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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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NASA NTRS1980

The solar wind-magnetosphere energy coupling and magnetospheric disturbances

Energy coupling between the solar wind and the magnetosphere is examined and the influence of this coupling on magnetospheric disturbances is discussed. Following a review of the components of the total energy production rate of the magnetosphere and progress in the study of solar wind-magnetosphere correlations, the derivation of the solar wind-magnetosphere energy coupling function, which has been found to correlate well with the total magnetospheric energy production rate, is presented. Examination of the relations between the energy coupling function and the type of magnetic disturbance with which it is associated indicates that magnetic storms with a large sudden storm commencement and a weak main phase are associated with small energy coupling, while values of the coupling function greater than 5 x 10 to the 18th to 10 to the 19th erg/sec are required for the development of a major geomagnetic storm. The magnetospheric substorm is shown to be a direct result of increased solar wind-magnetosphere energy coupling rather than the sudden conversion of stored magnetic energy. Finally, it is indicated that at energy couplings greater than 10 to the 19th erg/sec, the positive feedback process responsible for substorms breaks down, resulting in the abnormal growth of the ring current.

Akasofu, S.-I.↗
NASA NTRS1993

The earth's magnetosphere under continued forcing - Substorm activity during the passage of an interplanetary magnetic cloud

Magnetic field and energetic particle observations from six spacecraft in the near-earth magnetotail are described and combined with ground magnetograms to document for the first time the magnetospheric substorm activity during a 30-hour long transit of an interplanetary cloud at 1 AU. During an earlier 11-hr interval when B(z) was continuously positive, the magnetosphere was quiescent, while in a later 18-hr interval when B(z) was uninterruptedly negative a large magnetic storm was set off. In the latter interval the substorm onsets recurred on average every 50 min. Their average recurrence frequency remained relatively undiminished even when the magnetic cloud B(z) and other measures of the interplanetary energy input decreased considerably. These results concur with current models of magnetospheric substorms based on deterministic nonlinear dynamics. The substorm onset occurred when the cloud's magnetic field had a persistent northward component but was predominantly westward pointing.

Farrugia, C. J.↗
NASA NTRS1976

Pc 4 and Pc 5 pulsations during storm recovery

A strong pulsation event was observed in the magnetosphere near L = 5 with the flux gate magnetometer on Explorer 45. The event occurred near 2300 UT on June 18, 1972, during the recovery phase of a large magnetic storm. Explorer 45 was in the afternoon quadrant, and the event was also observed at many day side, ground level observatories at high and low latitudes. The event had a complex spectrum with distinct pulsations near 2, 6, and 14 mHz (500-, 160-, and 70-s periods). The two lower-frequency pulsations were also observed on the ground. A comparison of the frequencies and polarizations of satellite and ground observations indicates that the event was similar to events observed recently along a latitudinal chain of ground stations in Canada.

Lin, C. C.↗
NASA NTRS2002

The LWS Geospace Storm Investigations Exploring the Extremes of Space Weather

The Geospace mission of the Living With a Star program is a family of investigations focusing on the compelling science questions that advance our ability to specify, understand, and predict the societal impact of solar variance. Two key areas have been identified as combining both importance to society and potential for scientific progress: 1) characterization and understanding of the acceleration, global distribution, and variability of energetic electrons and ions in the inner magnetosphere, and 2) characterization and understanding of the ionosphere and irregularities that affect communications, navigation and radar systems. Under these broad categories specific science questions have emerged as the priority science objectives for the first Geospace Investigations: How and why do relativistic electrons in the outer zone and slot region vary during geomagnetic storms? How does the long- and short-term variability of the Sun affect the global-scale behavior of the ionospheric electron density and irregularities, especially during magnetic storms and at mid-latitudes? The first Geospace mission will attempt to answer these questions.

Source record↗
NASA NTRS2002

HALOE Observations of Perturbations in High Northern Latitude NO and O3 During the April 2002 Solar Storm Episode

The April 2002 solar storm event provides a unique opportunity to study the resulting effects on upper atmospheric constituents such as NO and O3. Two sources may perturb these constituents. For a magnetic-storm-source, energetic particles collide with and dissociate N2 in the lower thermosphere to produce excited nitrogen atoms which then combine with O to produce NO. The NO subsequently is transported down to lower altitudes where it reacts with and thus destroys mesospheric and possibly stratospheric ozone. For a solar-particle-event-source, high energy particles penetrate directly into the mesosphere, break apart N2 and water vapor, creating NOx and HOx to destroy ozone in the middle atmosphere. We present perturbations in high northern latitude NO and O3 as measured by the Halogen Occultation Experiment (HALOE) aboard the Upper Atmosphere Research Satellite between April 20-27. HALOE observations show an order of magnitude increase in mesospheric NO and a factor of approximately 2 decrease in mesospheric O3. We will also compare these observations with NASA GSFC 2D model computations.

