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Results for “IONOSPHERIC COMPOSITION”

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 NTRS1979

Energy and mass transport in the thermosphere

Examples illustrating the effects of large scale energy and mass transport in the thermosphere discussed include: (1) The seasonal variations reveal temperature, composition, and ionospheric anomalies involving energy exchange between the thermosphere and mesosphere. (2) The midnight temperature maximum in the thermosphere is interpreted as a signature of tidal waves emanating from the mesosphere and momentum coupling associated with ion drag. (3) The ionospheric storm in the F region illustrates the intricate effects of large scale atmospheric winds driven by magnetospheric energization processes. (4) Atmospheric signatures of Joule heating and electric field momentum coupling are markedly different.

Mayr, H. G.↗
NASA NTRS1992

Ion composition of the topside equatorial ionosphere during solar minimum

Observations from both the Bennett ion mass spectrometer and the retarding potential analyzer on board the Atmosphere Explorer E satellite were used to study the longitudinally averaged O(+), H(+), and He(+) concentrations from 150 to 1100 km in the equatorial ionosphere during the 1975-1976 solar minimum. The results suggest that the ion mass spectrometer measurements need to be increased by a factor of 2.15 to agree with the densities from the retarding potential analyzer and with ground-based measurements. The peak H(+) concentrations are about 2.5 x 10 exp 4/cu cm during the day and 10 exp 4/cu cm at night and vary little with season. The O(+)/H(+) transition altitude lies between 750 and 825 km during the day and between 550 and 600 km at night. He(+) is a minor species at all altitudes; its concentration is highly variable with a maximum value of about 10 exp 3/cu cm during equinox daytime.

Gonzalez, S. A.↗
NASA NTRS1991

The use of transition heights for the representation of ion composition

Several characteristic transition heights can be found in ionospheric ion-composition profiles. These are the boundaries between the regions dominated by light ions, atomic oxygen ions, molecular ions, and cluster ions, respectively. Ion-composition modeling can benefit from the use of these transition heights. Special emphasis is given to the 'upper' transition height H sub T (light ions to atomic oxygen) and to the 'lower' transition height h sub t (atomic oxygen to molecular ions). Transition-height models deduced from rocket and satellite measurements are compared with the heights predicted by the International Reference Ionosphere. Considerable discrepancies are found between the different models as well as between the models and independent measurements.

Bilitza, Dieter↗
NASA NTRS1980

Modulation of terrestrial ion escape flux composition /by low-altitude acceleration and charge exchange chemistry/

Motivated by recent observations of highly variable hot plasma composition in the magnetosphere, control of the ionospheric escape flux composition by low-altitude particle dynamics and ion chemistry has been investigated for an e(-), H(+), O(+) ionosphere. It is found that the fraction of the steady state escape flux which is O(+) can be controlled very sensitively by the occurrence of parallel or transverse ion acceleration at altitudes below the altitude where the neutral oxygen density falls rapidly below the neutral hydrogen density and the ionospheric source of O(+) tends to be rapidly converted by charge exchange to H(+). The acceleration is required both to overcome the gravitational confinement of O(+) and to violate charge exchange equilibrium so that the neutral hydrogen atmosphere appears 'optically' thin to escaping O(+). Constraints are placed on the acceleration processes, and it is shown that O(+) escape is facilitated by observed ionospheric responses to magnetic activity.

Moore, T. E.↗
NASA NTRS1982

The ionosphere as a source for magnetospheric ions

Ion composition measurements within the past several years have shown O(+), He(+), and other ions of terrestrial origin to compose a substantial fraction of the magnetospheric ion population. This review examines (1) observations of topside ionospheric composition, (2) mechanisms for energization and injection of ionospheric ions into the magnetosphere, and (3) observations of ions of ionospheric origin in various regions of the magnetosphere, including the plasmasphere, ring current, magnetotail plasma sheet and lobes, and boundary layer and magnetosheath.

Horwitz, J. L.↗
NASA NTRS1971

Studies of positive-ion composition in the equatorial D-region ionosphere.

Evaluation of two daytime D-region positive-ion composition measurements performed at Thumba, India, for solar zenith angles of 53.2 and 27.8 deg. Comparison of upleg ram with downleg wake data shows a large increase in the concentration of heavy ions 48(+), NO(+) . H2O; 55(+), H3O(+) . (H2O)2; and M(+) greater than 65(+) for the downleg reduced shock condition. Peak concentrations of 48(+) and 55(+) occur at unit optical depth for Lyman alpha radiation. The ion 37(+), H3O(+) . H2O, is dominant for chi = 27.8 deg, but not for chi = 53.2 deg, consistent above 80 km with an origin from the X-ray production of O2(+). Laboratory measurements have shown that the ion, NO(+), can be transferred to heavy hydrates 48(+), 55(+), and M(+) greater than 65(+) by a reaction chain starting with NO(+) + X + M = NO(+) . X + M, where X can be O2, N2, CO2 or a combination of all three, depending on the rate of reaction. This chain, together with a similar reaction scheme starting with O2(+) and ending in 19(+), 37(+), and heavier clusters, is used to provide a consistent explanation for the hydrated ions observed in the D region.

