Search NASA⌕ Search

SEARCH · Search NASA

Results for “MAGNETIC STORM”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
NASA NTRS1981

Ion composition and energy distribution during 10 magnetic storms

Data from the plasma composition experiment of ISEE 1 are used to investigate the relative quantities and energy characteristics of H(+), He(++), He(+), and O(+) ions in the near-equatorial magnetosphere during magnetic storm conditions. The ions in the study had energies between 0.1 and 17 keV/e and pitch angles between 45 and 135 deg. The data were obtained during 10 storms, for the most part at or immediately following the peak Dst, covering all major local time sectors and geocentric distances between 2 and 15 earth radii. The ion fluxes are averaged over the spacecraft spin angle and over time for periods ranging from about 20 min close to the earth to more than an hour in most distant regions. The inferred 'isotropic' number densities are characterized by a large to dominant fraction of terrestrial ions throughout the energy range covered. The data are found to be consistent with a terrestrial origin for all of the O(+), most of the He(+), and a large but varying fraction of the H(+), whereas the He(++) and part of the H(+) appear to be of solar wind origin.

Lennartsson, W.↗
NASA NTRS1974

Features of polar cusp electron precipitation associated with a large magnetic storm

Measurements of precipitating electrons made by the OGO-4 satellite reveal several interesting phenomena in the polar cusp. Extremely high fluxes of 0.7 keV electrons were observed in the polar cusp ninety minutes following the sudden commencement of a very large magnetic storm. Structured, fairly high fluxes of 7.3 keV electrons were also observed in the cusp region, accompanied by very strong search coil magnetometer fluctuations, indicative of strong field-aligned currents. The observations confirm previously reported latitudinal shifts in the location of the polar cusp in response to southward interplanetary magnetic fields.

Berko, F. W.↗
NASA NTRS1975

The L = 6.6 Oosik barium plasma injection experiment and magnetic storm of March 7, 1972

A high-explosive shaped charge vaporizing a hollow conical liner of Ba metal and producing a fast field-aligned jet of plasma was detonated at high altitude, during a quiescent phase of a magnetic storm initiated by an ssc 10 hrs prior to the experiment, in an attempt to trace out and observe the dynamics of an auroral field line in the magnetosphere. Observations offer evidence for an upward Birkeland current sheet at the poleward edge of the auroral spiral of 8 x 10 to the minus second power A/m. Unusual features of the substorm leave open the possibility that the plasma injection may have triggered it.

Wescott, E. M.↗
NASA NTRS1977

A search for helium ions in the recovery phase of a magnetic storm

Data from an energetic ion mass spectrometer experiment on the low-latitude polar-orbiting satellite 1971-89A were examined for evidence of helium ions in the region of the ring current during the recovery phase of the December 17-18, 1971 magnetic storm. The principal precipitating ion species with energies between 0.7 and 12 keV were observed to be O+ and H+. No evidence for He+ was obtained. Inferences about the composition of the trapped population are made on the basis of simultaneous observations in the equatorial plane by Explorer 45. Coordinated observations with Explorer 45 and the Fritz Peak Observatory during the period of a stable auroral red arc have provided some information on the ionospheric and magnetospheric processes associated with the arc. A comparison of charge exchange and precipitation lifetimes during the recovery phase of the December 17-18 storm has shown both processes to be of comparable importance as ring current decay mechanisms in the energy range of the observations.

Sharp, R. D.↗
NASA NTRS1971

Composition of ions and neutral gases during a magnetic storm

Study of the variation in composition of ions and neutral gases on the basis of numerical solutions of a coupled differential equation system describing the fundamental properties of the ionosphere and atmosphere within the range of the thermosphere. It is shown that changes in ion composition observed during a magnetic storm can be represented by changes in neutral gas composition in the lower thermosphere. A reduction of the O/N2 ratio in the lower thermosphere starts a sequence of events that leads to an increase in neutral gas temperature, decrease in O(+) and increase in NO(+) concentration.

Chandra, S.↗
NASA NTRS1986

Ion composition of the bulk ring current during a magnetic storm - Observations with the CHEM-instrument on AMPTE-CCE

Ion composition measurements in the entire energy range of the ring current population, obtained with the Charge-, Energy-, Mass-spectrometer instrument on the Charge Composition Explorer in September 1984, are reported. From the energy spectra obtained for all major constituents during the main phase of a magnetic storm, the number densities, energy densities, and mean energies are calculated and displayed as radial profiles. The mean energies of He(2+) are found to be about twice that of H(+) and He(+) throughout this storm, and the time profiles for the mean energies of all major ions are seen to bunch together (when normalizing mean energies by the ionic charge), with the largest variations of the energy densities and mean energies occurring for O(+) ions.

