R. J.↗
NASA NTRS1973

Thermal electron energy distribution measurements in the ionosphere.

A recoverable payload instrumented for twilight airglow studies was launched by an Aerobee 150 from the White Sands Test Range on Feb. 8, 1971 at 13.56 UT. The payload included a low energy electron spectrometer (HARP) and a cylindrical Langmuir probe. The HARP electron spectrometer is a new device designed to make high resolution differential electron flux measurements. Measurements of ionospheric electron energy distribution in the range from about 0.2 to 4.0 eV are presented.

Hays, P. B.↗
NASA NTRS1973

Measurements of the Michigan Airglow Observatory from 1971 to 1973 at Ester Dome Alaska

The Michigan Airglow Observatory (MAO) was located at Ester Dome Observatory, College, Alaska (latitude: 64 deg 53'N, longitude: 148 deg 03'W) since October, 1971. The MAO houses a 6-inch Fabry-Perot interferometer, a 2-channel monitoring photometer and a 4-channel tilting filter photometer. The Fabry-Perot interferometer was used extensively during the winter observing seasons of 1971-72 and 1972-73 to measure temperature and mass motions of the neutral atmosphere above approximately 90 kilometers altitude. Neutral wind data from the 1971-72 observing season as measured by observing the Doppler shift of the gamma 6300 A atomic oxygen emission line are presented.

Mcwatters, K. D.↗
NASA NTRS1973

Impact of space shuttle orbiter reentry on mesospheric NOx.

Shuttle orbiter reentry will produce large amounts of nitric oxide (NO) through shock heating at mesospheric altitudes. The effects of this reentry are modeled by considering an impulsive source of NO in time-dependent equations including photochemistry and transport. The model uses an odd-nitrogen approach similar to Strobel's. Parameterized flux boundary conditions are imposed at the mesopause and stratopause and concentrations of the odd nitrogen species (NO, NO2, NO+, N(4S) and N(2D) are found numerically by a finite difference scheme. A localized disturbance can last many hours, depending on the effectiveness of eddy transport. Although the model is one-dimensional, effects of horizontal transport are also included approximately.

Stolarski, R. S.↗
NASA NTRS1973

Ogo 6 measurements of supercooled plasma in the equatorial exosphere.

Plasma measurements performed on Ogo 6 reveal electron and ion temperature values that on occasion appear to be well below the expected neutral gas temperature. The phenomenon is observed only at night above 500 km near the magnetic equator. It is suggested that the expansion cooling of the plasma is accomplished by downward motions of the F region plasma induced by winds or diffusion, by outward E x B drift, or more probably by the upward flow of plasma during interhemisphere transport along magnetic field lines. It is also suggested that preferential cooling of electrons because of their greater thermal conductivity should tend to give ion temperatures greater than electron temperatures during the postsunset cooling of the plasmasphere when photoelectrons are absent.

Hanson, W. B.↗
NASA NTRS1973

Comparison of Te and Ti from Ogo 6 and from various incoherent scatter radars.

Langmuir probe and retarding potential analyzer (RPA) data on the electron and ion temperatures Te and Ti obtained from Ogo 6 are compared with Te and Ti values obtained from the incoherent scatter network. The satellite to radar temperature ratio TeS/TeR is 1.15 on the average for these comparisons. This discrepancy is larger than the uncertainties usually placed on the probe and radar Te values. The ion temperature ratio TiS/TiR approximately 1.0, independent of the particular radar examined. This comparison serves as an intercalibration of the incoherent scatter network.

Mcclure, J. P.↗
NASA NTRS1972

OGO-F-02 data analysis

The OGO-VI satellite, which was launched on June 5, 1969 carried a complement of twenty-six experiments. One of those instruments, the F-02 package, was a cylindrical Langmuir probe experiment whose primary purpose was to measure ionospheric electron temperatures and densities. This report briefly describes the F-02 experiment itself, outlines the computer programs developed to analyze the raw data, and gives a summary of the scientific information obtained, with the aid of this experiment.

Nagy, A. F.↗
NASA NTRS1972

Satellite and ground-based observations of a red arc.

The results of simultaneous satellite and ground-based observations carried out during the red-arc period of August 8-9, 1970, are discussed in the light of present day theory. The formation of the arc at the electron temperature peak and density trough seems to support the thermal-conduction theory of red-arc formation.

Nagy, A. F.↗
NASA NTRS1972

Satellite and ground-based observations of a red arc.

Simultaneous observations carried out during the red-arc period of Aug. 8-9, 1970 at Richland, Washington and by the Ogo 6 satellite are examined in the light of the present-day theoretical knowledge. The observed formation of the arc at the electron temperature peak and density trough supports the thermal-conduction theory of red-arc formation. The lack of dc electric fields in the red-arc region rules out these fields as an excitation mechanism. Particle precipitation as a direct source of red-line emission can also be ruled out by the observations presented. The formation of the arc in the plasmapause region and the detection of low-frequency ac fields are consistent with a theory that predicts wave-particle interaction at the plasmapause as a mechanism for supplying thermal energy to the plasmasphere electrons.

Nagy, A. F.↗