Goldberg, R. A.↗
NASA NTRS1994

Ionospheric calibration for single frequency altimeter measurements

This study is a preliminary analysis of the effectiveness (in terms of altimeter calibration accuracy) of various ionosphere models and the Global Positioning System (GPS) to calibrate single frequency altimeter height measurements for ionospheric path delay. In particular, the research focused on ingesting GPS Total Electron Content (TEC) data into the physical Parameterized Real-Time Ionospheric Specification Model (PRISM), which estimates the composition of the ionosphere using independent empirical and physical models and has the capability of adjusting to additional ionospheric measurements. Two types of GPS data were used to adjust the PRISM model: GPS receiver station data mapped from line-of-sight observations to the vertical at the point of interest and a grid map (generated at the Jet Propulsion Laboratory) of GPS derived TEC in a sun-fixed longitude frame. The adjusted PRISM TEC values, as well as predictions by the International Reference Ionosphere (IRI-90), a climatological (monthly mean) model of the ionosphere, were compared to TOPEX dual-frequency TEC measurements (considered as truth) for a number of TOPEX sub-satellite tracks. For a 13.6 GHz altimeter, a Total Electron Content (TEC) of 1 TECU 10(exp 16) electrons/sq m corresponds to approximately 0.218 centimeters of range delay. A maximum expected TEC (at solar maximum or during solar storms) of 10(exp 18) electrons/sq m will create 22 centimeters of range delay. Compared with the TOPEX data, the PRISM predictions were generally accurate within the TECU when the sub-satellite track of interest passed within 300 to 400 km of the GPS TEC data or when the track passed through a night-time ionosphere. If neither was the case, in particular if the track passed through a local noon ionosphere, the PRISM values differed by more than 10 TECU and by as much as 40 TECU. The IRI-90 model, with no current ability to unseat GPS data, predicted TEC to a slightly higher error of 12 TECU. The performance of PRISM is very promising for predicting TEC and will prove useful for calibrating single frequency altimeter height measurements for ionospheric path delay. When adjusted to the GPS line-of-sight data the PRISM URSI empirical model predicted TEC over a day's period to within a global error of 8.60 TECU rms during a nighttime ionosphere and 9.74 TECU rms during the day. When adjusted to the GPS derived TEC grid, the PRISM parametrized model predicted TEC to within an error of 8.47 TECU rms for a nighttime ionosphere and 12.83 TECU rms during the day. However, the grid cannot be considered globally due to the lack of sufficient numbers of GPS stations and large latitude gaps in GPS data. It is the opinion of the authors that using the PRISM model and adjusting to the global sun-fixed TEC grid regenerated with a localized weighted interpolation offers the best possibility of meeting the 10 TECU global rms (or 2 cm at 13.6 GHz) ionosphere range correction accuracy requirement of TOPEX/Poseidon and should be the subject of further study. However, it is clear that the anticipated requirement of 34 TECU global rms for TOPEX/Poseidon Follow-On (corresponding to the TOPEX/Poseidon performance) can not be met with any realizable combination of existing models and data assimilation schemes.

Schreiner, William S.↗
NASA NTRS1982

The Venus environment; Proceedings of the International Conference, Palo Alto, CA, November 1-6, 1981

Attention is given to noble gases in planetary atmospheres, the photochemistry of the stratosphere of Venus, the chemistry of metastable species in the Venusian ionosphere, the Venus ionosphere at grazing incidence of solar radiation, disappearing ionospheres on the nightside of Venus, and the observed composition of the ionosphere of Venus. Other investigations considered are concerned with the predicted electrical conductivity between 0 and 80 km in the Venusian atmosphere, sulfuric acid vapor and other cloud-related gases in the Venus atmosphere, the composition and vertical structure of the lower cloud deck on Venus, amorphous sulfur as the ultraviolet absorber on Venus, and polarization studies of the Venus UV contrasts. A description is provided of topics related to temporal variability of ultraviolet cloud features in the Venus stratosphere, zonal mean circulation at the cloud level on Venus, the influence of thermospheric winds on exospheric hydrogen on Venus, and an analysis of Venus gravity data.

Source record↗
NASA NTRS1979

The auroral ionosphere - Comparison of a time-dependent model with composition measurements

A time-dependent model of the auroral ionosphere including the odd nitrogen species, NO, N(D-2), and N(S-4), is used for comparison with data from a coordinated rocket-satellite measurement of an auroral event. The chemical scheme and the adopted rate coefficients have been shown to be compatible with daytime mid-latitude ionospheric chemistry. The electron flux and neutral atmospheric parameters measured on the satellite are used to compute the appropriate ionization and dissociation rates. The calculated NO(plus), O2(plus), O(plus), Ne, and NO densities agree well with the rocket measurements. The calculated N2(plus) densities are larger than the measured densities by a factor of 3 at most altitudes. The calculations show that the nitric oxide content of the aurora (about 1.2 times 10 to the 9th NO molecules/cu cm at 105 km) is below the saturation value.

Gerard, J.-C.↗
NASA NTRS1984

Direct evidence for two-stage (bimodal) acceleration of ionospheric ions

Energetic ion composition spectrometer data gathered on hybrid conical ion distributions by the Dynamics Explorer 1 in the topside ionosphere are reported. The observed ion distributions were field-aligned and upward flowing, with energies up to 5 keV. Increases in ion energy were accompanied by a departure from field-alignment and a cone patterned upward flow, with the apex in the auroral field lines and the cone angle widening upward as the energy increased. Both transverse and parallel accelerations were imparted to the ions, with the transverse heating occurring in a 5000 km extent region centered at 18,000 km altitude. A bi-Maxwellian distribution, a temperature of 1.2 keV and a 260 eV parallel temperature were found at the top of the region.

Klumpar, D. M.↗
NASA NTRS1984

Theory, measurements, and models of the upper atmosphere and ionosphere of Saturn

The structure and composition of the thermosphere, exosphere, and ionosphere of saturn have been determined from observations at optical and radio wavelengths mainly by instruments aboard Voyager spacecraft. Techniques for determining the vertical profiles of temperature and density and the atmospheric vertical mixing in the upper Saturn atmosphere are discussed. Radio occultation measurements and theoretical models of Saturn's ionosphere are reviewed, and attempts to interpret the measurements using the models are discussed. Finally, mechanisms of thermospheric heating are examined.

Atreya, S. K.↗