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Sample records for average interplanetary magnetic

  1. Interplanetary magnetic holes: Theory

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Lemaire, J. F.

    1978-01-01

    Magnetic holes in the interplanetary medium are explained as stationary, non-propagating, equilibrium structures in which there are field-aligned enhancements of the plasma density and/or temperature. Magnetic anti-holes are considered to be associated with depressions in the plasma pressure. In this model, the observed changes in the magnetic field intensity and direction are due to diamagnetic currents that are carried by ions which drift in a sheath as the result of gradients in the magnetic field and in the plasma pressure within the sheath. The thickness of the sheaths considered is approximately a few ion Larmor radii. An electric field is normal to the magnetic field in the sheath. Solutions of Vlasov's equation and Maxwell's equations are presented which account for several types of magnetic holes, including null-sheets, that were observed.

  2. Interplanetary magnetic field data book

    NASA Technical Reports Server (NTRS)

    King, J. H.

    1975-01-01

    An interplanetary magnetic field (IMF) data set is presented that is uniform with respect to inclusion of cislunar IMF data only, and which has as complete time coverage as presently possible over a full solar cycle. Macroscale phenomena in the interplanetary medium (sector structure, heliolatitude variations, solar cycle variations, etc.) and other phenomena (e.g., ground level cosmic-ray events) for which knowledge of the IMF with hourly resolution is necessary, are discussed. Listings and plots of cislunar hourly averaged IMP parameters over the period November 27, 1963, to May 17, 1974, are presented along with discussion of the mutual consistency of the IMF data used herein. The magnetic tape from which the plots and listings were generated, which is available from the National Space Science Data Center (NSSDC), is also discussed.

  3. The interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Davis, L., Jr.

    1972-01-01

    Large-scale properties of the interplanetary magnetic field as determined by the solar wind velocity structure are examined. The various ways in which magnetic fields affect phenomena in the solar wind are summarized. The dominant role of high and low velocity solar wind streams that persist, with fluctuations and evolution, for weeks or months is emphasized. It is suggested that for most purposes the sector structure is better identified with the stream structure than with the magnetic polarity and that the polarity does not necessarily change from one velocity sector to the next. Several mechanisms that might produce the stream structure are considered. The interaction of the high and low velocity streams is analyzed in a model that is steady state when viewed in a frame that corotates with the sun.

  4. On the angle between the average interplanetary magnetic field and the propagation direction of plane large amplitude Alfven waves

    NASA Technical Reports Server (NTRS)

    Lichtenstein, B. R.; Sonett, C. P.

    1979-01-01

    The paper shows that the experimentally observed close alignment of magnetic field minimum variance direction with the average magnetic field for Alfven waves in the solar wind is consistent with theoretically predicted properties of plane large amplitude Alfven waves in the MHD approximation. The theoretical properties of these Alfven waves constrain the time averaged magnetic field to cluster around the direction of minimum variance, which is aligned with the wave normal. Thus, spacecraft magnetometer observations in the solar wind of minimum variance directions strongly peaked about the average magnetic field direction are consistent with plane large amplitude Alfven waves which have wave normals aligned with the directions of minimum variance. This does not imply that geometrical hydromagnetic calculations for Alfven wave propagation direction in the solar wind are incorrect, but there is a discrepancy between geometrical hydromagnetics theory and observations that IMF minimum variance directions tend to be aligned with the ideal Parker spiral instead of the radial direction.

  5. Evolution of the interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    McComas, D. J.

    Remote observations of magnetic field topologies in the solar corona and in situ observations of the solar wind and interplanetary magnetic field (IMF) in interplanetary space are used to examine the temporal evolution of the spatial distribution of open and closed field regions emanating from the Sun. The simple 'open' configuration of inward and outward pointing sectors in the IMF is periodically disrupted by magnetically distinct coronal mass ejections (CME's) which erupt from previously closed magnetic field regions in the corona into interplanetary space. At 1 AU, CME's contain counterstreaming halo electrons which indicate their distinct magnetic topologies. This topology is generally thought to be one of the following: plasmoids that are completely disconnected from the Sun; magnetic 'bottles,' still tied to the corona at both ends; or flux ropes which are only partially disconnected. Fully disconnected plasmoids would have no long term effect on the amount of open flux; however, both in situ observations of details of the halo electron distributions and remote coronagraph observations of radial fields following CME's indicate that CME's generally do retain at least partial attached to the Sun. Both the magnetic-bottle and flux rope geometries require some mitigating process to close off previously open fields in order to avoid a flux catastrophe. In addition, the average amount of magnetic flux observed in interplanetary space varies over the solar cycle, also indicating that there must be ways in which new flux is opened and previously open flux is closed off. The most likely scenario for closing off open magnetic fields is for reconnection to occur above helmet streamers, where oppositely directed field regions are juxtaposed in the corona. These events would serve to return closed field arches to the Sun and release open, U-shaped structures into the solar wind.

  6. Evolution of the interplanetary magnetic field

    SciTech Connect

    McComas, D.J.

    1993-01-01

    Remote observations of magnetic field topologies in the solar corona and in situ observations of the solar wind and interplanetary magnetic field (IMF) in interplanetary space are used to examine the temporal evolution of the spatial distribution of open and closed field regions emanating from the Sun. The simple open'' configuration of inward and outward pointing sectors in the IMF is periodically disrupted by magnetically distinct coronal mass ejections (CMEs) which erupt from previously closed magnetic field regions in the corona into interplanetary space. At 1 AU, CMEs contain counterstreaming halo electrons which indicate their distinct magnetic topologies. This topology is generally thought to be: plasmoids that are completely disconnected from the Sun; magnetic bottles,'' still tied to the corona at both ends; or flux ropes which are only partially disconnected. Fully disconnected plasmoids would have no long term effect on the amount of open flux; however, both in situ observations of details of the halo electron distributions and remote coronagraph observations of radial fields following CMEs indicate that CMEs generally do retain at least partial attached to the Sun. Both the magnetic-bottle and flux rope geometries require some mitigating process to close off previously open fields in order to avoid a flux catastrophe. In addition, the average amount of magnetic flux observed in interplanetary space varies over the solar cycle, also indicating that there must be ways in which new flux is opened and previously open flux is closed off. The most likely scenario for closing off open magnetic fields is for reconnection to occurs above helmet streamers, where oppositely directed field regions are juxtaposed in the corona. These events would serve to return closed field arches to the Sun and release open, U-shaped structures into the solar wind.

  7. Evolution of the interplanetary magnetic field

    SciTech Connect

    McComas, D.J.

    1993-05-01

    Remote observations of magnetic field topologies in the solar corona and in situ observations of the solar wind and interplanetary magnetic field (IMF) in interplanetary space are used to examine the temporal evolution of the spatial distribution of open and closed field regions emanating from the Sun. The simple ``open`` configuration of inward and outward pointing sectors in the IMF is periodically disrupted by magnetically distinct coronal mass ejections (CMEs) which erupt from previously closed magnetic field regions in the corona into interplanetary space. At 1 AU, CMEs contain counterstreaming halo electrons which indicate their distinct magnetic topologies. This topology is generally thought to be: plasmoids that are completely disconnected from the Sun; magnetic ``bottles,`` still tied to the corona at both ends; or flux ropes which are only partially disconnected. Fully disconnected plasmoids would have no long term effect on the amount of open flux; however, both in situ observations of details of the halo electron distributions and remote coronagraph observations of radial fields following CMEs indicate that CMEs generally do retain at least partial attached to the Sun. Both the magnetic-bottle and flux rope geometries require some mitigating process to close off previously open fields in order to avoid a flux catastrophe. In addition, the average amount of magnetic flux observed in interplanetary space varies over the solar cycle, also indicating that there must be ways in which new flux is opened and previously open flux is closed off. The most likely scenario for closing off open magnetic fields is for reconnection to occurs above helmet streamers, where oppositely directed field regions are juxtaposed in the corona. These events would serve to return closed field arches to the Sun and release open, U-shaped structures into the solar wind.

  8. Magnetic sails and interplanetary travel

    SciTech Connect

    Zubrin, R.M.; Andrews, D.G.

    1989-01-01

    A new concept, the magnetic sail, or 'magsail' is proposed which propels spacecraft by using the magnetic field generated by a loop of superconducting cable to deflect interplanetary or interstellar plasma winds. The performance of such a device is evaluated using both a plasma particle model and a fluid model, and the results of a series of investigations are presented. It is found that a magsail sailing on the solar wind at a radius of one astronautical unit can attain accelerations on the order of 0.01 m/sec squared, much greater than that available from a conventional solar lightsail, and also greater than the acceleration due to the sun's gravitational attraction. A net tangential force, or 'lift' can also be generated. Lift to drag ratios of about 0.3 appear attainable. Equations are derived whereby orbital transfers using magsail propulsion can be calculated analytically.

  9. Interplanetary stream magnetism - Kinematic effects

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Barouch, E.

    1976-01-01

    The particle density and the magnetic-field intensity and direction are calculated for volume elements of the solar wind as a function of the initial magnetic-field direction and the initial speed gradient. It is assumed that the velocity is constant and radial. These assumptions are approximately valid between about 0.1 and 1.0 AU for many streams. Time profiles of the particle density, field intensity, and velocity are calculated for corotating streams, neglecting effects of pressure gradients. The compression and rarefaction of the magnetic field depend sensitively on the initial field direction. By averaging over a typical stream, it is found that the average radial field intensity is inversely proportional to the square of the heliocentric distance, whereas the average intensity in the direction of the planets' motion does not vary in a simple way, consistent with deep space observations. Changes of field direction may be very large, depending on the initial angle; but when the initial angle at 0.1 AU is such that the base of the field line corotates with the sun, the spiral angle is the preferred direction at 1 AU. The theory is also applicable to nonstationary flows.

  10. Interplanetary Magnetic Field Guiding Relativistic Particles

    NASA Technical Reports Server (NTRS)

    Masson, S.; Demoulin, P.; Dasso, S.; Klein, K. L.

    2011-01-01

    The origin and the propagation of relativistic solar particles (0.5 to few Ge V) in the interplanetary medium remains a debated topic. These relativistic particles, detected at the Earth by neutron monitors have been previously accelerated close to the Sun and are guided by the interplanetary magnetic field (IMF) lines, connecting the acceleration site and the Earth. Usually, the nominal Parker spiral is considered for ensuring the magnetic connection to the Earth. However, in most GLEs the IMF is highly disturbed, and the active regions associated to the GLEs are not always located close to the solar footprint of the nominal Parker spiral. A possible explanation is that relativistic particles are propagating in transient magnetic structures, such as Interplanetary Coronal Mass Ejections (ICMEs). In order to check this interpretation, we studied in detail the interplanetary medium where the particles propagate for 10 GLEs of the last solar cycle. Using the magnetic field and the plasma parameter measurements (ACE/MAG and ACE/SWEPAM), we found widely different IMF configurations. In an independent approach we develop and apply an improved method of the velocity dispersion analysis to energetic protons measured by SoHO/ERNE. We determined the effective path length and the solar release time of protons from these data and also combined them with the neutron monitor data. We found that in most of the GLEs, protons propagate in transient magnetic structures. Moreover, the comparison between the interplanetary magnetic structure and the interplanetary length suggest that the timing of particle arrival at Earth is dominantly determined by the type of IMF in which high energetic particles are propagating. Finally we find that these energetic protons are not significantly scattered during their transport to Earth.

  11. Interplanetary magnetic clouds: Topology and driving mechanism

    NASA Astrophysics Data System (ADS)

    Chen, James; Garren, David A.

    1993-11-01

    A model is developed to study the origin and propagation of magnetic clouds. Starting with an equilibrium current loop embedded in an ambient plasma consistent with the solar corona, magnetic energy is injected by increasing the loop current. This causes the loop to rise, propelling plasma and magnetic field away from the Sun. Using a simple model of the interplanetary medium, the subsequent dynamics of the loop is calculated to 1 AU and beyond. The macroscopic properties of the resulting structures at 1 AU closely resemble those of observed magnetic clouds. Thermal effects indicate that clouds remain magnetically connected to the Sun in order to yield observed temperatures near 1 AU.

  12. Magnetic shielding for interplanetary spacecraft

    SciTech Connect

    Herring, J.S.; Merrill, B.J.

    1991-12-01

    The protection of spacecraft crews from the radiation produced by high energy electrons, protons and heavier ions in the space environment is a major health concern on long duration missions. Conventional approaches to radiation shielding in space have relied on thicker spacecraft walls to stop the high energy charged particles and to absorb the resulting gamma and bremsstrahlung photons. The shielding concept described here uses superconducting magnets to deflect charged particles before they collide with the spacecraft, thus avoiding the production of secondary particles. A number of spacecraft configurations and sizes have been analyzed, ranging from a small ``storm cellar`` for use during solar flares to continuous shielding for space stations having a crew of 15--25. The effectiveness of the magnetic shielding has been analyzed using a Monte Carlo program with incident proton energies from 0.5 to 1000 MeV. Typically the shield deflects 35--99 percent of the incident particles, depending, of course on particle energy and magnetic field strength. Further evaluation studies have been performed to assess weight comparisons between magnetic and conventional shielding; to determine magnet current distributions which minimize the magnetic field within the spacecraft itself; and to assess the potential role of ceramic superconductors. 2 figs., 8 tabs.

  13. Magnetic shielding for interplanetary spacecraft

    SciTech Connect

    Herring, J.S.; Merrill, B.J.

    1991-01-01

    The protection of spacecraft crews from the radiation produced by high energy electrons, protons and heavier ions in the space environment is a major health concern on long duration missions. Conventional approaches to radiation shielding in space have relied on thicker spacecraft walls to stop the high energy charged particles and to absorb the resulting gamma and bremsstrahlung photons. The shielding concept described here uses superconducting magnets to deflect charged particles before they collide with the spacecraft, thus avoiding the production of secondary particles. A number of spacecraft configurations and sizes have been analyzed, ranging from a small storm cellar'' for use during solar flares to continuous shielding for space stations having a crew of 15--25. The effectiveness of the magnetic shielding has been analyzed using a Monte Carlo program with incident proton energies from 0.5 to 1000 MeV. Typically the shield deflects 35--99 percent of the incident particles, depending, of course on particle energy and magnetic field strength. Further evaluation studies have been performed to assess weight comparisons between magnetic and conventional shielding; to determine magnet current distributions which minimize the magnetic field within the spacecraft itself; and to assess the potential role of ceramic superconductors. 2 figs., 8 tabs.

  14. Magnetic Reconnection in Interplanetary Coronal Mass Ejections

    NASA Astrophysics Data System (ADS)

    Fermo, R. L.; Opher, M.; Drake, J. F.

    2014-12-01

    Magnetic reconnection is a ubiquitous phenomenon in many varied space and astrophysical plasmas, and as such plays an important role in the dynamics of interplanetary coronal mass ejections (ICMEs). It is widely regarded that reconnection is instrumental in the formation and ejection of the initial CME flux rope, but reconnection also continues to affect the dynamics as it propagates through the interplanetary medium. For example, reconnection on the leading edge of the ICME, by which it interacts with the interplanetary medium, leads to flux erosion. However, recent in situ observations by Gosling et al. found signatures of reconnection exhausts in the interior. In light of this data, we consider the stability properties of systems with this flux rope geometry with regard to their minimum energy Taylor state. Variations from this state will result in the magnetic field relaxing back towards the minimum energy state, subject to the constraints that the toroidal flux and magnetic helicity remain invariant. In reversed field pinches, this relaxation is mediated by reconnection in the interior of the system, as has been shown theoretically and experimentally. By treating the ICME flux rope in a similar fashion, we show analytically that the the elongation of the flux tube cross section in the latitudinal direction will result in a departure from the Taylor state. The resulting relaxation of the magnetic field causes reconnection to commence in the interior of the ICME, in agreement with the observations of Gosling et al. We present MHD simulations in which reconnection initiates at a number of rational surfaces, and ultimately produces a stochastic magnetic field. If the time scales for this process are shorter than the propagation time to 1 AU, this result explains why many ICME flux ropes no longer exhibit the smooth, helical flux structure characteristic of a magnetic cloud.

  15. Regulation of the interplanetary magnetic flux

    SciTech Connect

    McComas, D.J.; Gosling, J.T.; Phillips, J.L.

    1991-01-01

    In this study we use a recently developed technique for measuring the 2-D magnetic flux in the ecliptic plane to examine (1) the long term variation of the magnetic flux in interplanetary space and (2) the apparent rate at which coronal mass ejections (CMEs) may be opening new flux from the Sun. Since there is a substantial variation ({approximately}50%) of the flux in the ecliptic plane over the solar cycle, we conclude that there must be some means whereby new flux can be opened from the Sun and previously open magnetic flux can be closed off. We briefly describe recently discovered coronal disconnections events which could serve to close off previously open magnetic flux. CMEs appear to retain at least partial magnetic connection to the Sun and hence open new flux, while disconnections appear to be likely signatures of the process that returns closed flux to the Sun; the combination of these processes could regulate the amount of open magnetic flux in interplanetary space. 6 refs., 3 figs.

  16. Fractal structure of the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Klein, L. W.

    1985-01-01

    Under some conditions, time series of the interplanetary magnetic field strength and components have the properties of fractal curves. Magnetic field measurements made near 8.5 AU by Voyager 2 from June 5 to August 24, 1981 were self-similar over time scales from approximately 20 sec to approximately 3 x 100,000 sec, and the fractal dimension of the time series of the strength and components of the magnetic field was D = 5/3, corresponding to a power spectrum P(f) approximately f sup -5/3. Since the Kolmogorov spectrum for homogeneous, isotropic, stationary turbulence is also f sup -5/3, the Voyager 2 measurements are consistent with the observation of an inertial range of turbulence extending over approximately four decades in frequency. Interaction regions probably contributed most of the power in this interval. As an example, one interaction region is discussed in which the magnetic field had a fractal dimension D = 5/3.

  17. An interplanetary magnetic field ensemble at 1 AU

    NASA Technical Reports Server (NTRS)

    Matthaeus, W. H.; Goldstein, M. L.; King, J. H.

    1985-01-01

    A method for calculation ensemble averages from magnetic field data is described. A data set comprising approximately 16 months of nearly continuous ISEE-3 magnetic field data is used in this study. Individual subintervals of this data, ranging from 15 hours to 15.6 days comprise the ensemble. The sole condition for including each subinterval in the averages is the degree to which it represents a weakly time-stationary process. Averages obtained by this method are appropriate for a turbulence description of the interplanetary medium. The ensemble average correlation length obtained from all subintervals is found to be 4.9 x 10 to the 11th cm. The average value of the variances of the magnetic field components are in the approximate ratio 8:9:10, where the third component is the local mean field direction. The correlation lengths and variances are found to have a systematic variation with subinterval duration, reflecting the important role of low-frequency fluctuations in the interplanetary medium.

  18. Interplanetary magnetic flux - Measurement and balance

    NASA Technical Reports Server (NTRS)

    Mccomas, D. J.; Gosling, J. T.; Phillips, J. L.

    1992-01-01

    A new method for determining the approximate amount of magnetic flux in various solar wind structures in the ecliptic (and solar rotation) plane is developed using single-spacecraft measurements in interplanetary space and making certain simplifying assumptions. The method removes the effect of solar wind velocity variations and can be applied to specific, limited-extent solar wind structures as well as to long-term variations. Over the 18-month interval studied, the ecliptic plane flux of coronal mass ejections was determined to be about 4 times greater than that of HFDs.

  19. Interplanetary magnetic clouds at 1 AU

    NASA Technical Reports Server (NTRS)

    Klein, L. W.; Burlaga, L. F.

    1981-01-01

    Magnetic clouds are defined as regions with a radial dimension approximately 0.25 AU (at 1 AU) in which the magnetic field strength is high and the magnetic field direction changes appreciably by means of rotation of one component of B nearly parallel to a plane. The magnetic field geometry in such a magnetic cloud is consistent with that of a magnetic loop, but it cannot be determined uniquely. Forty-five clouds were identified in interplanetary data obtained near Earth between 1967 and 1978; at least one cloud passed the Earth every three months. Three classes of clouds were identified, corresponding to the association of a cloud with a shock, a stream interface, or a CME. There are approximately equal numbers of clouds in each class, and the three types of clouds might be different manifestations of a coronal transient. The magnetic pressure inside the clouds is higher than the ion pressure and the sum is higher than the pressure of the material outside of the cloud.

  20. Solar cycle variations in the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Slavin, J. A.; Smith, E. J.

    1983-01-01

    ISEE 3 interplanetary magnetic field measurements have been used to extend the NSSDC hourly averaged IMF composite data set through mid-1982. Most of sunspot cycle 20 (start:1964) and the first half of cycle 21 (start:1976) are now covered. The average magnitude of the field was relatively constant over cycle 20 with approx. 5-10% decreases in 1969 and 1971, when the Sun's polar regions changed polarity, and a 20% decrease in 1975-6 around solar minimum. Since the start of the new cycle, the total field strength has risen with the mean for the first third of 1982 being about 40% greater than the cycle 20 average. As during the previous cycle, an approx. 10% drop in IMF magnitude accompanied the 1980 reversal of the solar magnetic field. While the interplanetary magnetic field is clearly stronger during the present solar cycle, another 5-7 years of observations will be needed to determine if cycle 21 exhibits the same modest variations as the last cycle. Accordingly, it appears at this time that intercycle changes in IMF magnitude may be much larger than the intracycle variations.

  1. EULERIAN DECORRELATION OF FLUCTUATIONS IN THE INTERPLANETARY MAGNETIC FIELD

    SciTech Connect

    Matthaeus, W. H.; Osman, K. T.; Dasso, S.; Weygand, J. M.; Kivelson, M. G.

    2010-09-20

    A method is devised for estimating the two-time correlation function and the associated Eulerian decorrelation timescale in turbulence. With the assumptions of a single decorrelation time and a frozen-in flow approximation for the single-point analysis, the method compares two-point correlation measurements with single-point correlation measurements at the corresponding spatial lag. This method is applied to interplanetary magnetic field measurements from the Advanced Composition Explorer and Wind spacecraft. An average Eulerian decorrelation time of 2.9 hr is found. This measures the total rate of distortion of turbulent fluid elements-including sweeping, nonlinear distortion, and wave propagation.

  2. Large-scale properties of the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Schatten, K. H.

    1972-01-01

    Early theoretical work of Parker is presented along with the observational evidence supporting his Archimedes spiral model. Variations present in the interplanetary magnetic field from the spiral angle are related to structures in the solar wind. The causes of these structures are found to be either nonuniform radial solar wind flow or the time evolution of the photospheric field. Coronal magnetic models are related to the connection between the solar magnetic field and the interplanetary magnetic field. Direct extension of the solar field-magnetic nozzle controversy is discussed along with the coronal magnetic models. Effects of active regions on the interplanetary magnetic field is discussed with particular reference to the evolution of interplanetary sectors. Interplanetary magnetic field magnitude variations are shown throughout the solar cycle. The percentage of time the field magnitude is greater than 10 gamma is shown to closely parallel sunspot number. The sun's polar field influence on the interplanetary field and alternative views of the magnetic field structure out of the ecliptic plane are presented. In addition, a variety of significantly different interplanetary field structures are discussed.

  3. Interplanetary magnetic sector polarity inferred from polar geomagnetic field observations

    NASA Technical Reports Server (NTRS)

    Friis-Christensen, E.; Lassen, K.; Wilcox, J. M.; Gonzalez, W.; Colburn, D. S.

    1971-01-01

    In order to infer the interplanetary sector polarity from polar geomagnetic field diurnal variations, measurements were carried out at Godhavn and Thule (Denmark) Geomagnetic Observatories. The inferred interplanetary sector polarity was compared with the polarity observed at the same time by Explorer 33 and 35 magnetometers. It is shown that the polarity (toward or away from the sun) of the interplanetary magnetic field can be reliably inferred from observations of the polar cap geomagnetic fields.

  4. Correlation length for interplanetary magnetic field fluctuations.

    NASA Technical Reports Server (NTRS)

    Fisk, L. A.; Sari, J. W.

    1973-01-01

    It is argued that it is necessary to consider two correlation lengths for interplanetary magnetic field fluctuations. For particles with gyroradii large enough to encounter and be scattered by large-scale tangential discontinuities in the field (particles with energies of above several GeV/nucleon) the appropriate correlation length is simply the mean spatial separation between the discontinuities. Particles with gyroradii much less than this mean separation appear to be unaffected by the discontinuities and respond only to smaller-scale field fluctuations. With this system of two correlation lengths the cosmic ray diffusion tensor may be altered from what was predicted by, for example, Jokipii and Coleman, and the objections raised recently by Klimas and Sandri to the diffusion analysis of Jokipii may apply only at relatively low energies (about 50 MeV/nucleon).

  5. Magnetic holes in the solar wind. [(interplanetary magnetic fields)

    NASA Technical Reports Server (NTRS)

    Turner, J. M.; Burlaga, L. F.; Ness, N. F.; Lemaire, J. F.

    1976-01-01

    An analysis is presented of high resolution interplanetary magnetic field measurements from the magnetometer on Explorer 43 which showed that low magnetic field intensities in the solar wind at 1 AU occur as distinct depressions or 'holes'. These magnetic holes are new kinetic-scale phenomena, having a characteristic dimension on the order of 20,000 km. They occurred at a rate of 1.5/day in the 18-day time span (March 18 to April 6, 1971) that was analyzed. Most of the magnetic holes are characterized by both a depression in the absolute value of the magnetic field, and a change in the magnetic field direction; some of these are possibly the result of magnetic merging. However, in other cases the magnetic field direction does not change; such holes are not due to magnetic merging, but might be a diamagnetic effect due to localized plasma inhomogeneities.

  6. Interplanetary magnetic sector polarity inferred from polar geomagnetic field observations

    NASA Technical Reports Server (NTRS)

    Eriss-Christensen, E.; Lassen, K.; Wilcox, J. M.; Gonzalez, W.; Colburn, D. S.

    1971-01-01

    With the use of a prediction technique it is shown that the polarity (toward or away from the sun) of the interplanetary magnetic field can be reliably inferred from observations of the polar geomagnetic field.

  7. The interplanetary and solar magnetic field sector structures, 1962 - 1968

    NASA Technical Reports Server (NTRS)

    Jones, D. E.

    1972-01-01

    The interplanetary magnetic field sector structure was observed from late 1962 through 1968. During this time it has been possible to study the manner in which the sector pattern and its relation to the photospheric magnetic field configuration changes from solar minimum to solar maximum. Observations were also made relating sector boundaries to specific regions on the solar disk. These and other observations related to the solar origin of the interplanetary field are briefly reviewed.

  8. Heliocentric distance dependence of the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Behannon, K. W.

    1977-01-01

    Recent and ongoing planetary missions have provided extensive observations of the variations of the Interplanetary Magnetic Field (IMF) both in time and with heliocentric distance from the sun. Large time variations in both the IMF and its fluctuations were observed. These are produced predominantly by dynamical processes in the interplanetary medium associated with stream interactions. Magnetic field variations near the sun are propagated to greater heliocentric distances, also contributing to the observed variablity of the IMF. Temporal variations on a time-scale comparable to or less than the corotation period complicate attempts to deduce radial gradients of the field and its fluctuations from the various observations. However, recent measurements inward to 0.46 AU and outward to 5 AU suggest that the radial component of the field on average decreases approximately as r to the minus second power, while the azimuthal component decreases more rapidly than the r to the minum first power dependence predicted by simple theory. This, and other observations, are discussed.

  9. Magnetic field line lengths inside interplanetary magnetic flux ropes

    NASA Astrophysics Data System (ADS)

    Hu, Qiang; Qiu, Jiong; Krucker, Sam

    2015-07-01

    We report on the detailed and systematic study of field line twist and length distributions within magnetic flux ropes embedded in interplanetary coronal mass ejections (ICMEs). The Grad-Shafranov reconstruction method is utilized together with a constant-twist nonlinear force-free (Gold-Hoyle) flux rope model to reveal the close relation between the field line twist and length in cylindrical flux ropes, based on in situ Wind spacecraft measurements. We show that the field line twist distributions within interplanetary flux ropes are inconsistent with the Lundquist model. In particular, we utilize the unique measurements of magnetic field line lengths within selected ICME events as provided by Kahler et al. () based on energetic electron burst observations at 1 AU and the associated type III radio emissions detected by the Wind spacecraft. These direct measurements are compared with our model calculations to help assess the flux rope interpretation of the embedded magnetic structures. By using the different flux rope models, we show that the in situ direct measurements of field line lengths are consistent with a flux rope structure with spiral field lines of constant and low twist, largely different from that of the Lundquist model, especially for relatively large-scale flux ropes.

  10. A survey of long term interplanetary magnetic field variations

    NASA Technical Reports Server (NTRS)

    King, J. H.

    1975-01-01

    Interplanetary magnetic field data from 10 IMP, AIMP, and HEOS spacecraft were merged into a composite data set spanning 1963 to 1974. A consideration of the mutual consistency of the individual data sets reveals agreement typically to within 0.2 gamma. Composite data set analysis reveals: (1) whereas the yearly averaged magnitudes of all field vectors show virtually no solar cycle variation, the yearly averaged magnitudes of positive- and negative-polarity field vectors show separate solar cycle variations, consistent with variations in the average azimuthal angles of positive- and negative-polarity field vectors, (2) there is no heliolatitude dependence of long time average field magnitudes, (3) field vectors parallel to the earth-sun line are on the average 1 gamma less in magnitude than field vectors perpendicular to this line, and (4) the heliolatitude-dependent dominant polarity effect exhibits a complex sign reversal in the 1968 to 1971 period and a measure of symmetry in 1972 to 1974 not found in earlier data.

  11. A survey of long-term interplanetary magnetic field variations

    NASA Technical Reports Server (NTRS)

    King, J. H.

    1976-01-01

    Interplanetary-magnetic-field data from the IMP-10, IMP-A, and Heos spacecraft have been merged into a composite data set spanning the period from 1963 to 1974. Consideration of the mutual consistency of the individual data sets reveals agrement typically to within 0.2 gamma. Analysis of the composite data set reveals the following: (1) although the yearly averaged magnitudes of all field vectors show virtually no solar-cycle variation, the yearly averaged magnitudes of positive- and negative-polarity field vectors show separate solar-cycle variations consistent with variations in the average azimuthal angles of positive- and negative-polarity field vectors; (2) there is no solar latitude dependence of long-time average field magnitudes; (3) field vectors parallel to the earth-sun line are on the average 1 gamma less in magnitude than field vectors perpendicular to this line; and (4) the solar latitude-dependent dominant polarity effect exhibits a complex sign reversal in the period from 1968 to 1971 and a measure of symmetry in 1972 through 1974 not found in earlier data.

  12. Solar sources of the interplanetary magnetic field and solar wind

    NASA Technical Reports Server (NTRS)

    Levine, R. H.; Altschuler, M. D.; Harvey, J. W.

    1977-01-01

    Open magnetic field lines, those which extend from the solar photosphere to interplanetary space, are traced in the current-free (potential field) approximation using measured photospheric fields as a boundary condition. It is found that (1) only a relatively small fraction of the photospheric area connects via open field lines to the interplanetary magnetic field; (2) those photospheric areas which do contribute open field lines lie beneath coronal holes and within the boundaries of the holes as projected onto the photosphere or else between loop systems of an active region; (3) the interplanetary magnetic field in the plane of the sun's equator, essentially the field in the ecliptic plane, may connect to photospheric regions of high latitude; and (4) the fastest solar wind streams are correlated with those magnetic flux tubes which expand least in cross-sectional area over the distance between the photosphere and the coronal height where the solar wind begins.

  13. The spiral interplanetary magnetic field: A polarity and sunspot cycle variation

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.; Wilcox, J. M.

    1974-01-01

    Spacecraft observations near the earth of the yearly average direction of the interplanetary magnetic field during the sunspot maximum year 1968 showed a deviation from the spiral field. The angle between the average field direction when the field polarity was away from the sun and the average direction for toward polarity was 168 deg, rather than 180 deg. This effect appears to have a sunspot cycle variation.

  14. The spiral interplanetary magnetic field - A polarity and sunspot cycle variation

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.; Wilcox, J. M.

    1974-01-01

    Spacecraft observations near the earth of the average direction of the interplanetary magnetic field during the sunspot maximum year 1968 showed a deviation from the spiral field of Parker's classical description. The included angle between the average field direction when the field polarity was away from the sun and the average direction when the field polarity was toward the sun was 168 deg, rather than 180 deg as predicted by Parker. This effect appears to have a sunspot cycle variation.

  15. Interplanetary magnetic field effects on high latitude ionospheric convection

    NASA Technical Reports Server (NTRS)

    Heelis, R. A.

    1985-01-01

    Relations between the electric field and the electric current in the ionosphere can be established on the basis of a system of mathematical and physical equations provided by the equations of current continuity and Ohm's law. For this reason, much of the synthesis of electric field and plasma velocity data in the F-region is made with the aid of similar data sets derived from field-aligned current and horizontal current measurements. During the past decade, the development of a self-consistent picture of the distribution and behavior of these measurements has proceeded almost in parallel. The present paper is concerned with the picture as it applies to the electric field and plasma drift velocity and its dependence on the interplanetary magnetic field. Attention is given to the southward interplanetary magnetic field and the northward interplanetary magnetic field.

  16. Interplanetary magnetic fields, their fluctuations, and cosmic ray variations

    NASA Technical Reports Server (NTRS)

    Barouch, E.; Sari, J. W.

    1975-01-01

    The cause of Forbush decreases is examined using neutron monitor data and measurements of the interplanetary magnetic field. It is found that for the period examined (Dec. 15, 1965 to April 23, 1966) large enhancements of the interplanetary magnetic field correlate well with decreases in cosmic ray intensity, while various parameters connected with the fluctuations in the field do not display such good correlation. The inference is drawn that Forbush decreases are not related to the turbulence or random motions in the field but to the large scale features of the field.

  17. Average Spatial Distribution of Cosmic Rays behind the Interplanetary Shock—Global Muon Detector Network Observations

    NASA Astrophysics Data System (ADS)

    Kozai, M.; Munakata, K.; Kato, C.; Kuwabara, T.; Rockenbach, M.; Dal Lago, A.; Schuch, N. J.; Braga, C. R.; Mendonça, R. R. S.; Jassar, H. K. Al; Sharma, M. M.; Duldig, M. L.; Humble, J. E.; Evenson, P.; Sabbah, I.; Tokumaru, M.

    2016-07-01

    We analyze the galactic cosmic ray (GCR) density and its spatial gradient in Forbush Decreases (FDs) observed with the Global Muon Detector Network (GMDN) and neutron monitors (NMs). By superposing the GCR density and density gradient observed in FDs following 45 interplanetary shocks (IP-shocks), each associated with an identified eruption on the Sun, we infer the average spatial distribution of GCRs behind IP-shocks. We find two distinct modulations of GCR density in FDs, one in the magnetic sheath and the other in the coronal mass ejection (CME) behind the sheath. The density modulation in the sheath is dominant in the western flank of the shock, while the modulation in the CME ejecta stands out in the eastern flank. This east–west asymmetry is more prominent in GMDN data responding to ∼60 GV GCRs than in NM data responding to ∼10 GV GCRs, because of the softer rigidity spectrum of the modulation in the CME ejecta than in the sheath. The geocentric solar ecliptic-y component of the density gradient, G y , shows a negative (positive) enhancement in FDs caused by the eastern (western) eruptions, while G z shows a negative (positive) enhancement in FDs caused by the northern (southern) eruptions. This implies that the GCR density minimum is located behind the central flank of IP-shocks and propagating radially outward from the location of the solar eruption. We also confirmed that the average G z changes its sign above and below the heliospheric current sheet, in accord with the prediction of the drift model for the large-scale GCR transport in the heliosphere.

  18. How are Forbush decreases related to interplanetary magnetic field enhancements?

    NASA Astrophysics Data System (ADS)

    Arunbabu, K. P.; Antia, H. M.; Dugad, S. R.; Gupta, S. K.; Hayashi, Y.; Kawakami, S.; Mohanty, P. K.; Oshima, A.; Subramanian, P.