Anderson, John↗
NASA NTRS1979

Forecasts of geomagnetic activities and HF radio propagation conditions made at Hiraiso/Japan

The Hiraiso Branch of RRL prediction techniques are summarized separately for the 27 day recurrent storm and the flare-associated storm. The storm predictions are compared with the actual geomagnetic activities in two ways. The first one is the comparison on a day to day basis. In the second comparison, the accuracy of the storm predictions during 1965-1976 are evaluated. In addition to the storm prediction, short-term predictions of HF radio propagation conditions are conducted at Hiraiso. The HF propagation predictions are briefly described as an example of the applications of the magnetic storm prediction.

Marubashi, K.↗
NASA NTRS2006

Self-Consistent Ring Current Modeling with Propagating Electromagnetic Ion Cyclotron Waves in the Presence of Heavy Ions

The self-consistent treatment of the RC ion dynamics and EMIC waves, which are thought to exert important influences on the ion dynamical evolution, is an important missing element in our understanding of the storm-and recovery-time ring current evolution. Under certain conditions, relativistic electrons, with energies 21 MeV, can be removed from the outer radiation belt by EMIC wave scattering during a magnetic storm. That is why the modeling of EMIC waves is critical and timely issue in magnetospheric physics. To describe the RC evolution itself this study uses the ring current-atmosphere interaction model (RAM). RAM solves the gyration and bounce-averaged Boltzmann-Landau equation inside of geosynchronous orbit. Originally developed at the University of Michigan, there are now several branches of this model currently in use as describe by Liemohn namely those at NASA Goddard Space Flight Center This study will generalize the self-consistent theoretical description of RC ions and EMIC waves that has been developed by Khazanov and include the heavy ions and propagation effects of EMIC waves in the global dynamic of self-consistent RC - EMIC waves coupling. The results of our newly developed model that will be presented at GEM meeting, focusing mainly on the dynamic of EMIC waves and comparison of these results with the previous global RC modeling studies devoted to EMIC waves formation. We also discuss RC ion precipitations and wave induced thermal electron fluxes into the ionosphere.

Khazanov, George V.↗
NASA NTRS2006

Analyzing Electric Field Morphology Through Data-Model Comparisons of the GEM IM/S Assessment Challenge Events

The storm-time inner magnetospheric electric field morphology and dynamics are assessed by comparing numerical modeling results of the plasmasphere and ring current with many in situ and remote sensing data sets. Two magnetic storms are analyzed, April 22,2001 and October 21-23,2001, which are the events selected for the Geospace Environment Modeling (GEM) Inner Magnetosphere/Storms (IM/S) Assessment Challenge (IMSAC). The IMSAC seeks to quantify the accuracy of inner magnetospheric models as well as synthesize our understanding of this region. For each storm, the ring current-atmosphere interaction model (RAM) and the dynamic global core plasma model (DGCPM) were run together with various settings for the large-scale convection electric field and the nightside ionospheric conductance. DGCPM plasmaspheric parameters were compared with IMAGE-EUV plasmapause extractions and LANL-MPA plume locations and velocities. RAM parameters were compared with Dst*, LANL-MPA fluxes and moments, IMAGE-MENA images, and IMAGE-HENA images. Both qualitative and quantitative comparisons were made to determine the electric field morphology that allows the model results to best fit the plasma data at various times during these events. The simulations with self-consistent electric fields were, in general, better than those with prescribed field choices. This indicates that the time-dependent modulation of the inner magnetospheric electric fields by the nightside ionosphere is quite significant for accurate determination of these fields (and their effects). It was determined that a shielded Volland-Stern field description driven by the 3-hour Kp index yields accurate results much of the time, but can be quite inconsistent. The modified Mcllwain field description clearly lagged in overall accuracy compared to the other fields, but matched some data sets (like Dst*) quite well. The rankings between the simulations varied depending on the storm and the individual data sets, indicating that each field description did well for some place, time, and energy range during the events, as well as doing less well in other places, times, and energies. Several unresolved issues regarding the storm-time inner magnetospheric electric field are discussed.