Stuedemann, W.↗
NASA NTRS2007

Influence of the Convection Electric Field Models on Predicted Plasmapause Positions During Magnetic Storms

In the present work, we determine how three well documented models of the magnetospheric electric field, and two different mechanisms proposed for the formation of the plasmapause influence the radial distance, the shape and the evolution of the plasmapause during the geomagnetic storms of 28 October 2001 and of 17 April 2002. The convection electric field models considered are: Mcllwain's E51) electric field model, Volland-Stern's model and Weimer's statistical model compiled from low-Earth orbit satellite data. The mechanisms for the formation of the plasmapause to be tested are: (i) the MHD theory where the plasmapause should correspond to the last-closed- equipotential (LCE) or last-closed-streamline (LCS), if the E-field distribution is stationary or time-dependent respectively; (ii) the interchange mechanism where the plasmapause corresponds to streamlines tangent to a Zero-Parallel-Force surface where the field-aligned plasma distribution becomes convectively unstable during enhancements of the E-field intensity in the nightside local time sector. The results of the different time dependent simulations are compared with concomitant EUV observations when available. The plasmatails or plumes observed after both selected geomagnetic storms are predicted in all simulations and for all E-field models. However, their shapes are quite different depending on the E-field models and the mechanisms that are used. Despite the partial success of the simulations to reproduce plumes during magnetic storms and substorms, there remains a long way to go before the detailed structures observed in the EUV observations during periods of geomagnetic activity can be accounted for very precisely by the existing E-field models. Furthermore, it cannot be excluded that the mechanisms currently identified to explain the formation of "Carpenter's knee" during substorm events, will', have to be revised or complemented in the cases of geomagnetic storms.

Pierrard, V.↗
NASA NTRS1972

Changes in the distribution of low-energy trapped protons associated with the April 17, 1965, magnetic storm.

The absolute intensity of geomagnetically trapped protons in the energy ranges from 0.52 to 4.0 MeV and from 0.90 to 1.8 MeV has been measured with the solid-state proton detector on the satellite Injun 4 for the period from Mar. 1 to May 31, 1965. A study of the temporal variations of these fluxes associated with the Apr. 17, 1965, magnetic storm shows a general redistribution of these protons for L greater than 2.5. The effect of the sudden commencement was a general depression in the intensities and a hardening of the energy spectra, although the intensities recovered to their prestorm level during the initial phase. The major redistribution was apparently initiated by the polar substorm. During the recovery phase, a secondary peak developed in the intensity profile at L of about 3.5 for 0.52-MeV protons that had no counterpart at this energy at the equator. No such peak was observed for 0.9-MeV protons.

Burns, A. L.↗
NASA NTRS1974

Plasmaspheric hiss intensity variations during magnetic storms

The storm time intensity variations of ELF electromagnetic emissions have been studied by using the Ogo 6 search coil magnetometer. Low-latitude signals exhibit a sharp low-frequency cutoff and are identified as plasmaspheric hiss. Such waves show pronounced intensification during the recovery phase of magnetic storms but remain close to background levels during the storm main phase. This behavior is consistent with cyclotron resonant generation within the plasmasphere as the latter expands into the intensified belt of outer zone electrons during the storm recovery.

Smith, E. J.↗
NASA NTRS1994

Interpretation of satellite airglow observations during the March 22, 1979, magnetic storm, using the coupled ionosphere-thermosphere model developed at University College, London

The University of California, Berkeley, extreme ultraviolet spectrometer aboard the U.S. Air Force STP 78-1 satellite measured emission features in the Earth's dayglow due to neutral and ionized species in the atmosphere, in the 35 to 140-nm range. The spectrometer was operating between March 1979 and March 1980, including the period of the magnetic storm on March 22, 1979. Some of these measurements are interpreted using the predictions of the three-dimensional time-dependent coupled ionosphere-thermosphere model developed at University College, London. The observations show a reduction in the atomic oxygen 130.4-nm airglow emission at high northern latitudes following the storm. Model simulations show that this reduction in 130.4-nm emission is associated with an increase in the O2/O ratio. Analysis of model results using electron transport and radiative transport codes show that the brightness of 130.4-nm emission at high latitudes due to resonantly scattered sunlight is approximately twice that due to photoelectron impact excitation. However, the observed decrease in the brightness at high northern latitudes is mainly due to a change in the photoelectron impact source, which contributes approximately 75% of the total, as well as its multiple scattering component; for the photoelectron impact source at 70 deg latitude and 200 km altitude, the reduction in multiple scattering is 1.5 times greater than the reduction in the initial excitation. The reduction in the airglow emission is visible only in the norther n hemisphere because the south pole was not sunlit over the storm period. The comparison of model results with observations suggests that 130.4-nm emission may be useful as a tracer for global changes in the concentration of atomic energy.