    2015-08-01

    Aims: A Forbush decrease (FD) is a transient decrease followed by a gradual recovery in the observed galactic cosmic ray intensity. We seek to understand the relationship between the FDs and near-Earth interplanetary magnetic field (IMF) enhancements associated with solar coronal mass ejections (CMEs). Methods: We used muon data at cutoff rigidities ranging from 14 to 24 GV from the GRAPES-3 tracking muon telescope to identify FD events. We selected those FD events that have a reasonably clean profile, and magnitude >0.25%. We used IMF data from ACE/WIND spacecrafts. We looked for correlations between the FD profile and that of the one-hour averaged IMF. We wanted to find out whether if the diffusion of high-energy protons into the large scale magnetic field is the cause of the lag observed between the FD and the IMF. Results: The enhancement of the IMF associated with FDs occurs mainly in the shock-sheath region, and the turbulence level in the magnetic field is also enhanced in this region. The observed FD profiles look remarkably similar to the IMF enhancement profiles. The FDs typically lag behind the IMF enhancement by a few hours. The lag corresponds to the time taken by high-energy protons to diffuse into the magnetic field enhancement via cross-field diffusion. Conclusions: Our findings show that high-rigidity FDs associated with CMEs are caused primarily by the cumulative diffusion of protons across the magnetic field enhancement in the turbulent sheath region between the shock and the CME. Appendices are available in electronic form at http://www.aanda.org

  19. SIGNATURES OF MAGNETIC RECONNECTION AT BOUNDARIES OF INTERPLANETARY SMALL-SCALE MAGNETIC FLUX ROPES

    SciTech Connect

    Tian Hui; Yao Shuo; Zong Qiugang; Qi Yu; He Jiansen

    2010-09-01

    The interaction between interplanetary small-scale magnetic flux ropes and the magnetic field in the ambient solar wind is an important topic in the understanding of the evolution of magnetic structures in the heliosphere. Through a survey of 125 previously reported small flux ropes from 1995 to 2005, we find that 44 of them reveal clear signatures of Alfvenic fluctuations and thus classify them as Alfven wave trains rather than flux ropes. Signatures of magnetic reconnection, generally including a plasma jet of {approx}30 km s{sup -1} within a magnetic field rotational region, are clearly present at boundaries of about 42% of the flux ropes and 14% of the wave trains. The reconnection exhausts are often observed to show a local increase in the proton temperature, density, and plasma beta. About 66% of the reconnection events at flux rope boundaries are associated with a magnetic field shear angle larger than 90{sup 0} and 73% of them reveal a decrease of 20% or more in the magnetic field magnitude, suggesting a dominance of anti-parallel reconnection at flux rope boundaries. The occurrence rate of magnetic reconnection at flux rope boundaries through the years 1995-2005 is also investigated and we find that it is relatively low around the solar maximum and much higher when approaching solar minima. The average magnetic field depression and shear angle for reconnection events at flux rope boundaries also reveal a similar trend from 1995 to 2005. Our results demonstrate for the first time that boundaries of a substantial fraction of small-scale flux ropes have properties similar to those of magnetic clouds, in the sense that both of them exhibit signatures of magnetic reconnection. The observed reconnection signatures could be related either to the formation of small flux ropes or to the interaction between flux ropes and the interplanetary magnetic fields.

  20. The extension of solar magnetic fields into interplanetary space

    NASA Astrophysics Data System (ADS)

    McComas, D. J.; Phillips, J. L.

    The flow of coronal plasma into interplanetary space results in outward transport of the solar magnetic field. The prevailing open interplanetary magnetic field is rooted in the corona and wraps up into a spiral due to the rotation of the Sun. This simple configuration, however, is disrupted by magnetically distinct coronal mass ejections (CME's) which erupt from the solar corona into interplanetary space. Observations of CME's at 1 AU reveal electron signatures indicating a closed magnetic topology, postulated to be: (1) magnetic bottles tied to the corona at both ends; (2) plasmoids that are completely disconnected from the Sun; or (3) flux ropes which have topologies intermediate between (1) and (2). With either the magnetic-bottle or flux rope hypothesis, the inward and outward flux at 1 AU should increase indefinitely as CME's continue to erupt. Using a new technique to calculate the 2-D flux through 1 AU from single spacecraft measurements, we show that while there is a solar cycle variation to the magnetic flux, it clearly does not grow without bound. This suggests that either CME's are closed plasmoids which add to no new flux to the interplanetary medium, or that the opening of new flux by CME's is balanced via reconnection elsewhere in the corona. We suggest that the latter process may be dominant and describe observation from the Solar Maximum Mission coronagraph which are consistent with reconnection above helmet streamers in the corona. Such disconnections would serve to return closed field arches to the Sun and release open, U-shaped structures into the solar wind. Coronal disconnections appear in some cases to be triggered by pressure pulses caused by CME eruption elsewhere, suggesting a dynamic flux-balance process. We describe a class of solar wind structures, called heat flux dropouts, in which the solar wind electron heat flux, driven by magnetic connection to the hot corona, is absent or greatly reduced.

  1. Polytropic relationship in interplanetary magnetic clouds

    NASA Technical Reports Server (NTRS)

    Osherovich, V. A.; Farrugia, C. J.; Burlaga, L. F.; Lepping, R. P.; Fainberg, J.; Stone, R. G.

    1993-01-01

    High time-resolution data from the ISEE 3 and IMP 8 spacecraft are presented for the magnetic field and the proton and electron populations of a number of magnetic clouds, in order to investigate such clouds' thermodynamics and the relationship between their magnetic and thermodynamic structures. It is judged on the basis of these data that while the magnetic flield of the cloud expands, the ions are cooled. Hot electrons are trapped by the magnetic field in the magnetic cloud's core. These conditions are favorable for the generation of ion-acoustic waves.

  2. On the limitations of geomagnetic measures of interplanetary magnetic polarity

    NASA Technical Reports Server (NTRS)

    Russell, C. T.; Rosenberg, R. L.

    1974-01-01

    The maximum attainable accuracy in inferring the interplanetary magnetic polarity from polar cap magnetograms is about 88%. This is achieved in practice, when high-latitude polar cap stations are used during local summer months, and the signature in the ground records is strong. An attempt by Svalgaard (1972) to use this effect to infer an index of interplanetary magnetic polarity back to 1926 has not been so successful. Furthermore, some of the properties of the index have changed with time. Prior to 1963, the inferred polarities are strongly dependent on geomagnetic activity, while after this time they are not. Thus, this index should not be used to separate solar-magnetic from solar-activity effects prior to 1963.

  3. Interplanetary Magnetic Field Strength 1902-1906

    NASA Astrophysics Data System (ADS)

    Svalgaard, L.; Cliver, E. W.

    2006-05-01

    Using geomagnetic measurements made by Robert F. Scott at Discovery Hut in the Antarctic polar cap 1902- 1903 and by Roald Amundsen at Gjøahavn in the Arctic polar cap 1903-1906 we determine the strength of the cross polar cap equivalent current. This quantity is controlled by the interplanetary electric field, E, (essentially the product VB of solar wind speed V and IMF strength B). Comparison with modern data from contemporary polar cap stations at similar latitudes and locations and from spacecraft yields the conversion factor from the variation measured on the ground to the electric field E. Our geomagnetic activity indices IDV and IHV measure B and BV22, respectively, thus allowing both B and V to be determined since at least 1882. Their product VB agrees well with VB determined from the early polar cap data, providing an important independent confirmation of the validity of all three methods. We find that B during 1902-1906 was ~6 nT, comparable to present day values ~100 years later.

  4. Studies of the interplanetary magnetic field: IMP's to Voyager

    NASA Technical Reports Server (NTRS)

    Ness, Norman F.

    1987-01-01

    During the last two decades, spacecraft projects and individual experiments for which Frank McDonald was a leader have contributed very significantly to the current understanding of the structure of interplanetary space and the correlation between solar and interplanetary disturbances. Studies on the IMP, HELIOS, and Pioneer spin-stabilized spacecraft and the larger attitude-stabilized Voyager spacecraft have provided data sets from which the modern view of the heliosphere has evolved. That concept in which the inner solar system is shown to be dominated by individual streams associated with specific source regions on the Sun is illustrated. As these high-speed streams overtake the preexisting solar plasma, they coalesce and modify the characteristics so that at larger heliocentric distances, these disturbances appear as radially propagating concentric shells of compressed magnetic fields and enhanced fluctuations

  5. Further study of the theta component of the interplanetary magnetic field.

    NASA Technical Reports Server (NTRS)

    Rosenberg, R. L.; Coleman, P. J., Jr.; Ness, N. F.

    1973-01-01

    Measurements of the interplanetary magnetic field taken with Imp 3, Pioneer 6, and Explorer 34 constitute a large portion of the data available at low and moderate solar activity and provide nearly continuous coverage from mid-1965 through 1966 without radial effects. Study of these observations provides further evidence for the following B sub theta effect initially discovered with Mariners 2, 4, and 5. At low or moderate solar activity, the mean value of B sub theta is negative (approximately northward in the observations) above the solar equatorial plane and positive below it for an interplanetary field directed outward from the sun, and vice versa for an inward field. Thus, for an outward field, the r-theta component of a line of magnetic force above or below the equatorial plane was skewed relative to the average value of r in the direction away from the equatorial plane. Comparisons between different spacecraft are discussed.

  6. Magnetic Reconnection in the Interior of Interplanetary Coronal Mass Ejections

    NASA Astrophysics Data System (ADS)

    Fermo, R. L.; Opher, M.; Drake, J. F.

    2014-07-01

    Recent in situ observations of interplanetary coronal mass ejections (ICMEs) found signatures of reconnection exhausts in their interior or trailing edge. Whereas reconnection on the leading edge of an ICME would indicate an interaction with the coronal or interplanetary environment, this result suggests that the internal magnetic field reconnects with itself. In light of this data, we consider the stability properties of flux ropes first developed in the context of astrophysics, then further elaborated upon in the context of reversed field pinches (RFPs). It was shown that the lowest energy state of a flux rope corresponds to ∇×B=λB with λ a constant, the so-called Taylor state. Variations from this state will result in the magnetic field trying to reorient itself into the Taylor state solution, subject to the constraints that the toroidal flux and magnetic helicity are invariant. In reversed field pinches, this relaxation is mediated by the reconnection of the magnetic field, resulting in a sawtooth crash. If we likewise treat the ICME as a flux rope, any deviation from the Taylor state will result in reconnection within the interior of the flux tube, in agreement with the observations by Gosling et al. Such a departure from the Taylor state takes place as the flux tube cross section expands in the latitudinal direction, as seen in magnetohydrodynamic (MHD) simulations of flux tubes propagating through the interplanetary medium. We show analytically that this elongation results in a state which is no longer in the minimum energy Taylor state. We then present magnetohydrodynamic simulations of an elongated flux tube which has evolved away from the Taylor state and show that reconnection at many surfaces produces a complex stochastic magnetic field as the system evolves back to a minimum energy state configuration.

  7. Interplanetary gas. XXV - A solar wind and interplanetary magnetic field interpretation of cometary light outbursts

    NASA Technical Reports Server (NTRS)

    Niedner, M. B., Jr.

    1980-01-01

    Possible relationships of cometary brightness outbursts with the solar wind and interplanetary magnetic field are examined. Two types of outburst are distinguished: those which involve a significant brightening of both the head and the tail in a comet with a conspicuous plasma tail (Class I), and those involving the brightening of the central condensation of a previously faint comet with no detectable plasma tail (Class II). Class I bursts, as exemplified by Comet Morehouse 1908c, are attributed to the generation in the head of enhanced amounts of ions and their injection into the tail shortly before it disconnects, with ionization provided by sector boundary crossings. Class II events, as exhibited by Comet P/Tuttle-Giacobini-Kresak 1973b, are interpreted as the result of the bombardment of the nucleus by disturbed solar wind near corotated high-speed streams and sector boundaries, leading to highly exothermic chemical reactions.

  8. Interplanetary Magnetic Field Power Spectrum Variations: A VHO Enabled Study

    NASA Technical Reports Server (NTRS)

    Szabo, A.; Koval, A.; Merka, J.; Narock, T.

    2011-01-01

    The newly reprocessed high time resolution (11/22 vectors/sec) Wind mission interplanetary magnetic field data and the solar wind key parameter search capability of the Virtual Heliospheric Observatory (VHO) affords an opportunity to study magnetic field power spectral density variations as a function of solar wind conditions. In the reprocessed Wind Magnetic Field Investigation (MFI) data, the spin tone and its harmonics are greatly reduced that allows the meaningful fitting of power spectra to the 2 Hz limit above which digitization noise becomes apparent. The power spectral density is computed and the spectral index is fitted for the MHD and ion inertial regime separately along with the break point between the two for various solar wind conditions. The time periods of fixed solar wind conditions are obtained from VHO searches that greatly simplify the process. The functional dependence of the ion inertial spectral index and break point on solar wind plasma and magnetic field conditions will be discussed

  9. Interplanetary Magnetic Field Power Spectrum Variations: A VHO Enabled Study

    NASA Technical Reports Server (NTRS)

    Szabo, A.; Koval, A.; Merka, J.; Narock, T.

    2010-01-01

    The newly reprocessed high time resolution (11/22 vectors/sec) Wind mission interplanetary magnetic field data and the solar wind key parameter search capability of the Virtual Heliospheric Observatory (VHO) affords an opportunity to study magnetic field power spectral density variations as a function of solar wind conditions. In the reprocessed Wind Magnetic Field Investigation (MFI) data, the spin tone and its harmonics are greatly reduced that allows the meaningful fitting of power spectra to the approx.2 Hz limit above which digitization noise becomes apparent. The power spectral density is computed and the spectral index is fitted for the MHD and ion inertial regime separately along with the break point between the two for various solar wind conditions . The time periods of fixed solar wind conditions are obtained from VHO searches that greatly simplify the process. The functional dependence of the ion inertial spectral index and break point on solar wind plasma and magnetic field conditions will be discussed

  10. Large-scale interplanetary magnetic fields: Voyager 1 and 2 observations between 1 AU and 9.5 AU

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Klein, L. W.; Lepping, R. P.; Behannon, K. W.

    1984-01-01

    The large-scale radial and temporal variations of the interplanetary magnetic field strength B observed by Voyagers 1 and 2 are discussed. Two components of the magnetic field strength were considered: (1) an average component, B sub zero, based on solar rotation averages, and (2) a fluctuation component, delta B, expressed by 10- or 24-hour averages of B normalized by the best-fit average field for the corresponding time and distance. Observations of the sector structure, interfaces, and shocks are presented to further describe magnetic field strength.

  11. The topology of intrasector reversals of the interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Kahler, S. W.; Crooker, N. U.; Gosling, J. T.

    1996-11-01

    A technique has been developed recently to determine the polarities of interplanetary magnetic fields relative to their origins at the Sun by comparing energetic electron flow directions with local magnetic field directions. Here we use heat flux electrons from the Los Alamos National Laboratory (LANL) plasma detector on the ISEE 3 spacecraft to determine the field polarities. We examine periods within well-defined magnetic sectors when the field directions appear to be reversed from the normal spiral direction of the sector. About half of these intrasector field reversals (IFRs) are cases in which the polarities match those of the surrounding sectors, indicating that those fields have been folded back toward the Sun. The more interesting cases are those with polarity reversals. We find no clear cases of isolated reverse polarity fields, which suggests that islands of reverse polarity in the solar source dipole field probably do not exist. The IFRs with polarity reversals are strongly associated with periods of bidirectional electron flows, suggesting that those fields occur only in conjunction with closed fields. We propose that both those IFRs and the bidirectional flows are signatures of coronal mass ejections (CMEs). In that case, many interplanetary CMEs are larger and more complex than previously thought, consisting of both open and closed field components.

  12. Ground state alignment as a tracer of interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Yan, H.

    2012-12-01

    We demonstrate a new way of studying interplanetary magnetic field -- spectropolarimetry based on ground state alignment. Ground state alignment is a new promising way of sub-gausian magnetic fields in radiation-dominated environment. The polarization of spectral lines that are pumped by the anisotropic radiation from the sun is influenced by the magnetic alignment, which happens for sub-gausian magnetic field. As a result, the linear polarization becomes an excellent tracer of the embedded magnetic field. The method is illustrated by our synthetic obser- vation of the Jupiter's Io and comet Halley. A uniform density distribution of Na was considered and polar- ization at each point was then constructed. Both spa- tial and temporal variations of turbulent magnetic field can be traced with this technique as well. Instead of sending thousands of space probes, ground state alignment allows magnetic mapping with any ground telescope facilities equipped with spectrometer and polarimeter. For remote regions like the the boundary of interstellar medium, ground state alignment provides a unique diagnostics of magnetic field, which is crucial for understanding the physical processes such as the IBEX ribbons.

  13. Counterstreaming electrons in small interplanetary magnetic flux ropes

    NASA Astrophysics Data System (ADS)

    Feng, H. Q.; Zhao, G. Q.; Wang, J. M.

    2015-12-01

    Small interplanetary magnetic flux ropes (SIMFRs) are commonly observed by spacecraft at 1 AU, and their origin still remains disputed. We investigated the counterstreaming suprathermal electron (CSE) signatures of 106 SIMFRs measured by Wind during 1995-2005. We found that 79 (75%) of the 106 flux ropes contain CSEs, and the percentages of counterstreaming vary from 8% to 98%, with a mean value of 51%. CSEs are often observed in magnetic clouds (MCs), and this indicates these MCs are still attached to the Sun at both ends. CSEs are also related to heliospheric current sheets (HCSs) and the Earth's bow shock. We divided the SIMFRs into two categories: The first category is far from HCSs, and the second category is in the vicinity of HCSs. The first category has 57 SIMFRs, and only 7 of 57 ropes have no CSEs. This ratio is similar to that of MCs. The second category has 49 SIMFRs; however, 20 of the 49 events have no CSEs. This ratio is larger than that of MCs. These two categories have different origins. One category originates from the solar corona, and most ropes are still connected to the Sun at both ends. The other category is formed near HCSs in the interplanetary space.

  14. Interplanetary magnetic field variations and the electromagnetic state of the equatorial ionosphere

    NASA Technical Reports Server (NTRS)

    Patel, V. L.

    1978-01-01

    The Esq phenomena were selected in order to examine the effect of the interplanetary magnetic field (IMF) on the ionospheric plasma and to obtain insight into the interplanetary ionospheric coupling processes. January-March 1973 interplanetary magnetic field data of Explorer 43, Huancayo ionograms, and surface equatorial magnetograms were used. The IMF observations from Explorer 43 in the form of 15-sec averages were examined around the time of disappearance of the Esq. The IMF z-component was observed to change from a negative to a positive value before the disappearance of the Esq in four events where simultaneous data were available. The general explanation is that the induced electric field becomes westward from a previous eastward direction, coinciding with the IMF z-component reversal. Thus, just before the Esq disappears, the magnetosphere is subjected to the westward electric field. If this field is impressed to the low-latitude ionosphere, the resultant electric field in the equatorial ionosphere changes from eastward (westward) to westward (eastward) in the daytime (nighttime).

  15. Three-dimensional interplanetary stream magnetism and energetic particle motion

    NASA Technical Reports Server (NTRS)

    Barouch, E.; Burlaga, L. F.

    1976-01-01

    Cosmic rays interact with mesoscale configurations of the interplanetary magnetic field. A technique is presented for calculating such configurations in the inner solar system, which are due to streams and source conditions near the sun, and maps of magnetic field are constructed for some plausible stream and source conditions. One effect of these mesoscale configurations on galactic cosmic rays is shown to be an out-of-the-ecliptic gradient drift sufficient to explain Forbush decreases. The effects on solar energetic particles include small polar drifts due to the field gradients and a possibly large modification of the time-intensity profiles and anisotropy characteristics due to the formation of mirror configurations in space. If a diffusion model is applicable to solar particles, the true diffusion coefficient will be masked by the effects of streams. A conceptual model which incorporates these ideas and those of several other models is presented.

  16. Transport of solar electrons in the turbulent interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Ablaßmayer, J.; Tautz, R. C.; Dresing, N.

    2016-01-01

    The turbulent transport of solar energetic electrons in the interplanetary magnetic field is investigated by means of a test-particle Monte-Carlo simulation. The magnetic fields are modeled as a combination of the Parker field and a turbulent component. In combination with the direct calculation of diffusion coefficients via the mean-square displacements, this approach allows one to analyze the effect of the initial ballistic transport phase. In that sense, the model complements the main other approach in which a transport equation is solved. The major advancement is that, by recording the flux of particles arriving at virtual detectors, intensity and anisotropy-time profiles can be obtained. Observational indications for a longitudinal asymmetry can thus be explained by tracing the diffusive spread of the particle distribution. The approach may be of future help for the systematic interpretation of observations for instance by the solar terrestrial relations observatory (STEREO) and advanced composition explorer (ACE) spacecrafts.

  17. Interplanetary magnetic field enhancements in the solar wind Statistical properties at 1 AU

    NASA Technical Reports Server (NTRS)

    Arghavani, M. R.; Russell, C. T.; Luhmann, J. G.; Elphic, R. C.

    1985-01-01

    The present investigation is concerned with interplanetary magnetic field (IMF) enhancements which do not resemble any of the previously reported amplifications in the IMF. The magnetic field enhacements observed increase slowly at first and then more rapidly to a peak followed by a symmetrical decay. Interplanetary magnetic field enhacement observed by ISEE-3 on various dates are considered, giving attention to observations on June 5, 1979; September 8-9, 1980; February 5, 1981; and June 14-15, 1981. Interplanetary magnetic field enhancement observed with the aid of IMP-8 are also considered. A total of 45 events is found in surveying a 9-year period of magnetic field data.

  18. Charged Dust Grain Dynamics Subject to Solar Wind, Poynting–Robertson Drag, and the Interplanetary Magnetic Field

    NASA Astrophysics Data System (ADS)

    Lhotka, Christoph; Bourdin, Philippe; Narita, Yasuhito

    2016-09-01

    We investigate the combined effect of solar wind, Poynting–Robertson drag, and the frozen-in interplanetary magnetic field on the motion of charged dust grains in our solar system. For this reason, we derive a secular theory of motion by the means of an averaging method and validate it with numerical simulations of the unaveraged equations of motions. The theory predicts that the secular motion of charged particles is mainly affected by the z-component of the solar magnetic axis, or the normal component of the interplanetary magnetic field. The normal component of the interplanetary magnetic field leads to an increase or decrease of semimajor axis depending on its functional form and sign of charge of the dust grain. It is generally accepted that the combined effects of solar wind and photon absorption and re-emmision (Poynting–Robertson drag) lead to a decrease in semimajor axis on secular timescales. On the contrary, we demonstrate that the interplanetary magnetic field may counteract these drag forces under certain circumstances. We derive a simple relation between the parameters of the magnetic field, the physical properties of the dust grain, as well as the shape and orientation of the orbital ellipse of the particle, which is a necessary conditions for the stabilization in semimajor axis.

  19. Helioseismology with Seismometers: II Coherence with the Interplanetary Magnetic Field

    NASA Astrophysics Data System (ADS)

    Thomson, David J.; Vernon, Frank L.

    2015-04-01

    Since the discovery of seismic "hum'' in 1998 unexpected lines have been observed in terrestrial seismology.In this talk we give further evidence that these lines originate as normal modes of the Sun. Frequencies observed in terrestrial seismic and geomagnetic data are often split by multiples of a cycle/day and, unexpectedly, by multiples of one-half cycle per sidereal day.There is coherence between the interplanetary magnetic field (IMF) at ACE (located at L_1) and terrestrial geomagnetic and seismic data. There are slight frequency offsets between colocated geomagnetic and seismic data similar to those observed in normal modes excited by earthquakes. These have been attributed to dispersion from large-scale structure in the Earth.Both the splitting and coherence with the IMF give further confirmation that solar modes propagatethrough interplanetary space and are sufficiently strong to literally shake the Earth. This gives another method to detect and possibly identify solar gravity and low--frequency P-modes.

  20. Pioneer Solar Plasma and Magnetic Field Measurements in Interplanetary Space During August 2-17, 1972

    NASA Technical Reports Server (NTRS)

    Mihalov, J. D.; Colburn, D. S.; Collard, H. R.; Smith, B. F.; Sonett, C. P.; Wolfe, J. H.

    1974-01-01

    Solar wind plasma and magnetic field measurements from Pioneers 9 and 10 during August 2-17, 1972, reveal complex and large-amplitude variations on a one-hour time scale and numerous discontinuities. During this time period an approximate radial alignment of the two spacecraft as seen from the Sun occurred with heliocentric distances of 0.8 AU for Pioneer 9 and 2.2 AU for Pioneer 10, both at 45 deg east of the Earth's solar longitude. The peak hourly average solar wind proton bulk velocity measured at Pioneer 9 was 990 km sec (exp -1) during hour 0 UT of August 5. The peak hourly average proton number density was 62 cm (exp -3) during hour 11 UT of August 3. The peak solar wind speeds are generally much reduced at Pioneer 10 compared with those observes at Pioneer 9. The peak 30 minute average magnetic field magnitude was 85 gamma during 1245 - 1315 UT of August 3. The Pioneer 9 data indicate passage of four fast forward interplanetary shocks, and one slow forward interplanetary shock.

  1. Time delay of interplanetary magnetic field penetration into Earth's magnetotail

    NASA Astrophysics Data System (ADS)

    Rong, Z. J.; Lui, A. T. Y.; Wan, W. X.; Yang, Y. Y.; Shen, C.; Petrukovich, A. A.; Zhang, Y. C.; Zhang, T. L.; Wei, Y.

    2015-05-01

    Many previous studies have demonstrated that the interplanetary magnetic field (IMF) can control the magnetospheric dynamics. Immediate magnetospheric responses to the external IMF have been assumed for a long time. The specific processes by which IMF penetrates into magnetosphere, however, are actually unclear. Solving this issue will help to accurately interpret the time sequence of magnetospheric activities (e.g., substorm and tail plasmoids) exerted by IMF. With two carefully selected cases, we found that the penetration of IMF into magnetotail is actually delayed by 1-1.5 h, which significantly lags behind the magnetotail response to the solar wind dynamic pressure. The delayed time appears to vary with different auroral convection intensity, which may suggest that IMF penetration in the magnetotail is controlled considerably by the dayside reconnection. Several unfavorable cases demonstrate that the penetration lag time is more clearly identified when storm/substorm activities are not involved.

  2. Inferring interplanetary magnetic field polarities from geomagnetic variations

    NASA Astrophysics Data System (ADS)

    Vokhmyanin, M. V.; Ponyavin, D. I.

    2012-06-01

    In this paper, we propose a modified procedure to infer the interplanetary magnetic field (IMF) polarities from geomagnetic observations. It allows to identify the polarity back to 1905. As previous techniques it is based on the well-known Svalgaard-Mansurov effect. We have improved the quality and accuracy of polarity inference compared with the previous results of Svalgaard (1975) and Vennerstroem et al. (2001) by adding new geomagnetic stations and extracting carefully diurnal curve. The data demonstrates an excess of one of the two IMF sectors within equinoxes (Rosenberg-Coleman rule) evidencing polar field reversals at least for the last eight solar cycles. We also found a predominance of the two-sector structure in late of descending phase of solar cycle 16.

  3. Magnetic shielding of interplanetary spacecraft against solar flare radiation

    NASA Technical Reports Server (NTRS)

    Cocks, Franklin H.; Watkins, Seth

    1993-01-01

    The ultimate objective of this work is to design, build, and fly a dual-purpose, piggyback payload whose function is to produce a large volume, low intensity magnetic field and to test the concept of using such a magnetic field (1) to protect spacecraft against solar flare protons, (2) to produce a thrust of sufficient magnitude to stabilize low satellite orbits against orbital decay from atmospheric drag, and (3) to test the magsail concept. These all appear to be capable of being tested using the same deployed high temperature superconducting coil. In certain orbits, high temperature superconducting wire, which has now been developed to the point where silver-sheathed high T sub c wires one mm in diameter are commercially available, can be used to produce the magnetic moments required for shielding without requiring any mechanical cooling system. The potential benefits of this concept apply directly to both earth-orbital and interplanetary missions. The usefulness of a protective shield for manned missions needs scarcely to be emphasized. Similarly, the usefulness of increasing orbit perigee without expenditure of propellant is obvious. This payload would be a first step in assessing the true potential of large volume magnetic fields in the US space program. The objective of this design research is to develop an innovative, prototype deployed high temperature superconducting coil (DHTSC) system.

  4. Evidence linking coronal mass ejections with interplanetary magnetic clouds

    NASA Technical Reports Server (NTRS)

    Wilson, R. M.; Hildner, E.

    1983-01-01

    Using proxy data for the occurrence of those mass ejections from the solar corona which are directed earthward, we investigate the association between the post-1970 interplanetary magnetic clouds of Klein and Burlaga and coronal mass ejections. The evidence linking magnetic clouds following shocks with coronal mass ejections is striking; six of nine clouds observed at Earth were preceded an appropriate time earlier by meter-wave type II radio bursts indicative of coronal shock waves and coronal mass ejections occurring near central meridian. During the selected periods when no clouds were detected near Earth, the only type II bursts reported were associated with solar activity near the limbs. Where the proxy solar data to be sought are not so clearly suggested, that is, for clouds preceding interaction regions and clouds within cold magnetic enhancements, the evidence linking the clouds and coronal mass ejections is not as clear; proxy data usually suggest many candidate mass-ejection events for each cloud. Overall, the data are consistent with and support the hypothesis suggested by Klein and Burlaga that magnetic clouds observed with spacecraft at 1 AU are manifestations of solar coronal mass ejection transients.

  5. Magnetic field directional discontinuities. I - Minimum variance errors. [of interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Lepping, R. P.; Behannon, K. W.

    1980-01-01

    The paper deals with a statistical analysis of the errors associated with a minimum variance analysis of directional discontinuities by use of an idealized model of these discontinuities and various simulations, and also by an examination of actual Mariner 10 interplanetary magnetic field data. An empirical expression is derived for the magnitude of the error in an estimated discontinuity normal component, relative to the total field across the directional discontinuity. The analysis was performed primarily to aid in differentiating between interplanetary tangential and rotational discontinuities observed by Mariner 10.

  6. Tongues, bottles, and disconnected loops: The opening and closing of the interplanetary magnetic field

    SciTech Connect

    McComas, D.J.

    1994-06-01

    For years the field of Space Physics has had a problem, a really big problem for it occurs on the largest spatial scales in Space physics -- across the entire region under the Sun`s influence, the heliosphere. The problem is that the Sun appears to keep opening new magnetic flux into interplanetary space with no obvious way for this flux to close back off again. This state of affairs, without some previously unknown method for closing the open interplanetary magnetic field (IMF), leads to an ever growing amount of magnetic flux in interplanetary space: the magnetic flux catastrophe. Recently, considerable progress has been made in understanding why this catastrophic state is not the observed state of the heliosphere. This brief article paints the newly emerging picture of the opening and closing of the IMF and how these processes may account for the observed variation in the amount of magnetic flux in interplanetary space over the solar cycle.

  7. Polar cap electric field distributions related to the interplanetary magnetic field direction

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.

    1972-01-01

    The correlations between the azimuthal direction of the interplanetary magnetic field and the most simple polar cap signatures are discussed. Only the spatial distribution of the dawn-dusk polar cap field is considered. For each OGO 6 traverse across the northern or southern polar cap, the simultaneous values of the interplanetary magnetic field in solar-equatorial coordinates were recorded by the Explorer 33 magnetometer. Histograms of these values are presented and are discussed. The high degree of correlation with the longitudinal angle indicates that the relative geometry of the interplanetary magnetic field and magnetospheric magnetic fields must be fundamental to explaining the distribution of polar cap electric fields. The sign of the solar-equatorial component perpendicular to the sun-earth line appears to be a more critical parameter than the sign of the component toward the sun. The Svalgaard-Mansurov correlation and the correspondence between fast convection and parallel magnetospheric and interplanetary magnetic fields are described.

  8. The local dayside reconnection rate for oblique interplanetary magnetic fields

    NASA Astrophysics Data System (ADS)

    Komar, C. M.; Cassak, P. A.

    2016-06-01

    We present an analysis of local properties of magnetic reconnection at the dayside magnetopause for various interplanetary magnetic field (IMF) orientations in global magnetospheric simulations. This has heretofore not been practical because it is difficult to locate where reconnection occurs for oblique IMF, but new techniques make this possible. The approach is to identify magnetic separators, the curves separating four regions of differing magnetic topology, which map the reconnection X line. The electric field parallel to the X line is the local reconnection rate. We compare results to a simple model of local two-dimensional asymmetric reconnection. To do so, we find the plasma parameters that locally drive reconnection in the magnetosheath and magnetosphere in planes perpendicular to the X line at a large number of points along the X line. The global magnetohydrodynamic simulations are from the three-dimensional Block-Adaptive, Tree Solarwind Roe-type Upwind Scheme (BATS-R-US) code with a uniform resistivity, although the techniques described here are extensible to any global magnetospheric simulation model. We find that the predicted local reconnection rates scale well with the measured values for all simulations, being nearly exact for due southward IMF. However, the absolute predictions differ by an undetermined constant of proportionality, whose magnitude increases as the IMF clock angle changes from southward to northward. We also show similar scaling agreement in a simulation with oblique southward IMF and a dipole tilt. The present results will be an important component of a full understanding of the local and global properties of dayside reconnection.

  9. Interplanetary stream magnetism: Kinematic effects. [solar magnetic fields and wind

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Barouch, E.

    1974-01-01

    The particle density, and the magnetic field intensity and direction are calculated in corotating streams of the solar wind, assuming that the solar wind velocity is constant and radial and that its azimuthal variations are not two rapid. The effects of the radial velocity profile in corotating streams on the magnetic fields were examined using kinematic approximation and a variety of field configurations on the inner boundary. Kinematic and dynamic effects are discussed.

  10. Correlation of the 27-day variation of cosmic rays to the interplanetary magnetic field strength

    NASA Astrophysics Data System (ADS)

    Sabbah, I.

    2001-08-01

    We analyze cosmic ray data as well as interplanetary magnetic field (IMF) data, to examine the relation and correlation between their 27-day variations during the time interval 1965-1995. The amplitude of the 27day variation of galactic cosmic rays is linearly correlated with: the IMF strength (B), the z-component (Bz) of the IMF vector and the product of the solar wind speed (V) times B (VB). It is well correlated with the heliospheric current sheet tiltangle.Thecross-correlationfunctionofthe27-daycosmic ray variation versus the solar wind speed shows a negative correlation. The solar wind speed leads the cosmic ray variation by 2 years. The 27-day variation of cosmic rays is correlated with the variation in both the xand y-components of the IMF, it lags with 3-5 years. 1. Introduction Galactic cosmic rays are modulated (modified) through their propagation in the heliosphere by the effect of the large scale structure of the interplanetary medium. A wavy structured neutralcurrentsheet(NCS) separatesthe heliosphereintotwo regions of opposite magnetic polarity. During positive magnetic phase, the interplanetary magnetic field (IMF) is directed away from the Sun above the NCS and toward the Sun south of it. During negative magnetic phase the IMF direction is reversed. The angle between the Sun's equatorial plane and the NCS is referred as the tilt angle R, of the neutral sheet. It exhibits a solar activity dependence, R is small near sunspot minimum and large near solar maximum. The 27-day variations of galactic cosmic rays have been related to the changing position of the interplanetary NCS (Swinson and Yasue, 1992; Valdes-Galicia and Dorman, 1997). Here we examine the effect of the interplanetary parameters upon the 27-day variation of galactic cosmic rays during the last three solar cycles. 2. Solar Cycle Dependance We used hourly averaged cosmic ray counts observed with neutron monitors at Deep River (DR) and Huancayo (HU) and muon surface telescope at Nagoya (NA

  11. The Bastille Day Magnetic Clouds and Upstream Shocks: Near Earth Interplanetary Observations

    NASA Technical Reports Server (NTRS)

    Lepping, R. P.; Berdichevsky, D. B.; Burlaga, L. F.; Lazarus, A. J.; Kasper, J.; Desch, M. D.; Wu, C.-C.; Reames, D. V.; Singer, H. J.; Singer, H. J.; Vondrak, Richard R. (Technical Monitor)

    2001-01-01

    The energetic charged particle, interplanetary magnetic field, and plasma characteristics of the 'Bastille Day' shock and ejecta/magnetic cloud events at 1 AU occurring over the days 14-16 July 2000 are described. Profiles of MeV (WIND/LEMT) energetic ions help to organize the overall sequence of events from the solar source to 1 AU. Stressed are analyses of an outstanding magnetic cloud (MC2) starting late on 15 July and its upstream shock about 4 hours earlier in WIND magnetic field and plasma data. Also analyzed is a less certain, but likely, magnetic cloud (MC1) occurring early on 15 July; this was separated from MC2 by its upstream shock and many heliospheric current sheet (HCS) crossings. Other HCS crossings occurred throughout the 3-day period. Overall this dramatic series of interplanetary events caused a large multi-phase magnetic storm with min Dst lower than -300 nT. The very fast solar wind speed (greater than or equal to 1100 km/s) in and around the front of MC2 (for near average densities) was responsible for a very high solar wind ram pressure driving in the front of the magnetosphere to geocentric distances estimated to be as low as approx. 5 R(sub E), much lower than the geosynchronous orbit radius. This was consistent with magnetic field observations from two GOES satellites which indicated they were in the magnetosheath for extended times. A static force free field model is used to fit the two magnetic cloud profiles providing estimates of the clouds' physical and geometrical properties. MC2 was much larger than MCI, but their axes were nearly antiparallel, and their magnetic fields had the same left-handed helicity. MC2's axis and its upstream shock normal were very close to being perpendicular to each other, as might be expected if the cloud were driving the shock at the time of observation. The estimated axial magnetic flux carried by MC2 was 52 x 10(exp 20) Mx, which is about 5 times the typical magnetic flux estimated for other magnetic

  12. Three Dimensional Probability Distributions of the Interplanetary Magnetic Field

    NASA Astrophysics Data System (ADS)

    Podesta, J. J.

