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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1972

On the determination of thermospheric atomic-oxygen densities with rocket-borne mass spectrometers.

The experimental investigation of the atomic oxygen response of an open-source mass spectrometer conducted in a high-velocity molecular-beam facility is described, and its results are evaluated. These preliminary results illustrate the value of studies of this type and tentatively support the thesis that in rocket flights of open-source mass spectrometers atomic oxygen loss is not a serious problem.

Neir, A. O.↗
NASA NTRS1978

An empirical model of the interrelationship of electron temperature and density in the daytime thermosphere at solar minimum

The AE-C satellite measurements of electron temperature and ion concentration are used to construct a model of the relationship between these parameters and its variation with altitude in the daytime, nonauroral ionosphere. The major features of the model are that electron temperature is independent of ion concentration at altitudes below 200 km and that electron temperature varies inversely with ion concentration above perhaps 250 km. This behavior is qualitatively consistent with current theoretical models of ionospheric heating and cooling.

Brace, L. H.↗
NASA NTRS1977

Empirical model of atomic nitrogen in the upper thermosphere

Atomic nitrogen number densities in the upper thermosphere measured by the open source neutral mass spectrometer (OSS) on Atmosphere Explorer-C during 1974 and part of 1975 have been used to construct a global empirical model at an altitude of 375 km based on a spherical harmonic expansion. The most evident features of the model are large diurnal and seasonal variations of atomic nitrogen and only a moderate and latitude-dependent density increase during periods of geomagnetic activity. Maximum and minimum N number densities at 375 km for periods of low solar activity are 3.6 x 10 to the 6th/cu cm at 1500 LST (local solar time) and low latitude in the summer hemisphere and 1.5 x 10 to the 5th/cu cm at 0200 LST at mid-latitudes in the winter hemisphere.

Engebretson, M. J.↗
NASA NTRS1979

A model of the neutral and ion nitrogen chemistry in the daytime thermosphere of Venus

Density profiles of N(4S), NO, N(2D), NO(+), and N(+) are calculated for the thermosphere of Venus. The results show that N(4S) is the dominant odd nitrogen species throughout the thermosphere and has a maximum density of 18 million atoms/cu cm at 132 km. The calculated NO(+) density agrees well with recent Pioneer Venus measurements, but the calculated N(+) densities are a factor of two to five less than the measurements. The production of N(4S) atoms generated in the model is adequate to explain recent measurements of the nitric oxide chemiluminescent emission on the night side of Venus.

Rusch, D. W.↗
NASA NTRS2022

On the Importance of Neutral Composition and Temperature Measurements in the 100–200 km Altitude Region

Currently, thermospheric species densities and temperatures between ∼100 and 200 km are not known to the accuracy needed to fully characterize how the thermosphere transitions from a well-mixed atmosphere to a diffusively separated atmosphere with zero temperature gradient. This greatly inhibits scientific discovery attainable from either models or observations in this region, especially the understanding of mechanisms that drive thermosphere and ionospheric variability from space weather to climatological time scales. The purpose of this paper is to highlight the importance and critical need for new, global, height-resolved neutral composition (O, O2, N2) and temperature measurements in the new ignorosphere: the 100–200 km region of the thermosphere. We conclude with observation recommendations and requirements for new comprehensive composition and temperature measurements in the 100–200 km altitude region that would lead to significant advances in thermosphere-ionosphere science, space weather, and space climate.

thermosphere↗
NASA NTRS1977

Temperature, density, and composition in the disturbed thermosphere from Esro 4 gas analyzer measurements - A global model

An analysis of density measurements of Ar, N2, O, and He made at 280 km with the gas analyzer aboard the polar-orbiting satellite Esro 4 has yielded a global model of the variations in temperature, density, and composition that occur in the disturbed thermosphere. In the model the increase of temperature over quiet conditions is a nonlinear function of the planetary geomagnetic index, its latitude profile being approximated by a fourth-power sin phi law, where phi is the 'invariant' magnetic latitude. A density wave proceeding from high latitudes is approximated by a fourth power cos phi law. A strong nonlinearity in the relation between the temperature variations and the variations in the height of the homopause explains a previously found behavioral difference in the variation of atomic oxygen during magnetic storms and during periods of sustained geomagnetic activity.

Jacchia, L. G.↗
NASA NTRS1990

Thermosphere-ionosphere coupling - An experiment in interactive modeling

Using the NCAR thermosphere general circulation model, a series of controlled experiments is performed to investigate the interactive coupling between ionospheric plasma densities and thermospheric neutral winds. The interaction is accomplished by parameterizing the F layer peak height, h(m)F2, in an empirical ionospheric model in terms of the meridional wind, v(south), and by forcing the h(m)F2 and the v(south) parameters to remain mutually coupled in a dynamical calculation. It was found that mutual coupling between forcing and meridional wind is weak during the daytime when the F layer exhibits a broad vertical structure. At night, when the F2 layer is more localized, the neutral dynamical structure is dependent on whether forcing is significantly above or below the altitude (about 275-300 km) at which ion drag effectively competes with viscosity in the neutral momentum balance.

Forbes, Jeffrey M.↗
NASA NTRS1990

Upper atmosphere models and research; Proceedings of Workshops X and XI and the Topical Meeting of the 27th COSPAR Plenary Meeting, Espoo, Finland, July 18-29, 1988

Topics are presented on the updating of CIRA, the trace constituents of the middle and upper atmosphere, and the localized response of the lower thermosphere and ionosphere at high latitude. Papers are presented on mean temperature fields in the lower thermosphere, a comparison of the thermosphere total density model TD 88 with CIRA 86, improved reference models for the middle-atmosphere ozone, a reference model for CH4 and N2O and trends, reference models for thermospheric NO, and a simulation of odd nitrogen distribution in the thermosphere. Other papers are on the response of the ionosphere-thermosphere system to magnetospheric forcing, microinstabilities driven by nonthermal plasma in the high-latitude F-region, the characteristics of the high-latitude trough, the lower thermospheric coupling study of the CEDAR and WITS programs, and numerical simulations of the seasonal response of the thermosphere to propagating tides.

Rycroft, M. J.↗
NASA NTRS1994

Variations in the FUV dayglow after intense auroral activity

A localized approximately 55% decrease is observed in the brightness of Earth's FUV dayglow in the morning sector at 130.4 nm after an interval of intense geomagnetic activity. This large decrease is interpreted as being the consequence of auroral-associated heating which reduces the thermospheric column density of O relative to that of N2. Spatial extent of the observed decrease exceeds 10(exp 7) km(exp 2) at the -25% level, and the depth of the decrease lessens during more than two hours of observations. These remote observations provide the first instantaneous, two-dimensional measurement of the large-scale spatial extent of such a change in thermospheric composition.

Craven, J. D.↗
NASA NTRS1969

A theory of thermospheric dynamics. II.

Thermospheric neutral density amplitudes and phases using one dimensional model of geomagnetic activity effect, 27 day variation and semiannual variation

Volland, H.↗