Parish, H. F.↗
NASA NTRS1974

Electron contamination in a mid-latitude soft X-ray astronomy experiment during an intense magnetic storm

A large area X-ray sky survey payload was launched from White Sands Missile Range (106 deg W 32 deg N) on 1 Nov. 1972 at 0530 hours U.T. The launch time coincided with intense geomagnetic activity (3 hour K sub p index = 8) following a solar flare. The data have been analyzed to determine possible contamination of X-ray data by large fluxes of low energy electrons that can precipitate down to low altitudes during magnetic storms. There is clear evidence in the data for low energy electrons of 10 - 50 keV contributing appreciably at about 200 km altitude in the 1 - 10 keV X-ray energy channels of the proportional counters used for the X-ray observations. The McIlwain parameters L and B for this altitude at White Sands are 1.25 and 0.46G, respectively.

Naranan, S.↗
NASA NTRS1987

Criteria of interplanetary parameters causing intense magnetic storms (Dst less than -100nT)

Ten intense storms occurred during the 500 days of August 16, 1978 to December 28, 1979. From the analysis of ISEE-3 field and plasma data, it is found that the interplanetary cause of these storms are long-duration, large and negative IMF B sub Z events, associated with interplanetary duskward-electric fields greater than 5 mV/m. Because a one-to-one relationship was found between these interplanetary events and intense storms, it is suggested that these criteria can, in the future, be used as predictors of intense storms by an interplanetary monitor such as ISEE-3. These B sub Z events are found to occur in association with large amplitudes of the IMF magnitude within two days after the onset of either high-speed solar wind streams or of solar wind density enhancement events, giving important clues to their interplanetary origin. Some obvious possibilities will be discussed. The close proximity of B sub Z events and magnetic storms to the onset of high speed streams or density enhancement events is in sharp contrast to interplanetary Alfven waves and HILDCAA events previously reported, and thus the two interplanetary features corresponding geomagnetic responses can be thought of as being complementary in nature. An examination of opposite polarity B sub Z events with the same criteria show that their occurrence is similar both in number as well as in their relationship to interplanetary disturbances, and that they lead to low levels of geomagnetic activity.

Gonzalez, Walter D.↗
NASA NTRS1979

Magnetic storm effects in electric power systems and prediction needs

Geomagnetic field fluctuations produce spurious currents in electric power systems. These currents enter and exit through points remote from each other. The fundamental period of these currents is on the order of several minutes which is quasi-dc compared to the normal 60 Hz or 50 Hz power system frequency. Nearly all of the power systems problems caused by the geomagnetically induced currents result from the half-cycle saturation of power transformers due to simultaneous ac and dc excitation. The effects produced in power systems are presented, current research activity is discussed, and magnetic storm prediction needs of the power industry are listed.

Albertson, V. D.↗
NASA NTRS2013

Uplift of Ionospheric Oxygen Ions During Extreme Magnetic Storms

Research reported earlier in literature was conducted relating to estimation of the ionospheric electrical field, which may have occurred during the September 1859 Carrington geomagnetic storm event, with regard to modern-day consequences. In this research, the NRL SAMI2 ionospheric code has been modified and applied the estimated electric field to the dayside ionosphere. The modeling was done at 15-minute time increments to track the general ionospheric changes. Although it has been known that magnetospheric electric fields get down into the ionosphere, it has been only in the last ten years that scientists have discovered that intense magnetic storm electric fields do also. On the dayside, these dawn-to-dusk directed electric fields lift the plasma (electrons and ions) up to higher altitudes and latitudes. As plasma is removed from lower altitudes, solar UV creates new plasma, so the total plasma in the ionosphere is increased several-fold. Thus, this complex process creates super-dense plasmas at high altitudes (from 700 to 1,000 km and higher).

Tsurutani, Bruce T.↗
NASA NTRS1970

Relativistic electron precipitation during magnetic storm main phase

Relativistic electrons can have cyclotron resonances with electromagnetic cyclotron waves. The resonant energy is generally well above 1 MeV throughout the magnetosphere, but it can fall to 1 MeV just within the plasmapause. This also corresponds to the region where ring current (10 to 50 keV) protons are expected to be strongly unstable. The resulting ion cyclotron wave amplitudes necessary to precipitate ring current protons leads to electron lifetimes near the strong diffusion limit ( 100 sec). Thus, 1 MeV electrons whose drift orbits intersect the stormtime plasmapause should rapidly be precipitated in the region 3 L 5 during the initial phase of a magnetic storm.

Thorne, R. M.↗