    2014-12-01

    Empirical probability density functions (PDFs) of the interplanetary magnetic field (IMF) have been derived from spacecraft data since the early years of the space age. A survey of the literature shows that past studies have investigated the separate Cartesian components of the magnetic field, the vector magnitude, and the direction of the IMF by means of one-dimensional or two-dimensional PDFs. But, to my knowledge, there exist no studies which investigate the three dimensional nature of the IMF by means of three dimensional PDFs, either in (Bx,By,Bz)(B_x,B_y,B_z)-coordinates or (BR,BT,BN)(B_R,B_T,B_N)-coordinates or some other appropriate system of coordinates. Likewise, there exist no studies which investigate three dimensional PDFs of magnetic field fluctuations, that is, vector differences bmB(t+τ)-bmB(t)bm{B}(t+tau)-bm{B}(t). In this talk, I shall present examples of three dimensional PDFs obtained from spacecraft data that demonstrate the solar wind magnetic field possesses a very interesting spatial structure that, to my knowledge, has not previously been identified. Perhaps because of the well known model of Barnes (1981) in which the magnitude of the IMF remains constant, it may be commonly believed that there is nothing new to learn from a full three dimensional PDF. To the contrary, there is much to learn from the investigation of three dimensional PDFs of the solar wind plasma velocity and the magnetic field, as well as three dimensional PDFs of their fluctuations. Knowledge of these PDFs will not only improve understanding of solar wind physics, it is an essential prerequisite for the construction of realistic models of the stochastic time series measured by a single spacecraft, one of the longstanding goals of space physics research. In addition, three dimensional PDFs contain valuable information about the anisotropy of solar wind fluctuations in three dimensional physical space, information that may help identify the reason why the three

  13. The large-scale magnetic field in the solar wind. [astronomical models of interplanetary magnetics and the solar magnetic field

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Ness, N. F.

    1976-01-01

    A literature review is presented of theoretical models of the interaction of the solar wind and interplanetary magnetic fields. Observations of interplanetary magnetic fields by the IMP and OSO spacecraft are discussed. The causes for cosmic ray variations (Forbush decreases) by the solar wind are examined. The model of Parker is emphasized. This model shows the three dimensional magnetic field lines of the solar wind to have the form of spirals wrapped on cones. It is concluded that an out-of-the-ecliptic solar probe mission would allow the testing and verification of the various theoretical models examined. Diagrams of the various models are shown.

  14. Magnetopause shape under a radial interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Grygorov, Kostiantyn; Nemecek, Zdenek; Safrankova, Jana; Shue, Jih-Hong; Pi, Gilbert

    2016-07-01

    The orientation of the interplanetary magnetic field (IMF) is the most important factor influencing the magnetopause processes and, consequently, a transfer of solar wind mass and momentum into the magnetosphere. A role of the north-south IMF component is more or less well understood in terms of changes of a location of the reconnection site(s) on the magnetopause surface that leads to the changes of the magnetopause location and flaring angle. A very rarely observed radial IMF results in a shift of magnetopause locations up to several radii farther from the Earth and probably leads to a specific magnetopause shape. We present several case studies of magnetopause crossings observed by the fleet of THEMIS spacecraft under a long lasting radial IMF and analyze the difference between observed magnetopause positions and those which are predicted by empirical magnetopause models. We use the data propagated from the L1 point as well as observations of near-Earth solar wind monitors (if available) as a model input. We discuss possible processes that can lead to the magnetopause displacement and to changes of its shape.

  15. The correlation length for interplanetary magnetic field fluctuations

    NASA Technical Reports Server (NTRS)

    Fisk, L. A.; Sari, J. W.

    1972-01-01

    It is argued that it is appropriate to consider two correlation lengths for interplanetary magnetic field fluctuations. For particles with gyro-radii large enough to encounter and be scattered by large-scale tangential discontinuities in the field (particles with energies greater than or approximately equal to several GeV/nucleon) the appropriate correlation length is simply the mean spatial separation between the discontinuities, L approximately 2 x 10 to the 11th power. Particles with gyro-radii much less than this mean separation (energies less than or approximately equal to 100 MeV/nucleon) appear to be unaffected by the discontinuities and respond only to smaller-scale field fluctuations. For these particles the correlation length is shown to be L approximately 10 to the 10th power cm. With this system of two correlation lengths the cosmic-ray diffusion tensor may be altered from what was predicted by, for example, Jokipii and Coleman, and the objections raised recently by Klimas and Sandri to the diffusion analysis of Jokipii may apply only at relatively low energies (approximately 50 MeV/nucleon).

  16. Intense interplanetary magnetic fields observed by geocentric spacecraft during 1963-1975

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; King, J. H.

    1979-01-01

    In the present paper, interplanetary magnetic field and plasma data are reviewed over a period exceeding one full solar cycle for intervals in which the magnetic intensity was greater than 13 gammas. One hundred forty nine intervals of this type, with almost complete plasma and magnetic field data, are identified. Most (79%) of these enhancements could be associated either with interplanetary shocks or with high-speed stream interfaces. Half of the remaining 21% of the enhancements could be identified as cold magnetic enhancements, while the other half could not be associated with a single shock, interface, or cold magnetic enhancement.

  17. PUZZLES OF THE INTERPLANETARY MAGNETIC FIELD IN THE INNER HELIOSPHERE

    SciTech Connect

    Khabarova, Olga; Obridko, Vladimir

    2012-12-20

    Deviations of the interplanetary magnetic field (IMF) from Parker's model are frequently observed in the heliosphere at different distances r from the Sun. Usually, it is supposed that the IMF behavior corresponds to Parker's model overall, but there is some turbulent component that impacts and disrupts the full picture of the IMF spatial and temporal distribution. However, the analysis of multi-spacecraft in-ecliptic IMF measurements from 0.29 AU to 5 AU shows that the IMF radial evolution is rather far from expected. The radial IMF component decreases with the adiabatic power index (|B{sub r} | {proportional_to} r {sup -5/3}), the tangential component |B{sub r}| {proportional_to} r {sup -1}, and the IMF strength B {proportional_to} r {sup -1.4}. This means that the IMF is not completely frozen in the solar wind. It is possible that turbulent processes in the inner heliosphere significantly influence the IMF expansion. This is confirmed by the analysis of the B{sub r} distribution's radial evolution. B{sub r} has a well-known bimodal histogram only at 0.7-2.0 AU. The bimodality effect gradually disappears from 1 AU to 4 AU, and B{sub r} becomes quasi-normally distributed at 3-4 AU (which is a sign of rapid vanishing of the stable sector structure with heliocentric distance). We consider a quasi-continuous magnetic reconnection, occurring both at the heliospheric current sheet and at local current sheets inside the IMF sectors, to be a key process responsible for the solar wind turbulization with heliocentric distance as well as for the breakdown of the ''frozen-in IMF'' law.

  18. Variation with interplanetary sector of the total magnetic field measured at the OGO 2, 4, and 6 satellites

    NASA Technical Reports Server (NTRS)

    Langel, R. A.

    1973-01-01

    Variations in the scalar magnetic field (delta B) from the polar orbiting OGO 2, 4, and 6 spacecraft are examined as a function of altitude for times when the interplanetary magnetic field is toward the sun and for times when the interplanetary magnetic field away from the sun. This morphology is basically the same as that found when all data, irrespective of interplanetary magnetic sector, are averaged together. Differences in delta B occur, both between sectors and between seasons, which are similar in nature to variations in the surface delta Z found by Langel (1973c). The altitude variation of delta B at sunlit local times, together with delta Z at the earth's surface, demonstrates that the delta Z and delta B which varies with sector has an ionospheric source. Langel (1973b) showed that the positive delta B region in the dark portion of the hemisphere is due to at least two sources, the westward electrojet and an unidentified non-ionospheric source(s). Comparison of magnetic variations between season/sector at the surface and at the satellite, in the dark portion of the hemisphere, indicates that these variations are caused by variations in the latitudinally narrow electrojet currents and not by variations in the non-ionospheric source of delta B.

  19. Interplanetary magnetic field as a detector of turbulence in the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Khabarova, O.

    2013-12-01

    Analysis of the interplanetary magnetic field (IMF) behavior at different scales may give a key for understanding of turbulence spatial evolution in the heliosphere. It has been known that the solar wind plasma becomes more and more turbulent with heliocentric distance. Recent multi-spacecraft investigations of the large-scale IMF [1] show unexpectedly fast lost of the regular sector structure of the solar wind in the inner heliosphere. In the ecliptic plane, it seems to be broken at 3-4 AU, much closer to the Sun than the Parker spiral gets perpendicular to the sunward direction. At the same time, the high-latitude solar wind remains more structured at the same heliocentric distances [2]. This fact may bear evidence of radial increase of turbulence and intermittency in the solar wind due to magnetic reconnection. The magnetic reconnection recurrently occurs at the large-scale heliospheric current sheet (HCS) as well as at smaller-scale current sheets during the solar wind expansion [3]. As a result, a significant part of the heliosphere is filled with secondary current sheets as well as with waves and accelerated particles in some vicinity of the HCS. Under averaging, it looks as a radial increase of turbulence, especially in low latitudes. It also can be considered as one of the main causes of the break of the expected IMF radial dependence law [1, 2]. Results of the consequent multi-spacecraft analysis of plasma and magnetic filed turbulence characteristics at different heliocentric distances and heliolatitudes will be discussed. 1. O. Khabarova, V. Obridko, Puzzles of the Interplanetary Magnetic Field in the Inner Heliosphere, 2012, Astrophysical Journal, 761, 2, 82, doi:10.1088/0004-637X/761/2/82, http://arxiv.org/pdf/1204.6672v2.pdf 2. O.V. Khabarova, The interplanetary magnetic field: radial and latitudinal dependences, Astronomy Reports, 2013, 57, 11, http://arxiv.org/ftp/arxiv/papers/1305/1305.1204.pdf 3. V. Zharkova, O. Khabarova, Particle Acceleration in

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

    NASA Technical Reports Server (NTRS)

    Gonzalez, Walter D.; Tsurutani, Bruce T.

    1987-01-01

    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.

  1. Relationships Among Geomagnetic Storms, Interplanetary Shocks, Magnetic Clouds, and Sunspot Number During 1995 - 2012

    NASA Astrophysics Data System (ADS)

    Wu, Chin-Chun; Lepping, Ronald P.

    2016-01-01

    During 1995 - 2012, the Wind spacecraft has recorded 168 magnetic clouds (MCs), 197 magnetic cloud-like structures (MCLs), and 358 interplanetary (IP) shocks. Ninety-four MCs and 56 MCLs had upstream shock waves. The following features are found: i) The averages of the solar wind speed, interplanetary magnetic field (IMF), duration (< Δ t >), the minimum of B_{min}, and intensity of the associated geomagnetic storm/activity (Dst_{min}) for MCs with upstream shock waves (MC_{shock}) are higher (or stronger) than those averages for the MCs without upstream shock waves (MC_{no-shock}). ii) The average < Δ t > of MC_{shock} events ({≈} 19.8 h) is 9 % longer than that for MC_{no-shock} events ({≈} 17.6 h). iii) For the MC_{shock} events, the average duration of the sheath (<Δ t_{sheath}>) is 12.1 h. These findings could be very useful for space weather predictions, i.e. IP shocks driven by MCs are expected to arrive at Wind (or at 1 AU) about 12 h ahead of the front of the MCs on average. iv) The occurrence frequency of IP shocks is well associated with sunspot number (SSN). The average intensity of geomagnetic storms measured by < Dst_{min}> for MC_{shock} and MC_{no-shock} events is -102 and -31 nT, respectively. The average values < {Dst}_{min} > are -78, -70, and -35 nT for the 358 IP shocks, 168 MCs, and 197 MCLs, respectively. These results imply that IP shocks, when they occur with MCs/MCLs, must play an important role in the strength of geomagnetic storms. We speculate about the reason for this. Yearly occurrence frequencies of MC_{shock} and IP shocks are well correlated with solar activity ( e.g., SSN). Choosing the correct Dst_{min} estimating formula for predicting the intensity of MC-associated geomagnetic storms is crucial for space weather predictions.

  2. Influence of interplanetary magnetic field and solar wind on auroral brightness in different regions

    NASA Astrophysics Data System (ADS)

    Yang, Y. F.; Lu, J. Y.; Wang, J.-S.; Peng, Z.; Zhou, L.

