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Brinton, H. C.

Publications and source records attributed to Brinton, H. C..

At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1979

An experimental and theoretical study of the mean diurnal variation of O/+/, NO/+/, O2/+/, and N2/+/ ions in the mid-latitude F1 layer of the ionosphere

A theoretical model of the diurnal variations in the compositions of the ions O(+), NO(+), O2(+) and N2(+) in the midlatitude F1 layer is presented and compared with measurements made by AE-C. The theoretical model includes the rate coefficients and branching ratios for the dissociative recombination of NO(+), O2(+) and N2(+) with electrons and the ion-atom interchanges of O(+) with N2 and N2(+) with O. Input parameters to the model comprise measurements of ion and electron temperatures, neutral atmosphere composition, the solar EUV flux and the photoelectron spectrum. In general, model calculations are found to agree with satellite measurements, confirming the major ion sources and sinks of the photochemical model, which has an accuracy of + or - 60%.

Torr, D. G.↗
NASA NTRS1979

Ionosphere of Venus - First observations of the dayside ion composition near dawn and dusk

Independent Bennett radio-frequency ion mass spectrometers on the Pioneer Venus bus and orbiter spacecraft obtained in situ measurements of the composition of the ionosphere of Venus. The spectrometer on the bus explored the dawn region while the spectrometer on the orbiter explored the duskside region. Information on the ion composition in the topside, the lower ionosphere, and the upper ionosphere is presented. Below the O(+) peak near 200 km, the ions are found to exhibit scale heights consistent with a neutral gas temperature of about 180 K near the terminator. In the upper ionosphere, scale heights of all species reflect the effects of plasma transport.

Taylor, H. A., Jr.↗
NASA NTRS1979

Ionosphere of Venus - First observations of the effects of dynamics on the dayside ion composition

Data obtained by Bennett radio-frequency ion mass spectrometers indicate that the ionosphere envelope, dominated above 200 km by O(+), responds dramatically to variations in the solar wind pressure. The pressure compresses the thermal ion distributions from heights as great as 1800 km inward to 280 km. At the thermal ion boundary, or ionopause, the ambient ions are swept away by the solar wind, while at higher altitudes energetic ion currents are detected. Within the ionosphere, ion convection stimulated by the solar wind interaction causes pass-to-pass differences in the ion scale heights.

Taylor, H. A., Jr.↗
NASA NTRS1979

About the influence of electron temperature and relative ionic composition on ion depletion in the wake of the AE-C satellite

Data from the cylindrical electrostatic probe and from the Bennett ion mass spectrometer on board the AE-C satellite were examined in order to determine the influence of electron temperature (Te) and ion composition on the amount of ion depletion in the wake of an ionospheric satellite. It is observed that both electron temperature and ionic composition significantly influence the amount of ion depletion in the near wake zone, as measured by the ion current collected by the cylindrical probe mounted about 32 cm from the surface of the satellite. The ion current in the wake in an O(+) dominated plasma decreases with respect to ambient by about two orders of magnitude at a Te of about 1000 K and by a factor of about 30 at a Te of about 3000 K. For a plasma where the O(+) density equals the H(+) density, the ion current decreases by a factor of 6 in the wake at a Te of about 1000 K and by a factor of 2.3 at 3000 K.

Samir, U.↗
NASA NTRS1979

Global model of longitude/UT variations in thermospheric composition and temperature based on mass spectrometer data

Measurements of N2, O, He, and Ar densities from neutral gas mass spectrometers on four satellites and inferred O2 and H densities from an ion mass spectrometer have been combined to produce a model of longitude/UT variations in thermospheric neutral composition and temperature. The longitude/UT model is an extension of the mass spectrometer-incoherent scatter thermospheric model (Hedin et al., 1977) and uses spherical harmonic terms dependent on geographic latitude, longitude, and UT. The combined longitude and UT variations reflect the influence of the geomagnetic field but indicate that the variations may not simply be represented in magnetic coordinates.