Liemohn, Michael W.↗
NASA NTRS1981

Comparison of storm-time changes of geomagnetic field at ground and at MAGSAT altitudes

Computations concerning variations of the geomagnetic field at MAGSAT altitudes were investigated. Using MAGSAT data for the X, Y, and Z components of the geomagnetic field, a computer conversion to yield the H component was performed. Two methods of determining delta H normalized to a constant geocentric distance R sub 0 = 6800 were investigated, and the utility of elta H at times of magnetic storms was considered. Delta H at a geographical latitude of 0 at dawn and dusk, the standard Dst, and K sub p histograms were plotted and compared. Magnetic anomalies are considered. Examination of data from the majority of the 400 passes of MAGSAT considered show a reasonable delta H versus latitude variation. Discrepancies in values are discussed.

Kane, R. P.↗
NASA NTRS1992

Reduction of Marine Magnetic Data for Modeling the Main Field of the Earth

The marine data set archived at the National Geophysical Data Center (NGDC) consists of shipborne surveys conducted by various institutes worldwide. This data set spans four decades (1953, 1958, 1960-1987), and contains almost 13 million total intensity observations. These are often less than 1 km apart. These typically measure seafloor spreading anomalies with amplitudes of several hundred nanotesla (nT) which, since they originate in the crust, interfere with main field modeling. The source for these short wavelength features are confined within the magnetic crust (i.e., sources above the Curie isotherm). The main field, on the other hand, is of much longer wavelengths and originates within the earth's core. It is desirable to extract the long wavelength information from the marine data set for use in modeling the main field. This can be accomplished by averaging the data along the track. In addition, those data which are measured during periods of magnetic disturbance can be identified and eliminated. Thus, it should be possible to create a data set which has worldwide data distribution, spans several decades, is not contaminated with short wavelengths of the crustal field or with magnetic storm noise, and which is limited enough in size to be manageable for the main field modeling. The along track filtering described above has proved to be an effective means of condensing large numbers of shipborne magnetic data into a manageable and meaningful data set for main field modeling. Its simplicity and ability to adequately handle varying spatial and sampling constraints has outweighed consideration of more sophisticated approaches. This filtering technique also provides the benefits of smoothing out short wavelength crustal anomalies, discarding data recorded during magnetically noisy periods, and assigning reasonable error estimates to be used in the least square modeling. A useful data set now exists which spans 1953-1987.

Baldwin, R. T.↗
NASA NTRS2006

Self-Consistent Ring Current Modeling with Propagating Electromagnetic Ion Cyclotron Waves in the Presence of Heavy Ions

The self-consistent treatment of the RC ion dynamics and EMlC waves, which are thought to exert important influences on the ion dynamical evolution, is an important missing element in our understanding of the storm-and recovery-time ring current evolution. Under certain conditions, relativistic electrons, with energies greater than or equal to 1 MeV, can be removed from the outer radiation belt by EMlC wave scattering during a magnetic storm (Summers and Thorne, 2003; Albert, 2003). That is why the modeling of EMlC waves is critical and timely issue in magnetospheric physics. This study will generalize the self-consistent theoretical description of RC ions and EMlC waves that has been developed by Khazanov et al. [2002, 2003] and include the heavy ions and propagation effects of EMlC waves in the global dynamic of self-consistent RC - EMlC waves coupling. The results of our newly developed model that will be presented at Huntsville 2006 meeting, focusing mainly on the dynamic of EMlC waves and comparison of these results with the previous global RC modeling studies devoted to EMlC waves formation. We also discuss RC ion precipitations and wave induced thermal electron fluxes into the ionosphere.

Khazanov, G. V.↗
NASA NTRS1984

Sydney Chapman and his early studies of magnetic disturbances

Sydney Chapman's 1918 and 1927 papers on magnetic storms and disturbances of lesser intensity and the background in which these papers were prepared are described from a historical point of view. In spite of the greatly limited availability of observations, the average characteristics of the magnetic variations during these disturbances derived by Chapman are remarkably accurate. An attempt is made to portray Chapman's rigorous and conscientious method of data analysis.

Sugiura, M.↗
NASA NTRS1983

A revised thermospheric model based on mass spectrometer and incoherent scatter data - MSIS-83

It is noted that the model presented here extends the previous description of neutral parameters to the base of the thermosphere in a continuous manner while maintaining the basic structure of the MSIS model at higher altitudes. As the altitude decreases, the composition approaches lower atmosphere values, whereas yearly, and to a lesser extent daily, variations in temperature and density are in reasonable agreement with earlier results for the lower thermosphere. An alternate description is given of magnetic storm variations on the basis of the three hour ap indices and an 8- to 10-hour exponential decay in thermospheric density and temperature response after a heating event. Additional coefficients are included for the time independent and magnetic activity terms, among them a longitudinally dependent seasonal magnetic activity effect. The description of molecular oxygen derives from mass spectrometer and EUV absorption measurements rather than ion chemistry.