    2013-01-01

    Abstract<p label="1">By integrating and <span class="hlt">averaging</span> the auroral brightness from Polar Ultraviolet Imager auroral images, which have the whole auroral ovals, and combining the observation data of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) and solar wind from NASA Operating Missions as a Node on the Internet (OMNI), we investigate the influence of IMF and solar wind on auroral activities, and analyze the separate roles of the solar wind dynamic pressure, density, and velocity on aurora, respectively. We statistically analyze the relations between the <span class="hlt">interplanetary</span> conditions and the auroral brightness in dawnside, dayside, duskside, and nightside. It is found that the three components of the IMF have different effects on the auroral brightness in the different regions. Different from the nightside auroral brightness, the dawnside, dayside, and duskside auroral brightness are affected by the IMF Bx, and By components more significantly. The IMF Bx and By components have different effects on these three regional auroral brightness under the opposite polarities of the IMF Bz. As expected, the nightside aurora is mainly affected by the IMF Bz, and under southward IMF, the larger the |Bz|, the brighter the nightside aurora. The IMF Bx and By components have no visible effects. On the other hand, it is also found that the aurora is not intensified singly with the increase of the solar wind dynamic pressure: when only the dynamic pressure is high, but the solar wind velocity is not very fast, the aurora will not necessarily be intensified significantly. These results can be used to qualitatively predict the auroral activities in different regions for various <span class="hlt">interplanetary</span> conditions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850023275&hterms=Magnetic+anomaly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMagnetic%2Banomaly','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850023275&hterms=Magnetic+anomaly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DMagnetic%2Banomaly"><span id="translatedtitle">Geologic analysis of <span class="hlt">averaged</span> <span class="hlt">magnetic</span> satellite anomalies</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Goyal, H. K.; Vonfrese, R. R. B.; Ridgway, J. R.; Hinze, W. J.</p> <p>1985-01-01</p> <p>To investigate relative advantages and limitations for quantitative geologic analysis of <span class="hlt">magnetic</span> satellite scalar anomalies derived from arithmetic <span class="hlt">averaging</span> of orbital profiles within equal-angle or equal-area parallelograms, the anomaly <span class="hlt">averaging</span> process was simulated by orbital profiles computed from spherical-earth crustal <span class="hlt">magnetic</span> anomaly modeling experiments using Gauss-Legendre quadrature integration. The results indicate that <span class="hlt">averaging</span> can provide reasonable values at satellite elevations, where contributing error factors within a given parallelogram include the elevation distribution of the data, and orbital noise and geomagnetic field attributes. Various inversion schemes including the use of equivalent point dipoles are also investigated as an alternative to arithmetic <span class="hlt">averaging</span>. Although inversion can provide improved spherical grid anomaly estimates, these procedures are problematic in practice where computer scaling difficulties frequently arise due to a combination of factors including large source-to-observation distances ( 400 km), high geographic latitudes, and low geomagnetic field inclinations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770027147','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770027147"><span id="translatedtitle">Sources of <span class="hlt">magnetic</span> fields in recurrent <span class="hlt">interplanetary</span> streams</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burlaga, L. F.; Behannon, K. W.; Hansen, S. F.; Pneuman, G. W.; Feldman, W. C.</p> <p>1977-01-01</p> <p>The sources of <span class="hlt">magnetic</span> fields in recurrent streams were examined. Most fields and plasmas at 1 AU were related to coronal holes, and the <span class="hlt">magnetic</span> field lines were open in those holes. Some of the <span class="hlt">magnetic</span> fields and plasmas were related to open field line regions on the sun which were not associated with known coronal holes, indicating that open field lines are more basic than coronal holes as sources of the solar wind. <span class="hlt">Magnetic</span> field intensities in five equatorial coronal holes ranged from 2G to 18G. <span class="hlt">Average</span> measured photospheric <span class="hlt">magnetic</span> fields along the footprints of the corresponding unipolar fields on circular equatorial arcs at 2.5 solar radii had a similar range and <span class="hlt">average</span>, but in two cases the intensities were approximately three times higher than the projected intensities. The coronal footprints of the sector boundaries on the source surface at 2.5 solar radii, meandered between -45 deg and +45 deg latitude, and their inclination ranged from near zero to near ninety degrees.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770027122','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770027122"><span id="translatedtitle"><span class="hlt">Interplanetary</span> medium data book, appendix</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>King, J. H.</p> <p>1977-01-01</p> <p>Computer generated listings of hourly <span class="hlt">average</span> <span class="hlt">interplanetary</span> plasma and <span class="hlt">magnetic</span> field parameters are given. Parameters include proton temperature, proton density, bulk speed, an identifier of the source of the plasma data for the hour, <span class="hlt">average</span> <span class="hlt">magnetic</span> field magnitude and cartesian components of the <span class="hlt">magnetic</span> field. Also included are longitude and latitude angles of the vector made up of the <span class="hlt">average</span> field components, a vector standard deviation, and an identifier of the source of <span class="hlt">magnetic</span> field data.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Icar..263...10H','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Icar..263...10H"><span id="translatedtitle"><span class="hlt">Interplanetary</span> <span class="hlt">magnetic</span> field structure at Saturn inferred from nanodust measurements during the 2013 aurora campaign</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hsu, H.-W.; Kempf, S.; Badman, S. V.; Kurth, W. S.; Postberg, F.; Srama, R.</p> <p>2016-01-01</p> <p>Interactions between the solar wind and planetary magnetospheres provide important diagnostic information about the magnetospheric dynamics. The lack of monitoring of upstream solar wind conditions at the outer planets, however, restrains the overall scientific output. Here we apply a new method, using Cassini nanodust stream measurements, to derive the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field structure during the 2013 Saturn aurora campaign. Due to the complex dynamical interactions with the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field, a fraction of fast nanodust particles emerging from the Saturnian system is sent back into the magnetosphere and can be detected by a spacecraft located within. The time-dependent directionality caused by the variable <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field enable these particles to probe the solar wind structure remotely. Information about the arrival time of solar wind compression regions (coupled with the heliospheric current sheet crossings) as well as the field direction associated with the solar wind sector structure can be inferred. Here we present a tentative identification of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field sector structure based on Cassini nanodust and radio emission measurements during the 2013 Saturn aurora campaign. Our results show that, the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field near Saturn during 2013-080 to 176 was consistent with a two-sector structure. The intensifications of aurora and the radio emission on 2013-095, 112 and 140 coincide with the IMF sector boundaries, indicating that the encounter of the compressed solar wind is the main cause of the observed activities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910060875&hterms=magnetic+fields+interactions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmagnetic%2Bfields%2Binteractions','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910060875&hterms=magnetic+fields+interactions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dmagnetic%2Bfields%2Binteractions"><span id="translatedtitle"><span class="hlt">Interplanetary</span> <span class="hlt">magnetic</span> field control of the Mars bow shock - Evidence for Venuslike interaction</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zhang, T. L.; Schwingenschuh, K.; Lichtenegger, H.; Riedler, W.; Russell, C. T.</p> <p>1991-01-01</p> <p>The Mars bow shock location and shape have been determined by examining the Phobos spacecraft magnetometer data. Observations show that the position of the terminator bow shock varies with <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field orientation in the same way as at Venus. The shock is farthest from Mars in the direction of the <span class="hlt">interplanetary</span> electric field, consistent with the idea that mass loading plays an important role in the solar wind interaction with Mars. The shock cross section at the terminator plane is asymmetric and is controlled by the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field. The shock is farther from Mars during solar maximum. Thus the solar wind interaction with Mars appears to be Venuslike, with a <span class="hlt">magnetic</span> moment too small to affect significantly the solar wind interaction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1995SoPh..157..367A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1995SoPh..157..367A"><span id="translatedtitle">The solar wind angular momentum and energy carried by the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Alexander, P.; de La Torre, A.</p> <p>1995-03-01</p> <p>Solutions already found by one of the authors with a two-region model of the solar coronal expansion are used to analyze the transport of angular momentum and energy by the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field. In agreement with observations, it is predicted that the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field plays an insignificant role for the flux of energy, but carries a large amount of angular momentum. The appropriate description might be related to the replacement of classical transport coefficients by a collisionless heat flux equation in the outer region of the model. The Sun's loss of angular momentum may affect the strength of the solar rotation in the long term.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22270946','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22270946"><span id="translatedtitle">DECLINE AND RECOVERY OF THE <span class="hlt">INTERPLANETARY</span> <span class="hlt">MAGNETIC</span> FIELD DURING THE PROTRACTED SOLAR MINIMUM</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Smith, Charles W.; Schwadron, Nathan A.; DeForest, Craig E. E-mail: N.Schwadron@unh.edu</p> <p>2013-09-20</p> <p>The <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) is determined by the amount of solar <span class="hlt">magnetic</span> flux that passes through the top of the solar corona into the heliosphere, and by the dynamical evolution of that flux. Recently, it has been argued that the total flux of the IMF evolves over the solar cycle due to a combination of flux that extends well outside of 1 AU and is associated with the solar wind, and additionally, transient flux associated with coronal mass ejections (CMEs). In addition to the CME eruption rate, there are three fundamental processes involving conversion of <span class="hlt">magnetic</span> flux (from transient to wind-associated), disconnection, and interchange reconnection that control the levels of each form of <span class="hlt">magnetic</span> flux in the <span class="hlt">interplanetary</span> medium. This is distinct from some earlier models in which the wind-associated component remains steady across the solar cycle. We apply the model of Schwadron et al. that quantifies the sources, interchange, and losses of <span class="hlt">magnetic</span> flux to 50 yr of <span class="hlt">interplanetary</span> data as represented by the Omni2 data set using the sunspot number as a proxy for the CME eruption rate. We do justify the use of that proxy substitution. We find very good agreement between the predicted and observed <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> flux. In the absence of sufficient CME eruptions, the IMF falls on the timescale of ∼6 yr. A key result is that rising toroidal flux resulting from CME eruption predates the increase in wind-associated IMF.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19770038810&hterms=magnetic+separation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmagnetic%2Bseparation','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19770038810&hterms=magnetic+separation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dmagnetic%2Bseparation"><span id="translatedtitle">The August 1972 solar-terrestrial events - <span class="hlt">Interplanetary</span> <span class="hlt">magnetic</span> field observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Smith, E. J.</p> <p>1976-01-01</p> <p><span class="hlt">Interplanetary-magnetic</span>-field measurements made by Pioneers 9 and 10, HEOS 2, and Explorer 41 during early August 1972 are reviewed. It is noted that the two Pioneers were nearly radially aligned during the flare events, with Pioneer 9 at a distance of 0.78 AU from the sun and Pioneer 10 at a distance of 2.2 AU. The data obtained by Pioneer 9, Pioneer 10, and the two near-earth satellites are analyzed separately, and the major flare-associated shocks are identified. An attempt is made to identify corresponding shocks at the different locations and to determine their propagation velocities in the region between 0.8 and 2.2 AU. It is found that there was an obvious tendency for the <span class="hlt">average</span> shock velocities to decrease with increasing radial distance from the sun and that the local velocities at the Pioneer locations were significantly smaller than the appropriate <span class="hlt">average</span> values. A comparison of these local velocities indicates that there was a large deceleration of the shocks between the sun and some distance within 0.8 AU but little, if any, deceleration beyond that distance. A plot of <span class="hlt">average</span> shock velocities from the sun to 1.0 AU as a function of longitude separation between the flares and Pioneer 9 is shown to suggest a pronounced deviation of the shock fronts from spherical symmetry.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004AGUFMSH31A1178W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004AGUFMSH31A1178W"><span id="translatedtitle">Orientation Of <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Clouds Associated With Filament Eruptions And Major Geomagnetic Storms</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Y.; Ye, P.; Zhou, G.; Wang, S.; Wang, J.</p> <p>2004-12-01</p> <p>As a major source of non-recurrent geomagnetic storms, more than half of <span class="hlt">magnetic</span> clouds in the <span class="hlt">interplanetary</span> medium are associated with filament eruptions [Subramanian and Dere, 2001]. The strength of south component of the <span class="hlt">magnetic</span> field inside <span class="hlt">magnetic</span> cloud and its duration are consider the very important factors in causing geomagnetic storm. Obviously, these factors are related to the orientation of <span class="hlt">magnetic</span> cloud in terms of flux rope model. By investigating the observations of SOHO and ACE spacecraft from 2000 to 2003, the relationship between the orientation of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> clouds which were associated with filament eruptions and major geomagnetic storms are studied. Two issues are discussed: (1) the effect of <span class="hlt">magnetic</span> cloud's orientation on the intensity of geomagnetic storm, and (2) the possible factors in influencing the cloud's orientation. The results will be worked out.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1981ICRC....3..113Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1981ICRC....3..113Z"><span id="translatedtitle">Low-energy particles in <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field near the sectorial boundary on September 26, 1977</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zeldovich, M. A.; Kuzhevskii, B. M.</p> <p></p> <p>Prognoz-6 data are used to examine effects of the sign reversal in the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field of September 26, 1977 on the 70-keV to 40 MeV proton fluxes, and the 10-30 keV and 40-500 keV electron fluxes. The sectorial boundary of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field traversed the earth at 2300 UT, and in that period the <span class="hlt">interplanetary</span> space was filled with the solar cosmic ray particles generated in the flare of September 24, 1977, whose intensity decreased in time. Results indicate that the event of September 26, 1977 was the first observation where effects of the sectorial boundary were traced up to proton energies of 40-50 MeV.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720015727','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720015727"><span id="translatedtitle">Effects of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field azimuth on auroral zone and polar cap <span class="hlt">magnetic</span> activity</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burch, J. L.</p> <p>1972-01-01</p> <p>During relatively quiet times in the period 1964-1968, AE is found to be greater when the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (b sub IMF) is directed toward the sun in Jan., Feb., and Apr., and when B sub IMF is directed away from the sun in Oct. to Dec. Using Murmansk hourly H values and the AE components, AU and AL, it is shown that this sector dependence is present only in the negative H deviations. This observation supports the idea that negative bay magnitudes are determined chiefly by particle-produced ionization, while positive bay magnitudes are rather insensitive to increases in particle precipitation. The ratio of DP2-type <span class="hlt">magnetic</span> activity in the southern polar cap to that in the northern polar cap is found to be greater by a factor of about 1.75 for B sub IMF toward the sun.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E1678S&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016cosp...41E1678S&link_type=ABSTRACT"><span id="translatedtitle">Structure of magnetopause layers formed by a radial <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Safrankova, Jana; Simunek, Jiri; Nemecek, Zdenek; Prech, Lubomir; Grygorov, Kostiantyn; Shue, Jih-Hong; Samsonov, Andrey; Pi, Gilbert</p> <p>2016-07-01</p> <p>The magnetopause location is generally believed to be determined by the solar wind dynamic pressure and by the sign and value of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) vertical (Bz) component. A contribution of other parameters is usually assumed to be minor or negligible near the equatorial plane. However, recent papers have shown a magnetopause expansion during intervals of a nearly radial IMF (large IMF Bx component). Under such conditions, the total pressure exerted on the subsolar magnetopause is significantly lower than the solar wind dynamic pressure as demonstrate both MHD simulations and statistical investigations. During a long-duration radial IMF, all parameters - the IMF magnitude, solar wind speed, density, and especially the temperature are depressed in comparison with their yearly <span class="hlt">averages</span>. Moreover, in this case, the structures of the LLBL change; the LLBL shows different profiles at both hemispheres for negative and positive IMF Bx polarities. This asymmetry changes over time and influences the LLBL structures due to <span class="hlt">magnetic</span> reconnection. We present an overview of important physical quantities controlling the magnetopause compression and new results that deal with the structure of the magnetopause and adjacent layers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2010JGRA..11510320W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2010JGRA..11510320W"><span id="translatedtitle">Statistical maps of geomagnetic perturbations as a function of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weimer, D. R.; Clauer, C. R.; Engebretson, M. J.; Hansen, T. L.; Gleisner, H.; Mann, I.; Yumoto, K.</p> <p>2010-10-01</p> <p>Mappings of geomagnetic perturbations are shown for different combinations of the solar wind velocity, <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF), and dipole tilt angle (season). <span class="hlt">Average</span> maps were derived separately for the northward, eastward, and vertical (downward) components of the geomagnetic disturbances, using spherical cap harmonics in least error fits of sorted measurements. The source data are obtained from 104 ground-based magnetometer stations in the Northern Hemisphere at geomagnetic latitudes over 40° during the years 1998 through 2001. Contour maps of statistical fits are shown along-side scatter plots of individual measurements in corrected geomagnetic apex coordinates. The patterns are consistent with previous mappings of ionospheric electric potential. Interestingly, the vertical component of the <span class="hlt">magnetic</span> perturbations closely resembles maps of the overhead, field-aligned currents, including the Northward IMF configuration. The maximum and minimum values from the statistical mappings are graphed to show their changes as a function of southward IMF magnitude, solar wind velocity, and seasons. It is expected that this work will lead to better advance predictions of the geomagnetic perturbations that are based on real-time IMF measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19730037253&hterms=kawasaki&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dkawasaki','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19730037253&hterms=kawasaki&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Dkawasaki"><span id="translatedtitle">Cross-correlation analysis of the AE index and the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field Bz component.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Meng, C.-I.; Tsurutani, B.; Kawasaki, K.; Akasofu, S.-I.</p> <p>1973-01-01</p> <p>A cross-correlation study between magnetospheric activity (the AE index) and the southward-directed component of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) is made for a total of 792 hours (33 days) with a time resolution of about 5.5 min. The peak correlation tends to occur when the <span class="hlt">interplanetary</span> data are shifted approximately 40 min later with respect to the AE index data. Cross-correlation analysis is conducted on some idealized wave forms to illustrate that this delay between southward turning of the IMF and the AE index should not be interpreted as being the duration of the growth phase.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JGRA..119.3979W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JGRA..119.3979W"><span id="translatedtitle">Strong ionospheric field-aligned currents for radial <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Hui; Lühr, Hermann; Shue, Jih-Hong; Frey, Harald. U.; Kervalishvili, Guram; Huang, Tao; Cao, Xue; Pi, Gilbert; Ridley, Aaron J.</p> <p>2014-05-01</p> <p>The present work has investigated the configuration of field-aligned currents (FACs) during a long period of radial <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) on 19 May 2002 by using high-resolution and precise vector <span class="hlt">magnetic</span> field measurements of CHAMP satellite. During the interest period IMF By and Bz are weakly positive and Bx keeps pointing to the Earth for almost 10 h. The geomagnetic indices Dst is about -40 nT and AE about 100 nT on <span class="hlt">average</span>. The cross polar cap potential calculated from Assimilative Mapping of Ionospheric Electrodynamics and derived from DMSP observations have <span class="hlt">average</span> values of 10-20 kV. Obvious hemispheric differences are shown in the configurations of FACs on the dayside and nightside. At the south pole FACs diminish in intensity to magnitudes of about 0.1 μA/m2, the plasma convection maintains two-cell flow pattern, and the thermospheric density is quite low. However, there are obvious activities in the northern cusp region. One pair of FACs with a downward leg toward the pole and upward leg on the equatorward side emerge in the northern cusp region, exhibiting opposite polarity to FACs typical for duskward IMF orientation. An obvious sunward plasma flow channel persists during the whole period. These ionospheric features might be manifestations of an efficient <span class="hlt">magnetic</span> reconnection process occurring in the northern magnetospheric flanks at high latitude. The enhanced ionospheric current systems might deposit large amount of Joule heating into the thermosphere. The air densities in the cusp region get enhanced and subsequently propagate equatorward on the dayside. Although geomagnetic indices during the radial IMF indicate low-level activity, the present study demonstrates that there are prevailing energy inputs from the magnetosphere to both the ionosphere and thermosphere in the northern polar cusp region.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770027121','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770027121"><span id="translatedtitle"><span class="hlt">Interplanetary</span> medium data book</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>King, J. H.</p> <p>1977-01-01</p> <p>Unresolved questions on the physics of solar wind and its effects on magnetospheric processes and cosmic ray propagation were addressed with hourly <span class="hlt">averaged</span> <span class="hlt">interplanetary</span> plasma and <span class="hlt">magnetic</span> field data. This composite data set is described with its content and extent, sources, limits of validity, and the mutual consistency studies and normalizations to which the input data were subjected. Hourly <span class="hlt">averaged</span> parameters were presented in the form of digital listings and 27-day plots. The listings are contained in a separately bound appendix.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730002064','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730002064"><span id="translatedtitle">Comments on the measurement of power spectra of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, C. T.</p> <p>1972-01-01</p> <p>Examination of possible noise sources in the measurement of the power spectrum of fluctuations in the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field shows that most measurements by fluxgate magnetometers are limited by digitization noise whereas the search coil magnetometer is limited by instrument noise. The folding of power about the Nyquist frequency or aliasing can be a serious problem at times for many magnetometers, but it is not serious during typical solar wind conditions except near the Nyquist frequency. Waves in the solar wind associated with the presence of the earth's bow shock can contaminate the <span class="hlt">interplanetary</span> spectrum in the vicinity of the earth. However, at times the spectrum in this region is the same as far from the earth. Doppler shifting caused by the convection of waves by the solar wind makes the interpretation of <span class="hlt">interplanetary</span> spectra difficult.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014EGUGA..16.1263W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014EGUGA..16.1263W"><span id="translatedtitle">Response of ionosphere and thermosphere during radial <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wang, Hui; Luehr, Hermann; Shue, Jihong</p> <p>2014-05-01</p> <p>The configurations of ionosphere and thermosphere have been investigated by using high-resolution measurements of CHAMP satellite. During the period IMF By and Bz components are weak and Bx keeps pointing to the Earth for almost 10 hours. The geomagnetic indices Dst is about -40 nT and AE about 100 nT on <span class="hlt">average</span> during the interest period. The CPCP (cross polar cap potential) output by AMIE and calculated from DMSP observations have <span class="hlt">average</span> values of 15-20 kV. Obvious hemispheric differences are shown in the configurations of FACs on the dayside and nightside. In the south pole FACs diminish in intensity with magnitudes below 0.25 µA/m2, the plasma convection retains its quiet time two cell flow pattern, and the air density is quiet low. However, there are obvious activities in the north cusp FACs. One pair of FACs emerges in the north cusp region, which shows opposite polarities to DPY FACs. The new type of currents is accompanied by sunward plasma flow channels. These ionospheric features might be manifestations of the <span class="hlt">magnetic</span> reconnection processes occurring in the north magnetospheric flanks. The enhanced ionospheric current systems have deposited large amount of energies into the thermosphere, causing enhanced air densities in the cusp region, which subsequently propagate equatorward both on the dayside and nightside. Although the radial IMF is considered as geomagnetic quiet condition, the present study has demonstrated for the first time there are prevailing energy inputs from the magnetosphere to both the ionosphere and thermosphere in the polar cusp region.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_3");'>3</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li class="active"><span>5</span></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_5 --> <div id="page_6" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="101"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730002088','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730002088"><span id="translatedtitle">Effects of interstellar particles upon the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Coleman, P. J., Jr.; Winter, E. M.</p> <p>1972-01-01</p> <p>The flow of interstellar neutral particles into the <span class="hlt">interplanetary</span> medium and their subsequent ionization in the presence of the electromagnetic field of the solar wind can cause a loss of field angular momentum by the solar wind. One effect of this loss of field angular momentum is a significant unwinding of the spiral field. This effect is evaluated using simple models for neutral density and ion production. For a free-stream interstellar medium with a neutral hydrogen density of 1 per cubic centimeter and a velocity relative to the sun of 10 to 20 km per second, the spiral angle at the orbit of Jupiter will be less than its nominal value of 45 deg at the orbit of the earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19760040203&hterms=E-LAYER&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DE-LAYER','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19760040203&hterms=E-LAYER&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DE-LAYER"><span id="translatedtitle">Effect of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field on ionosphere over the <span class="hlt">magnetic</span> equator</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rastogi, R. G.; Patel, V. L.</p> <p>1975-01-01</p> <p>Large and quick changes of the latitude of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field from its southward to northward direction are shown to be associated with the disappearance of the Es-q layer (Knecht, 1959) at the equatorial ionosphere during the daytime or with the reversal of E region horizontal and F region vertical electron drifts during both night and day. This phenomenon is suggested as the imposition of an electric field in the ionosphere in a direction opposite to that of the Sq electric field. The resultant electrostatic field on the equatorial ionosphere would be decreased or even reversed from its normal direction, resulting in the reduction of electron drift velocity. When the normal Sq field is over-compensated by the magnetospheric electric field, the electron drifts are reversed and the irregularities in the E region due to the cross-field instabilities are inhibited, resulting in the sudden disappearance of the Es-q layers.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850026500','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850026500"><span id="translatedtitle">Low energy proton bidirectional anisotropies and their relation to transient <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> structures: ISEE-3 observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Marsden, R. G.; Sanderson, T. R.; Wenzel, K. P.; Smith, E. J.</p> <p>1985-01-01</p> <p>It is known that the <span class="hlt">interplanetary</span> medium in the period approaching solar maximum is characterized by an enhancement in the occurrence of transient solar wind streams and shocks and that such systems are often associated with looplike <span class="hlt">magnetic</span> structures or clouds. There is observational evidence that bidirectional, field aligned flows of low energy particles could be a signature of such looplike structures, although detailed models for the <span class="hlt">magnetic</span> field configuration and injection mechanisms do not exist at the current time. Preliminary results of a survey of low energy proton bidirectional anisotropies measured on ISEE-3 in the <span class="hlt">interplanetary</span> medium between August 1978 and May 1982, together with <span class="hlt">magnetic</span> field data from the same spacecraft are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19720046848&hterms=magnetic+fields+interactions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmagnetic%2Bfields%2Binteractions','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19720046848&hterms=magnetic+fields+interactions&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmagnetic%2Bfields%2Binteractions"><span id="translatedtitle">The effects of boundary condition asymmetries on the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field-moon interaction.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Reisz, A. C.; Paul, D. L.; Madden, T. R.</p> <p>1972-01-01</p> <p>Boundary condition asymmetries inherent in the solar wind flow past the moon are included in a cylindrical model of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field-moon interaction. Numerical examinations of the sunward side response of this model are compared in the frequency domain with those of symmetrically excited spherical and cylindrical models and two characteristic differences are observed: the response of the asymmetric model is depressed at low frequencies due to <span class="hlt">magnetic</span> diffusion around a conducting core, and is flattened at high frequencies because of the finite application time of the incident <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field. The diffusion of field lines around the core is also evident in the time response of the model in the antisolar cavity. The above features of the lunar response resulting from boundary condition asymmetries are shown to be evident in observational measurements.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19760033553&hterms=Statistical+Energy+Analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DStatistical%2BEnergy%2BAnalysis','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19760033553&hterms=Statistical+Energy+Analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DStatistical%2BEnergy%2BAnalysis"><span id="translatedtitle">Statistical properties of the <span class="hlt">interplanetary</span> microscale fluctuations. [in plasma velocity and <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Belcher, J. W.</p> <p>1975-01-01</p> <p>Results are reported for a statistical study of short-period fluctuations in the <span class="hlt">interplanetary</span> plasma velocity and <span class="hlt">magnetic</span> field. The data base used consists of measurements of the <span class="hlt">interplanetary</span> plasma and <span class="hlt">magnetic</span> field by Pioneer 6 with a time resolution of 72 sec and by Mariner 5 with a resolution of 5 min. The analysis is conducted to characterize the parent population from which all individual microscale events on these time scales are drawn. The microscale changes are grouped according to their energy densities relative to the energy density of the background <span class="hlt">magnetic</span> field, and it is found that each grouping exhibits certain statistical properties within the limits of observational uncertainty. It is noted that these statistical properties are purely observational and independent of any physical model which may be used to interpret them. The results are discussed in the context of MHD discontinuity theory for a thermally anisotropic plasma.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930046797&hterms=cosmic+geometry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dcosmic%2Bgeometry','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930046797&hterms=cosmic+geometry&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dcosmic%2Bgeometry"><span id="translatedtitle">Long-term variations of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field spectra with implications for cosmic ray modulation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bieber, John W.; Chen, Jiasheng; Matthaeus, William H.; Smith, Charles W.; Pomerantz, Martin A.</p> <p>1993-01-01</p> <p>The paper calculates yearly <span class="hlt">averaged</span> power spectra of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field turbulence at 1 AU over the period 1965-1988 for fluctuations in the frequency range 5.8 x 10 exp -6 to 4.6 x 10 exp -5 Hz, corresponding to periods of 6-48 hr. The amplitudes of the spectra vary with the sunspot cycle and are inversely correlated with the intensity of about 10-GeV cosmic rays. The observed spectra are used to calculate a lower limit to the cosmic ray scattering mean free path employing resonant magnetostatic quasi-linear theory for both 'slab' and isotropic geometries of the turbulence. The mean free paths thus obtained are typically about 0.1 AU in the slab model and about 0.3 AU in the isotropic model, but they are not significantly correlated with the modulated galactic cosmic ray intensity recorded by neutron monitors. It is inferred that the scattering processes described by resonant magnetostatic theory play, at best, a very minor role in the solar modulation of about 10-GeV cosmic rays.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810004452','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810004452"><span id="translatedtitle"><span class="hlt">Magnetic</span> field directional discontinuities. 2: Characteristics between 0.46 and 1.0 AU. [<span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> fields</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lepping, R. P.; Benhannon, K. W.</p> <p>1980-01-01</p> <p>The characteristics of directional discontinuities (DD's) in the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field are studied using data from the Mariner 10 primary mission between 1.0 and 0.46 AU. Statistical and visual survey methods for DD identification resulted in a total of 644 events. Two methods were used to estimate the ratio of the number of tangential discontinuities (TD's) to the number of rotational discontinuities (RD's). Both methods show that the ratio of TD's to RD's varied with time and decreased with decreasing radial distance. A decrease in <span class="hlt">average</span> discontinuity thickness of approx. 40 percent was found between 1.0 and 0.72 AU and approx. 54 percent between 1.0 and 0.46 AU, independent of type (TD or RD). This decrease in thickness for decreasing r is in qualitative agreement with Pioneer 10 observations between 1 and 5 AU. When the individual DD thickness are normalized with respect to the estimated local proton gyroradius (RA sub L), the <span class="hlt">average</span> thickness at the three locations is nearly constant, 43 + or - 6 R sub L. This also holds true for both RD's and TD's separately. Statistical distributions of other properties, such as normal components and discontinuity plane angles, are presented.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19780068596&hterms=1607&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2526%25231607','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19780068596&hterms=1607&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3D%2526%25231607"><span id="translatedtitle">Sources of <span class="hlt">magnetic</span> fields in recurrent <span class="hlt">interplanetary</span> streams</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burlaga, L. F.; Behannon, K. W.; Hansen, S. F.; Pneuman, G. W.; Feldman, W. C.</p> <p>1978-01-01</p> <p>The paper examines sources of <span class="hlt">magnetic</span> fields in recurrent streams observed by the Imp 8 and Heos spacecraft at 1 AU and by Mariner 10 en route to Mercury between October 31, 1973 and February 9, 1974, during Carrington rotations 1607-1610. Although most fields and plasmas at 1 AU were related to coronal holes and the <span class="hlt">magnetic</span> field lines were open in those holes, some of the <span class="hlt">magnetic</span> fields and plasmas at 1 AU were related to open field line regions on the sun which were not associated with known coronal holes, indicating that open field lines may be more basic than coronal holes as sources of the solar wind. <span class="hlt">Magnetic</span> field intensities in five equatorial coronal holes, certain photospheric <span class="hlt">magnetic</span> fields, and the coronal footprints of the sector boundaries on the source surface are characterized.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19750062208&hterms=polarity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dpolarity','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750062208&hterms=polarity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3Dpolarity"><span id="translatedtitle">Comparison of inferred and observed <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field polarities, 1970-1972</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilcox, J. M.; Svalgaard, L.; Hedgecock, P. C.</p> <p>1975-01-01</p> <p>The inferred polarity (toward or away from the sun) of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field at earth using polar observations of the geomagnetic field has been compared with spacecraft observations. A list published by Svalgaard (1974) of the inferred field polarities in the period from 1970 to 1972 is found to be correct on 82% of the days. A near real-time (same day) method of inferring the polarity of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field using geomagnetic observations at Vostok and Thule is in use at the NOAA Space Environment Laboratory, Boulder, Colorado. During 1972, this method is found to be correct on 87% of the days. A list of 'well-defined' sector boundaries at earth from 1970 to 1972 is given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19740048154&hterms=polarity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dpolarity','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19740048154&hterms=polarity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dpolarity"><span id="translatedtitle">The relation between the polarity of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field and the polar geomagnetic field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Svalgaard, L.</p> <p>1973-01-01</p> <p>The relation between the azimuthal component of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field and the polar cap geomagnetic field is discussed. The geomagnetic effects can be described as produced by an ionospheric current system encircling the <span class="hlt">magnetic</span> pole. The sense of the current is clockwise during toward-sectors and reversed during away-sectors. The importance of this very direct solar-terrestrial relation is stressed. A recent <span class="hlt">magnetic</span> sunspot cycle model is discussed as inferred from this relationship, the basic feature being that the sun reproduces the same sector pattern during every sunspot cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1999GeoRL..26..401O','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1999GeoRL..26..401O"><span id="translatedtitle">Multi-tube model for <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> clouds</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Osherovich, Vladimir A.; Fainberg, J.; Stone, R. G.</p> <p></p> <p>Measurements of the polytropic index γ inside a <span class="hlt">magnetic</span> cloud showed that there are two non-equal tubes inside the cloud [Fainberg et al., 1996; Osherovich et al., 1997]. For both tubes, γ < 1, but each tube has its own polytrope. We test equilibrium solutions which are a superposition of solutions with cylindrical and helical symmetry [Krat and Osherovich, 1978] as a new paradigm for a multi-tube model. Comparison of <span class="hlt">magnetic</span> and gas pressure profiles for these bounded MHD states with observations suggests that complex <span class="hlt">magnetic</span> clouds can be viewed as multiple helices embedded in a cylindrically symmetric flux rope.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19880053447&hterms=ENERGY+SOLAR&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DENERGY%2BSOLAR','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19880053447&hterms=ENERGY+SOLAR&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DENERGY%2BSOLAR"><span id="translatedtitle">Transport equations for low-energy solar particles in evolving <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> fields</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ng, C. K.</p> <p>1988-01-01</p> <p>Two new forms of a simplified Fokker-Planck equation are derived for the transport of low-energy solar energetic particles in an evolving <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field, carried by a variable radial solar wind. An idealized solution suggests that the 'invariant' anisotropy direction reported by Allum et al. (1974) may be explained within the conventional theoretical framework. The equations may be used to relate studies of solar particle propagation to solar wind transients, and vice versa.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860064504&hterms=low+frequency+noise&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dlow%2Bfrequency%2Bnoise','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860064504&hterms=low+frequency+noise&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dlow%2Bfrequency%2Bnoise"><span id="translatedtitle">Low-frequency 1/f noise in the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Matthaeus, W. H.; Goldstein, M. L.</p> <p>1986-01-01</p> <p>Spacecraft observations of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field at 1 AU are shown to have frequency spectra with a 1/f dependence in the range 2.7-80 microHz. It is suggested that the 1/f spectrum results from the superposition of uncorrelated samples of solar surface turbulence that have log-normal distributions of correlation lengths corresponding to a scale-invariant distribution of correlation times over an appropriate range of parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1996JGR...10113303W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1996JGR...10113303W"><span id="translatedtitle">Synthesis models of dayside field-aligned currents for strong <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field By</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Watanabe, Masakazu; Iijima, Takesi; Rich, Frederick J.</p> <p>1996-06-01</p> <p>Using particle and <span class="hlt">magnetic</span> field data acquired with DMSP-F6 and DMSP-F7 satellites, we have investigated <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) By dependence of the global pattern of plasma regime and field-aligned currents (FACs) on dayside high latitudes during strong IMF By (<span class="hlt">averaged</span> |By|>3.7 nT) and geomagnetically disturbed (mainly IMF Bz<0) periods. From particle data we have identified five plasma regimes: inner plasma sheet, outer plasma sheet, cleft, cusp, and mantle. All the plasma domains except the inner plasma sheet show By dependence in spatial distribution. Region 1 and ``traditional cusp'' currents appear in cusp/mantle domains, which we call midday region 1 and region 0 currents, respectively, in this paper. These currents perfectly reverse their flow directions depending on IMF By polarity. Traditional region 1 currents occurring in cleft and outer plasma sheet almost always flow into the ionosphere in the prenoon sector and flow away from the ionosphere in the postnoon sector regardless of By polarity. Thus the midday region 1 and region 0 current system that appears at local noon is not a simple continuation of flankside region 1/region 2 current system. Midday region 1 and region 0 currents are not necessarily balanced in intensity; region 0 current intensity occasionally exceeds midday region 1 current intensity. Furthermore, intensity imbalance also appears in cleft-associated region 1 currents; that is, region 1 current in the farside cleft from the reconnection site (``downstreamside'' cleft) is larger than region 1 current in the nearside cleft (``upstreamside'' cleft). On the basis of these observational facts we discuss the source mechanisms of the dayside FAC system: (1) directly coupled generation of region 0 and midday region 1 current in the cusp/mantle domains around noon and (2) generation of extra region 0 current in the tail magnetopause which is connected to the extra downstreamside cleft-associated region 1 current.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUSMSH41A..04B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUSMSH41A..04B"><span id="translatedtitle">SEPs Dropout Events Associated with Advected <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Structures</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bruno, R.; Trenchi, L.; Telloni, D.; D'Amicis, R.; Marcucci, F.; Zurbuchen, T.; Weberg, M. J.</p> <p>2013-05-01</p> <p>The intensity profile of energetic particles from impulsive solar flares (SEP) often shows abrupt dropouts affecting all energies simultaneously, without time-dispersion. Part of the community thinks that these modulations are directly related to the presence of <span class="hlt">magnetic</span> structures with a different <span class="hlt">magnetic</span> topology advected by the wind, a sort of <span class="hlt">magnetic</span> flux tubes. During the expansion, following the dynamical interaction between plasma regions travelling at different speed, these structures would be partially tangled up in a sort of spaghetti-like bundle. These flux tubes would be alternatively connected or not connected with the flare site and, consequently, they would be filled or devoid of SEPs. When the observer passes through them, he would observe clear particles dropout signatures. We will report about results from a detailed analysis of SEP events which showed several signatures in the local <span class="hlt">magnetic</span> field and/or plasma parameters associated with SEP modulations. These findings corroborate the idea of a possible link between these particles events observed at the Earth's orbit and <span class="hlt">magnetic</span> connection or disconnection of the ambient <span class="hlt">magnetic</span> field with the flare region at the Sun. We will also discuss the advantages represented by future Solar Orbiter in-situ observations. As a matter of fact, Solar Orbiter, from its orbital vantage point during the quasi corotation phase, will be a priviledged observer of this kind of phenomenon since it will observe the advected structure of the solar wind not yet reprocessed by dynamical interaction due to wind expansion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19930005148','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19930005148"><span id="translatedtitle">Venus internal <span class="hlt">magnetic</span> field and its interaction with the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Knudsen, W. C.</p> <p>1992-01-01</p> <p>In a previous study, Knudsen et al. suggested that Venus has a weak internal <span class="hlt">magnetic</span> dipole field of the order of 7 x 10 + 20 G cm(exp -3) that is manifested in the form of <span class="hlt">magnetic</span> flux tubes threading the ionospheric holes in the Venus nightside ionosphere. They pointed out that any internal field of Venus, dipole or multipole, would be weakened in the subsolar region and concentrated in the antisolar region of the planet by the supersonic transterminator convection of the dayside ionosphere into the nightside hemisphere. The inferred magnitude of the dipole field does not violate the upper limit for an internal <span class="hlt">magnetic</span> field established by the Pioneer Venus magnetometer experiment. The most compelling objection to the model suggested by Knudsen et al. has been the fact that it does not explain the observed <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) control of the polarity of the ionospheric hole flux tubes. In this presentation I suggest that a <span class="hlt">magnetic</span> reconnection process analogous to that occurring at earth is occurring at Venus between the IMF and a weak internal dipole field. At Venus in the subsolar region, the reconnection occurs within the ionosphere. At Earth it occurs at the magnetopause. Reconnection will occur only when the IMF has an appropriate orientation relative to that of the weak internal field. Thus, reconnection provides a process for the IMF to control the flux tube polarity. The reconnection in the subsolar region takes place in the ionosphere as the barrier <span class="hlt">magnetic</span> field is transported downward into the lower ionosphere by downward convection of ionospheric plasma and approaches the oppositely directed internal <span class="hlt">magnetic</span> field that is diffusing upward. The reconnected flux tubes are then transported anti-Sunward by the anti-Sunward convecting ionospheric plasma as well as by the anti-Sunward-flowing solar wind. Reconnection will also occur in the Venus <span class="hlt">magnetic</span> tail region, somewhat analogously to the reconnection that occurs in the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19750025912','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19750025912"><span id="translatedtitle">The large-scale <span class="hlt">magnetic</span> field in the solar wind. [<span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> fields/solar activity effects</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burlaga, L. F.; Ness, N. F.