Hedin, A. E.↗
NASA NTRS1978

The high-latitude winter F region at 300 km - Thermal plasma observations from AE-C

Results are presented for a comprehensive survey of thermal ion composition and electron temperature (Te) variations in the southern high-latitude winter F region near 300-km altitude. The data are obtained from the Atmosphere Explorer (AE-C) satellite during a magnetically quiet period centered on the June 1976 solstice. Prominent ionospheric features, including the nightside main trough, a high-latitude ionization hole, and the dayside auroral zone-cusp region, are characterized in terms of composition and Te variations. The structures under study are qualitatively interpreted in terms of known processes.

Brinton, H. C.↗
NASA NTRS1978

Fe/+/ ions in the high latitude F-region

Ion mass-spectrometer measurements on Atmosphere Explorer C orbits from December 1974 to December 1976 were surveyed poleward of + or - 30 deg for instances in which the Fe(+) number density exceeded the spectrometer threshold sensitivity of 30/cu cm. The occurrences of Fe(+) within the altitude range covered by the orbit, 220 to 320 km, revealed a distinct pattern apparently associated with regions of upward plasma transport. At night a band of such events occurred between 50 and 60 deg invariant latitude, which typically corresponded to the location of the main ionospheric trough. In this region large upward ion drifts due to the drag of an equatorward-blowing neutral wind are expected. The Fe(+) band extends past 0600 MLT to about 1100 MLT during the summer, but is not observed in the afternoon. The dayside distributions possibly result from the upward drifts of F-region ions detected by backscatter techniques after dawn during summer. At higher latitudes patches of Fe(+) were detected in regions where strong plasma drifts often prevail and hence where poleward E x B drift motions and atmospheric expansion through Joule heating can lift the ions upwards.

Grebowsky, J. M.↗
NASA NTRS1977

Comparison of measured and calculated thermospheric molecular oxygen densities

The open source neutral mass spectrometers on the AE-C, -D, and -E satellites were equipped with a 'fly-through' mode of operation which has provided direct measurements of molecular oxygen densities over a large portion of the globe. A complementary set of O2 densities is derived by using AE ion measurements and a scheme based on the daytime ion chemistry of O2(+) in the thermosphere. A comparison of the two data sets reveals general agreement over northern latitudes during periods of relatively low Ap and F10.7. The simplifying assumptions made in the photochemical scheme require that caution be used in calculating O2, especially at high latitudes and altitudes below 200 km

Potter, W. E.↗
NASA NTRS1977

Determination of the N2 recombination rate coefficient in the ionosphere

Measurements of aeronomic parameters made by the Atmosphere Explorer-C satellite are used to determine the recombination rate coefficient of N2(+) in the ionosphere. The rate is found to increase significantly with decreasing electron density. Values obtained range from approximately 1.4 x 10 to the -7th to 3.8 x 10 to the -7th cu cm/sec. This variation is explained in a preliminary way in terms of an increase in the rate coefficient with vibrational excitation. Thus, high electron densities depopulate high vibrational levels reducing the effective recombination rate, whereas, low electron densities result in an enhancement in the population of high vibrational levels, thus, increasing the effective recombination rate.

Orsini, N.↗
NASA NTRS1977

Observations of neutral composition and related ionospheric variations during a magnetic storm in February 1974

The neutral-atmosphere composition experiment on Atmosphere Explorer C measured N2, O, Ar, and He densities during a magnetic storm at altitudes down to about 160 km. At latitudes above 45 deg N, N2 and Ar densities generally increase during the storm, while He and O densities decrease. Below 45 deg N all densities tend to increase during the storm. The density increases at perigee indicate that density- or temperature-profile changes are taking place below 160 km. The return to prestorm conditions is very slow, demonstrating the integrating effect of the atmospheric response. A recent theoretical model incorporating thermospheric circulation and diffusion effects reproduces the longitudinally averaged data, including latitude trends and the asymmetry about the storm maximum. Comparison with the mass-spectrometer and incoherent-scatter empirical model shows qualitative agreement with latitude trends but not with storm asymmetry, while the earlier J71 model based on total mass density is not in agreement with observed latitudinal trends. A close correlation is found between in situ O/N2 measurements and in situ and ground-based ionosonde measurements of electron density.