Hedin, A. E.↗
NASA NTRS1980

Energetics of the magnetosphere

The approximate magnitudes of several power inputs and energies associated with the Earth's magnetosphere will be derived. They include: Solar wind power impinging on the dayside magnetopause approximately 1.4 10 to the 13th power watt; power input to cross tail current approximately 3 10 to the 11th power watt; energy of moderate magnetic storm approximately 2 10 to the 15th power joule; power related to the flow of j approximately 1 to 3 10 to the 11th power watt; average power deposited by the aurora approximately 2 10 to the 10th power watt. Stored magnetic energy: released in a substorm approximately 1.5 10 to the 14th power joule. Compared to the above, the rate at which energy is released locally in magnetospheric regions where magnetic merging occurs is probably small. Merging is essential, however, for the existence of open field lines, which provide the most likely explanation for some major energy inputs listed here. Merging is also required if part of the open flux of the tail lobes is converted into closed flux, as seems to happen during substorms. Again, most of the energy release becomes evident only beyond the merging region, though some particles may gain appreciable energy in that region itself, if the plasma sheet is completely squeezed out and the high latitude lobes interact directly.

Stern, D. P.↗
NASA NTRS1998

The Ionosphere and Upper Atmosphere

Because our society is becoming increasingly dependent on technological systems that can be affected by ionospheric phenomena during geomagnetic storms, the ionosphere, its electrodynamics, and its coupling with the neutral atmosphere and the magnetosphere are being studied as part of a coordinated program of "space weather" research. This research seeks to characterize the variability of ionospheric density and electric currents during magnetic storms, and to determine to what extent valid predictions of those phenomena and their effects can be made.

Richmond, A. D.↗
NASA NTRS1977

Observations of ion cyclotron waves within the plasmasphere by Hawkeye 1

A survey of the plasma wave data from the Hawkeye 1 spacecraft has been performed in search of ion cyclotron waves associated with the scattering and loss of ring current ions within and near the plasmapause. During an 18-month period, encompassing about 270 orbits, a total of five events have been found with clearly detectable electric and magnetic fields at frequencies below the proton gyrofrequency. Comparisons of the electric and magnetic field amplitudes for these events provide strong evidence that these waves are ion cyclotron waves. All five events occurred during recovery phases of magnetic storms inside or very close to the plasmapause boundary. The results of this survey confirm and are consistent with the earlier identification of ion cyclotron waves by the Explorer 45 satellites. The Hawkeye 1 observations show that ion cyclotron waves of substantial amplitude occur at magnetic latitudes well away (about 28 deg) from the magnetic equator.

Kintner, P. M.↗
NASA NTRS1994

Dynamics explorer interdisciplinary scientist investigations

This document is a final report on research activities and accomplishments that occurred during the funding period of 10-1-90 through 1-30-94. The focus of our interdisciplinary investigation during the Dynamics Explorer Mission was on the complex coupling processes that tap the magnetic-storm energy, stored in the ring current particle reservoir, and transport this energy into the subauroral, midlatitude and even equatorial ionospheric regions. The transport of energy through the inner magnetosphere and into the underlying ionospheric regions is a critical element in our understanding of the impact of solar and magnetic disturbances on upper atmospheric and ionospheric regions equatorward of the auroral zone.

Kozyra, Janet U.↗
NASA NTRS1986

Wave and plasma observations during a compressional Pc 5 wave event August 10, 1982

Magnetometer and thermal plasma instruments on the polar-orbiting Dynamics Explorer 1 satellite observed a small-amplitude ultralow frequency pulsation event at the outer edge of the plasmapause near the geomagnetic equator in the midafternoon sector on August 10, 1982, during the recovery phase of a magnetic storm. Transverse pulsations of 30-50 s period were observed throughout the event, and a 270-s period, purely compressional Pc 5 pulsation with several shifts in phase occurred within + or - 5 deg of the geomagnetic equator. Electric fields and the motion of thermal ions appeared to be in quadrature with pulsations in magnetic field magnitude throughout the event. This suggests that the net Poynting flux for the compressional waves was zero, consistent with their being standing waves. Large fluxes of trapped 90 deg pitch angle 10-eV protons, also symmetric about the geomagnetic equator, were observed in conjunction with the waves. These may serve as a source of free energy for the pulsations. These observations lend support to recent studies suggesting that many dayside compressional wave events are related to localized field line resonance near plasmapauselike boundaries, but also include features that cannot be explained by existing theories.

Engebretson, M. J.↗