</p> <p>1975-01-01</p> <p>A large-scale, three dimensional <span class="hlt">magnetic</span> field in the <span class="hlt">interplanetary</span> medium with an expected classical spiral pattern to zeroth order is discussed. Systematic and random deviations which are expected are treated. The sector structure which should be evident at high latitudes is examined. <span class="hlt">Interplanetary</span> streams are discussed as determining the patterns of <span class="hlt">magnetic</span> field intensity. It was proposed that the large-scale spiral field can induce a meridional flow which might alter the field geometry somewhat. The nonuniformities caused by streams will probably significantly influence the motion of solar and galactic particles. It was concluded that knowledge of the 3-dimensional field and its dynamical effects can be obtained by in situ measurements by a probe which goes over the sun's poles. Diagrams of the <span class="hlt">magnetic</span> fields are given.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFMSH41A2167H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013AGUFMSH41A2167H&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Magnetic</span> Field-line Twist in <span class="hlt">Interplanetary</span> Flux Ropes and its Implications for Their Solar Sources</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Q.; Qiu, J.</p> <p>2013-12-01</p> <p><span class="hlt">Interplanetary</span> flux ropes, embedded within <span class="hlt">interplanetary</span> coronal mass ejections (ICMEs), are often detected in-situ by spacecraft ACE, Wind, and STEREO. Both <span class="hlt">magnetic</span> field and plasma measurements sampled along the spacecraft path across the ICME structure are available for quantitative analysis. We apply the Grad-Shafranov reconstruction technique to examine the configuration of the flux ropes and to derive relevant physical quantities, such as <span class="hlt">magnetic</span> flux content, relative <span class="hlt">magnetic</span> helicity, and the field-line twist. We select recent events during the rising phase of enhanced solar activity, and utilize additional imaging observations from STEREO and SDO spacecraft. Both detailed analyses of solar source region characteristics including flaring and <span class="hlt">magnetic</span> reconnection sequence, and the corresponding flux rope structures will be presented. In particular, we examine the distribution of <span class="hlt">magnetic</span> field-line twist in flux ropes on nested cylindrical iso-surfaces of the <span class="hlt">magnetic</span> flux function. We compare the in-situ characterization of these flux-rope structures with their corresponding solar source region properties. We discuss the implications of such comparison for the origination of flux ropes on the Sun.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920037011&hterms=magnetic+separation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmagnetic%2Bseparation','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920037011&hterms=magnetic+separation&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dmagnetic%2Bseparation"><span id="translatedtitle">Multipoint observations of planar <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field structures</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Farrugia, C. J.; Lepping, R. P.; Dunlop, M. W.; Elliott, S.; Balogh, A.; Cowley, S. W. H.; Freeman, M. P.; Sibeck, D. G.</p> <p>1991-01-01</p> <p>IMF data made on November 1, 1984, by three spatially well-separated spacecraft in the solar wind are presented. The IMF measured by each of the spacecraft is found to consist of a multiplicity of structures within which the <span class="hlt">magnetic</span> field varies in parallel planes. The orientations of these planes at the three spacecraft locations are similar. The planes are inclined at a large angle to the ecliptic, and they lie almost perpendicular to the nominal Parker spiral direction in the ecliptic. Intercomparisons of the measurements at the various spacecraft show that the IMF features at one spacecraft are clearly reproduced at another, with time delays required for signal propagation. From these time delays and the mutual separations of the spacecraft, it is inferred that the structures are convecting with the ambient flow. Simultaneous observations made downstream of the bow shock in the magnetosheath reveal that the magnetosheath <span class="hlt">magnetic</span> field, too, is planar.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015TESS....121204H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2015TESS....121204H&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Magnetic</span> Field-line Twist and Length Distributions inside <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Flux Ropes</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Qiang; Qiu, Jiong; Krucker, Sam</p> <p>2015-04-01</p> <p>​We report on the detailed and systematic study of field-line twist and length distributions within <span class="hlt">magnetic</span> flux ropes embedded in <span class="hlt">Interplanetary</span> Coronal Mass Ejections (ICMEs). The Grad-Shafranov reconstruction method is utilized together with a constant-twist nonlinear force-free (Gold-Hoyle) flux rope model and the commonly known Lundquist (linear force-free) model to reveal the close relation between the field-line twist and length in cylindrical flux ropes, based on in-situ spacecraft <span class="hlt">magnetic</span> field and plasma measurements. In particular, we utilize energetic electron burst observations at 1 AU together with associated type III radio emissions detected by the Wind spacecraft to provide unique measurements of <span class="hlt">magnetic</span> field-line lengths within selected ICME events. These direct measurements are compared with flux-rope model calculations to help assess the fidelity of different models and to provide diagnostics of internal structures. We show that our initial analysis of field-line twist indicates clear deviation from the Lundquist model, but better consistency with the Gold-Hoyle model. By using the different flux-rope models, we conclude that the in-situ direct measurements of field-line lengths are consistent with a flux-rope structure with spiral field lines of constant and low twist, largely different from that of the Lundquist model, especially for relatively large-scale flux ropes. We will also discuss the implications of our analysis of flux-rope structures on the origination and evolution processes in their corresponding solar source regions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_4");'>4</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li class="active"><span>6</span></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_6 --> <div id="page_7" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="121"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950046378&hterms=solar+wind+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsolar%2Bwind%2Bmagnetic%2Bfield','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950046378&hterms=solar+wind+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dsolar%2Bwind%2Bmagnetic%2Bfield"><span id="translatedtitle">The population of the magnetosphere by solar winds ions when the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field is northward</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Richard, Robert L.; Walker, Raymond J.; Ashour-Abdalla, Maha</p> <p>1994-01-01</p> <p>We have examined some possible entry mechanisms of solar wind ions into the magnetosphere by calculating the trajectories of thousands of non-interacting ions in the <span class="hlt">magnetic</span> and electric fields from a three dimensional global magnetohydrodynamic (MHD) simulation of the magnetosphere and the magnetosheath, under northward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) conditions. Particles, launched in the solar wind, entered the magnetosphere and formed the low latitude boundary layer (LLBL), plasma sheet and a region of trapped particles near the Earth. The densities and temperatures we obtained in these regions were realistic, with the exception of trapped particle densities. The dominant entry mechanism was convection into the magnetosphere on reconnecting field lines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1982Ge%26Ae..22.1016B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1982Ge%26Ae..22.1016B"><span id="translatedtitle">Dynamics of the frequency spectrum of fluctuations of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field and cosmic rays</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bezrodnykh, I. P.; Kuzmin, V. A.; Kozlov, V. I.; Morozova, E. I.; Shafer, Iu. G.</p> <p>1982-12-01</p> <p>Prognoz-6 data on the dynamics of the fluctuation spectrum of low-energy cosmic-rays tends to support the hypothesis that the modulation of the cosmic-ray fluctuation spectrum has an <span class="hlt">interplanetary</span> origin. The results indicate that an analogous dynamics is observed in the fluctuation spectrum of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF), the dynamics in the frequency spectra of cosmic rays and the IMF occurring simultaneously. This suggests that the dynamics of the fluctuation spectrum of cosmic rays is conditioned by the dynamics of the IMF irregularity spectrum. The results also indicate the presence of two bursts of fluctuations of galactic cosmic rays and the IMF in the event of June 9-10, 1968, when the passage of a shock front was noted.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AdSpR..58..175P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AdSpR..58..175P"><span id="translatedtitle">Draping of strongly flow-aligned <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field about the magnetopause</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Petrinec, S. M.</p> <p>2016-07-01</p> <p>Many dynamic processes of the magnetosphere are directly driven by the solar wind and the occurrence of <span class="hlt">magnetic</span> merging at the magnetopause. The location of magnetopause <span class="hlt">magnetic</span> merging, or reconnection, is now fairly well understood when the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) contains large By and Bz components in relation to the Bx component (in Geocentric Solar Magnetospheric (GSM) coordinates). However, when the IMF contains a large X-component (i.e., is closely flow-aligned), it is not yet well understood how the shocked IMF drapes about the magnetopause, and how this affects the occurrence and location of <span class="hlt">magnetic</span> merging. In this initial study, we examine from observations how a nearly flow-aligned IMF drapes about the magnetopause. The results of this study are expected to be useful for comparisons with both analytic and global numerical models of the magnetosheath <span class="hlt">magnetic</span> field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..18.5192R&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016EGUGA..18.5192R&link_type=ABSTRACT"><span id="translatedtitle">Dependence of the location of the Martian <span class="hlt">magnetic</span> lobes on the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field direction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Romanelli, Norberto; Mazelle, Christian; Bertucci, Cesar; Gomez, Daniel</p> <p>2016-04-01</p> <p>The <span class="hlt">magnetic</span> field topology surrounding the Martian atmosphere is mainly the result of gradients in the velocity of the solar wind (SW). Such variations in the SW velocity are in turn the result of a massloading process and forces associated with electric currents flowing around the ionosphere of Mars [Nagy et al 2004, Mazelle et al 2004, Brain et al 2015]. In particular, in the regions where the collisionless regime holds, the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) frozen into the SW piles up in front of the stagnation region of the flow. At the same time, the <span class="hlt">magnetic</span> field lines are stretched in the direction of the unperturbed SW as this stream moves away from Mars, giving rise to a magnetotail [Alfvén, 1957]. As a result and in contrast with an obstacle with and intrinsic global <span class="hlt">magnetic</span> field, the structure and organization of the <span class="hlt">magnetic</span> field around Mars depends on the direction of the IMF and its variabilities [Yeroshenko et al., 1990; Crider et al., 2004; Bertucci et al., 2003; Romanelli et al 2015]. In this study we use magnetometer data from the Mars Global Surveyor (MGS) spacecraft during portions of the premapping orbits of the mission to study the variability of the Martian-induced magnetotail as a function of the orientation of the IMF. The time spent by MGS in the magnetotail lobes during periods with positive solar wind flow-aligned IMF component B∥IMF suggests that their location as well as the position of the central polarity reversal layer (PRL) are displaced in the direction antiparallel to the IMF cross-flow component B⊥IMF . Analogously, in the cases where B∥IMF is negative, the lobes are displaced in the direction of B⊥IMF. We find this behavior to be compatible with a previously published B⊥IMF analytical model of the IMF draping, where for the first time, the displacement of a complementary reversal layer (denoted as IPRL for inverse polarity reversal layer) is deduced from first principles [Romanelli et al 2014]. We also</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016Ap%26SS.361..242B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016Ap%26SS.361..242B"><span id="translatedtitle">Role of solar wind speed and <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field during two-step Forbush decreases caused by <span class="hlt">Interplanetary</span> Coronal Mass Ejections</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bhaskar, Ankush; Vichare, Geeta; Arunbabu, K. P.; Raghav, Anil</p> <p>2016-07-01</p> <p>The relationship of Forbush decreases (FDs) observed in Moscow neutron monitor with the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (B) and solar wind speed (Vsw) is investigated in detail for the FDs associated with <span class="hlt">Interplanetary</span> Coronal Mass Ejections (ICMEs) during 2001-2004. The classical two-step FD events are selected, and characteristics of the first step (mainly associated with shock), as well as of complete decrease (main phase) and recovery phase, are studied here. It is observed that the onset of FD occurs generally after zero to a few hours of shock arrival, indicating in the post-shock region that mainly sheath and ICME act as important drivers of FD. A good correlation is observed between the amplitude of B and associated FD magnitude observed in the neutron count rate of the main phase. The duration of the main phase observed in the neutron count rate also shows good correlation with B. This might indicate that stronger <span class="hlt">interplanetary</span> disturbances have a large dimension of <span class="hlt">magnetic</span> field structure which causes longer fall time of FD main phase when they transit across the Earth. It is observed that Vsw and neutron count rate time profiles show considerable similarity with each other during complete FD, especially during the recovery phase of FD. Linear relationship is observed between time duration/e-folding time of FD recovery phase and Vsw. These observations indicate that the FDs are influenced by the inhibited diffusion of cosmic rays due to the enhanced convection associated with the <span class="hlt">interplanetary</span> disturbances. We infer that the inhibited cross-field diffusion of the cosmic rays due to enhanced B is mainly responsible for the main phase of FD whereas the expansion of ICME contributes in the early recovery phase and the gradual variation of Vsw beyond ICME boundaries contributes to the long duration of FD recovery through reduced convection-diffusion.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19790012789','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19790012789"><span id="translatedtitle">Contributions to the Fourth Solar Wind Conference. [<span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> fields and medium</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Acuna, M. H.; Behannon, K. W.; Burlaga, L. F.; Lepping, R.; Ness, N.; Ogilvie, K.; Pizzo, J.</p> <p>1979-01-01</p> <p>Recent results in <span class="hlt">interplanetary</span> physics are examined. These include observations of shock waves and post-shock <span class="hlt">magnetic</span> fields made by Voyager 1, 2; observations of the electron temperature as a function of distance between 1.36 AU and 2.25 AU; and observations of the structure of sector boundaries observed by Helios 1. A theory of electron energy transport in the collisionless solar wind is presented, and compared with observations. Alfven waves and Alvenic fluctuations in the solar wind are also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSH14A..06R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSH14A..06R"><span id="translatedtitle">Predicting the <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field using Approaches Based on Data Mining and Physical Models</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riley, P.; Russell, C. T.; de Koning, C. A.; Biesecker, D. A.; Linker, J.; Owens, M. J.; Lugaz, N.; Martens, P.; Angryk, R.; Reinard, A.; Ulrich, R. K.; Horbury, T. S.; Pizzo, V. J.; Liu, Y.; Hoeksema, T.</p> <p>2015-12-01</p> <p>An accurate prediction of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field, and, in particular, its z-component (Bz) is a crucial capability for any space weather forecasting system, and yet, thus far, it has remained largely elusive (a point exemplified by the fact that no prediction center currently provides a forecast for Bz). In this presentation, we discuss the various physical processes that can produce non-zero values of Bz and summarize a selection of promising approaches that may ultimately lead to reliable forecasts of Bz. We describe the first steps we have taken to develop a framework for assessing these techniques, and show preliminary results of their efficacy.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20030014815','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20030014815"><span id="translatedtitle"><span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field Control of the Entry of Solar Energetic Particles into the Magnetosphere</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Richard, R. L.; El-Alaoui, M.; Ashour-Abdalla, M.; Walker, R. J.</p> <p>2002-01-01</p> <p>We have investigated the entry of energetic ions of solar origin into the magnetosphere as a function of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field orientation. We have modeled this entry by following high energy particles (protons and 3 He ions) ranging from 0.1 to 50 MeV in electric and <span class="hlt">magnetic</span> fields from a global magnetohydrodynamic (MHD) model of the magnetosphere and its interaction with the solar wind. For the most part these particles entered the magnetosphere on or near open field lines except for some above 10 MeV that could enter directly by crossing field lines due to their large gyroradii. The MHD simulation was driven by a series of idealized solar wind and <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) conditions. It was found that the flux of particles in the magnetosphere and transport into the inner magnetosphere varied widely according to the IMF orientation for a constant upstream particle source, with the most efficient entry occurring under southward IMF conditions. The flux inside the magnetosphere could approach that in the solar wind implying that SEPs can contribute significantly to the magnetospheric energetic particle population during typical SEP events depending on the state of the magnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19770034012&hterms=Geomagnetic+pulsations&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DGeomagnetic%2Bpulsations','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19770034012&hterms=Geomagnetic+pulsations&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3DGeomagnetic%2Bpulsations"><span id="translatedtitle"><span class="hlt">Magnetic</span> pulsations as a probe of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field - A test of the Borok B index</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Russell, C. T.; Fleming, B. K.</p> <p>1976-01-01</p> <p>A <span class="hlt">magnetic</span> pulsation index based on the periods of Pc 2-4 pulsations as recorded in earth current measurements at the Borok Geophysical Observatory has been claimed to be a measure of the <span class="hlt">interplanetary</span> field. Tests of this index for the period 1972 to June 1974 show only a 27% success rate. However, a simple recalibration of the index improves the success rate to 51%. The success of the index indicates that the source of many terrestrial <span class="hlt">magnetic</span> pulsations is external to the magnetosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920059735&hterms=electrodynamics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Delectrodynamics','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920059735&hterms=electrodynamics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3Delectrodynamics"><span id="translatedtitle">Small-scale electrodynamics of the cusp with northward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Basinska, Ewa M.; Burke, William J.; Maynard, Nelson C.; Hughes, W. J.; Winningham, J. D.; Hanson, W. B.</p> <p>1992-01-01</p> <p>Possible low-altitude field signatures of merging occurring at high latitudes during a period of strong northward directed <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field are reported. Large electric and <span class="hlt">magnetic</span> field spikes detected at the poleward edge of the magnetosheathlike particle precipitation are interpreted as field signatures of the low-altitude footprint of such merging line locations. A train of phase-shifted, almost linearly polarized electric and <span class="hlt">magnetic</span> field fluctuations was detected just equatorward of the large electromagnetic spike. It is argued that these may be due to either ion cyclotron waves excited by penetrating magnetosheath ions or transient oscillations in the frame of convecting plasma, brought about by the sudden change in the flow at the magnetospheric end of the field line.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRA..120.1478B','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRA..120.1478B"><span id="translatedtitle"><span class="hlt">Interplanetary</span> <span class="hlt">magnetic</span> field and solar cycle dependence of Northern Hemisphere F region joule heating</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Bjoland, L. M.; Chen, X.; Jin, Y.; Reimer, A. S.; Skjæveland, Å.; Wessel, M. R.; Burchill, J. K.; Clausen, L. B. N.; Haaland, S. E.; McWilliams, K. A.</p> <p>2015-02-01</p> <p>Joule heating in the ionosphere takes place through collisions between ions and neutrals. Statistical maps of F region Joule heating in the Northern Hemisphere polar ionosphere are derived from satellite measurements of thermospheric wind and radar measurements of ionospheric ion convection. Persistent mesoscale heating is observed near postnoon and postmidnight <span class="hlt">magnetic</span> local time and centered around 70° <span class="hlt">magnetic</span> latitude in regions of strong relative ion and neutral drift. The magnitude of the Joule heating is found to be largest during solar maximum and for a southeast oriented <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field. These conditions are consistent with stronger ion convection producing a larger relative flow between ions and neutrals. The global-scale Joule heating maps quantify persistent (in location) regions of heating that may be used to provide a broader context compared to small-scale studies of the coupling between the thermosphere and ionosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19790045591&hterms=Longitude&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DLongitude','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19790045591&hterms=Longitude&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DLongitude"><span id="translatedtitle"><span class="hlt">Interplanetary</span> <span class="hlt">magnetic</span> field polarity and the size of low-pressure troughs near 180 deg W longitude</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilcox, J. M.; Duffy, P. B.; Schatten, K. H.; Svalgaard, L.; Scherrer, P. H.; Roberts, W. O.; Olson, R. H.</p> <p>1979-01-01</p> <p>The relationship between <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field polarity and the area of low pressure (300 mbar) troughs near 180 deg W longitude is examined. For most of the winters from 1951 to 1973, the trough size, as indicated by the vorticity area index, is found to be significantly greater when the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field is directed away from the sun than when the field is directed towards the sun. This relationship is shown to hold for various combinations of winters and for most months within a winter, and be most pronounced at the time when polarity was determined. It is suggested that the phenomenon is caused by merging of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field lines, when polarity is directed away from the sun, with geomagnetic field lines in the Northern Hemisphere (where these measurements were made), allowing energetic particle fluxes to have access to the north polar region</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeoRL..43.7319Y&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016GeoRL..43.7319Y&link_type=ABSTRACT"><span id="translatedtitle">The influences of solar wind pressure and <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field on global <span class="hlt">magnetic</span> field and outer radiation belt electrons</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yu, J.; Li, L. Y.; Cao, J. B.; Reeves, G. D.; Baker, D. N.; Spence, H.</p> <p>2016-07-01</p> <p>Using the Van Allen Probe in situ measured <span class="hlt">magnetic</span> field and electron data, we examine the solar wind dynamic pressure and <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) effects on global <span class="hlt">magnetic</span> field and outer radiation belt relativistic electrons (≥1.8 MeV). The dynamic pressure enhancements (>2 nPa) cause the dayside <span class="hlt">magnetic</span> field increase and the nightside <span class="hlt">magnetic</span> field reduction, whereas the large southward IMFs (Bz-IMF < -2nT) mainly lead to the decrease of the nightside <span class="hlt">magnetic</span> field. In the dayside increased <span class="hlt">magnetic</span> field region (<span class="hlt">magnetic</span> local time (MLT) ~ 06:00-18:00, and L > 4), the pitch angles of relativistic electrons are mainly pancake distributions with a flux peak around 90° (corresponding anisotropic index A > 0.1), and the higher-energy electrons have stronger pancake distributions (the larger A), suggesting that the compression-induced betatron accelerations enhance the dayside pancake distributions. However, in the nighttime decreased <span class="hlt">magnetic</span> field region (MLT ~ 18:00-06:00, and L ≥ 5), the pitch angles of relativistic electrons become butterfly distributions with two flux peaks around 45° and 135° (A < 0). The spatial range of the nighttime butterfly distributions is almost independent of the relativistic electron energy, but it depends on the <span class="hlt">magnetic</span> field day-night asymmetry and the <span class="hlt">interplanetary</span> conditions. The dynamic pressure enhancements can make the nighttime butterfly distribution extend inward. The large southward IMFs can also lead to the azimuthal expansion of the nighttime butterfly distributions. These variations are consistent with the drift shell splitting and/or magnetopause shadowing effect.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/pages/biblio/1304818-influences-solar-wind-pressure-interplanetary-magnetic-field-global-magnetic-field-outer-radiation-belt-electrons','SCIGOV-DOEP'); return false;" href="http://www.osti.gov/pages/biblio/1304818-influences-solar-wind-pressure-interplanetary-magnetic-field-global-magnetic-field-outer-radiation-belt-electrons"><span id="translatedtitle">The influences of solar wind pressure and <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field on global <span class="hlt">magnetic</span> field and outer radiation belt electrons</span></a></p> <p><a target="_blank" href="http://www.osti.gov/pages">DOE PAGESBeta</a></p> <p>Yu, J.; Li, L. Y.; Cao, J. B.; Reeves, Geoffrey D.; Baker, D. N.; Spence, H.</p> <p>2016-07-22</p> <p>Using the Van Allen Probe in situ measured <span class="hlt">magnetic</span> field and electron data, we examine the solar wind dynamic pressure and <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) effects on global <span class="hlt">magnetic</span> field and outer radiation belt relativistic electrons (≥1.8 MeV). The dynamic pressure enhancements (>2 nPa) cause the dayside <span class="hlt">magnetic</span> field increase and the nightside <span class="hlt">magnetic</span> field reduction, whereas the large southward IMFs (Bz-IMF < –2nT) mainly lead to the decrease of the nightside <span class="hlt">magnetic</span> field. In the dayside increased <span class="hlt">magnetic</span> field region (<span class="hlt">magnetic</span> local time (MLT) ~ 06:00–18:00, and L > 4), the pitch angles of relativistic electrons are mainly pancakemore » distributions with a flux peak around 90° (corresponding anisotropic index A > 0.1), and the higher-energy electrons have stronger pancake distributions (the larger A), suggesting that the compression-induced betatron accelerations enhance the dayside pancake distributions. However, in the nighttime decreased <span class="hlt">magnetic</span> field region (MLT ~ 18:00–06:00, and L ≥ 5), the pitch angles of relativistic electrons become butterfly distributions with two flux peaks around 45° and 135° (A < 0). The spatial range of the nighttime butterfly distributions is almost independent of the relativistic electron energy, but it depends on the <span class="hlt">magnetic</span> field day-night asymmetry and the <span class="hlt">interplanetary</span> conditions. The dynamic pressure enhancements can make the nighttime butterfly distribution extend inward. The large southward IMFs can also lead to the azimuthal expansion of the nighttime butterfly distributions. As a result, these variations are consistent with the drift shell splitting and/or magnetopause shadowing effect.« less</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003EAEJA.....7961P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003EAEJA.....7961P"><span id="translatedtitle">The dependence of solar wind ion entry on the direction of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Peroomian, V.</p> <p>2003-04-01</p> <p>We have investigated the entry characteristics of solar wind ions into the magnetosphere by tracing particle orbits in time-dependent electric and <span class="hlt">magnetic</span> fields obtained from a three-dimensional global magnetohydrodynamic (MHD) simulation of the magnetosphere. The MHD simulation used in the study began with a 2-hour period of northward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF). The IMF then rotated by 45^o every two hours. The final four hours of the simulation had southward IMF. Millions of ions were launched in the solar wind, upstream of the bowshock, at x = 17 R_E, at time intervals corresponding to the midpoint of each IMF interval and collected after crossing the magnetopause current layer. We found that the region of the upstream solar wind that mapped to the magnetopause entry regions was parallel to the y z orientation of the IMF. Moreover, ions entry into the magnetosphere was in general agreement with the regions identified by Luhmann et al. [1984]. However, there were significant asymmetries in the entry locations due to the direction of the <span class="hlt">interplanetary</span> electric field and the acceleration experienced by ions in crossing the magnetopause current layer. In all cases the ions entering the magnetosphere did so in sufficient numbers to account for the plasma observed within that region and successfully populated the plasma sheet and ring current regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22270882','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22270882"><span id="translatedtitle">AN ANALYSIS OF MAGNETOHYDRODYNAMIC INVARIANTS OF <span class="hlt">MAGNETIC</span> FLUCTUATIONS WITHIN <span class="hlt">INTERPLANETARY</span> FLUX ROPES</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Telloni, D.; Perri, S.; Carbone, V.; Bruno, R.; D Amicis, R.</p> <p>2013-10-10</p> <p>A statistical analysis of <span class="hlt">magnetic</span> flux ropes, identified by large-amplitude, smooth rotations of the <span class="hlt">magnetic</span> field vector and a low level of both proton density and temperature, has been performed by computing the invariants of the ideal magnetohydrodynamic (MHD) equations, namely the <span class="hlt">magnetic</span> helicity, the cross-helicity, and the total energy, via <span class="hlt">magnetic</span> field and plasma fluctuations in the <span class="hlt">interplanetary</span> medium. A technique based on the wavelet spectrograms of the MHD invariants allows the localization and characterization of those structures in both scales and time: it has been observed that flux ropes show, as expected, high <span class="hlt">magnetic</span> helicity states (|σ{sub m}| in [0.6: 1]), but extremely variable cross-helicity states (|σ{sub c}| in [0: 0.8]), which, however, are not independent of the <span class="hlt">magnetic</span> helicity content of the flux rope itself. The two normalized MHD invariants observed within the flux ropes tend indeed to distribute, neither trivially nor automatically, along the √(σ{sub m}{sup 2}+σ{sub c}{sup 2})=1 curve, thus suggesting that some constraint should exist between the <span class="hlt">magnetic</span> and cross-helicity content of the structures. The analysis carried out has further showed that the flux rope properties are totally independent of their time duration and that they are detected either as a sort of interface between different portions of solar wind or as isolated structures embedded in the same stream.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19930042362&hterms=Magnetohydrodynamics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DMagnetohydrodynamics','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19930042362&hterms=Magnetohydrodynamics&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D90%26Ntt%3DMagnetohydrodynamics"><span id="translatedtitle">A global magnetohydrodynamic simulation of the magnetosheath and magnetosphere when the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field is northward</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Ogino, Tatsuki; Walker, Raymond I.; Ashour-Abdalla, Maha</p> <p>1992-01-01</p> <p>We have used a new high-resolution global magnetohydrodynamic simulation model to investigate the configuration of the magnetosphere when the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) is northward. For northward IMF the magnetospheric configuration is dominated by <span class="hlt">magnetic</span> reconnection at the tail lobe magnetopause tailward of the polar cusp. This results in a local thickening of the plasma sheet equatorward of the region of reconnection and the establishment of a convection system with two cells in each lobe. In the magnetosheath the plasma density and pressure decrease near the subsolar magnetopause, forming a depletion region. Along the flanks of the magnetosphere the magnetosheath flow is accelerated to values larger than the solar wind velocity. The magnetopause shape from the simulations is consistent with the empirically determined shape.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19730051463&hterms=Statistical+Energy+Analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DStatistical%2BEnergy%2BAnalysis','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19730051463&hterms=Statistical+Energy+Analysis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DStatistical%2BEnergy%2BAnalysis"><span id="translatedtitle">Observation and analysis of abrupt changes in the <span class="hlt">interplanetary</span> plasma velocity and <span class="hlt">magnetic</span> field.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Martin, R. N.; Belcher, J. W.; Lazarus, A. J.</p> <p>1973-01-01</p> <p>This paper presents a limited study of the physical nature of abrupt changes in the <span class="hlt">interplanetary</span> plasma velocity and <span class="hlt">magnetic</span> field based on 19 day's data from the Pioneer 6 spacecraft. The period was chosen to include a high-velocity solar wind stream and low-velocity wind. Abrupt events were accepted for study if the sum of the energy density in the <span class="hlt">magnetic</span> field and velocity changes was above a specified minimum. A statistical analysis of the events in the high-velocity solar wind stream shows that Alfvenic changes predominate. This conclusion is independent of whether steady state requirements are imposed on conditions before and after the event. Alfvenic changes do not dominate in the lower-speed wind. This study extends the plasma field evidence for outwardly propagating Alfvenic changes to time scales as small as 1 min (scale lengths on the order of 20,000 km).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22304094','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22304094"><span id="translatedtitle">Simulation of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field B{sub y} penetration into the magnetotail</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Guo, Jiuling; Shen, Chao; Liu, Zhenxing</p> <p>2014-07-15</p> <p>Based on our global 3D magnetospheric MHD simulation model, we investigate the phenomena and physical mechanism of the B{sub y} component of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) penetrating into the magnetotail. We find that the dayside reconnected <span class="hlt">magnetic</span> field lines move to the magnetotail, get added to the lobe fields, and are dragged in the IMF direction. However, the B{sub y} component in the plasma sheet mainly originates from the tilt and relative slippage of the south and north lobes caused by plasma convection, which results in the original B{sub z} component in the plasma sheet rotating into a B{sub y} component. Our research also shows that the penetration effect of plasma sheet B{sub y} from the IMF B{sub y} during periods of northward IMF is larger than that during periods of southward IMF.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20020088125','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20020088125"><span id="translatedtitle">Long-term Trends in <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field Strength and Solar Wind Structure during the 20th Century</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Richardson, I. G.; Cliver, E. W.; Cane, H. V.; White, Nicholas E. (Technical Monitor)</p> <p>2002-01-01</p> <p>Lockwood et al have recently reported an approximately 40% increase in the radial component of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) at Earth between 1964 and 1996. We argue that this increase does not constitute a secular trend but is largely the consequence of lower than <span class="hlt">average</span> fields during solar cycle 20 (1964-1976) in comparison with surrounding cycles. For times after 1976 the <span class="hlt">average</span> IMF strength has actually decreased slightly. Examination of the cosmic ray intensity, an indirect measure of the IMF strength, over the last five solar cycles (19-23) also indicates that cycle <span class="hlt">averages</span> of the IMF strength have been relatively constant since approximately 1954. We also consider the origin of the well-documented increase in the geomagnetic alphaalpha index that occurred primarily during the first half of the twentieth century. We surmise that the coronal mass ejection (CME) rate for recent solar cycles was approximately twice as high as that for solar cycles 100 years ago. However, this change in the CME rate and the accompanying increase in 27-day recurrent storm activity reported by others are unable to account completely for the increase in alphaalpha. Rather, the CMEs and recurrent high-speed streams at the beginning of the twentieth century must have been embedded in a background of slow solar wind that was less geoeffective (having, for example, lower IMF strength and/or flow speed) than its modern counterpart.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_5");'>5</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li class="active"><span>7</span></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_7 --> <div id="page_8" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="141"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015P%26SS..119..264V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015P%26SS..119..264V"><span id="translatedtitle">The effect of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field orientation on the solar wind flux impacting Mercury's surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Varela, J.; Pantellini, F.; Moncuquet, M.</p> <p>2015-12-01</p> <p>The aim of this paper is to study the plasma flows on the Mercury surface for different <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field orientations on the day side of the planet. We use a single fluid MHD model in spherical coordinates to simulate the interaction of the solar wind with the Hermean magnetosphere for six solar wind realistic configurations with different <span class="hlt">magnetic</span> field orientations: Mercury-Sun, Sun-Mercury, aligned with the <span class="hlt">magnetic</span> axis of Mercury (Northward and Southward) and with the orbital plane perpendicular to the previous cases. In the Mercury-Sun (Sun-Mercury) simulation the Hermean <span class="hlt">magnetic</span> field is weakened in the South-East (North-East) of the magnetosphere leading to an enhancement of the flows on the South (North) hemisphere. For a Northward (Southward) orientation there is an enhancement (weakening) of the Hermean <span class="hlt">magnetic</span> field in the nose of the bow shock so the fluxes are reduced and drifted to the poles (enhanced and drifted to the equator). If the solar wind <span class="hlt">magnetic</span> field is in the orbital plane the magnetosphere is tilted to the West (East) and weakened at the nose of the shock, so the flows are enhanced and drifted to the East (West) in the Northern hemisphere and to the West (East) in the Southern hemisphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860056292&hterms=dbs&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddbs','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860056292&hterms=dbs&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Ddbs"><span id="translatedtitle">On the association of <span class="hlt">magnetic</span> clouds with disappearing filaments. [<span class="hlt">interplanetary</span> phenomena associated with coronal mass ejection</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Wilson, R. M.; Hildner, E.</p> <p>1986-01-01</p> <p>Evidence is presented that an <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> cloud preceding an interaction region, observed at earth on January 24, 1974, is associated with the eruptive filament of disparition brusque (DB) near central meridian on January 18. The DB was also associated with a long-decay soft X ray transient and a long-duration gradual-rise-and-fall radio burst. To assess whether <span class="hlt">magnetic</span> clouds are generally associated with DBs, results from statistical testing of the relation of 33 <span class="hlt">magnetic</span> clouds (and 33 control samples without <span class="hlt">magnetic</span> clouds) to disappearing filaments near central meridian (approximately less than 45 deg central meridian distance) are presented. The hypothesis that <span class="hlt">magnetic</span> cloud are the 1-AU counterparts of either eruptive filaments or the coronal mass ejections which probably accompany them is supported. The major result is that disappearing filaments occur more frequently on the days when <span class="hlt">magnetic</span> clouds are launched than on control days, a result obtained with greater than 99 pct confidence. There is a suggestion that clouds following shocks, probably launched at times of solar flares, are not as strongly associated with disappearing filaments as are clouds launched less violently.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19790061224&hterms=media+relations&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmedia%2Brelations','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19790061224&hterms=media+relations&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3Dmedia%2Brelations"><span id="translatedtitle">Spatial distribution of large-scale solar <span class="hlt">magnetic</span> fields and their relation to the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Levine, R. H.</p> <p>1979-01-01</p> <p>The spatial organization of the observed photospheric <span class="hlt">magnetic</span> field as well as its relation to the polarity of the IMF have been studied using high resolution magnetograms from the Kitt Peak National Observatory. Systematic patterns in the large scale field are due to contributions from both concentrated flux and more diffuse flux. The polarity of the photospheric field, determined on various spatial scales, correlates with the polarity of the IMF. Analyses based on several spatial scales in the photosphere suggest that new flux in the <span class="hlt">interplanetary</span> medium is often due to relatively small photospheric features which appear in the photosphere up to one month before they are manifest at the earth.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM51C2194D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM51C2194D"><span id="translatedtitle"><span class="hlt">Magnetic</span> and plasma response of the Earth's magnetosphere to <span class="hlt">interplanetary</span> shock</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Du, A.; Cao, X.; Wang, R.; Zhang, Y.</p> <p>2013-12-01</p> <p>In this paper, we investigate the global response of magnetosphere to <span class="hlt">interplanetary</span> shock, and focus on the <span class="hlt">magnetic</span> and plasma variations related to aurora. The analysis utilizes data from simultaneous observations of <span class="hlt">interplanetary</span> shocks from available spacecraft in the solar wind and the Earth's magnetosphere such as ACE, Wind and SOHO in solar wind, LANL and GOES in outer magnetosphere, TC1 in the midinight neutral plasma sheet, Geotail and Polar in dusk side of plasma sheet, and Cluster in downside LLBL. The shock front speed is ~1051 km/s in the solar wind, and ~981km/s in the Earth's magnetosphere. The shock is propagating anti-sunward (toward the Earth) in the plasma frame with a speed of ~320 km/s. After the shock bumps at the magnetopause, the dayside aurora brightens, then nightside aurora brightens and expanses to poleward. During the aurora activity period, the fast earthward and tailward flows in plasma sheet are observed by TC1 (X~7.1 Re, Y~1.2 Re). The variation of <span class="hlt">magnetic</span> field and plasma in duskside of magnetosphere is weaker than that in dawnside. At low latitude boundary layer (LLBL), the Cluster spacecraft detected rolled-up large scale vortices generated by the Kelvin-Helmholtz instability (KHI). Toroidal oscillations of the <span class="hlt">magnetic</span> field in the LLBL might be driven by the Kelvin-Helmholtz instability. The strong IP shock highly compresses the magnetopause and the outer magnetosphere. This process may also lead to particle precipitation and auroral brightening (Zhou and Tsurutani, 1999; Tsurutani et al., 2001 and 2003).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/22039339','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/22039339"><span id="translatedtitle"><span class="hlt">MAGNETIC</span> VARIANCES AND PITCH-ANGLE SCATTERING TIMES UPSTREAM OF <span class="hlt">INTERPLANETARY</span> SHOCKS</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Perri, Silvia; Zimbardo, Gaetano E-mail: gaetano.zimbardo@fis.unical.it</p> <p>2012-07-20</p> <p>Recent observations of power-law time profiles of energetic particles accelerated at <span class="hlt">interplanetary</span> shocks have shown the possibility of anomalous, superdiffusive transport for energetic particles throughout the heliosphere. Those findings call for an accurate investigation of the <span class="hlt">magnetic</span> field fluctuation properties at the resonance frequencies upstream of the shock's fronts. Normalized <span class="hlt">magnetic</span> field variances, indeed, play a crucial role in the determination of the pitch-angle scattering times and then of the transport regime. The present analysis investigates the time behavior of the normalized variances of the <span class="hlt">magnetic</span> field fluctuations, measured by the Ulysses spacecraft upstream of corotating interaction region (CIR) shocks, for those events which exhibit superdiffusion for energetic electrons. We find a quasi-constant value for the normalized <span class="hlt">magnetic</span> field variances from about 10 hr to 100 hr from the shock front. This rules out the presence of a varying diffusion coefficient and confirms the possibility of superdiffusion for energetic electrons. A statistical analysis of the scattering times obtained from the <span class="hlt">magnetic</span> fluctuations upstream of the CIR events has also been performed; the resulting power-law distributions of scattering times imply long range correlations and weak pitch-angle scattering, and the power-law slopes are in qualitative agreement with superdiffusive processes described by a Levy random walk.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007JGRA..112.2202D&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2007JGRA..112.2202D&link_type=ABSTRACT"><span id="translatedtitle">Separator reconnection at Earth's dayside magnetopause under generic northward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dorelli, John C.; Bhattacharjee, Amitava; Raeder, Joachim</p> <p>2007-02-01</p> <p>We investigate the global properties of <span class="hlt">magnetic</span> reconnection at the dayside terrestrial magnetopause under generic northward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) conditions. In particular, we consider a zero dipole tilt case where the y and z components of the IMF (in GSM coordinates) are equal in magnitude, using three-dimensional resistive magnetohydrodynamics (MHD) simulations to address the following questions: (1) What is the geometry of the dayside X line? (2) How is current density distributed over the magnetopause surface? Using a technique described by Geene (1992) to track the <span class="hlt">magnetic</span> nulls in the system, we identify the dayside X line as a <span class="hlt">magnetic</span> separator line, a segment of a <span class="hlt">magnetic</span> field line which extends across the dayside magnetopause, terminating in the cusps. We demonstrate that the separator line is the intersection of two separatrix surfaces which define volumes containing topologically distinct field lines. Parallel current density, proportional to the parallel electric field in our resistive MHD simulations, is distributed in a broad, thin sheet which extends across the separator line and terminates in the cusps. Thus separator reconnection at the dayside magnetopause displays features of both antiparallel (near the cusp nulls) and component (near the subsolar separator line) reconnection. We discuss some implications of our results for spacecraft observations of reconnection signatures.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20110023374','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20110023374"><span id="translatedtitle"><span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field Power Spectrum Variations in the Inner Heliosphere: A Wind and MESSENGER Study</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Szabo, Adam; Koval, A.