Hedin, A. E.↗
NASA NTRS1977

A global thermospheric model based on mass spectrometer and incoherent scatter data MSIS. II - Composition

Measurements of O, He, and Ar from neutral gas mass spectrometers on four satellites (Ogo 6, San Marco 3, Aeros A, and AEC-C) and inferred oxygen and hydrogen densities from an ion mass spectrometer on AE-C have been combined with a neutral temperature and nitrogen density model to produce a global model of thermospheric composition in terms of inferred variations at 120 km. The data set covers the time period from mid-1969 to mid-1975. The MSIS (mass spectrometer and incoherent scatter data) model is compared with the Ogo 6 model (Hedin et al., 1974). Ar variations at 120 km tend to be in phase with temperature variations and inverse to the He, O, and H variations.

Hedin, A. E.↗
NASA NTRS1976

Recombination of O2/+/ in the ionosphere

In spite of the excellent agreement between various laboratory measurements of the recombination rate of O2(+) with electrons, it is still questionable whether the laboratory results apply in the ionosphere, because although the radiative lifetime of vibrating O2(+) is not well known, indications are that it may be very long. Whether the laboratory results apply in the atmosphere depends on whether the recombination rate is dependent on the vibrational state of the O2(+) ion and on whether the ions are deactivated (or not) in both the laboratory experiments and the atmosphere prior to recombination. To obtain reliable answers to these questions, the present study was carried out to determine the recombination of O2(+) in the ionosphere from in situ measurements of the relevant temperatures and densities made by the open source mass spectrometer carried by the AE-C satellite. The photochemistry involved is discussed. The results show that the ionospheric determination of the recombination rate of O2(+) with electrons agrees with the laboratory measurements of Walls and Dunn (1974) for electron temperatures between 1200 and 2000 K.

Torr, D. G.↗
NASA NTRS1976

Ion chemistry of N2/+/ and the solar ultraviolet flux in the thermosphere

We have analyzed daytime composition measurements in the thermosphere from Atmosphere Explorer-C by use of a theory of the ion chemistry. Predicted and measured N2(+) densities are compared to infer global variation of the solar ionizing flux. Results indicate that the solar flux of Hinteregger measured on Atmosphere Explorer-C provides an adequate basis for the calculation of solar ultraviolet photoionization rates. The role of metastable species is examined, and theoretical O+(2D) densities are presented.

Oppenheimer, M.↗
NASA NTRS1976

The O I /5577-A wavelength/ airglow - Observations and excitation mechanisms

Analysis of the O I /5577-A wavelength/ airglow observations conducted on board the Atmosphere Explorer C satellite yields the following results when combined with simultaneous measurements of ion and neutral composition. A volume emission rate profile derived after sunset requires the production of an O(1S) atom in 8% of the O2(+) recombinations. Photoelectric impact on atomic oxygen and the dissociative recombination of O2(+) are important sources of O(1S) in the dayglow; however, the airglow measurements require a large additional production of O(1S) below 200 km in addition to these. The reaction N + O2(+) yielding NO(+) + O(1S) can provide the missing O(1S) source if the rate coefficient is near 2.5 times 10 to the minus 11th cu cm per sec.

Frederick, J. E.↗
NASA NTRS1976

Recombination of NO/+/ in the ionosphere

Simultaneous nighttime measurements of ion and neutral concentrations and temperatures made by the Atmosphere Explorer-C satellite were used to determine the recombination rate coefficient of NO(+) as a function of electron temperature. The results agree in shape and absolute magnitude to within one standard deviation with those of Walls and Dunn (1974), indicating that NO(+) ions in the ionosphere may be in the ground vibrational state.

Torr, D. G.↗