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At least 73 records · Page 4
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Composition measurements of the topside ionosphere using a magnetic mass spectrometer, ion mass spectrometer on ISIS-2 spacecraft

The ion mass spectrometer (IMS) on the ISIS-II satellite is described; it measures the composition and distribution of positive ions in the earth's ionosphere in the mass range of 1 to 64 atomic mass units. Significant data were received which show a wide variation in ion composition at night near the equator and in the daytime poleward of the plasmapause. It was found that these data enable further study of the polar wind and that the experiment produced timely data during the August, 1972 magnetic storm to show the development of a unique ionosphere above the plasmapause during the period of the storm. The scientific objectives and results of the experiment, the technical description of the instrument, a bibliography with sample papers attached, and a summary of recommendations for further study are presented.

Hoffman, J. H.↗
NASA NTRS1995

High latitude ion composition

A data base comprised of all available ionosphere satellite ion composition measurements - the Goddard Comprehensive Ionosphere Data Base (GCID) - has been set upon optical disks for convenient merging and accessing of data from different satellites. This data has recentely been expanded to include all accessible satellite electron density and plasma temperature measurements. This paper demonstrates with a couple examples, the potential of GCID as an alternative to empirical models for undertanding ionsophere physics and chemistry. Through binning techniques GCID provdes a tool that complements and improves on the International Reference Ionosphere model (IRI) in delineating the topology of high latitude ion composition. GCID provides at a glance a measure of the local statistical variabilty of the ion compostions that is not in empirical models such as IRI. Furthermusing the data to determine the spatial and geophysical parameter range over which the minor ion species are approximately in chemical equilibrium, the number of data points available for empirical ion composition models can be increased by using the statiscally more reliable neutral and electron empirical models to derive ions composition. Currently available empirical models are not capable of adequately defining the comples high latitude distribution - a measure of the variablity is needed.

Grebowsky, J. M.↗
NASA NTRS1982

UK participation in the Middle Atmosphere Programme

Three general areas of study were identified: stratospheric composition; mesospheric and lower ionospheric structure and composition; and middle atmospheric dynamics. The role of chemical reactions and spectroscope in the study of the middle atmosphere is discussed.

Thomas, L.↗
NASA NTRS1979

Ionosphere of Venus - First observations of day-night variations of the ion composition

Preliminary observations of day-night variations in the ion composition of the ionosphere of Venus, obtained by the Pioneer Venus Orbiter ion mass spectrometer experiment, are reported. A remarkable abundance and extent of ionization in the deep regions of the nightside ionosphere was observed, in spite of the long Venus night. A comparison of dayside and nightside ion distributions reveals a nightside composition similar in several respects to that of the dayside, with the ions O(+) and O2(+) forming the nightside F 2 and F 1 regions, respectively, as in the dayside. Important differences include a greater abundance of low-latitude ionization in the nightside, a significant increase of H(+) and NO(+) ions with increasing solar zenith angle, and extreme dynamic variability of the nightside region above 160 km. Ion composition data support the view that the nightside ionosphere can be maintained by the transport of ionization from the dayside.

Taylor, H. A., Jr.↗
NASA NTRS1985

Simulations and observations of plasma depletion, ion composition, and airglow emissions in two auroral ionospheric depletion experiments

Observations of plasma depletion, ion composition modification, and airglow emissions in the Waterhole experiments are presented. The detailed ion chemistry and airglow emission processes related to the ionospheric hole formation in the experiment are examined, and observations are compared with computer simulation results. The latter indicate that the overall depletion rates in different parts of the depletion region are governed by different parameters.

Yau, A. W.↗
NASA NTRS1981

A theoretical study of the high-latitude winter F region at solar minimum for low magnetic activity

A simple plasma convection model is combined with an ionospheric-atmospheric composition model in order to study the high-latitude winter F region at the solar minimum for low magnetic activity. The high latitude ionospheric features, such as the main trough, the ionization hole, the tongue of ionization, the aurorally produced ionization peaks, and the universal time effects are a natural consequence of the competition between the various chemical and transport processes known to be operating in the high-latitude ionosphere. In the polar hole, the F region peak electron density is below 300 km, and the dominant process at 300 km for NO(+) ions is diffusion.

Sojka, J. J.↗
NASA NTRS1967

Ion composition and temperature in the topside ionosphere.