</p> <p>2011-01-01</p> <p>The newly reprocessed high time resolution (11/22 vectors/sec) Wind mission <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field data and the similar observations made by the MESSENGER spacecraft in the inner heliosphere affords an opportunity to compare <span class="hlt">magnetic</span> field power spectral density variations as a function of radial distance from the Sun under different solar wind conditions. In the reprocessed Wind <span class="hlt">Magnetic</span> Field Investigation (MFI) data, the spin tone and its harmonics are greatly reduced that allows the meaningful fitting of power spectra to the approx.2 Hz limit above which digitization noise becomes apparent. The powe'r spectral density is computed and the spectral index is fitted for the MHD and ion inertial regime separately along with the break point between the two for various solar wind conditions. Wind and MESSENGER <span class="hlt">magnetic</span> fluctuations are compared for times when the two spacecraft are close to radial and Parker field alignment. The functional dependence of the ion inertial spectral index and break point on solar wind plasma and <span class="hlt">magnetic</span> field conditions will be discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140016484','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140016484"><span id="translatedtitle">The B-dot Earth <span class="hlt">Average</span> <span class="hlt">Magnetic</span> Field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Capo-Lugo, Pedro A.; Rakoczy, John; Sanders, Devon</p> <p>2013-01-01</p> <p>The <span class="hlt">average</span> Earth's <span class="hlt">magnetic</span> field is solved with complex mathematical models based on mean square integral. Depending on the selection of the Earth <span class="hlt">magnetic</span> model, the <span class="hlt">average</span> Earth's <span class="hlt">magnetic</span> field can have different solutions. This paper presents a simple technique that takes advantage of the damping effects of the b-dot controller and is not dependent of the Earth <span class="hlt">magnetic</span> model; but it is dependent on the <span class="hlt">magnetic</span> torquers of the satellite which is not taken into consideration in the known mathematical models. Also the solution of this new technique can be implemented so easily that the flight software can be updated during flight, and the control system can have current gains for the <span class="hlt">magnetic</span> torquers. Finally, this technique is verified and validated using flight data from a satellite that it has been in orbit for three years.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AdSpR..55..401K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AdSpR..55..401K"><span id="translatedtitle">Variations of solar, <span class="hlt">interplanetary</span>, and geomagnetic parameters with solar <span class="hlt">magnetic</span> multipole fields during Solar Cycles 21-24</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kim, Bogyeong; Lee, Jeongwoo; Yi, Yu; Oh, Suyeon</p> <p>2015-01-01</p> <p>In this study we compare the temporal variations of the solar, <span class="hlt">interplanetary</span>, and geomagnetic (SIG) parameters with that of open solar <span class="hlt">magnetic</span> flux from 1976 to 2012 (from Solar Cycle 21 to the early phase of Cycle 24) for a purpose of identifying their possible relationships. By the open flux, we mean the <span class="hlt">average</span> <span class="hlt">magnetic</span> field over the source surface (2.5 solar radii) times the source area as defined by the potential field source surface (PFSS) model of the Wilcox Solar Observatory (WSO). In our result, most SIG parameters except the solar wind dynamic pressure show rather poor correlations with the open solar <span class="hlt">magnetic</span> field. Good correlations are recovered when the contributions from individual multipole components are counted separately. As expected, solar activity indices such as sunspot number, total solar irradiance, 10.7 cm radio flux, and solar flare occurrence are highly correlated with the flux of <span class="hlt">magnetic</span> quadrupole component. The dynamic pressure of solar wind is strongly correlated with the dipole flux, which is in anti-phase with Solar Cycle (SC). The geomagnetic activity represented by the Ap index is correlated with higher order multipole components, which show relatively a slow time variation with SC. We also found that the unusually low geomagnetic activity during SC 23 is accompanied by the weak open solar fields compared with those in other SCs. It is argued that such dependences of the SIG parameters on the individual multipole components of the open solar <span class="hlt">magnetic</span> flux may clarify why some SIG parameters vary in phase with SC and others show seemingly delayed responses to SC variation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012cosp...39...49A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012cosp...39...49A"><span id="translatedtitle">Substorm aurora and <span class="hlt">magnetic</span> tail dynamics during <span class="hlt">interplanetary</span> shock compression: THEMIS observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Angelopoulos, Vassilis; Zhou, Xiaoyan</p> <p>2012-07-01</p> <p>Fast and forward <span class="hlt">interplanetary</span> shocks compress and squeeze the Earth magnetosphere and cause a series of magnetospheric and ionospheric reactions. In addition to the enhancement of chorus, electromagnetic ion cyclotron (EMIC) waves and magnetospheric hiss, the ionospheric convection is enhanced as well. Shock aurora is generated, which is a phenomenon first an auroral brightness onset near local noon right after the shock impingement then followed by a fast anti-sunward auroral propagation along the oval. It has been found that substorm auroral activity can be significantly intensified by the shock compression when the shock upstream <span class="hlt">magnetic</span> field was in southward in a certain period of time. This paper will present recent results based on the THEMIS spacecraft and ground-based observations. With multiple spacecraft in the magnetotail, the complex dynamics of the compressed tail is identified and analyzed. Correlations between the tail dynamics and substorm auroral variations will be discussed. *On-leave from Jet Propulsion Laboratory</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19850026690','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19850026690"><span id="translatedtitle">The effect of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field on sidereal variations observed at medium depth underground detectors</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Humble, J. E.; Fenton, A. G.</p> <p>1985-01-01</p> <p>It has been known for some years that the intensity variations in sidereal time observed by muon detectors at moderate underground depths are sensitive to the polarity of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (ipmf) near the Earth. There are differences in the response to these anisotropies as observed in the Norhtern and southern hemispheres. When fully understood, the nature of the anisotropy seems likely to provide information on the 3-dimensional structure of the heliomagnetosphere, its time variations, and its linking with the local interstellar field. The summation harmonic dials for the sidereal diurnal variation during 1958 to 1982 show that there is a strong dependence on whether the ipmf near the Earth is directed outwards from the Sun or inwards it.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19770005004','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19770005004"><span id="translatedtitle">Radio observations of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field structures out of the ecliptic</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Fitzenreiter, R. J.; Fainberg, J.; Weber, R. R.; Alvarez, H.; Haddock, F. T.; Potter, W. H.</p> <p>1976-01-01</p> <p>New observations of the out-of-the ecliptic trajectories of type 3 solar radio bursts have been obtained from simultaneous direction finding measurements on two independent satellite experiments, IMP-6 with spin plane in the ecliptic, and RAE-2 with spin plane normal to the ecliptic. Burst exciter trajectories were observed which originated at the active region and then crossed the ecliptic plane at about 0.8 AU. A considerable large scale north-south component of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field is followed by the exciters. The apparent north-south and east-west angular source sizes observed by the two spacecraft are approximately equal, and range from 25 deg at 600 KHz to 110 deg at 80 KHz.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19750043957&hterms=polarity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dpolarity','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19750043957&hterms=polarity&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dpolarity"><span id="translatedtitle">The latitude dependencies of the solar wind. [of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field polarity and configurations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Rosenberg, R. L.; Winge, C. R., Jr.</p> <p>1974-01-01</p> <p>The motion of spacecraft following the earth's orbit occurs within the solar latitude range of 7 deg 15 min N on approximately September 7 to 7 deg 15 min S on approximately March 6. The latitude dependencies so far detected within this range have shown that the photospheric dipole-like field of the sun makes very important contributions to the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) observed near the ecliptic. Changes in geomagnetic activity from even to odd numbered 11-year solar cycles are related to changes in the sun's dipolar field. The north-south IMF component and meridional, nonradial flow are important to a complete understanding of steady-state solar wind dynamics. Coronal conditions must be latitude-dependent in a way that accounts for the observed latitude dependence of the velocity and density of the solar wind.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20040171460&hterms=solar+wind+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsolar%2Bwind%2Bmagnetic%2Bfield','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20040171460&hterms=solar+wind+magnetic+field&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsolar%2Bwind%2Bmagnetic%2Bfield"><span id="translatedtitle">In-Situ Solar Wind and <span class="hlt">Magnetic</span> Field Signatures of <span class="hlt">Interplanetary</span> Coronal Mass Ejections</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zurbuchen, Thomas H.; Richardson, Ian G.</p> <p>2004-01-01</p> <p>The heliospheric counterparts of coronal mass ejections (CMEs) at the Sun, <span class="hlt">interplanetary</span> coronal mass ejections (ICMEs), can be identified in-situ based on a number of <span class="hlt">magnetic</span> field, plasma, compositional and energetic particle signatures, as well as combinations thereof. Although many of these signatures have been recognized since the early space era, recent observations from improved instrumentation on spacecraft such as Ulysses, Wind, and ACE, in conjunction with solar observations from SOHO, have advanced our understanding of the characteristics of ICMEs and their solar counterparts. We summarize these signatures and their implications for understanding the nature of these structures and the physical properties of coronal mass ejections. We conclude that our understanding of ICMEs is far from complete, and formulate several challenges that, if addressed, would substantially improve our knowledge of the relationship between CMEs at the Sun and in the heliosphere.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/227160','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/227160"><span id="translatedtitle">ULF cusp pulsations: Diurnal variations and <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field correlations with ground-based observations</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>McHarg, M.G.; Olson, J.V.; Newell, P.T.</p> <p>1995-10-01</p> <p>In this paper the authors establish the Pc 5 <span class="hlt">magnetic</span> pulsation signatures of the cusp and boundary regions for the high-latitude dayside cusp region. These signatures were determined by comparing spectrograms of the <span class="hlt">magnetic</span> pulsations with optical observations of particle precipitation regions observed at the cusp. The ULF pulsations have a diurnal variation, and a cusp discriminant is proposed using a particular narrow-band feature in the pulsation spectrograms. The statistical distribution of this pattern over a 253-day period resembles the statistical cusp description using particle precipitation data from the Defense Meterological Satellite Program (DMSP). The distribution of the ground-based cusp discriminant is found to peak 1 hour earlier than the DMSP cusp distribution. This offset is due to the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) being predominantly negative B{sub y} for the period when the data were collected. The authors find the diurnal variations so repeatable that only three main categories have statistically different IMF distributions. The identification of the signatures in the <span class="hlt">magnetic</span> spectrograms of the boundary regions and central cusp allows the spectrogram to be used as a {open_quotes}time line{close_quotes} that shows when the station passed under different regions of the dayside oval. 36 refs., 11 figs., 1 tab.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015ApJ...812..152Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015ApJ...812..152Z"><span id="translatedtitle">Strong Solar Wind Dynamic Pressure Pulses: <span class="hlt">Interplanetary</span> Sources and Their Impacts on Geosynchronous <span class="hlt">Magnetic</span> Fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zuo, Pingbing; Feng, Xueshang; Xie, Yanqiong; Wang, Yi; Xu, Xiaojun</p> <p>2015-10-01</p> <p>In this investigation, we first present a statistical result of the <span class="hlt">interplanetary</span> sources of very strong solar wind dynamic pressure pulses (DPPs) detected by WIND during solar cycle 23. It is found that the vast majority of strong DPPs reside within solar wind disturbances. Although the variabilities of geosynchronous <span class="hlt">magnetic</span> fields (GMFs) due to the impact of positive DPPs have been well established, there appears to be no systematic investigations on the response of GMFs to negative DPPs. Here, we study both the decompression effects of very strong negative DPPs and the compression from strong positive DPPs on GMFs at different <span class="hlt">magnetic</span> local time sectors. In response to the decompression of strong negative DPPs, GMFs on the dayside near dawn and near dusk on the nightside, are generally depressed. But near the midnight region, the responses of GMF are very diverse, being either positive or negative. For part of the events when GOES is located at the midnight sector, the GMF is found to abnormally increase as the result of magnetospheric decompression caused by negative DPPs. It is known that under certain conditions <span class="hlt">magnetic</span> depression of nightside GMFs can be caused by the impact of positive DPPs. Here, we find that a stronger pressure enhancement may have a higher probability of producing the exceptional depression of GMF at the midnight region. Statistically, both the decompression effect of strong negative DPPs and the compression effect of strong positive DPPs depend on the <span class="hlt">magnetic</span> local time, which are stronger at the noon sector.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013SoPh..284..129A&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2013SoPh..284..129A&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Magnetic</span> Field Configuration Models and Reconstruction Methods for <span class="hlt">Interplanetary</span> Coronal Mass Ejections</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Al-Haddad, N.; Nieves-Chinchilla, T.; Savani, N. P.; Möstl, C.; Marubashi, K.; Hidalgo, M. A.; Roussev, I. I.; Poedts, S.; Farrugia, C. J.</p> <p>2013-05-01</p> <p>This study aims to provide a reference for different <span class="hlt">magnetic</span> field models and reconstruction methods for <span class="hlt">interplanetary</span> coronal mass ejections (ICMEs). To understand the differences in the outputs of these models and codes, we analyzed 59 events from the Coordinated Data Analysis Workshop (CDAW) list, using four different <span class="hlt">magnetic</span> field models and reconstruction techniques; force-free fitting, magnetostatic reconstruction using a numerical solution to the Grad-Shafranov equation, fitting to a self-similarly expanding cylindrical configuration and elliptical, non-force-free fitting. The resulting parameters of the reconstructions for the 59 events are compared statistically and in selected case studies. The ability of a method to fit or reconstruct an event is found to vary greatly; this depends on whether the event is a <span class="hlt">magnetic</span> cloud or not. We find that the magnitude of the axial field is relatively consistent across models, but that the axis orientation of the ejecta is not. We also find that there are a few cases with different signs of the <span class="hlt">magnetic</span> helicity for the same event when we leave the boundaries free to vary, which illustrates that this simplest of parameters is not necessarily always clearly constrained by fitting and reconstruction models. Finally, we examine three unique cases in depth to provide a comprehensive idea of the different aspects of how the fitting and reconstruction codes work.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012JGRA..117.4218N','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012JGRA..117.4218N"><span id="translatedtitle">Substorm-like magnetospheric response to a discontinuity in the Bx component of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Nowada, M.; Lin, C.-H.; Pu, Z.-Y.; Fu, S.-Y.; Angelopoulos, V.; Carlson, C. W.; Auster, H.-U.</p> <p>2012-04-01</p> <p>We examined the magnetospheric <span class="hlt">magnetic</span> field and plasma responses to an encounter of a discontinuity in the Bx component of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF). The striking variations of simultaneous solar wind dynamic pressure and IMF-Bz were not observed. Furthermore, we found that this IMF-Bx discontinuity was a heliospheric current sheet, separating two high-speed solar wind streams with different velocity and <span class="hlt">magnetic</span> polarity. In this study, the <span class="hlt">magnetic</span> field and plasma data were obtained from Time History of Events and Macroscale Interactions during Substorms (THEMIS), Cluster, and GOES to investigate the magnetospheric responses, and those were taken from ACE and Geotail to monitor the solar wind conditions. Simultaneous geomagnetic field variations from the ground observatories and aurora activity from Polar were also examined. When the discontinuity encountered the magnetosphere, THEMIS-D, -E, and THEMIS-A observed abrupt and transient <span class="hlt">magnetic</span> field and plasma variations in the dawnside near-Earth magnetotail and tail-flank magnetopause. Significant <span class="hlt">magnetic</span> field perturbations were not observed by Cluster as located in the duskside magnetotail at this time interval. Although simultaneous dipolarization and negative bay variations with Pi2 waves were observed by GOES and the ground observatories, global auroral activities were not found. Around the dawnside tail-flank magnetopause, THEMIS-C and -A experienced the magnetopause crossings due to the magnetopause surface waves induced by Kelvin-Helmholtz instability. These results suggest that the <span class="hlt">magnetic</span> field and plasma variations in the near-Earth magnetotail and tail-flank magnetopause were caused by moderate substorm-like phenomena and magnetopause surface waves. They also indicate that clear magnetospheric disturbances can be brought even without significant variations in the solar wind.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016P%26SS..129...74V&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016P%26SS..129...74V&link_type=ABSTRACT"><span id="translatedtitle">Effect of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field orientation and intensity in the mass and energy deposition on the Hermean surface</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Varela, J.; Pantellini, F.; Moncuquet, M.</p> <p>2016-09-01</p> <p>The aim of the present study is to simulate the interaction between the solar wind and the Hermean magnetosphere. We use the MHD code PLUTO in spherical coordinates with an axisymmetric multipolar expansion of the Hermean <span class="hlt">magnetic</span> field, to perform a set of simulations with different <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field orientations and intensities. We fix the hydrodynamic parameters of the solar wind to study the distortions driven by the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field in the topology of the Hermean magnetosphere, leading to variations of the mass and energy deposition distributions, the integrated mass deposition, the oval aperture, the area covered by open <span class="hlt">magnetic</span> field lines and the regions of efficient particle sputtering on the planet surface. The simulations show a correlation between the reconnection regions and the local maxima of plasma inflow and energy deposition on the planet surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004cosp...35.3567F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004cosp...35.3567F"><span id="translatedtitle">A real-time solar wind and <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field model for space radiation analysis and prediction</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fry, C. D.; Detman, T. R.; Dryer, M.; Smith, Z.; Sun, W.; Deehr, C. S.; Akasofu, S.-I.; Wu, C.-C.</p> <p></p> <p>We describe an observation-driven model for assessing and predicting the solar wind and <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) environment. High energy particles generated during solar/<span class="hlt">interplanetary</span> disturbances will pose a serious hazard to crew members traveling beyond low-Earth orbit. In order to provide warnings of dangerous radiation conditions, mission operators will need accurate forecasts of solar energetic particle (SEP) fluxes and fluences in <span class="hlt">interplanetary</span> space. However, physics-based models for accelerating and propagating SEPs require specifications and predictions of the solar wind conditions and IMF configuration near the evolving <span class="hlt">interplanetary</span> shock region, and along the IMF lines connecting the shock to the observation point. We are presently using the Hakamada-Akasofu-Fry kinematic solar wind model to predict, in real time, solar wind conditions in the heliosphere, including at the location of Mars, and beyond. This model is being extended via a hybrid approach to include a 3D MHD model, the <span class="hlt">Interplanetary</span> Global Model, Vectorized (IGMV). We present our modeling results and conclude that uncertainties in determining, from real-time solar observations, the physical parameters used for model inputs are the biggest factors limiting the accuracy of solar wind models used for space radiation analysis and prediction.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_6");'>6</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li class="active"><span>8</span></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_8 --> <div id="page_9" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="161"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFMSH31A4104H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2014AGUFMSH31A4104H&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Magnetic</span> Field-line Length and Twist Distributions within <span class="hlt">Interplanetary</span> Flux Fopes from Wind Spacecraft Measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hu, Q.; Qiu, J.; Krucker, S.; Wang, L.; Wang, B.; Chen, Y.; Moestl, C.</p> <p>2014-12-01</p> <p>We report on the detailed and systematic study of field-line twist and length distributions within <span class="hlt">magnetic</span> flux ropes embedded in <span class="hlt">Interplanetary</span> Coronal Mass Ejections (ICMEs). In particular we will utilize energetic electron burst observations at 1 AU together with associated type III radio emissions detected by the Wind spacecraft to provide unique measurements of <span class="hlt">magnetic</span> field-line lengths within selected ICME events. These direct measurements will be compared with flux-rope model calculations to help assess the fidelity of different models and to provide diagnostics of internal structures. The Grad-Shafranov reconstruction method will be utilized together with a constant-twist nonlinear force-free (Gold-Hoyle) flux rope model and the commonly known Lundquist (linear force-free) model to reveal the close relation between the field-line twist and length in cylindrical flux ropes, based on in-situ Wind spacecraft <span class="hlt">magnetic</span> field and plasma measurements. We show that our initial analysis of field-line twist indicates clear deviation from the Lundquist model, but better consistency with the Gold-Hoyle model. We will also discuss the implications of our analysis of flux-rope structures on the origination and evolution processes in their corresponding solar source regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015SoPh..290..553L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015SoPh..290..553L"><span id="translatedtitle">Yearly Comparison of <span class="hlt">Magnetic</span> Cloud Parameters, Sunspot Number, and <span class="hlt">Interplanetary</span> Quantities for the First 18 Years of the Wind Mission</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lepping, R. P.; Wu, C.-C.; Berdichevsky, D. B.</p> <p>2015-02-01</p> <p>In the scalar part of this study, we determine various statistical relationships between estimated <span class="hlt">magnetic</span> cloud (MC) model fit-parameters and sunspot number (SSN) for the interval defined by the Wind mission, i.e., early 1995 until the end of 2012, all in terms of yearly <span class="hlt">averages</span>. The MC-fitting model used is that of Lepping, Jones, and Burlaga ( J. Geophys. Res. 95, 11957 - 11965, <CitationRef CitationID="CR19">1990). We also statistically compare the MC fit-parameters and other derived MC quantities [ e.g., axial <span class="hlt">magnetic</span> flux (ΦO) and total axial current density ( J O)] with some associated ambient <span class="hlt">interplanetary</span> quantities (including the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field ( B IMF), proton number density ( N P), and others). Some of the main findings are that the minimum SSN is nearly simultaneous with the minimum in the number of MCs per year ( N MC), which occurs in 2008. There are various fluctuations in N MC and the MC model-fit quality ( Q') throughout the mission, but the last four years (2009 - 2012) are markedly different from the others; Q' is low and N MC is large over these four years. N MC is especially large for 2012. The linear correlation coefficient (c.c.≈0.75) between the SSN and each of the three quantities J O, MC diameter (2 R O), and B IMF, is moderately high, but none of the MC parameters track the SSN well in the sense defined in this article. However, there is good statistical tracking among the following: MC axial field, B IMF, 2 R O, <span class="hlt">average</span> MC speed ( V MC), and yearly <span class="hlt">average</span> solar wind speed ( V SW) with relatively high c.c.s among most of these. From the start of the mission until late 2005, J O gradually increases, with a slight violation in 2003, but then a dramatic decrease (by more than a factor of five) occurs to an almost steady and low value of ≈ 3 μA km-2 until the end of the interval of interest, i.e., lasting for at least seven years. This tends to split the overall 18-year interval into two phases with a separator at</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19990056482&hterms=Ulysses&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DUlysses','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19990056482&hterms=Ulysses&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DUlysses"><span id="translatedtitle">Self-similar evolution of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> clouds and Ulysses measurements of the polytropic index inside the cloud</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Osherovich, Vladimir A.; Fainberg, J.; Stone, R. G.; MacDowall, R. J.; Berdichevsky, D.</p> <p>1997-01-01</p> <p>A self similar model for the expanding flux rope is developed for a magnetohydrodynamic model of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> clouds. It is suggested that the dependence of the maximum <span class="hlt">magnetic</span> field on the distance from the sun and the polytropic index gamma has the form B = r exp (-1/gamma), and that the ratio of the electron temperature to the proton temperature increases with distance from the sun. It is deduced that ion acoustic waves should be observed in the cloud. Both predictions were confirmed by Ulysses observations of a 1993 <span class="hlt">magnetic</span> cloud. Measurements of gamma inside the cloud demonstrate sensitivity to the internal topology of the <span class="hlt">magnetic</span> field in the cloud.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19820005721','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19820005721"><span id="translatedtitle">Large-scale variations of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field: Voyager 1 and 2 observations between 1-5 AU</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burlaga, L. F.; Lepping, R. P.; Behannon, K. W.; Klein, L. W.; Neubauer, F. M.</p> <p>1981-01-01</p> <p>Observations by the Voyager 1 and 2 spacecraft of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field between 1 and 5 AU were used to investigate the large scale structure of the IMF in a period of increasing solar activity. The Voyager spacecraft found notable deviations from the Parker axial model. These deviations are attributed both to temporal variations associated with increasing solar activity, and to the effects of fluctuations of the field in the radial direction. The amplitude of the latter fluctuations were found to be large relative to the magnitude of the radial field component itself beyond approximately 3 AU. Both Voyager 1 and Voyager 2 observed decreases with increasing heliocentric distance in the amplitude of transverse fluctuations in the <span class="hlt">averaged</span> field strength (B) which are consistent with the presence of predominantly undamped Alfven waves in the solar wind, although and necessarily implying the presence of them. Fluctuations in the strength of B (relative to mean field strength) were found to be small in amplitude, with a RMS which is approximately one third of that for the transverse fluctuations and they are essentially independent of distance from the Sun.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19970026617','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19970026617"><span id="translatedtitle">Penetration of the <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field B(sub y) into Earth's Plasma Sheet</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Hau, L.-N.; Erickson, G. M.</p> <p>1995-01-01</p> <p>There has been considerable recent interest in the relationship between the cross-tail <span class="hlt">magnetic</span> field component B(sub y) and tail dynamics. The purpose of this paper is to give an overall description of the penetration of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) B(sub y) into the near-Earth plasma sheet. We show that plasma sheet B(sub y) may be generated by the differential shear motion of field lines and enhanced by flux tube compression. The latter mechanism leads to a B(sub y) analogue of the pressure-balance inconsistency as flux tubes move from the far tail toward the Earth. The growth of B(sub y), however, may be limited by the dawn-dusk asymmetry in the shear velocity as a result of plasma sheet tilting. B(sub y) penetration into the plasma sheet implies field-aligned currents flowing between hemispheres. These currents together with the IMF B(sub y) related mantle field-aligned currents effectively shield the lobe from the IMF B(sub y).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRA..120.8327Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRA..120.8327Z"><span id="translatedtitle">Excitation of dayside chorus waves due to <span class="hlt">magnetic</span> field line compression in response to <span class="hlt">interplanetary</span> shocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhou, Chen; Li, Wen; Thorne, Richard M.; Bortnik, Jacob; Ma, Qianli; An, Xin; Zhang, Xiao-jia; Angelopoulos, Vassilis; Ni, Binbin; Gu, Xudong; Fu, Song; Zhao, Zhengyu</p> <p>2015-10-01</p> <p>The excitation of magnetospheric whistler-mode chorus in response to <span class="hlt">interplanetary</span> (IP) shocks is investigated using wave data from the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft. As an example, we show a typical chorus wave excitation following an IP shock event that was observed by THEMIS in the postnoon sector near the magnetopause on 3 August 2010. We then analyze characteristic changes during this event and perform a survey of similar events during the period 2008-2014 using the THEMIS and OMNI data set. Our statistical analysis demonstrates that the chorus wave excitation/intensification in response to IP shocks occurs only at high L shells (L > 8) on the dayside. We analyzed the variations of <span class="hlt">magnetic</span> curvature following the arrival of the IP shock and found that IP shocks lead to more homogeneous background <span class="hlt">magnetic</span> field configurations in the near-equatorial dayside magnetosphere; and therefore, the threshold of nonlinear chorus wave growth is likely to be reduced, favoring chorus wave generation. Our results provide the observational evidence to support the concept that the geomagnetic field line configuration plays a key role in the excitation of dayside chorus.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFMSA14A..08K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009AGUFMSA14A..08K&link_type=ABSTRACT"><span id="translatedtitle">Enhanced Thermospheric Density: The Roles of East-West and Northward <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Knipp, D. J.; Drake, K. A.; Lei, J.; Crowley, G.</p> <p>2009-12-01</p> <p>During 2005 solar EUV energy input to the thermosphere waned as Solar Cycle 23 declined. The reduction allowed a clearer delineation of episodic density disturbances caused by geomagnetic storms. We show new views of these disturbances based on Poynting flux calculations from the Defense Meteorological Satellite Program (DMSP) F-series satellites, as well as from 1) accelerometer data from polar orbiting satellites, 2) the assimilative mapping of ionospheric electrodynamics (AMIE) procedure and 3) the Thermospheric Ionospheric Electrodynamic General Circulation Model (TIEGCM). The new Poynting flux estimates and TIEGCM results allow us to trace the origins of disturbances that are poorly specified by ground indices. In particular we find that intervals of enhanced northward <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field (IMF) combined with strong east-west components of the IMF allow significant electromagnetic energy input into localized dayside regions of the high-latitude thermosphere. In some cases this energy deposition is consistent with IMF-geomagnetic field merging tailward of the Earth’s <span class="hlt">magnetic</span> cusps. In other cases the energy is deposited in the vicinity of an extremely narrow convection throat. This mode of interaction provides little energy to the magnetotail; and instead concentrates the energy in the dayside thermosphere. We discuss the solar cycle variability of this type of interaction. as well as compare the relative value of Poynting flux and particle energy deposition for such events.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...826...15F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...826...15F"><span id="translatedtitle">Observations of an <span class="hlt">Interplanetary</span> Intermediate Shock Associated with a <span class="hlt">Magnetic</span> Reconnection Exhaust</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Feng, H. Q.; Li, Q. H.; Wang, J. M.; Zhao, G. Q.</p> <p>2016-07-01</p> <p>Two intermediate shocks (ISs) in <span class="hlt">interplanetary</span> space have been identified via one spacecraft observation. However, Feng et al. suggested that the analysis using a single spacecraft observation based only on the Rankine–Hugoniot (R-H) relations could misinterpret a tangential discontinuity (TD) as an IS. The misinterpretation can be fixed if two spacecraft observations are available. In this paper, we report an IS-like discontinuity associated with a <span class="hlt">magnetic</span> reconnection exhaust, which was observed by Wind on 2000 August 9 at 1 au. We investigated this discontinuity by fitting the R-H relations and referring to the Advanced Composition Explorer (ACE) observations. As a result, we found that the observed <span class="hlt">magnetic</span> field and plasma data satisfy the R-H relations well, and the discontinuity satisfies all the requirements of the 2\\to 3 type IS. Although the discontinuity cannot be identified strictly by using two spacecraft observations, in light of the ACE observations we consider that the discontinuity should be an IS rather than a TD.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.8709Y','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.8709Y"><span id="translatedtitle">Dependence of efficiency of <span class="hlt">magnetic</span> storm generation on the types of <span class="hlt">interplanetary</span> drivers.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Yermolaev, Yuri; Nikolaeva, Nadezhda; Lodkina, Irina</p> <p>2015-04-01</p> <p>To compare the coupling coefficients between the solar-wind electric field Ey and Dst (and corrected Dst*) index during the <span class="hlt">magnetic</span> storms generated by different types of <span class="hlt">interplanetary</span> drivers, we use the Kyoto Dst-index data, the OMNI data of solar wind plasma and <span class="hlt">magnetic</span> field measurements, and our "Catalog of large scale phenomena during 1976-2000" (published in [1] and presented on websites: ftp://ftp.iki.rssi.ru/pub/omni/). Both indexes at the main phase of <span class="hlt">magnetic</span> storms are approximated by the linear dependence on the following solar wind parameters: integrated electric field of solar wind (sumEy), solar wind dynamic pressure (Pd), and the level of <span class="hlt">magnetic</span> field fluctuations (sB), and the fitting coefficients are determined by the technique of least squares. We present the results of the main phase modelling for <span class="hlt">magnetic</span> storms with Dst<-50 nT induced by 4 types of the solar wind streams: MC (10 events), CIR (41), Sheath (26), Ejecta (45). Our analysis [2, 3] shows that the coefficients of coupling between Dst and Dst* indexes and integral electric field are significantly higher for Sheath (for Dst*and Dst they are -3.4 and -3.3 nT/V m-1 h, respectively) and CIR (-3.0 and -2.8) than for MC (-2.0 and -2.5) and Ejecta (-2.1 and -2.3). Thus we obtained additional confirmation of experimental fact that Sheath and CIR have higher efficiency in generation of <span class="hlt">magnetic</span> storms than MC and Ejecta. This work was supported by the RFBR, project 13-02-00158a, and by the Program 9 of Presidium of Russian Academy of Sciences. References 1. Yu. I. Yermolaev, N. S. Nikolaeva, I. G. Lodkina, and M. Yu. Yermolaev, Catalog of Large-Scale Solar Wind Phenomena during 1976-2000, Cosmic Research, 2009, Vol. 47, No. 2, pp. 81-94. 2. N.S. Nikolaeva, Yu.I. Yermolaev, I.G. Lodkina, Modeling of Dst-index temporal profile on the main phase of the <span class="hlt">magnetic</span> storms generated by different types of solar wind, Cosmic Research, 2013, Vol. 51, No. 6, pp. 401-412 3. Nikolaeva N.S., Yermolaev</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.5006K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.5006K"><span id="translatedtitle">Observations of Particle Acceleration Associated with Small-Scale <span class="hlt">Magnetic</span> Islands Downstream of <span class="hlt">Interplanetary</span> Shocks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khabarova, Olga V.; Zank, Gary P.; Li, Gang; Malandraki, Olga E.; le Roux, Jakobus A.; Webb, Gary M.</p> <p>2016-04-01</p> <p>We have recently shown both theoretically (Zank et al. 2014, 2015; le Roux et al. 2015) and observationally (Khabarova et al. 2015) that dynamical small-scale <span class="hlt">magnetic</span> islands play a significant role in local particle acceleration in the supersonic solar wind. We discuss here observational evidence for particle acceleration at shock waves that is enhanced by the recently proposed mechanism of particle energization by both island contraction and the reconnection electric field generated in merging or contracting <span class="hlt">magnetic</span> islands downstream of the shocks (Zank et al. 2014, 2015; le Roux et al. 2015). Both observations and simulations suppose formation of <span class="hlt">magnetic</span> islands in the turbulent wake of heliospheric or <span class="hlt">interplanetary</span> shocks (ISs) (Turner et al. 2013; Karimabadi et al. 2014; Chasapis et al. 2015). A combination of the DSA mechanism with acceleration by <span class="hlt">magnetic</span> island dynamics explain why the spectra of energetic particles that are supposed to be accelerated at heliospheric shocks are sometimes harder than predicted by DSA theory (Zank et al. 2015). Moreover, such an approach allows us to explain and describe other unusual behaviour of accelerated particles, such as when energetic particle flux intensity peaks are observed downstream of heliospheric shocks instead of peaking directly at the shock according to DSA theory. Zank et al. (2015) predicted the peak location to be behind the heliospheric termination shock (HTS) and showed that the distance from the shock to the peak depends on particle energy, which is in agreement with Voyager 2 observations. Similar particle behaviour is observed near strong ISs in the outer heliosphere as observed by Voyager 2. Observations show that heliospheric shocks are accompanied by current sheets, and that IS crossings always coincide with sharp changes in the IMF azimuthal angle and the IMF strength, which is typical for strong current sheets. The presence of current sheets in the vicinity of ISs acts to <span class="hlt">magnetically</span></p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRA..120.7737R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRA..120.7737R"><span id="translatedtitle">Dependence of the location of the Martian <span class="hlt">magnetic</span> lobes on the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field direction: Observations from Mars Global Surveyor</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Romanelli, N.; Bertucci, C.; Gómez, D.; Mazelle, C.</p> <p>2015-09-01</p> <p>We use magnetometer data from the Mars Global Surveyor (MGS) spacecraft during portions of the premapping orbits of the mission to study the variability of the Martian-induced magnetotail as a function of the orientation of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF). The time spent by MGS in the magnetotail lobes during periods with positive solar wind flow-aligned IMF component B∥IMF suggests that their location as well as the position of the central polarity reversal layer (PRL) are displaced in the direction antiparallel to the IMF cross-flow component B⊥IMF. Analogously, in the cases where B∥IMF is negative, the lobes are displaced in the direction of B⊥IMF. This behavior is compatible with a previously published analytical model of the IMF draping, where for the first time, the displacement of a complementary reversal layer (denoted as IPRL for inverse polarity reversal layer) is deduced from first principles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015TESS....140503K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015TESS....140503K"><span id="translatedtitle">The <span class="hlt">magnetic</span> flux excess effect as a consequence of non-Parker radial evolution of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Khabarova, Olga</p> <p>2015-04-01</p> <p>The “<span class="hlt">magnetic</span> flux excess” effect is exceeding of <span class="hlt">magnetic</span> flux Fs=4π|Br|r2 measured by distant spacecraft over the values obtained through measurements at the Earth’s orbit (Owens et al., JGR, 2008). Theoretically, its conservation should take place at any heliocentric distance r further than 10 solar radii, which means that the difference between the flux measured at 1 AU and Fs observed in another point in the heliosphere should be zero. However, the difference is negative closer to the Sun and increasingly positive at larger heliocentric distances. Possible explanations of this effect are continuously discussed, but the consensus is yet not reached.It is shown that a possible source of this effect is the solar wind expansion not accordingly with the Parker solution at least at low heliolatitudes. The difference between the experimentally found (r-5/3) and commonly used (r-2) radial dependence of the radial component of the IMF Br may lead to mistakes in the IMF point-to-point recalculations (Khabarova & Obridko, ApJ, 2012; Khabarova, Astronomy Reports, 2013). Using the observed Br (r) dependence, it is easy to find the variation of difference between the <span class="hlt">magnetic</span> flux Fs(r) at certain heliocentric distance r and Fs_1AU at 1 AU, which can be calculated as Fs(r)-Fs_1AU =4π·(B1AU /[1AU]-5/3) (r2-5/3 -[1AU]2-5/3) (Khabarova, Astronomy Reports, 2013).The possible influence of presence of the heliospheric current sheet near the ecliptic plane on the picture of <span class="hlt">magnetic</span> field lines and consequent deviation from the Parker's model is discussed.- Khabarova Olga, and Obridko Vladimir, Puzzles of the <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field in the Inner Heliosphere, 2012, Astrophysical Journal, 761, 2, 82, doi:10.1088/0004-637X/761/2/82, http://arxiv.org/pdf/1204.6672v2.pdf- Olga V. Khabarova, The <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field: radial and latitudinal dependences. Astronomy Reports, 2013, Vol. 57, No. 11, pp. 844-859, http://arxiv.org/ftp/arxiv/papers/1305/1305.1204.pdf</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008cosp...37.3183T','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008cosp...37.3183T"><span id="translatedtitle">Coherence between <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field at ACE and geomagnetic observatory data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Thomson, David J.</p> <p></p> <p>µnullDespite considerable evidence that oscillations in geomagnetic observatory data are driven by oscillations in the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF), the subject remains contentious. At least two of the reasons for this are physical: first, geomagnetic data consists of background components plus local effects due to ionospheric currents and convection so that the data is complicated; second, at frequencies below about 10 uHz, gas pressure in the solar wind is usually larger than <span class="hlt">magnetic</span> pressure and, because most of the power is at low frequencies, the more easily observed effects of the gas pressure dominates. The third reason is that much of the analysis of these effects has been done using statistical techniques that are poorly matched to the task. Here we use long sections of data at one-minute resolution from the St. John's, Ottawa, and Victoria observatories together with IMF data from the ACE spacecraft. It is well established that solar p-modes, (approximately 5 minutes period) of a given degree are spaced by approximately 136 uHz and, as one cannot separate the various degrees in <span class="hlt">magnetic</span> field data, long data sections - more than ten days - are required to obtain adequate frequency resolution. Using the nine series of geomagnetic data as one group and the three from ACE as a second, we compute canonical coherences between the two groups. The peak coherences, mostly corresponding to low degree solar modes, are so high that they cannot occur by chance. These peaks are superimposed on a coherent background, possibly from unresolved modes or from a fossil turbulence signature. The coherences are higher at high frequencies, 5 mHz and above, than they are at low frequencies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/207220','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/207220"><span id="translatedtitle">Dynamic response of the cusp morphology to the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field changes: An example observed by Viking</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yamauchi, M.; Lundin, R.; Potemra, T.A.</p> <p>1995-05-01</p> <p>In this article the authors discuss a unique obsevation made in the cusp region by the IMP 8 satellite of ion signatures during a step change in the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field from southward to northward, and back southward. The solar wind was relatively steady in density and velocity during this stepwise change. The ion population is observed to have two independent populations, well separated in energy, along the same field lines.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4497471','PMC'); return false;" href="http://www.pubmedcentral.nih.gov/articlerender.fcgi?tool=pmcentrez&artid=4497471"><span id="translatedtitle">Saturn's dayside ultraviolet auroras: Evidence for morphological dependence on the direction of the upstream <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pmc">PubMed Central</a></p> <p>Meredith, C J; Alexeev, I I; Badman, S V; Belenkaya, E S; Cowley, S W H; Dougherty, M K; Kalegaev, V V; Lewis, G R; Nichols, J D</p> <p>2014-01-01</p> <p>We examine a unique data set from seven Hubble Space Telescope (HST) “visits” that imaged Saturn's northern dayside ultraviolet emissions exhibiting usual circumpolar “auroral oval” morphologies, during which Cassini measured the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) upstream of Saturn's bow shock over intervals of several hours. The auroras generally consist of a dawn arc extending toward noon centered near ∼15° colatitude, together with intermittent patchy forms at ∼10° colatitude and poleward thereof, located between noon and dusk. The dawn arc is a persistent feature, but exhibits variations in position, width, and intensity, which have no clear relationship with the concurrent IMF. However, the patchy postnoon auroras are found to relate to the (suitably lagged and <span class="hlt">averaged</span>) IMF Bz, being present during all four visits with positive Bz and absent during all three visits with negative Bz. The most continuous such forms occur in the case of strongest positive Bz. These results suggest that the postnoon forms are associated with reconnection and open flux production at Saturn's magnetopause, related to the similarly interpreted bifurcated auroral arc structures previously observed in this local time sector in Cassini Ultraviolet Imaging Spectrograph data, whose details remain unresolved in these HST images. One of the intervals with negative IMF Bz however exhibits a prenoon patch of very high latitude emission extending poleward of the dawn arc to the <span class="hlt">magnetic</span>/spin pole, suggestive of the occurrence of lobe reconnection. Overall, these data provide evidence of significant IMF dependence in the morphology of Saturn's dayside auroras. Key Points We examine seven cases of joint HST Saturn auroral images and Cassini IMF data The persistent but variable dawn arc shows no obvious IMF dependence Patchy postnoon auroras are present for northward IMF but not for southward IMF PMID:26167441</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2004JGRA..10912203E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2004JGRA..10912203E"><span id="translatedtitle">Global control of merging by the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field: Cluster observations of dawnside flank magnetopause reconnection</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eriksson, S.; Elkington, S. R.; Phan, T. D.; Petrinec, S. M.; RèMe, H.; Dunlop, M. W.; Wiltberger, M.; Balogh, A.; Ergun, R. E.; André, M.</p> <p>2004-12-01</p> <p>Detailed Cluster observations of flank magnetopause reconnection are presented for two events on the Northern and the Southern Hemispheric dawnside flanks when the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) clock angle ? = arctan(By/Bz) is within ˜45° of the equatorial plane. The event selection is based on the relative proximity between the Cluster spacecraft 1 position and the predicted magnetospheric sash where antiparallel merging is expected to develop. MHD simulations performed for the two events indicate that the Cluster spacecraft were passing through the MHD sash region in the Northern Hemisphere on 30 June 2001, while crossing the magnetopause equatorward of the Southern Hemispheric sash on 29 May 2001. Accelerated and decelerated plasma flows relative to the magnetosheath velocity were detected by Cluster on both occasions. The Walén test confirms that the observed ΔV is directly correlated with the predicted <span class="hlt">magnetic</span> field rotation ΔB/? with the expected direction of the normal <span class="hlt">magnetic</span> field and so we interpret them as speed changes due to <span class="hlt">magnetic</span> reconnection. The observed directions of ΔV compare very well with the location of the simulated MHD sash relative to Cluster. The <span class="hlt">magnetic</span> field shear in the locally tangential plane of the magnetopause ranges between 171° and 177° for the 30 June event in good agreement with antiparallel merging at the MHD sash. The corresponding local field shear for the 29 May event is only 144°, either suggesting a component merging site in the direction of the sash or indicating that Cluster is farther away from the location where the neutral line was initially formed as compared with the 30 June event. A comparison between the projected regions of antiparallel and component merging onto the magnetopause and the quasi-steady direction of plasma acceleration detected by Cluster on 29 May and 30 June support the view that the IMF controls the expected global location of <span class="hlt">magnetic</span> reconnection at limited regions of the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19720018182','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19720018182"><span id="translatedtitle">Precipitation of low energy electrons at high latitudes: Effects of substorms, <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field and dipole tilt angle</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burch, J. L.