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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1973

Direct observations in the dusk hours of the characteristics of the storm-time ring current particles during the beginning of magnetic storms

The characteristic features of the initial enhancement of the storm-time ring current particles in the evening hours are consistent with flow patterns resulting from a combination of inward convection, gradient drift, and corotation which carries plasma sheet protons into low L-values near midnight and the higher energy proton component into the plasmasphere and through the evening hours. Data from four magnetic storms during the early life of Explorer 45, when the local time of apogee was in the afternoon and evening hours, show that protons with lower magnetic moments penetrate deeper into the magnetosphere until a low limit, determined by the corotation and gradient drift forces, is reached. Such particle motions produce the stable energy dependent inner boundary of the ring current protons inside the plasmapause in the dusk sector and also provide the mechanism for energy injection into the ring current region. From the analyses of the pitch angle distributions it is evident that charge exchange and wave particle interactions are not the dominant causes of this inner boundary.

Smith, P. H.↗
NASA NTRS1989

Solar wind-magnetosphere coupling during intense magnetic storms (1978-1979)

The solar wind-magnetosphere coupling problem during intense magnetic storms was investigated for ten intense magnetic storm events occurring between August 16, 1978 to December 28, 1979. Particular attention was given to the dependence of the ring current energization on the ISEE-measured solar-wind parameters and the evolution of the ring current during the main phase of the intense storms. Several coupling functions were tested as energy input, and several sets of the ring current decay time-constant were searched for the best correlation with the Dst response. Results indicate that a large-scale magnetopause reconnection operates during an intense storm event and that the solar wind ram pressure plays an important role in the energization of the ring current.

Gonzalez, Walter D.↗
NASA NTRS1992

The effects of magnetic storm phases on F-layer irregularities

The effects of magnetic storm phases on F-layer irregularities from auroral to equatorial latitudes in a nearly constant western longitude zone are presented by considering scintillation, spread F, and low-energy (less than 12 eV) electron precipitation data for eight magnetic storms that occurred during the high solar flux period September-November 1981. In the equatorial region, F-layer irregularities can be inhibited during the main phase. In the high latitude region, F-layer irregularities are found to be generated at the auroral latitudes during the main phase. During the recovery phase, when there are conditions of low magnetic activity, low auroral irregularities, and low-energy electron precipitation crossing the subauroral regions, strong F-layer irregularities are found to be generated in the subauroral regions.

Balan, N.↗
NASA NTRS1978

Equatorial irregularity belt and its movement during a magnetic storm

Evidence for an equatorial irregularity belt and its movement during a magnetic storm has been obtained from Faraday rotation measurements at a chain of 140-MHz radio beacons receiving from the ATS-6 satellite. The stations covered a latitude region from the magnetic equator to the 45 deg N dip on the Indian subcontinent. An irregularity belt extending from the magnetic equator to about 27 deg N latitude was observed during the main phase of the magnetic storm of 10 January, 1976.

Vats, H. O.↗
NASA NTRS1998

Magnetic Storms

One of the oldest mysteries in geomagnetism is the linkage between solar and geomagnetic activity. The 11-year cycles of both the numbers of sunspots and Earth geomagnetic storms were first noted by Sabine. A few years later, speculation on a causal relationship between flares and storms arose when Carrington reported that a large magnetic storm followed the great September 1859 solar flare. However, it was not until this century that a well-accepted statistical survey on large solar flares and geomagnetic storms was performed, and a significant correlation between flares and geomagnetic storms was noted. Although the two phenomena, one on the Sun and the other on the Earth, were statistically correlated, the exact physical linkage was still an unknown at this time. Various hypotheses were proposed, but it was not until interplanetary spacecraft measurements were available that a high-speed plasma stream rich in helium was associated with an intense solar flare. The velocity of the solar wind increased just prior to and during the helium passage, identifying the solar ejecta for the first time. Space plasma measurements and Skylab's coronagraph images of coronal mass elections (CMES) from the Sun firmly established the plasma link between the Sun and the Earth. One phenomenon associated with magnetic storms is brilliant "blood" red auroras, as shown.

Tsurutani, Bruce T.↗
NASA NTRS2011

Changes in the High-Latitude Topside Ionospheric Vertical Electron-Density Profiles in Response to Solar-Wind Perturbations During Large Magnetic Storms

The latest results from an investigation to establish links between solar-wind and topside-ionospheric parameters will be presented including a case where high-latitude topside electron-density Ne(h) profiles indicated dramatic rapid changes in the scale height during the main phase of a large magnetic storm (Dst < -200 nT). These scale-height changes suggest a large heat input to the topside ionosphere at this time. The topside profiles were derived from ISIS-1 digital ionograms obtained from the NASA Space Physics Data Facility (SPDF) Coordinated Data Analysis Web (CDA Web). Solar-wind data obtained from the NASA OMNIWeb database indicated that the magnetic storm was due to a magnetic cloud. This event is one of several large magnetic storms being investigated during the interval from 1965 to 1984 when both solar-wind and digital topside ionograms, from either Alouette-2, ISIS-1, or ISIS-2, are potentially available.

Benson, Robert F.↗
NASA NTRS1977

Spherical asymmetry in thermospheric magnetic storms

It is suggested that spherical asymmetries in heat-input distribution during magnetic storms could be important in moving the center of thermospheric circulation toward the equator. Circumstantial evidence from neutral-composition data obtained by two satellites during a series of strong geomagnetic substorms is shown to suggest a pronounced hemispherical asymmetry in magnetic-storm-related energy deposition and to support the circulation concept. Ground-based observations of the F2 peak density in both hemispheres are used to complement the composition data and to confirm the concept of hemispherical asymmetry. The composition data are analyzed quantitatively on the basis of a linear circulation model for the cases of a zero heat source in the Northern Hemisphere, factor-of-two differences between the heat sources in the Northern and Southern Hemispheres, and identical heat sources in both hemispheres. The results are found to be in qualitative agreement with the suggestion of pronounced asymmetry in thermospheric circulation.

Mayr, H. G.↗
NASA NTRS1973

Magnetic storm characteristics of the thermosphere.

Energy and diffusive mass transport associated with the thermospheric circulation are considered in a self-consistent, though mathematically relatively simple, form to describe in a three-dimensional two-constituent model magnetic storm characteristics in composition (N2, O, and He), temperature, and mass-density. It is shown that during disturbed conditions the latitudinal variations of composition and gas temperature reflect the local nature of the magnetic storm heat input assumed to be primarily confined to the auroral zones. Thereby gas temperature and N2 increase, He decreases, and O remains constant through the auroral zones at exospheric heights (due to the superposition of temperature and diffusion effects) in agreement with Ogo 6 mass spectrometer measurements. In contrast, the magnetic storm response in the total mass density is characterized by a strong worldwide component and a relatively insignificant increase toward the poles.

Mayr, H. G.↗