Particle and energy continuity equations derived and solved by computer method ion composition and plasma temperature measured by Explorer XXII PARTICLE and energy continuity equations derived and solved by computer method for ion composition and plasma temperature measured by Explorer XXII

IONOSPHERIC ION DENSITY↗
NASA NTRS1981

Plasma density features associated with strong convection in the winter high-latitude F region

A single plasma convection model was combined with an ionospheric-atmospheric composition model to study plasma density features associated with string convection in the winter high-latitude F region. Time dependent, three-dimensional, ion density distributions for NO(+), O2(+), N2(+), O(+) and He(+) were produced, and the ionosphere above 42 deg N magnetic latitude was covered for 24 hours. The study found that for strong and weak convection, electron density exhibited a variation with altitude, latitude, longitude and universal time. Ionospheric features were evident for strong convection, but modified in comparison with those found for slow convection. Also found for strong convection was a more pronounced tongue of ionization, the appearance of a new polar hole in the polar cap, and a midlatitude electron density trough that was not as deep as found for a weak convection. In addition, good agreement was found between predictions and Atmosphere Explorer measurements of ion composition variation with latitude and local time.

Sojka, J. J.↗
NASA NTRS1974

Ion composition and drift observations in the nighttime equatorial ionosphere

The first in situ measurements of ion composition in the nighttime equatorial E and F region ionospheres (90-300 km) are presented and discussed. These profiles were obtained by two rocket-borne ion mass spectrometers launched from Thumba, India on March 9-10, 1970 at solar zenith angles of 112 deg and 165 deg. Ionosonde data established that the composition was measured at times bounding a period of F region downward drift. During this period the ions O(+) and N(+) were enhanced by one to three orders of magnitude between 220 and 300 km. Below the drift region (200 km), O(+) ceased to be the major ionic constituent, but the concentrations of O(+) and N(+) remained larger than predicted from known radiation sources and loss processes. Here also, both the O2(+) and NO(+) profiles retained nearly the same shape and magnitude throughout the night in agreement with theories assuming scattered UV radiation to be the maintaining source. Light metallic ions including Mg(+), Na(+) and possibly Si(+) were observed to altitude approaching 300 km, while the heavier ions Ca(+) and K(+) were seen in reduced quantity to 200 km. All metal ion profiles exhibited changes which can be ascribed to vertical drifting.

Goldberg, R. A.↗
NASA NTRS1974

Ion composition and drift observations in the nighttime equatorial ionosphere

The first in situ measurements of ion composition in the nighttime equatorial E- and F-region ionospheres are presented and discussed. These profiles were obtained by two rocket-borne ion mass spectrometers launched from Thumba, India, on March 9-10, 1970. Ionosonde data established that the composition was measured at times bounding a period of F-region downward drift. During this period, the ions O(+) and N(+) were enhanced by 1-3 orders of magnitude between 220 and 300 km. Below the drift region, O(+) ceased to be the major ionic constituent, but the concentrations of O(+) and N(+) remained larger than predicted from known radiation sources and loss processes. Here also, both the O2(+) and the NO(+) profiles retained nearly the same shape and magnitude throughout the night in agreement with theories assuming scattered UV radiation to be the maintaining source.

Goldberg, R. A.↗
NASA NTRS1982

Seasonal variations of the high-latitude F region for strong convection

A plasma convection model is combined with an ionospheric-atmospheric composition model in order to study the seasonal variations of the high-latitude F region for geomagnetic conditions leading to strong convection. In a model calculation, a field tube of plasma is followed as it moves along a convection trajectory through a moving neutral atmosphere. Altitude profiles of the ion densities are obtained by solving the appropriate continuity, momentum, and energy equations including numerous high-latitude processes. It is found that the high-latitude ionosphere exhibits a significant UT variation both during the winter and summer. In general, the electron density at high-latitudes is lower in winter than in summer. In both summer and winter, the major region of low electron density is associated with the 'main' or mid-latitude' trough.

Sojka, J. J.↗
NASA NTRS1981

High-latitude ionospheric model - First step towards a predictive capability

In order to study the plasma density features associated with both weak and strong convection in the winter high-latitude F-region, a simple plasma convection model was combined with an ionospheric-atmospheric composition model. In a model calculation, a field tube of plasma is followed as it moves along a convection trajectory through a moving, neutral atmosphere. The altitude profiles of the ion densities are obtained by solving the appropriate continuity, momentum and energy equations, including many high-latitude processes. The result of following many such plasma field tubes is a time-dependent, three-dimensional ion density distribution for the ions NO(+), O2(+), O(+), N(+), and He(+). The high-latitude ionosphere is covered over one complete day above 42 deg N magnetic latitude, at altitudes of 160-800 km.

Schunk, R. W.↗