</p> <p>1972-01-01</p> <p>Data from the auroral particles experiment on OGO-4 were used to study effects of substorm activity, <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field latitutde, and dipole tilt angle on high-latitude precipitation of 700 eV electrons. It was found that: (1) The high-latitude zone of 700 eV electron precipitation in late evening and early morning hours moves equatorward by 5 to 10 deg during substorms. (2) The low-latitude boundary of polar cusp electron precipitation at 9 to 15 hours MLT also moves equatorward by several degrees during substorms and, in the absence of significant substorm activity, after a period of southward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field. (3) With times containing substorm activity or a southward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field eliminated, the low-latitude boundary of polar cusp electron precipitation is found to move by approximately 4 deg over the total yearly range of tilt angles. At maximum winter and summer conditions the invariant latitude of the boundary is shown to shift by approximately -3 deg and +1 deg respectively from its equinox location.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19960021421&hterms=spaghetti&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dspaghetti','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19960021421&hterms=spaghetti&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dspaghetti"><span id="translatedtitle">Field lines and <span class="hlt">magnetic</span> surfaces in a two-component slab/2D model of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> fluctuations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Matthaeus, W. H.; Pontius, D. H., Jr.; Gray, P. C.; Bieber, J. W.</p> <p>1995-01-01</p> <p>A two-component model for the spectrum of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> fluctuations was proposed on the basis of ISEE observations, and has found an intriguing level of application in other solar wind studies. The model fluctuations consist of a fraction of 'slab' fluctuations, varying only in the direction parallel to the locally uniform mean <span class="hlt">magnetic</span> field B(0) and a complement of 2D (two-dimensional) fluctuations that vary in the directions transverse to B(0). We have developed an spectral method computational algorithm for computing the <span class="hlt">magnetic</span> flux surfaces (flux tubes) associated with the composite model, based upon a precise analogy with equations for ideal transport of a passive scalar in planar two dimensional geometry. Visualization of various composite models will be presented, including the 80 percent 2D/ 20 percent slab model with delta B/B(0) approximately equals 1 and a minus 5/3 spectral law, that is thought to approximately represent a snapshot of solar wind turbulence. Characteristically, the visualizations show that flux tubes, even when defined as regular on some plane, shred and disperse rapidly as they are viewed along the parallel direction. This diffusive process, which generalizes the standard picture of field line random walk, will be discussed in detail. Evidently, the traditional picture that flux tubes randomize like strands of spaghetti with a uniform tangle along the axial direction is in need of modification.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014AGUFMSH42A..05R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014AGUFMSH42A..05R"><span id="translatedtitle">Propagation and Evolution of <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Clouds: Global Simulations and Comparisons with Observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Riley, P.; Ben-Nun, M.; Linker, J.; Torok, T.; Lionello, R.; Downs, C.</p> <p>2014-12-01</p> <p>In this talk, we explore the evolution of <span class="hlt">interplanetary</span> coronal mass ejections (ICMEs), and fast <span class="hlt">magnetic</span> clouds (MCs) in particular. We address three specific issues. First, What are the large-scale forces acting on ejecta as they travel from the Sun to 1 AU through a realistic ambient solar wind, and how does they affect the large-scale structure of the event? Second, what are the dominant waves/shocks associated with fast ICMEs? And third, how are the properties of ICMEs different during cycle 24 than during the previous cycle? To accomplish these objectives, we employ a variety of numerical approaches, including global resistive MHD models that incorporate realistic energy transport processes. We also compare and contrast model results with both remote solar and in-situ measurements of ICMEs at 1 AU and elsewhere, including the so-called ``Bastille Day'' event of July 14, 2000, and the more recent ``extreme ICME'' observed by STEREO-A on July 23, 2012.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFM.P41B2074M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFM.P41B2074M"><span id="translatedtitle">Multi-parameter Correlation of Jovian Radio Emissions with Solar Wind and <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field Data</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>MacDowall, R. J.; Golla, T.; Reiner, M. J.; Farrell, W. M.</p> <p>2015-12-01</p> <p>Variability of the numerous varieties of Jovian radio emission has been associated with aspects of solar wind (SW) and <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) parameters outside the magnetosphere. Here we demonstrate multiple-parameter correlations that relate each of several Jovian emissions, including bKOM and quasi-periodic bursts, to the SW and IMF impacting the Jovian magnetosphere. The data used are from the Ulysses spacecraft with radio data from the Unified Radio and Plasma wave (URAP) instrument, which provides high-quality remote radio observations of the Jovian emissions. The URAP observations are correlated with SW and IMF data from the relevant instruments on Ulysses, propagated to the nose of the Jovian magnetosphere with a sophisticated code. Because the aphelion of the Ulysses orbit was at the Jovian distance from the Sun, Ulysses spent ample time near Jupiter in 1991-1992 and 2003-2004, which are the intervals analyzed. Our results can be inverted such that radio observations by a Jovian orbiter, such as Cassini or Juno, are able to identify SW/IMF changes based on the behavior of the radio emissions.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_7");'>7</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li class="active"><span>9</span></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_9 --> <div id="page_10" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="181"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.5025K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.5025K"><span id="translatedtitle">Predicting the <span class="hlt">magnetic</span> structure of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> clouds and their sheath regions: Space weather perspective</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kilpua, Emilia</p> <p>2016-04-01</p> <p><span class="hlt">Magnetic</span> clouds and their turbulent sheath regions drive the majority of intense space weather storms. The magnitude and the details of the <span class="hlt">magnetic</span> storm (timing, affected current systems, response of the high energy radiation belt electron fluxes, etc.) depend strongly on the <span class="hlt">magnetic</span> topology of the CME flux rope and whether the sheath region makes a significant contribution. Sheath regions are particularly geoeffective due to their large-amplitude <span class="hlt">magnetic</span> field fluctuations and high Alfven Mach numbers, which may enhance solar wind - magnetospheric coupling efficiency. In this presentation I will present examples of space weather responses driven by different CME structures to demonstrate the necessity to develop detailed prediction models/scenarios for different <span class="hlt">magnetic</span> field configurations and characteristics. The constraints for solar observations and models will be also discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2012cosp...39.2080V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2012cosp...39.2080V"><span id="translatedtitle">Magnetopause position dependence on the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field: Bz or cone angle</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Verigin, Mikhail; Galina, Kotova; Tatrallyay, Mariella; Erdos, Geza</p> <p>2012-07-01</p> <p>New magnetopause model is developed that is applicable for large <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) values. It is shown that magnetopause observations by the Prognoz satellites can be described by the following 2-D model: [X(Y)=r_{0} -\\frac{D^{2} }{2π ^{2} R_{0} } \\tan ^{2} (\\frac{π Y}{D} )] where X is the geocentric distance in the aberrated solar wind direction, Y is the distance from the X-axis, r_{0} =11.16R_{e} \\cdot P^{{-1 6}} is the subsolar magnetopause distance, R_{0} =16.51R_{e} \\cdot P^{{-1 6}} is the subsolar magnetopause curvature radius, D=98.06R_{e} \\cdot P^{{-1 6}} is the magnetotail asymptotic downstream diameter, and P is the total thermal and <span class="hlt">magnetic</span> pressure at the magnetopause nose. This pressure can be evaluated as: [P=kρ V^{2} (1+\\frac{4Sin^{2} \\vartheta _{bv} }{kM_{a}^{2} } +\\frac{4Sin^{2} \\vartheta _{bv} }{kM_{a}^{2} } \\sqrt{1+\\frac{kM_{a}^{2} }{2Sin^{2} \\vartheta _{bv} } } ),] where ρ V^{2} is the solar wind ram pressure, k ≈ 0.88, Ma is the solar wind Alfvenic Mach number , and \\vartheta _{bv} is the cone angle between the solar wind and IMF directions. The above model describes the magnetopause position reasonably well also at geostationary ˜ 6.6Re GOES 10, 12 orbits. Additional check of the model is based on a fair reproduction of the subsolar magnetopause dependence on \\vartheta _{bv} that was found recently in THEMIS observations. This work was partially supported by stocktickerRAS P4, P22 programs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011AcAau..68.1430S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011AcAau..68.1430S"><span id="translatedtitle">Superconducting <span class="hlt">magnets</span> and mission strategies for protection from ionizing radiation in <span class="hlt">interplanetary</span> manned missions and <span class="hlt">interplanetary</span> habitats</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Spillantini, Piero</p> <p>2011-05-01</p> <p>First order evaluations for active shielding based on superconducting <span class="hlt">magnetic</span> lenses were made in the past in ESA supported studies. The present increasing interest of permanent space complexes, to be considered in the far future as 'bases' rather than 'stations', located in 'deep' space (as it has been proposed for the L1 libration's point between Earth and Moon, or for Stations in orbit around Mars), requires that this preliminary activity continues, envisaging the problem of the protection from cosmic ray (CR) action at a scale allowing long permanence in 'deep' space, not only for a relatively small number of dedicated astronauts but also to citizens conducting there 'normal' activities. Part of the personnel of such a 'deep space base' should stay and work there for a long period of time. It is proposed that the activities and life of these personnel will be concentrated in a sector protected from Galactic CR (GCR) during the whole duration of their mission. In the exceptional case of an intense flux of Solar Energetic Protons (SEP), this sector could be of use as a shelter for all the other personnel normally located in other sectors of the Space Base. The realization of the <span class="hlt">magnetic</span> protection of the long permanence sector by well-established current materials and techniques is in principle possible, but not workable in practice for the huge required mass of the superconductor, the too low operating temperature (10-15 K) and the corresponding required cooling power and thermal shielding. However the fast progress in the production of reliable High Temperature Superconducting (HTS) or MgB 2 cables and of cryocoolers suitable for space operation opens the perspective of practicable solutions. In fact these cables, when used at relatively low temperature, but in any case higher than for NbTi and Nb 3Sn, show a thermodynamically much better behavior. Quantitative evaluations for the protection of the sector of the 'Space Base' to be protected from GCRs (and</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19730018611','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19730018611"><span id="translatedtitle">The relation between the azimuthal component of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field and the geomagnetic field in the polar caps</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Svalgaard, L.</p> <p>1973-01-01</p> <p>The recently discovered relation between the azimuthal component of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field and <span class="hlt">magnetic</span> variations in the earth's polar caps is reviewed. When the IMF azimuthal component is positive (typical of an <span class="hlt">interplanetary</span> sector with <span class="hlt">magnetic</span> field directed away from the sun) geomagnetic perturbations directed away from the earth are observed within 8 deg from the corrected geomagnetic pole. When the IMF azimuthal component is negative (typically within toward sectors) the geomagnetic perturbations are directed towards the earth at both poles. These perturbations can also be described by an equivalent current flowing at a constant <span class="hlt">magnetic</span> latitude of 80 - 82 deg clockwise around the <span class="hlt">magnetic</span> poles during toward sectors and counterclockwise during away sectors. This current fluctuates in magnitude and direction with the azimuthal component of the IMF, with a delay time of the order of 20 minutes. The importance of this effect for understanding of both solar <span class="hlt">magnetism</span> and magnetospheric physics is stressed in view of the possibility for investigating the solar sector structure during the last five sunspot cycles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20110023536&hterms=car+events&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcar%2Bevents','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20110023536&hterms=car+events&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dcar%2Bevents"><span id="translatedtitle"><span class="hlt">Magnetic</span> Field-Line Lengths in <span class="hlt">Interplanetary</span> Coronal Mass Ejections Inferred from Energetic Electron Events</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kahler, S. W.; Haggerty, D. K.; Richardson, I. G.</p> <p>2011-01-01</p> <p>About one quarter of the observed <span class="hlt">interplanetary</span> coronal mass ejections (ICMEs) are characterized by enhanced <span class="hlt">magnetic</span> fields that smoothly rotate in direction over timescales of about 10-50 hr. These ICMEs have the appearance of <span class="hlt">magnetic</span> flux ropes and are known as "<span class="hlt">magnetic</span> clouds" (MCs). The total lengths of MC field lines can be determined using solar energetic particles of known speeds when the solar release times and the I AU onset times of the particles are known. A recent examination of about 30 near-relativistic (NR) electron events in and near 8 MCs showed no obvious indication that the field-line lengths were longest near the MC boundaries and shortest at the MC axes or outside the MCs, contrary to the expectations for a flux rope. Here we use the impulsive beamed NR electron events observed with the Electron Proton and Alpha Monitor instrument on the Advanced Composition Explorer spacecraft and type III radio bursts observed on the Wind spacecraft to determine the field-line lengths inside ICMEs included in the catalog of Richardson & Cane. In particular, we extend this technique to ICMEs that are not MCs and compare the field-line lengths inside MCs and non-MC ICMEs with those in the ambient solar wind outside the ICMEs. No significant differences of field-line lengths are found among MCs, ICMEs, and the ambient solar wind. The estimated number of ICME field-line turns is generally smaller than those deduced for flux-rope model fits to MCs. We also find cases in which the electron injections occur in solar active regions CARs) distant from the source ARs of the ICMEs, supporting CME models that require extensive coronal <span class="hlt">magnetic</span> reconnection with surrounding fields. The field-line lengths are found to be statistically longer for the NR electron events classified as ramps and interpreted as shock injections somewhat delayed from the type III bursts. The path lengths of the remaining spike and pulse electron events are compared with model calculations of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2008cosp...37.2948S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2008cosp...37.2948S"><span id="translatedtitle">MESSENGER observations of the response of Mercury's magnetosphere to northward and southward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Slavin, James</p> <p></p> <p>M. H. Acũa (2), B. J. Anderson (3), D. N. Baker (4), M. Benna (2), S. A. Boardsen (1), G. n Gloeckler (5), R. E. Gold (3), G. C. Ho (3), H. Korth (3), S. M. Krimigis (3), S. A. Livi (6), R. L. McNutt Jr. (3), J. M. Raines (5), M. Sarantos (1), D. Schriver (7), S. C. Solomon (8), P. Travnicek (9), and T. H. Zurbuchen (5) (1) Heliophysics Science Division, NASA GSFC, Greenbelt, MD 20771, USA, (2) Solar System Exploration Division, NASA GSFC, Greenbelt, MD 20771, USA, (3) The Johns Hopkins University Applied Physics Laboratory, Laurel, MD 20723, USA, (4) Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA, (5) Department of Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48109, USA (6) Southwest Research Institute, San Antonio, TX 28510, USA, (7) Institute for Geophysics and Planetary Physics, University of California, Los Angeles, CA 90024, USA, (8) Department of Terrestrial <span class="hlt">Magnetism</span>, Carnegie Institution of Washington, DC 20015, USA, and (9) Institute of Atmospheric Physics, Prague, Czech Republic, 14131 MESSENGER's 14 January 2008 encounter with Mercury has provided new observations of the solar wind interaction with this planet. Here we report initial results concerning this miniature magnetosphere's response to the north-south component of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF). This is the component of the IMF that is expected to exert the greatest influence over the structure of the magnetopause and the processes responsible for energy transfer into the magnetosphere. The IMF was northward immediately prior to and following the passage of the MESSENGER spacecraft through this small magnetosphere. However, several-minute episodes of southward IMF were observed in the magnetosheath during the inbound portion of the encounter. Evidence for reconnection at the dayside magnetopause in the form of welldeveloped flux transfer events (FTEs) was observed in the magnetosheath following some of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2011ApJ...736..106K','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2011ApJ...736..106K"><span id="translatedtitle"><span class="hlt">Magnetic</span> Field-line Lengths in <span class="hlt">Interplanetary</span> Coronal Mass Ejections Inferred from Energetic Electron Events</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kahler, S. W.; Haggerty, D. K.; Richardson, I. G.</p> <p>2011-08-01</p> <p>About one quarter of the observed <span class="hlt">interplanetary</span> coronal mass ejections (ICMEs) are characterized by enhanced <span class="hlt">magnetic</span> fields that smoothly rotate in direction over timescales of about 10-50 hr. These ICMEs have the appearance of <span class="hlt">magnetic</span> flux ropes and are known as "<span class="hlt">magnetic</span> clouds" (MCs). The total lengths of MC field lines can be determined using solar energetic particles of known speeds when the solar release times and the 1 AU onset times of the particles are known. A recent examination of about 30 near-relativistic (NR) electron events in and near 8 MCs showed no obvious indication that the field-line lengths were longest near the MC boundaries and shortest at the MC axes or outside the MCs, contrary to the expectations for a flux rope. Here we use the impulsive beamed NR electron events observed with the Electron Proton and Alpha Monitor instrument on the Advanced Composition Explorer spacecraft and type III radio bursts observed on the Wind spacecraft to determine the field-line lengths inside ICMEs included in the catalog of Richardson & Cane. In particular, we extend this technique to ICMEs that are not MCs and compare the field-line lengths inside MCs and non-MC ICMEs with those in the ambient solar wind outside the ICMEs. No significant differences of field-line lengths are found among MCs, ICMEs, and the ambient solar wind. The estimated number of ICME field-line turns is generally smaller than those deduced for flux-rope model fits to MCs. We also find cases in which the electron injections occur in solar active regions (ARs) distant from the source ARs of the ICMEs, supporting CME models that require extensive coronal <span class="hlt">magnetic</span> reconnection with surrounding fields. The field-line lengths are found to be statistically longer for the NR electron events classified as ramps and interpreted as shock injections somewhat delayed from the type III bursts. The path lengths of the remaining spike and pulse electron events are compared with model calculations of</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2009JGRA..11411101X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2009JGRA..11411101X"><span id="translatedtitle">Magnetohydrodynamic simulation of the interaction between two <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> clouds and its consequent geoeffectiveness: 2. Oblique collision</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiong, Ming; Zheng, Huinan; Wang, Shui</p> <p>2009-11-01</p> <p>The numerical studies of the <span class="hlt">interplanetary</span> coupling between multiple <span class="hlt">magnetic</span> clouds (MCs) are continued by a 2.5-dimensional ideal magnetohydrodynamic (MHD) model in the heliospheric meridional plane. The <span class="hlt">interplanetary</span> direct collision (DC)/oblique collision (OC) between both MCs results from their same/different initial propagation orientations. Here the OC is explored in contrast to the results of the DC. Both the slow MC1 and fast MC2 are consequently injected from the different heliospheric latitudes to form a compound stream during the <span class="hlt">interplanetary</span> propagation. The MC1 and MC2 undergo contrary deflections during the process of oblique collision. Their deflection angles of ∣δ$\\theta$1∣ and ∣δ$\\theta$2∣ continuously increase until both MC-driven shock fronts are merged into a stronger compound one. The ∣δ$\\theta$1∣, ∣δ$\\theta$2∣, and total deflection angle Δ$\\theta$ (Δ$\\theta$ = ∣δ$\\theta$1∣ + ∣δ$\\theta$2∣) reach their corresponding maxima when the initial eruptions of both MCs are at an appropriate angular difference. Moreover, with the increase of MC2's initial speed, the OC becomes more intense, and the enhancement of δ$\\theta$1 is much more sensitive to δ$\\theta$2. The ∣δ$\\theta$1∣ is generally far less than the ∣δ$\\theta$2∣, and the unusual case of ∣δ$\\theta$1∣ $\\simeq$ ∣δ$\\theta$2∣ only occurs for an extremely violent OC. But because of the elasticity of the MC body to buffer the collision, this deflection would gradually approach an asymptotic degree. As a result, the opposite deflection between the two MCs, together with the inherent <span class="hlt">magnetic</span> elasticity of each MC, could efficiently relieve the external compression for the OC in the <span class="hlt">interplanetary</span> space. Such a deflection effect for the OC case is essentially absent for the DC case. Therefore, besides the <span class="hlt">magnetic</span> elasticity, <span class="hlt">magnetic</span> helicity, and reciprocal compression, the deflection due to the OC should be considered for the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016P%26SS..120...78V','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016P%26SS..120...78V"><span id="translatedtitle">Parametric study of the solar wind interaction with the Hermean magnetosphere for a weak <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Varela, J.; Pantellini, F.; Moncuquet, M.</p> <p>2016-01-01</p> <p>The aim of this study is to simulate the interaction of the solar wind with the Hermean magnetosphere when the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field is weak, performing a parametric study for all the range of hydrodynamic values of the solar wind predicted on Mercury for the ENLIL + GONG WSA + Cone SWRC model: density from 12 to 180 cm-3, velocity from 200 to 500 km/s and temperatures from 2 ·104 to 18 ·104 K, and compare the results with a real MESSENGER orbit as reference case. We use the code PLUTO in spherical coordinates and an asymmetric multipolar expansion for the Hermean <span class="hlt">magnetic</span> field. The study shows for all simulations a stand off distance larger than the Mercury radius and the presence of close <span class="hlt">magnetic</span> field lines on the day side of the planet, so the dynamic pressure of the solar wind is not high enough to push the magnetopause on the planet surface if the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field is weak. The simulations with large dynamic pressure lead to a large compression of the Hermean <span class="hlt">magnetic</span> field modifying its topology in the inner magnetosphere as well as the plasma flows from the magnetosheath towards the planet surface.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950046667&hterms=bivariate&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dbivariate','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950046667&hterms=bivariate&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Dbivariate"><span id="translatedtitle">Magnetopause shape as a bivariate function of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field B(sub z) and solar wind dynamic pressure</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Roelof, Edmond C.; Sibeck, David G.</p> <p>1993-01-01</p> <p>We present a new method for determining the shape of the magnetopause as a bivariate function of the hourly <span class="hlt">averaged</span> solar wind dynamic pressure (p) and the north-south component of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) B(sub z). We represent the magnetopause (for X(sub GSE) greater than -40 R(sub E)) as an ellipsoid of revolution in solar-wind-aberrated coordinates and express the (p, B(sub z)) dependence of each of the three ellipsoid parameters as a second-order (6-term) bivariate expansion in Inp and B(sub z). We define 12 overlapping bins in a normalized dimensionless (p, B(sub z)) `control space' and fit an ellipsoid to those magnetopause crossings having (p, B(sub z)) values within each bin. We also calculate the bivariate (Inp, B(sub z)) moments to second order over each bin in control space. We can then calculate the six control-space expansion coefficients for each of the three ellipsoid parameters in configuration space. From these coefficients we can derive useful diagnosis of the magnetopause shape as joint functions of p and B(sub z): the aspect ratio of the ellipsoid's minor-to-major axes; the flank distance, radius of curvature, and flaring angle (at X(sub GSE) = 0); and the subsolar distance and radius of curvature. We confirm and quantify previous results that during periods of southward B(sub z) the subsolar magnetopause moves inward, while at X(sub GSE) = 0 the flank magnetopause moves outward and the flaring angle increases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20110007245&hterms=Butterfly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DButterfly','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20110007245&hterms=Butterfly&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D30%26Ntt%3DButterfly"><span id="translatedtitle">Solar Sources and Geospace Consequences of <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Clouds Observed During Solar Cycle 23</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Lepping, R. P.</p> <p>2007-01-01</p> <p>We present results of a statistical investigation of 99 <span class="hlt">magnetic</span> clouds (MCs) observed during 1995-2005. The MC-associated coronal mass ejections (CMEs) are faster and wider on the <span class="hlt">average</span> and originate within +/-30deg from the solar disk center. The solar sources of MCs also followed the butterfly diagram. The correlation between the <span class="hlt">magnetic</span> field strength and speed of MCs was found to be valid over a much wider range of speeds. The number of south-north (SN) MCs was dominant and decreased with solar cycle, while the number of north-south (NS) MCs increased confirming the odd-cycle behavior. Two-thirds of MCs were geoeffective; the Dst index was highly correlated with speed and <span class="hlt">magnetic</span> field in MCs as well as their product. Many (55%) fully northward (FN) MCs were geoeffective solely due to their sheaths. The non-geoeffective MCs were slower (<span class="hlt">average</span> speed approx. 382 km/s), had a weaker southward <span class="hlt">magnetic</span> field (<span class="hlt">average</span> approx. -5.2nT), and occurred mostly during the rise phase of the solar activity cycle.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011JGRA..11611316K&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011JGRA..11611316K&link_type=ABSTRACT"><span id="translatedtitle">Response of thermosphere density to changes in <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field sector polarity</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Kwak, Y.-S.; Kim, K.-H.; Deng, Y.; Forbes, J. M.</p> <p>2011-11-01</p> <p>A systematic analysis of the thermospheric density response to changes in the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) sector polarity is carried out. For this purpose we use a high-latitude southern thermospheric total mass density near 400 km altitude, derived from the high-accuracy accelerometer on board the Challenging Minisatellite Payload (CHAMP) spacecraft in 2003, a period of a well-defined IMF sector polarity change. The IMF sector polarity changes appear to strongly influence the high-latitude thermospheric density variations, especially in equinox seasons. After normalization to a constant solar flux level, densities in the Southern Hemisphere near the March equinox show a significant differences, depending on whether the IMF field polarity is toward the Sun (“toward sector,” i.e., +Bx and -By) or away from the Sun (“away sector,” i.e., -Bx and +By). Densities in the toward sector near the March equinox increase before the sector boundary passes the Earth, with strong enhancements in the cusp region and the premidnight sector. Densities in the away sector near the March equinox decrease before the sector boundary passes the Earth, with a significant decrease in the early morning hours. On the other hand, near the September equinox, densities in the Southern Hemisphere do not show significant changes associated with the IMF sector polarity changes. The IMF By and the Bz offsets associated with the IMF sector polarity changes are related to specific behaviors in terms of thermospheric densities. In the toward (away) sector near the March equinox, IMF conditions that increase (decrease) the high-latitude southern thermospheric densities, the negative (positive) By and the negative (positive) Bz offsets, are maintained. On the other hand, in the toward (away) sector near the September equinox, the negative (positive) IMF By condition, which increases (decreases) the high-latitude southern thermospheric densities, and the positive (negative) IMF Bz offset</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014JASTP.115...52C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014JASTP.115...52C"><span id="translatedtitle">IMF By-controlled field-aligned currents in the magnetotail during northward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Cheng, Z. W.; Shi, J. K.; Dunlop, M.; Liu, Z. X.</p> <p>2014-08-01</p> <p>The influence of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) By component on the field-aligned currents (FACs) in the plasma sheet boundary layer (PSBL) in the magnetotail during the northward IMF were investigated using the data from Cluster. There are 748 FACs cases selected to do analysis. We present that the IMF By component plays a very important role in controlling the flow direction of the FACs in the PSBL in the magnetotail. In the northern hemisphere, the influence of the positive (negative) IMF By is an earthward (tailward) FACs. To the contrary, in the southern hemisphere, the effect of the positive (negative) IMF By is a tailward (earthward) FACs. There is a clear north-south asymmetry of the polarity of the FACs in the PSBL when IMF By is positive or negative, and this asymmetry of the polarity is more distinct when IMF By is positive. The FAC density is controlled by IMF By only when |IMF By| is large. When |IMF By| is more than 10 nT the absolute FAC density in the PSBL has an obvious positive correlation with the |IMF By|. When |IMF By| is less than 10 nT, there is no correlation between the absolute FAC density and |IMF By|. There is a clear dusk-dawn asymmetry in the current densities for the FACs in the PSBL, with the dawn currents appearing larger than the dusk currents. The FAC with the largest (smallest) density is located in the range of 0100≤MLT<0200 (2100≤MLT<2200).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AdSpR..52.2112A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AdSpR..52.2112A"><span id="translatedtitle">Sunspot numbers, <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field, and cosmic ray intensity at earth: Nexus for the twentieth century</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ahluwalia, H. S.</p> <p>2013-12-01</p> <p>The pivotal role played by the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (B) in modulating galactic cosmic ray (GCR) intensity in the heliosphere is described. We show that the inverse correlation observed by Forbush (1958) between GCRs and sunspot numbers (SSNs) is reflected in high correlation between SSNs and B (cc = 0.94). The SSN data are available since 1700 and the derived B data since 1835. The paleo-cosmic ray data are available for several millennia in the form of 10Be radionuclide sequestered in polar ice. The data of the ion chambers (ICs) at the Cheltenham-Fredericksburg-Yakutsk (CFY) sites are combined to create a data string for 1937-1988. In turn, these data are used to extend the measurements of the low energy GCR ions (>0.1 GeV) at balloon altitudes at high latitudes in Russia to 1937. These data are then correlated to B and the fit parameters are used to extend the low energy ion data to 1900, creating the instrumental era GCR time series for the twentieth century. The derived GCR time series is compared to 10Be measured at two sites in Greenland, namely Dye 3 and NGRIP for 1900-2000 to check the internal consistency of datasets for the long-term trend. We find that the annual mean rate (%) for 1965 at NGRIP is an outlier. We replace it with the mean of 1964 and 1965 rates and construct a new re-normalized time series at NGIP, improving the agreement with the derived instrumental era GCR time series for the twentieth century as well. This should encourage its use by heliophysics community for varied applications.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20080015820&hterms=magnetic+modeling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmagnetic%2Bmodeling','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20080015820&hterms=magnetic+modeling&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3Dmagnetic%2Bmodeling"><span id="translatedtitle">An Alternative Interpretation of the Relationship between the Inferred Open Solar Flux and the <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Riley, Pete</p> <p>2007-01-01</p> <p>Photospheric observations at the Wilcox Solar Observatory (WSO) represent an uninterrupted data set of 32 years and are therefore unique for modeling variations in the <span class="hlt">magnetic</span> structure of the corona and inner heliosphere over three solar cycles. For many years, modelers have applied a latitudinal correction factor to these data, believing that it provided a better estimate of the line-of-sight <span class="hlt">magnetic</span> field. Its application was defended by arguing that the computed open flux matched observations of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) significantly better than the original WSO correction factor. However, no physically based argument could be made for its use. In this Letter we explore the implications of using the constant correction factor on the value and variation of the computed open solar flux and its relationship to the measured IMF. We find that it does not match the measured IMF at 1 AU except at and surrounding solar minimum. However, we argue that <span class="hlt">interplanetary</span> coronal mass ejections (ICMEs) may provide sufficient additional <span class="hlt">magnetic</span> flux to the extent that a remarkably good match is found between the sum of the computed open flux and inferred ICME flux and the measured flux at 1 AU. If further substantiated, the implications of this interpretation may be significant, including a better understanding of the structure and strength of the coronal field and I N providing constraints for theories of field line transport in the corona, the modulation of galactic cosmic rays, and even possibly terrestrial climate effects.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19730057099&hterms=Analysis+synthesis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DAnalysis%2Bsynthesis','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19730057099&hterms=Analysis+synthesis&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D80%26Ntt%3DAnalysis%2Bsynthesis"><span id="translatedtitle">Analysis and synthesis of coronal and <span class="hlt">interplanetary</span> energetic particle, plasma, and <span class="hlt">magnetic</span> field observations over three solar rotations.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Roelof, E. C.; Krimigis, S. M.</p> <p>1973-01-01</p> <p>In a previous paper (Krimigis et al., 1971), simultaneous observations in 1967 of solar particle events at low (less than 1 MeV) energies were presented. In the present paper, the full complement of simultaneous plasma, <span class="hlt">magnetic</span> field, and energetic particle data is combined, and a complete analysis is made of all the events discussed in the original paper. The essential concept of 'collimated convection' is introduced, whereby the bulk velocity along the field lines of low-energy solar particles is independent of solar local plasma velocity, and the particles are strongly collimated along the field line with no transverse velocity component other than that of the field line itself. Collimated convection effects are shown to exist in small-scale convection and large-scale evolution of particle fluxes; the particle fluxes are, in turn, used to delineate the small-scale and large-scale evolution of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field. Use of collimated convection is made in demonstrating a technique whereby energetic particle intensity profiles in the <span class="hlt">interplanetary</span> medium can be related to equatorial high coronal <span class="hlt">magnetic</span> field structures, by using the instantaneous solar wind velocity. This technique is applied in mapping particle intensities from Mariner 5 onto H alpha synoptic charts of chromospheric <span class="hlt">magnetic</span> field structures for Carrington rotations 1523 to 1525.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2001JGR...10629419S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2001JGR...10629419S"><span id="translatedtitle">Simulations of the magnetosphere for zero <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field: The ground state</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Sonnerup, Bengt U. Ö.; Siebert, Keith D.; White, Willard W.; Weimer, Daniel R.; Maynard, Nelson C.; Schoendorf, Jacqueline A.; Wilson, Gordon R.; Siscoe, George L.; Erickson, Gary M.</p> <p>2001-12-01</p> <p>A global MHD simulation code, the Integrated Space Weather Prediction Model, is used to examine the steady state properties of the magnetosphere for zero <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field. In this ``ground state'' of the system, reconnection at the magnetopause is absent. Topics reported here include (1) qualitative description of global <span class="hlt">magnetic</span> field, plasma flow, and current systems (Chapman-Ferraro, geotail, Region 1 and Region 2 currents); (2) quantitative parametric studies of shock jump conditions, magnetopause and shock standoff distance, polar cap voltage, and total Region 1 current for different solar wind speeds and ionospheric Pedersen conductances; and (3) quantitative analysis of the low-latitude boundary layer (LLBL) and its coupling to the ionosphere. The central part of the geomagnetic tail is found to be very long, extending beyond the downstream end of the simulation box at X=-300 RE. Along each flank a ``wing-like'' region containing closed, albeit strongly stretched, field lines is present. Each such region contains a narrow convection cell, consisting of the tailward flowing LLBL and an adjoining narrow channel of sunward return flow. These cells are the result of viscous-like interaction along the magnetospheric flanks, with an effective kinematic viscosity, entirely of numerical origin, estimated to be ν=1.8×108m2s-1. Except in certain regions near the magnetopause, the magnetosheath flow is steady and laminar while the internal motion in the tail displays turbulent vortical motion in the plasma sheet. Plasma transport in the tail occurs as a result of this turbulence, and substantial turbulent plasma entry across the equatorial magnetopause is seen in the region -10RE<X<0 RE behind the torus of dipolar field lines. The polar cap potential ΔϕPC is 29.9+/-1.4kV for VSW=400kms-1 and ΣP=6mho, which is in reasonable agreement with results inferred from satellite observations. About half of ΔϕPC can be attributed to the LLBLs with the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19760009906','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19760009906"><span id="translatedtitle">Observations of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field between 0.46 and 1 A.U. by the Mariner 10 spacecraft. Ph.D. Thesis - Catholic Univ. of Am.</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Behannon, K. W.</p> <p>1976-01-01</p> <p>Almost continuous measurement of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) at a sampling rate of 25 vectors/sec was performed by the <span class="hlt">magnetic</span> field experiment onboard the Mariner 10 spacecraft during the period November 3, 1973 to April 14, 1974, comprising approximately 5-2/3 solar rotations and extending in radial distance from the sun from 1 to 0.46 AU. A clearly discernible two-sector pattern of field polarity was observed during the last 3-1/2 months of the period, with the dominant polarity toward the sun below the solar equatorial plane. Two compound high-speed solar wind streams were also present during this period, one in each <span class="hlt">magnetic</span> field sector. Relative fluctuations of the field in magnitude and direction were found to have large time variations, but on <span class="hlt">average</span> the relative magnitude fluctuations were approximately constant over the range of heliocentric distance covered while the relative directional fluctuations showed a slight decrease on <span class="hlt">average</span> with increasing distance. The occurrence rate of directional discontinuities was also found to decrease with increasing radial distance from the sun.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19800011715','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19800011715"><span id="translatedtitle"><span class="hlt">Interplanetary</span> medium data book, supplement, 1975 - 1978</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>King, J. H.</p> <p>1979-01-01</p> <p>Since the issurance of the <span class="hlt">Interplanetary</span> Medium Data Book (NSSDC/WDC-A-R&S 77-04, 1977) which contains plots and listings of hourly <span class="hlt">average</span> <span class="hlt">interplanetary</span> field and plasma parameters covering the period November 27, 1963 through December 30, 1975, additional data are available which fill some 1975 data gaps and which extend the data coverage well into 1978. This supplement contains all the presently available data for the years 1975-1978, <span class="hlt">Interplanetary</span> <span class="hlt">magnetic</span> field (IMF) data are from the IMP 8 triaxial fluxgate magnetometer experiment. Derived plasma parameters are form the IMP 7 and IMP 8 instruments. Some of the early 1975 IMF data are from a HEOS 1 experiment.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E1531P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E1531P"><span id="translatedtitle">A Robust Method to Predict the Near-Sun and <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field Strength of Coronal Mass Ejections: Parametric and Case Studies</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Patsourakos, Spiros; Georgoulis, Manolis K.</p> <p>2016-07-01</p> <p>Predicting the near-Sun, and particularly the <span class="hlt">Interplanetary</span> (IP), <span class="hlt">magnetic</span> field structure of Coronal Mass Ejections (CMEs) and <span class="hlt">interplanetary</span> counterparts (ICMEs) is a topic of intense research activity. This is because Earth-directed CMEs with strong southward <span class="hlt">magnetic</span> fields are responsible for the most powerful geomagnetic storms. We have recently developed a simple two-tier method to predict the <span class="hlt">magnetic</span> field strength of CMEs in the outer corona and in the IP medium, using as input the <span class="hlt">magnetic</span>-helicity budget of the source solar active region and stereoscopic coronagraphic observations. Near-Sun CME <span class="hlt">magnetic</span> fields are obtained by utilizing the principle of <span class="hlt">magnetic</span> helicity conservation of flux-rope CMEs for coronagraphic observations. <span class="hlt">Interplanetary</span> propagation of the inferred values is achieved by employing power-law prescriptions of the radial evolution of the CME-ICME <span class="hlt">magnetic</span> fields. We hereby present a parametric study of our method, based on the observed statistics of input parameters, to infer the anticipated range of values for the near-Sun and <span class="hlt">interplanetary</span> CME-ICME <span class="hlt">magnetic</span> fields. This analysis is complemented by application of our method to several well-observed major CME-ICME events.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_8");'>8</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li class="active"><span>10</span></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_10 --> <div id="page_11" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="201"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016cosp...41E.393D','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016cosp...41E.393D"><span id="translatedtitle">Energetic particle transport and acceleration within the <span class="hlt">interplanetary</span> medium</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Dalla, Silvia</p> <p>2016-07-01</p> <p>The propagation through space of energetic particles accelerated at the Sun and in the inner heliosphere is governed by the characteristics of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field. At large scales, the <span class="hlt">average</span> Parker spiral configuration, on which transient <span class="hlt">magnetic</span> structures may be superimposed, dominates the transport, while at smaller scales turbulence scatters the particles and produces field line meandering. This talk will review the classical 1D approach to <span class="hlt">interplanetary</span> transport, mainly applied to Solar Energetic Particles (SEPs), as well as alternative models which allow for effects such as scattering perpendicular to the <span class="hlt">average</span> <span class="hlt">magnetic</span> field and field line meandering. The recently emphasized role of drifts in the propagation of SEPs will be discussed. The presentation will also review processes by which particle acceleration takes place within the <span class="hlt">interplanetary</span> medium and the overall way in which acceleration and transport shape in-situ observations of energetic particles.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2014cosp...40E2806R','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2014cosp...40E2806R"><span id="translatedtitle"><span class="hlt">Interplanetary</span> Charged Dust <span class="hlt">Magnetic</span> Clouds Striking the Magnetosphere: Coordinated Space-based and Ground-based Observations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Russell, C. T.; Chi, Peter; Lai, Hairong</p> <p></p> <p>In general, asteroids, meteoroids and dust do not interact with the plasma structures in the solar system, but after a collision between fast moving bodies the debris cloud contains nanoscale dust particles that are charged and behave like heavy ions. Dusty <span class="hlt">magnetic</span> clouds are then accelerated to the solar wind speed. While they pose no threat to spacecraft because of the particle size, the coherency imposed by the <span class="hlt">magnetization</span> of the cloud allows the cloud to interact with the Earth’s magnetosphere as well as the plasma in the immediate vicinity of the cloud. We call these clouds <span class="hlt">Interplanetary</span> Field Enhancements (IFEs). These IFEs are a unique class of <span class="hlt">interplanetary</span> field structures that feature cusp-shaped increases and decreases in the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field and a thin current sheet. The occurrence of IFEs is attributed to the interaction between the solar wind and dust particles produced in inter-bolide collisions. Previous spacecraft observations have confirmed that IFEs move with the solar wind. When IFEs strike the magnetosphere, they may distort the magnetosphere in several possible ways, such as producing a small indentation, a large scale compression, or a glancing blow. In any event if the IFE is slowed by the magnetosphere, the compression of the Earth’s field should be seen in the ground-based <span class="hlt">magnetic</span> records that are continuously recorded. Thus it is important to understand the magnetospheric response to IFE arrival. In this study, we investigate the IFE structure observed by spacecraft upstream of the magnetosphere and the induced <span class="hlt">magnetic</span> field perturbations observed by networks of ground magnetometers, including the THEMIS, CARISMA, McMAC arrays in North America and the IMAGE array in Europe. We find that, in a well-observed IFE event on December 24, 2006, all ground magnetometer stations observed an impulse at approximately 1217 UT when the IFE was expected to arrive at the Earth’s magnetopause. These ground stations spread across</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016SpWea..14...56S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016SpWea..14...56S"><span id="translatedtitle">Magnetohydrodynamic simulation of <span class="hlt">interplanetary</span> propagation of multiple coronal mass ejections with internal <span class="hlt">magnetic</span> flux rope (SUSANOO-CME)</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Shiota, D.; Kataoka, R.</p> <p>2016-02-01</p> <p>Coronal mass ejections (CMEs) are the most important drivers of various types of space weather disturbance. Here we report a newly developed magnetohydrodynamic (MHD) simulation of the solar wind, including a series of multiple CMEs with internal spheromak-type <span class="hlt">magnetic</span> fields. First, the polarity of the spheromak <span class="hlt">magnetic</span> field is set as determined automatically according to the Hale-Nicholson law and the chirality law of Bothmer and Schwenn. The MHD simulation is therefore capable of predicting the time profile of the southward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field at the Earth, in relation to the passage of a <span class="hlt">magnetic</span> cloud within a CME. This profile is the most important parameter for space weather forecasts of <span class="hlt">magnetic</span> storms. In order to evaluate the current ability of our simulation, we demonstrate a test case: the propagation and interaction process of multiple CMEs associated with the highly complex active region NOAA 10486 in October to November 2003, and present the result of a simulation of the solar wind parameters at the Earth during the 2003 Halloween storms. We succeeded in reproducing the arrival at the Earth's position of a large amount of southward <span class="hlt">magnetic</span> flux, which is capable of causing an intense <span class="hlt">magnetic</span> storm. We find that the observed complex time profile of the solar wind parameters at the Earth could be reasonably well understood by the interaction of a few specific CMEs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.4784P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.4784P"><span id="translatedtitle">Predicting the near-Sun and <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field of CMEs using photospheric magnetograms and coronagraph images</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Patsourakos, Spiros; Georgoulis, Manolis</p> <p>2016-04-01</p> <p>Earth-directed Coronal Mass Ejections (CMEs) containing a strong southward <span class="hlt">magnetic</span>-field component upon arrival at 1 AU statistically account for the most powerful geomagnetic storms. Unfortunately, though, we currently lack routine diagnostics of the <span class="hlt">magnetic</span> field of CMEs and its evolution in the inner heliosphere and the <span class="hlt">interplanetary</span> (IP) medium. We hereby present a simple, yet powerful and easy-to-implement, method to deduce the near-Sun and IP <span class="hlt">magnetic</span> field entrained in CMEs, by using photospheric magnetograms of the solar source regions and multi-viewpoint coronagraph images of the corresponding CMEs. The method relies on the principle of <span class="hlt">magnetic</span>-helicity conservation in low plasma-beta, flux-rope CMEs and a power-law prescription of the radial evolution of the CME <span class="hlt">magnetic</span> field in the IP medium. We outline a parametric study based on the observed statistics of input parameters to calculate a matrix of <span class="hlt">magnetic</span>-field solutions for 10000 synthetic CMEs. The robustness and possible limitations / ramifications of the method are deduced by a comparison with the distributions of the predicted CME-ICME <span class="hlt">magnetic</span> fields at 0.3 and 1 AU using actual Messenger and ACE published observations.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/183248','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/183248"><span id="translatedtitle">Magnetopause shape as a bivariate function of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field B{sub z} and solar wind dynamic pressure</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Roelof, E.C.; Sibeck, D.G.</p> <p>1993-12-01</p> <p>The authors present a new method for determining the shape of the magnetopause as a bivariate function of the hourly <span class="hlt">averaged</span> solar wind dynamic pressure (p) and the north-south component of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) B{sub z}. They represent the magnetopause (for X{sub GSE}>{minus}40R{sub E}) as an ellipsoid of revolution in solar-wind-aberrated coordinates and express the (p, B{sub z}) dependence of each of the three ellipsoid parameters as a second-order (6-term) bivariate expansion in lnp and B{sub z}. The authors define 12 overlapping bins in a normalized dimensionless (p,B{sub z}) {open_quotes}control space{close_quotes} and fit an ellipsoid to those magnetopause crossings having (p,B{sub z}) values within each bin. They also calculate the bivariate (lnp, B{sub z}) moments to second order over each bin in control space. They can then calculate the six control-space expansion coefficients for each of the three ellipsoid parameters in configuration space. From these coefficients they can derive useful diagnostics of the magnetopause shape as joint functions of p and B{sub z}: the aspect ratio of the ellipsoid`s minor-to-major axes the flank distance radius of curvature, and flaring angle (at X{sub GSE}=0); and the subsolar distance and radius of curvature. The authors confirm and quantify previous results that during periods of southward B{sub z} the subsolar magnetopause moves inward, while at X{sub GSE}=0 the flank magnetopause moves outward and the flaring angle increases. These changes are most pronounced during periods of low pressure, wherein all have a dependence on B{sub z} that is stronger and functionally different for B{sub z} southward as compared to B{sub z} northward. In contrast, all these changes are much less sensitive to IMF B{sub z} at the highest pressures. 44 refs., 22 figs., 6 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM33A2155A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM33A2155A"><span id="translatedtitle">Using ACE Observations of <span class="hlt">Interplanetary</span> Particles and <span class="hlt">Magnetic</span> Fields as Possible Contributors to Variations Observed at Van Allen Probes during Major events in 2013</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Armstrong, T. P.; Manweiler, J. W.; Gerrard, A. J.; Gkioulidou, M.; Lanzerotti, L. J.; Patterson, J. D.</p> <p>2013-12-01</p> <p>Observations from ACE EPAM including energy spectra of protons, helium, and oxygen will be prepared for coordinated use in estimating the direct and indirect access of energetic particles to inner and outer geomagnetic trapping zones. Complete temporal coverage from ACE at 12 seconds, 5 minutes, 17 minutes, hourly and daily cadences will be used to catalog <span class="hlt">interplanetary</span> events arriving at Earth including <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field sector boundaries, <span class="hlt">interplanetary</span> shocks, and <span class="hlt">interplanetary</span> coronal mass ejections, ICMEs. The first 6 months of 2013 have included both highly disturbed times, March 17 and May 22, and extended quiet periods of little or no variations. Among the specific questions that ACE and Van Allen Probes coordinated observations may aid in resolving are: 1. How much, if any, direct capture of <span class="hlt">interplanetary</span> energetic particles occurs and what conditions account for it? 2. How much influence do <span class="hlt">interplanetary</span> field and particle variations have on energization and/or loss of geomagnetically trapped populations? The poster will also present important links and describe methods and important details of access to numerically expressed ACE EPAM and Van Allen Probes RBSPICE observations that can be flexibly and easily accessed via the internet for student and senior researcher use.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20040171393','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20040171393"><span id="translatedtitle">The Fraction of <span class="hlt">Interplanetary</span> Coronal Mass Ejections That Are <span class="hlt">Magnetic</span> Clouds: Evidence for a Solar Cycle Variation</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Richardson, I. G.; Cane, H. V.</p> <p>2004-01-01</p> <p>"<span class="hlt">Magnetic</span> clouds" (MCs) are a subset of <span class="hlt">interplanetary</span> coronal mass ejections (ICMEs) characterized by enhanced <span class="hlt">magnetic</span> fields with an organized rotation in direction, and low plasma beta. Though intensely studied, MCs only constitute a fraction of all the ICMEs that are detected in the solar wind. A comprehensive survey of ICMEs in the near- Earth solar wind during the ascending, maximum and early declining phases of solar cycle 23 in 1996 - 2003 shows that the MC fraction varies with the phase of the solar cycle, from approximately 100% (though with low statistics) at solar minimum to approximately 15% at solar maximum. A similar trend is evident in near-Earth observations during solar cycles 20 - 21, while Helios 1/2 spacecraft observations at 0.3 - 1.0 AU show a weaker trend and larger MC fraction.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19830030751&hterms=1061&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2526%25231061','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830030751&hterms=1061&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3D%2526%25231061"><span id="translatedtitle">Dawn-dusk asymmetry of the tail region of the magnetosphere of Saturn and the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Akasofu, S.-I.; Roederer, M.; Krimigis, S. M.</p> <p>1982-01-01</p> <p>In connection with the findings of the Voyager 1 mission, it appears that the tail lobe of Saturn is very different from that of earth and Jupiter, in that the latter are devoid of energetic particles, and <span class="hlt">magnetic</span> field lines in this region are thought to be open and interconnecting with the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field at large distances in the antisolar direction. The present investigation is concerned with a possible explanation of these observations, taking into account a model of Saturn's magnetosphere. It is shown that the Voyager 1 spacecraft remained in the closed region of the magnetotail during its entire tail traversal and did not have an opportunity to penetrate into the high latitude lobe. It is concluded that Saturn probably has a tail lobe just like earth and Jupiter. However, this tail lobe was not traversed by Voyager.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016AdSpR..58..218A','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016AdSpR..58..218A"><span id="translatedtitle">The Kelvin-Helmholtz instability under Parker-Spiral <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field conditions at the magnetospheric flanks</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Adamson, E.; Nykyri, K.; Otto, A.</p> <p>2016-07-01</p> <p>We have generated fully three-dimensional, high-resolution magnetohydrodynamic (MHD) simulations of the Kelvin-Helmholtz (KH) Instability during Parker-Spiral <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field (IMF) conditions at the dawnside magnetospheric flank magnetopause. Results of these simulations show that, although the draping of a strong tangential <span class="hlt">magnetic</span> field component around the magnetopause, tailward of the terminator (due to the Parker-Spiral orientation), tends to stabilize the growth of such instabilities within the shear-flow plane, Kelvin-Helmholtz waves with a k -vector tilted out of this plane may, nonetheless, develop into the nonlinear phase. This result suggests that obliquely propagating KH waves may contribute to the dawn-dusk asymmetries observed in plasma sheet parameters.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015DPS....4750503L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015DPS....4750503L"><span id="translatedtitle">Impacts of an <span class="hlt">Interplanetary</span> Coronal Mass Ejection and the Crustal <span class="hlt">Magnetic</span> Fields to the Martian hot O corona</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Lee, Yuni; Combi, Michael; Tenishev, Valeriy; Bougher, Stephen</p> <p>2015-11-01</p> <p>An <span class="hlt">interplanetary</span> coronal mass ejection (ICME) is a large amount of mass entrained in the heliospheric <span class="hlt">magnetic</span> field and propagating outward from the Sun into the <span class="hlt">interplanetary</span> medium. Upon arrival at Mars, ICMEs interact with its upper atmosphere and ionosphere, causing important impacts in the planetary environment. In March 2015, a strong solar event was observed and associated with a major ICME. The major ICME events aroused a chain of events on Mars, which were detected by the instruments onboard Mars Atmosphere and Volatile EvolutioN (MAVEN). The consequences in the upper atmosphere are directly related to the important processes that lead to the atmospheric escape. We report here our examinations of the impacts of the March 8th ICME event on the Martian hot O corona by using our 3D framework, which couples the Mars application of the Adaptive Mesh Particle Simulator (M-AMPS), the Mars Global Ionosphere-Thermosphere Model (M-GITM), and the Mars multi-fluid MHD (MF-MHD) model. Also, we present the effects of the crustal <span class="hlt">magnetic</span> fields on the structure of the hot O corona to study the interesting signatures of the crustal <span class="hlt">magnetic</span> fields. Due to the minimal impacts of the ICME deep in the thermosphere and ionosphere, where the maximum production of hot O occurs, our model results showed a stable hot O corona during and after the peak ICME event. However, the structure of the corona was affected by the existence of the crustal <span class="hlt">magnetic</span> fields with a decrease in escape rate.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21576620','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21576620"><span id="translatedtitle">PROPAGATION OF SOLAR ENERGETIC PARTICLES IN THREE-DIMENSIONAL <span class="hlt">INTERPLANETARY</span> <span class="hlt">MAGNETIC</span> FIELDS: IN VIEW OF CHARACTERISTICS OF SOURCES</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>He, H.-Q.; Qin, G.; Zhang, M. E-mail: gqin@spaceweather.ac.cn</p> <p>2011-06-20</p> <p>In this paper, a model of solar energetic particle (SEP) propagation in the three-dimensional Parker <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field is calculated numerically. We study the effects of the different aspects of particle sources on the solar surface, which include the source location, coverage of latitude and longitude, and spatial distribution of source particle intensity, on propagation of SEPs with both parallel and perpendicular diffusion. We compute the particle flux and anisotropy profiles at different observation locations in the heliosphere. From our calculations, we find that the observation location relative to the latitudinal and longitudinal coverage of particle source has the strongest effects on particle flux and anisotropy profiles observed by a spacecraft. When a spacecraft is directly connected to the solar sources by the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field lines, the observed particle fluxes are larger than when the spacecraft is not directly connected. This paper focuses on the situations when a spacecraft is not connected to the particle sources on the solar surface. We find that when the <span class="hlt">magnetic</span> footpoint of the spacecraft is farther away from the source, the observed particle flux is smaller and its onset and maximum intensity occur later. When the particle source covers a larger range of latitude and longitude, the observed particle flux is larger and appears earlier. There is east-west azimuthal asymmetry in SEP profiles even when the source distribution is east-west symmetric. However, the detail of particle spatial distribution inside the source does not affect the profile of the SEP flux very much. When the <span class="hlt">magnetic</span> footpoint of the spacecraft is significantly far away from the particle source, the anisotropy of particles in the early stage of an SEP event points toward the Sun, which indicates that the first arriving particles come from outside of the observer through perpendicular diffusion at large radial distances.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950048767&hterms=1575&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2526%25231575','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950048767&hterms=1575&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3D%2526%25231575"><span id="translatedtitle">The determination of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field polarities around sector boundaries using E greater than 2 keV electrons</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Kahler, S.; Lin, R. P.</p> <p>1994-01-01</p> <p>The determination of the polarities of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> fields (whether the field direction is outward from or inward toward the sun) has been based on a comparison of observed field directions with the nominal Parker spiral angle. These polarities can be mapped back to the solar source field polarities. This technique fails when field directions deviate substantially from the Parker angle or when fields are substantially kinked. We introduce a simple new technique to determine the polarities of <span class="hlt">interplanetary</span> fields using E greater than 2 keV <span class="hlt">interplanetary</span> electrons which stream along field lines away from the sun. Those electrons usually show distinct unidirectional pitch-angle anisotropies either parallel or anti-parallel to the field. Since the electron flow direction is known to be outward from the sun, the anisotropies parallel to the field indicate outward-pointing, positive-polarity fields, and those anti-parallel indicate inward-pointing, negative-polarity fields. We use data from the UC Berkeley electron experiment on the International Sun Earth Explorer 3 (ISSE-3) spacecraft to compare the field polarities deduced from the electron data, Pe (outward or inward), with the polarities inferred from field directions, Pd, around two sector boundaries in 1979. We show examples of large (greater than 100 deg) changes in azimuthal field direction Phi over short (less than 1 hr) time scales, some with and some without reversals in Pe. The latter cases indicate that such large directional changes can occur in unipolar structures. On the other hand, we found an example of a change in Pe during which the rotation in Phi was less than 30 deg, indicating polarity changes in nearly unidirectional structures. The field directions are poor guides to the polarities in these cases.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2006JGRA..11111102X','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2006JGRA..11111102X"><span id="translatedtitle">Magnetohydrodynamic simulation of the interaction between <span class="hlt">interplanetary</span> strong shock and <span class="hlt">magnetic</span> cloud and its consequent geoeffectiveness: 2. Oblique collision</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Xiong, Ming; Zheng, Huinan; Wang, Yuming; Wang, Shui</p> <p>2006-11-01</p> <p>Numerical studies of the <span class="hlt">interplanetary</span> "shock overtaking <span class="hlt">magnetic</span> cloud (MC)" event are continued by a 2.5-dimensional magnetohydrodynamic (MHD) model in heliospheric meridional plane. <span class="hlt">Interplanetary</span> direct collision (DC)/oblique collision (OC) between an MC and a shock results from their same/different initial propagation orientations. For radially erupted MC and shock in solar corona, the orientations are only determined respectively by their heliographic locations. OC is investigated in contrast with the results in DC (Xiong, 2006). The shock front behaves as a smooth arc. The cannibalized part of MC is highly compressed by the shock front along its normal. As the shock propagates gradually into the preceding MC body, the most violent interaction is transferred sideways with an accompanying significant narrowing of the MC's angular width. The opposite deflections of MC body and shock aphelion in OC occur simultaneously through the process of the shock penetrating the MC. After the shock's passage, the MC is restored to its oblate morphology. With the decrease of MC-shock commencement interval, the shock front at 1 AU traverses MC body and is responsible for the same change trend of the latitude of the greatest geoeffectiveness of MC-shock compound. Regardless of shock orientation, shock penetration location regarding the maximum geoeffectiveness is right at MC core on the condition of very strong shock intensity. An appropriate angular difference between the initial eruption of an MC and an overtaking shock leads to the maximum deflection of the MC body. The larger the shock intensity is, the greater is the deflection angle. The interaction of MCs with other disturbances could be a cause of deflected propagation of <span class="hlt">interplanetary</span> coronal mass ejection (ICME).</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19950029575&hterms=sun+facts&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsun%2Bfacts','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19950029575&hterms=sun+facts&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D10%26Ntt%3Dsun%2Bfacts"><span id="translatedtitle"><span class="hlt">Interplanetary</span> <span class="hlt">magnetic</span> field dependency of stable Sun-aligned polar cap arcs</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Valladares, C. E.; Carlson, H. C., Jr.; Fukui, K.</p> <p>1994-01-01</p> <p>This is the first analysis, using a statistically significant data set, of the morphological dependence of the presence, orientation, and motion of stable sun-aligned polar cap arcs upon the vector <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF). For the one winter season analyzed we had 1392 all-sky 630.0-nm images of 2-min resolution containing a total of 150 polar cap arcs, all with corresponding values of the IMF as measured by International Monitoring Platform (IMP) 8 or International Sun Earth Explorer (ISEE) 2. After demonstrating an unbiased data set with smooth normal distributions of events versus the dimensions of time, space, and IMF component, we examine IMF dependencies of the properties of the optical arcs. A well-defined dependence for B(sub z) is found for the presence/absence of stable Sun-aligned polar cap arcs. Consistent with previous statistical studies, the probability of observing polar cap aurora steadily increases for larger positive values of B(sub z), and linearly decreases when B(sub z) becomes more negative. The probability of observing Sun-aligned arcs within the polar cap is determined to vary sharply as a function of the arc location; arcs were observed 40% of the time on the dawnside and only 10% on the duskside. This implies an overall probability of at least 40% for the whole polar cap. 20% of the arcs were observed during 'southward IMF conditions,' but in fact under closer inspection were found to have been formed under northward IMF conditions; these 'residual' positive B(sub z) arcs ha d a delayed residence time in the polar cap of about what would be expected after a north to south transition of B(sub z). A firm dependence on B(sub y) is also found for both the orientation and the dawn-dusk direction of motion of the arcs. All the arcs are Sun-aligned to a first approximation, but present deviations from this orientation, depending primarily upon the location of the arc in corrected geomagnetic (CG) coordinates. The arcs populating the</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850044803&hterms=sun+bear&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsun%2Bbear','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850044803&hterms=sun+bear&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dsun%2Bbear"><span id="translatedtitle"><span class="hlt">Magnetic</span> fields on the sun and the north-south component of transient variations of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field at 1 AU</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Tang, F.; Akasofu, S.-I.; Smith, E.; Tsurutani, B.</p> <p>1985-01-01</p> <p>In order to study the relationship between solar <span class="hlt">magnetic</span> fields and the transient variations of the north-south component B(Z) of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) at 1 AU, flares from unusual north-south oriented active regions, large IMF B(Z) events, and large flares with comprehensive flare index higher than 12 were collected. The associated IMF B(Z) changes or the <span class="hlt">magnetic</span> field of the initiating flares are investigated. For those cases where an association between a transient B(Z) variation and an initiating flare is plausible, it is found that, for a given flare field, the orientation of the corresponding transient variation of B(Z) may be in agreement with the flare field, opposite to it, or more often, fluctuating in both magnitude and direction. Conversely, an IMF B(Z) event may originate in a flare field in the same <span class="hlt">magnetic</span> orientation, opposite to it, or in the east-west orientation.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5313607','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5313607"><span id="translatedtitle">On the electrodynamical state of the auroral ionosphere during northward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field: A transpolar arc case study</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Marklund, G.T.; Blomberg, L.G. ); Murphree, J.S.; Elphinstone, R.D. ); Zanetti, L.J.; Erlandson, R.E. ); Sandahl, I. ); de la Beaujardiere, O. ); Opgenoorth, H. ); Rich, F.J. )</p> <p>1991-06-01</p> <p>The ionospheric electrodynamical state has been reconstructed for a transpolar arc event during northward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field conditions. An extensive set of observations by Viking and other satellites and by ground-based radars has been used to provide realistic model input data or to verify the modeling results. The resulting convection pattern is found to be consistent with the Viking electric field and intimately linked to the prevalent auroral distribution. It is characterized by a large evening cell, well extended across noon and split up by two separated potential minima, and a minor crescent-shaped morning cell. The convection signatures are found to vary a lot along the transpolar arc depending on the relative role of the arc-associated convection and the ambient convection. The transpolar arc is generally embedded in antisunward convective flow except near the connection points with the auroral oval, where sunward flow exists in localized regions.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19820029723&hterms=ZHUANG&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DZHUANG','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19820029723&hterms=ZHUANG&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D20%26Ntt%3DZHUANG"><span id="translatedtitle">The influence of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field and thermal pressure on the position and shape of the magnetopause</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Zhuang, H. C.; Russell, C. T.; Walker, R. J.</p> <p>1981-01-01</p> <p>An ellipsoidal model, in which the size of an ellipsoid of revolution with a constant eccentricity is inversely proportional to the sixth root of the stream pressure of the solar wind, is used to represent the location of the dayside magnetopause and to study the influences of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field and thermal pressure on its location. The effects of the IMF and thermal pressure on the location of the magnetopause are calculated analytically by using the Chapman-Ferraro theory. The changes in magnetopause size, shape and orientation caused by including the thermal pressure are inversely proportional to the square of the sonic Mach number of the solar wind and are sufficient to explain the observed slight departure of the magnetotail from the expected aberration due to the earth's orbital motion. The results suggest that little angular momentum is being carried away from the sun by the solar wind.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016EGUGA..18.1261P','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016EGUGA..18.1261P"><span id="translatedtitle">A data-driven coupled modeling approach to predicting the <span class="hlt">magnetic</span> structure of <span class="hlt">interplanetary</span> coronal mass ejections</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Pomoell, Jens; Kilpua, Emilia; Isavnin, Alexey; Palmerio, Erika; Lumme, Erkka</p> <p>2016-04-01</p> <p>Unraveling the formation and evolution of coronal mass ejections from the Sun to the Earth remains one of the outstanding goals in current solar-terrestrial physics and space weather research. In this work, we present our data-driven modeling principle designed to tackle specifically the question of predicting the <span class="hlt">magnetic</span> structure of <span class="hlt">interplanetary</span> coronal mass ejections. Our modeling paradigm consists of three components: a) a data-driven non-potential model of the coronal <span class="hlt">magnetic</span> field up to 2.5 RSun fed by a time-sequence of vector magnetograms b) a versatile flux rope <span class="hlt">magnetic</span> field model c) a three-dimensional MHD model that computes self-consistently the dynamics in the inner heliosphere from 0.1 AU up to the orbit of Mars (Euhforia). The key feature of our approach is to employ a flux rope model in Euhforia whose parameters are determined solely through data-driven modeling. While the time-dependent kinematics and morphology of the flux rope are fitted using EUV and coronagraph observations, the <span class="hlt">magnetic</span> parameters are directly obtained from the data-driven coronal model. In addition to presenting the modeling scheme, we showcase results of the modeling using well-observed case studies and comparisons with in-situ observations. Finally, we discuss future horizons for our model.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=20110023418&hterms=cosmic+rays&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3D%2528cosmic%2Brays%2529','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=20110023418&hterms=cosmic+rays&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3D%2528cosmic%2Brays%2529"><span id="translatedtitle">Galactic Cosmic Ray Intensity Response to <span class="hlt">Interplanetary</span> Coronal Mass Ejections/<span class="hlt">Magnetic</span> Clouds in 1995-2009</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Richardson, I. G.; Cane, H. V.</p> <p>2011-01-01</p> <p>We summarize the response of the galactic cosmic ray (CGR) intensity to the passage of the more than 300 <span class="hlt">interplanetary</span> coronal mass ejections (ICMEs) and their associated shocks that passed the Earth during 1995-2009, a period that encompasses the whole of Solar Cycle 23. In approx.80% of cases, the GCR intensity decreased during the passage of these structures, i.e., a "Forbush decrease" occurred, while in approx.10% there was no significant change. In the remaining cases, the GCR intensity increased. Where there was an intensity decrease, minimum intensity was observed inside the ICME in approx.90% of these events. The observations confirm the role of both post-shock regions and ICMEs in the generation of these decreases, consistent with many previous studies, but contrary to the conclusion of Reames, Kahler, and Tylka (Astrophys. 1. Lett. 700, L199, 2009) who, from examining a subset of ICMEs with flux-rope-like <span class="hlt">magnetic</span> fields (<span class="hlt">magnetic</span> clouds) argued that these are "open structures" that allow free access of particles including GCRs to their interior. In fact, we find that <span class="hlt">magnetic</span> clouds are more likely to participate in the deepest GCR decreases than ICMEs that are not <span class="hlt">magnetic</span> clouds.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19740020146','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19740020146"><span id="translatedtitle"><span class="hlt">Interplanetary</span> shock waves associated with solar flares</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Chao, J. K.; Sakurai, K.</p> <p>1974-01-01</p> <p>The interaction of the earth's <span class="hlt">magnetic</span> field with the solar wind is discussed with emphasis on the influence of solar flares. The geomagnetic storms are considerered to be the result of the arrival of shock wave generated by solar flares in <span class="hlt">interplanetary</span> space. Basic processes in the solar atmosphere and <span class="hlt">interplanetary</span> space, and hydromagnetic disturbances associated with the solar flares are discussed along with observational and theoretical problems of <span class="hlt">interplanetary</span> shock waves. The origin of <span class="hlt">interplanetary</span> shock waves is also discussed.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li class="active"><span>11</span></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_11 --> <div id="page_12" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="221"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016SoPh..291.2049H&link_type=ABSTRACT','NASAADS'); return false;" href="http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2016SoPh..291.2049H&link_type=ABSTRACT"><span id="translatedtitle"><span class="hlt">Interplanetary</span> Type IV Bursts</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Hillaris, A.; Bouratzis, C.; Nindos, A.</p> <p>2016-08-01</p> <p>We study the characteristics of moving type IV radio bursts that extend to hectometric wavelengths (<span class="hlt">interplanetary</span> type IV or type {IV}_{{IP}} bursts) and their relationship with energetic phenomena on the Sun. Our dataset comprises 48 <span class="hlt">interplanetary</span> type IV bursts observed with the Radio and Plasma Wave Investigation (WAVES) instrument onboard Wind in the 13.825 MHz - 20 kHz frequency range. The dynamic spectra of the Radio Solar Telescope Network (RSTN), the Nançay Decametric Array (DAM), the Appareil de Routine pour le Traitement et l' Enregistrement Magnetique de l' Information Spectral (ARTEMIS-IV), the Culgoora, Hiraso, and the Institute of Terrestrial <span class="hlt">Magnetism</span>, Ionosphere and Radio Wave Propagation (IZMIRAN) Radio Spectrographs were used to track the evolution of the events in the low corona. These were supplemented with soft X-ray (SXR) flux-measurements from the Geostationary Operational Environmental Satellite (GOES) and coronal mass ejections (CME) data from the Large Angle and Spectroscopic Coronagraph (LASCO) onboard the Solar and Heliospheric Observatory (SOHO). Positional information of the coronal bursts was obtained by the Nançay Radioheliograph (NRH). We examined the relationship of the type IV events with coronal radio bursts, CMEs, and SXR flares. The majority of the events (45) were characterized as compact, their duration was on <span class="hlt">average</span> 106 minutes. This type of events was, mostly, associated with M- and X-class flares (40 out of 45) and fast CMEs, 32 of these events had CMEs faster than 1000 km s^{-1}. Furthermore, in 43 compact events the CME was possibly subjected to reduced aerodynamic drag as it was propagating in the wake of a previous CME. A minority (three) of long-lived type {IV}_{{IP}} bursts was detected, with durations from 960 minutes to 115 hours. These events are referred to as extended or long duration and appear to replenish their energetic electron content, possibly from electrons escaping from the corresponding coronal</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1988KosIs..26..324E','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1988KosIs..26..324E"><span id="translatedtitle">Structure of <span class="hlt">interplanetary</span> streams according to plasma and <span class="hlt">magnetic</span>-field measurements on Prognoz-6 during November 25-26, 1977</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Eroshenko, E. G.; Ivanov, K. G.; Verigin, M. I.; Kotova, G. A.; Stiazhkin, V. A.</p> <p>1988-03-01</p> <p>The Prognoz-6 satellite studied <span class="hlt">magnetic</span>-field and plasma disturbances in the <span class="hlt">interplanetary</span> medium near the earth during the passage of an isolated flare stream and a quasi-steady stream from a coronal hole on November 25-26, 1977 (the fourth STIP period). Data indicate the strongly oblique incidence of the stream on the earth's magnetosphere, and provide evidence of the meridional flattening of this stream. The characteristics of the <span class="hlt">magnetic</span> cloud from the isolated flare were investigated.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2003GeoRL..30.1798F','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2003GeoRL..30.1798F"><span id="translatedtitle">Weighted <span class="hlt">averages</span> of <span class="hlt">magnetization</span> from <span class="hlt">magnetic</span> field measurements: A fast interpretation tool</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Fedi, Maurizio</p> <p>2003-08-01</p> <p><span class="hlt">Magnetic</span> anomalies may be interpreted in terms of weighted <span class="hlt">averages</span> of <span class="hlt">magnetization</span> (WAM) by a simple transformation. The WAM transformation consists of dividing at each measurement point the experimental <span class="hlt">magnetic</span> field by a normalizing field, computed from a source volume with a homogeneous unit-<span class="hlt">magnetization</span>. The transformation yields a straightforward link among source and field position vectors. A main WAM outcome is that sources at different depths appear well discriminated. Due to the symmetry of the problem, the higher the considered field altitude, the deeper the sources outlined by the transformation. This is shown for single and multi-source synthetic cases as well as for real data. We analyze the real case of Mt. Vulture volcano (Southern Italy), where the related anomaly strongly interferes with that from deep intrusive sources. The volcanic edifice is well identified. The deep source is estimated at about 9 km depth, in agreement with other results.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19920059359&hterms=heat+Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dheat%2BSolar','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19920059359&hterms=heat+Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D50%26Ntt%3Dheat%2BSolar"><span id="translatedtitle"><span class="hlt">Interplanetary</span> <span class="hlt">magnetic</span> field connection to the sun during electron heat flux dropouts in the solar wind</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Lin, R. P.; Kahler, S. W.</p> <p>1992-01-01</p> <p>The paper discusses observations of 2- to 8.5-keV electrons, made by measurements aboard the ISEE 3 spacecraft during the periods of heat flux decreases (HFDs) reported by McComas et al. (1989). In at least eight of the total of 25 HFDs observed, strong streaming of electrons that were equal to or greater than 2 keV outward from the sun was recorded. In one HFD, an impulsive solar electron event was observed with an associated type III radio burst, which could be tracked from the sun to about 1 AU. It is concluded that, in many HFDs, the <span class="hlt">interplanetary</span> field is still connected to the sun and that some energy-dependent process may produce HFDs without significantly perturbing electrons of higher energies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/servlets/purl/869326','DOE-PATENT-XML'); return false;" href="http://www.osti.gov/scitech/servlets/purl/869326"><span id="translatedtitle">High <span class="hlt">average</span> power <span class="hlt">magnetic</span> modulator for metal vapor lasers</span></a></p> <p><a target="_blank" href="http://www.osti.gov/doepatents">DOEpatents</a></p> <p>Ball, Don G.; Birx, Daniel L.; Cook, Edward G.; Miller, John L.</p> <p>1994-01-01</p> <p>A three-stage <span class="hlt">magnetic</span> modulator utilizing <span class="hlt">magnetic</span> pulse compression designed to provide a 60 kV pulse to a copper vapor laser at a 4.5 kHz repetition rate is disclosed. This modulator operates at 34 kW input power. The circuit includes a step up auto transformer and utilizes a rod and plate stack construction technique to achieve a high packing factor.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19810016474','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19810016474"><span id="translatedtitle"><span class="hlt">Magnetic</span> loop behind an <span class="hlt">interplanetary</span> shock: Voyager, Helios and IMP-8 observations</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burlaga, L.; Sittler, E.; Mariani, F.; Schwenn, R.</p> <p>1981-01-01</p> <p>The shock was followed by a turbulent sheath in which there were large fluctuations in both the strength and direction of the <span class="hlt">magnetic</span> field. This in turn was followed by a region (<span class="hlt">magnetic</span> cloud) in which the <span class="hlt">magnetic</span> field vectors were observed to change by rotating nearly parallel to a plane, consistent with the passage of a <span class="hlt">magnetic</span> loop. This loop extended at least 30 deg in longitude between 1-2 AU, and its radial dimension was approximately 0.5 AU. In the cloud the field strength was high and the density and temperature were relatively low. Thus, the dominant pressure in the cloud was that of the <span class="hlt">magnetic</span> field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/207234','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/207234"><span id="translatedtitle">Three-dimensional position and shape of the bow shock and their variation with Alfvenic, sonic and magnetosonic Mach numbers and <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field orientation</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Peredo, M.; Mazur, E.; Slavin, J.A.</p> <p>1995-05-01</p> <p>A large set of bow shock crossings (i.e., 1392) observed by 17 spacecraft has been used to explore the three-dimensional shape and location of the Earth`s bow shock and its dependence on solar wind and <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) conditions. This study investigates deviations from gas dynamic flow models associated with the <span class="hlt">magnetic</span> terms in the magnetohydrodynamic (MHD) equations. Empirical models predicting the statistical position and shape of the bow shock for arbitrary values of the solar wind pressure, IMF, and Alfvenic Mach number (M{sub A}) have been derived. Individual crossings have been taken into consideration by normalizing the observed crossings to the <span class="hlt">average</span> value <p> = 3.1 nPa. The resulting data set has been used to fit three-dimensional bow shock surfaces and to explore the variations in these surfaces with sonic (M{sub S}), Alfvenic (M{sub A}) and magnetosonic (M{sub MS}) Mach numbers. Analysis reveals that among the three Mach numbers, M{sub A} provides the best ordering of the least square bow shock curves. The subsolar shock is observed to move Earthward while the flanks flare outward in response to decreasing M{sub A}; the net change represents a 6-10% effect. Variations due to changes in the IMF orientation were investigated by rotating the crossings into geocentric <span class="hlt">interplanetary</span> medium coordinates. This study confirms a north-south versus east-west asymmetry and quantifies its variation with M{sub S}, M{sub A}, M{sub MS}, and IMF orientation. A 2-7% effect is measured, with the asymmetry being more pronounced at low Mach numbers. Combining the bow shock models with the magnetopause model of Roelof and Sibeck, variations in the magnetopause size at the subpolar point is found to be 1.46; at dawn and dusk, the ratios are found to be 1.89 and 1.93, respectively. The subsolar magnetosheath thickness is used to derive the polytropic index {gamma} according to the empirical relation of Spreiter. 55 refs., 6 figs., 3 tabs.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19830011396','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19830011396"><span id="translatedtitle">Dynamical evolution of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> fields and flows between 0.3 AU and 8.5 AU: Entrainment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burlaga, L. F.; Schwenn, R.; Rosenbauer, H.</p> <p>1983-01-01</p> <p>The radial evolution of <span class="hlt">interplanetary</span> flows and associated <span class="hlt">magnetic</span> fields between 0.3 AU and 8.5 was analyzed using data from Helios 1 and Voyager 1, respectively. During a 70 day interval Voyager 1 observed two streams which appeared to be recurrent and which had little fine structure. The corresponding flows observed by Helios 1 were much more complex, showing numerous small streams, transient flows and shocks as well as a few large corotating streams. It is suggested that in moving to 8 AU the largest corotating streams swept up the slower flows (transient and/or corotating streams) and shocks into a relatively thin region in which they coalesced to form a single large amplitude compression wave. This combined process of sweeping and coalescence is referred to as entrainment. The resulting large amplitude compression wave is different from that formed by the steepening of a corotating stream from a coronal hole, because different flows from distinct sources, with possibly different composition and <span class="hlt">magnetic</span> polarity, are brought together to form a single new structure.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.ncbi.nlm.nih.gov/pubmed/11776989','PUBMED'); return false;" href="http://www.ncbi.nlm.nih.gov/pubmed/11776989"><span id="translatedtitle">Radiation shielding of astronauts in <span class="hlt">interplanetary</span> flights: the CREAM surveyor to Mars and the <span class="hlt">magnetic</span> lens system for a spaceship.</span></a></p> <p><a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?DB=pubmed">PubMed</a></p> <p>Spillantini, P; Taccetti, F; Papini, P; Rossi, L; Casolino, M</p> <p>2001-01-01</p> <p>The radiation absorbed by astronauts during <span class="hlt">interplanetary</span> flights is mainly due to cosmic rays of solar origin (SCR). In the most powerful solar flares the dose absorbed in few hours can exceed that cumulated in one year of exposition to the galactic component of cosmic rays (GCR). At energies above the minimum one needed to cross the walls of the spaceship there are extrapolations and guesses, but no data, on the angular distribution of SCR's, an information that is necessary for establishing whatever defence strategy. It was therefore proposed of sending to Mars a measurement device, that should continuously collect data during the travel, and possibly also in the orbit around Mars and on the Mars surface. The device should identify the particle and privilege the completeness in the measurement of its parameters. In fact the high energy electrons travel at speed of the light and could be used in the and future dangerous proton component. Also the much less abundant but individually more dangerous ions should be identified. The device should indeed include a <span class="hlt">magnetic</span> spectrometer and a high granularity range telescope, and a good time of flight measurement. ASI is supporting an assessment study of a possible mission of such a device on board of the 2005 probe to Mars. A parallel technical study is also in progress to define the workable techniques and the possible configurations of a system of <span class="hlt">magnetic</span> lenses for protecting the crew of a spaceship. PMID:11776989</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJS..224...27S','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJS..224...27S"><span id="translatedtitle">A Statistical Study of the <span class="hlt">Average</span> Iron Charge State Distributions inside <span class="hlt">Magnetic</span> Clouds for Solar Cycle 23</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Song, H. Q.; Zhong, Z.; Chen, Y.; Zhang, J.; Cheng, X.; Zhao, L.; Hu, Q.; Li, G.</p> <p>2016-06-01</p> <p><span class="hlt">Magnetic</span> clouds (MCs) are the <span class="hlt">interplanetary</span> counterparts of coronal <span class="hlt">magnetic</span> flux ropes. They can provide valuable information regarding flux rope characteristics at their eruption stage in the corona, which is unable to be explored in situ at present. In this paper, we make a comprehensive survey of the <span class="hlt">average</span> iron charge-state (< Q> {Fe}) distributions inside 96 MCs for solar cycle 23 using Advanced Composition Explorer (ACE) data. Since the < Q> {Fe} in the solar wind are typically around 9+ to 11+, the Fe charge state is defined as being high when the < Q> {Fe} is larger than 12+, which implies the existence of a considerable amount of Fe ions with high charge states (e.g., ≥16+). The statistical results show that the < Q> {Fe} distributions of 92 (∼96%) MCs can be classified into four groups with different characteristics. In group A (11 MCs), the < Q> {Fe} shows a bi-modal distribution with both peaks being higher than 12+. Group B (4 MCs) presents a unimodal distribution of < Q> {Fe}, with its peak being higher than 12+. In groups C (29 MCs) and D (48 MCs), the < Q> {Fe} remains higher and lower than 12+ throughout ACE’s passage through the MC, respectively. Possible explanations of these distributions are discussed.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989Ge%26Ae..29..304I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989Ge%26Ae..29..304I"><span id="translatedtitle"><span class="hlt">Interplanetary</span> <span class="hlt">magnetic</span> cloud from the solar flare of Nov. 22, 1977</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ivanov, K. G.; Stiazhkin, V. A.; Kharshiladze, A. F.</p> <p>1989-04-01</p> <p>Attention is given to experimental Bx, By, and Bz profiles of the IMF measured by the Prognoz-6, ISEE-2, and IMP-8 satellites during the passage of a <span class="hlt">magnetic</span> cloud from the intense solar flare of Nov. 22, 1977. These profiles are compared with a theoretical model of a force-free diffusion-pinch <span class="hlt">magnetic</span> field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015EGUGA..17.3902C','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015EGUGA..17.3902C"><span id="translatedtitle">Maps of <span class="hlt">average</span> ionospheric vorticity ordered by relationship with the open-closed <span class="hlt">magnetic</span> field line boundary</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Chisham, Gareth</p> <p>2015-04-01</p> <p>Spatiotemporal variations of ionospheric vorticity are a measure of the dynamical coupling of the magnetosphere to the ionosphere via <span class="hlt">magnetic</span> field-aligned currents (FACs). Indeed, ionospheric vorticity measurements have often been used as proxy measurements for FACs. Previously, we have determined statistical models of ionospheric vorticity using 6 years of ionospheric convection velocity measurements made by the SuperDARN HF radar network in the northern hemisphere ionosphere and shown that the spatial variation of these probability distributions is well organised according to the well-established large-scale FAC structure in the polar ionosphere. However, to date, these statistical models have been parameterised solely by the state of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF), and as such do not account for the range of polar cap sizes that occur for a single IMF state. This leads to a distortion of the shape of the resulting statistical maps that makes features in the statistical variations appear smoother than those in instantaneous/short-time <span class="hlt">averaged</span> measurements. This is because the <span class="hlt">averaging</span> process does not consider the variable size of the polar cap, by which spatial features in the ionospheric vorticity variation are ordered. Using open-closed <span class="hlt">magnetic</span> field line boundary measurements determined from FUV imager data from the IMAGE spacecraft, we investigate the parameterisation of the statistical ionospheric vorticity models with polar cap size in addition to the state of the IMF. The results of this analysis have implications for other statistical models determined in this way, such as those for FACs and ionospheric convection.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19910042730&hterms=coils+mr&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcoils%2Bmr','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19910042730&hterms=coils+mr&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3Dcoils%2Bmr"><span id="translatedtitle">A deployable high temperature superconducting coil (DHTSC) - A novel concept for producing <span class="hlt">magnetic</span> shields against both solar flare and Galactic radiation during manned <span class="hlt">interplanetary</span> missions</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Cocks, F. Hadley</p> <p>1991-01-01</p> <p>The discovery of materials which are superconducting above 100 K makes possible the use of superconducting coils deployed beyong the hull of an <span class="hlt">interplanetary</span> spacecraft to produce a <span class="hlt">magnetic</span> shield capable of giving protection not only against solar flare radiation, but also even against Galactic radiation. Such deployed coils can be of very large size and can thus achieve the great <span class="hlt">magnetic</span> moments required using only relatively low currents. Deployable high-temperature-superconducting coil <span class="hlt">magnetic</span> shields appear to offer very substantial reductions in mass and energy compared to other concepts and could readily provide the radiation protection needed for a Mars mission or space colonies.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015MsT..........2M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015MsT..........2M"><span id="translatedtitle">Statistical Study of <span class="hlt">Interplanetary</span> Coronal Mass Ejections with Strong <span class="hlt">Magnetic</span> Fields</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Murphy, Matthew E.</p> <p></p> <p>Coronal Mass Ejections (CMEs) with strong <span class="hlt">magnetic</span> fields (B ) are typically associated with significant Solar Energetic Particle (SEP) events, high solar wind speed and solar flare events. Successful prediction of the arrival time of a CME at Earth is required to maximize the time available for satellite, infrastructure, and space travel programs to take protective action against the coming flux of high-energy particles. It is known that the <span class="hlt">magnetic</span> field strength of a CME is linked to the strength of a geomagnetic storm on Earth. Unfortunately, the correlations between strong <span class="hlt">magnetic</span> field CMEs from the entire sun (especially from the far side or non-Earth facing side of the sun) to SEP and flare events, solar source regions and other relevant solar variables are not well known. New correlation studies using an artificial intelligence engine (Eureqa) were performed to study CME events with <span class="hlt">magnetic</span> field strength readings over 30 nanoteslas (nT) from January 2010 to October 17, 2014. This thesis presents the results of this study, validates Eureqa to obtain previously published results, and presents previously unknown functional relationships between solar source <span class="hlt">magnetic</span> field data, CME initial speed and the CME <span class="hlt">magnetic</span> field. These new results enable the development of more accurate CME <span class="hlt">magnetic</span> field predictions and should help scientists develop better forecasts thereby helping to prevent damage to humanity's space and Earth assets.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/1989Ge%26Ae..29..265I','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/1989Ge%26Ae..29..265I"><span id="translatedtitle">An <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> cloud from the solar flare of November 22, 1977.</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Ivanov, K. G.; Styazhkin, V. A.; Kharshiladze, A. F.</p> <p>1989-10-01</p> <p>Experimental profiles of Bx, By, and Bz, the components of the IMF, obtained by the Prognoz-6, ISEE-2, and IMP-8 satellites during their passage through a <span class="hlt">magnetic</span> cloud from the powerful solar flare of November 22 are compared with the theoretical model of a force-free <span class="hlt">magnetic</span> field of a diffusion pinch. It is found that qualitative agreement between theory and experiment occurs for the permissible configuration and kinematic characteristics of a circular cylinder approximating the cloud.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015Ge%26Ae..55..158G','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015Ge%26Ae..55..158G"><span id="translatedtitle">The <span class="hlt">magnetic</span> hole as plasma inhomogeneity in the solar wind and related <span class="hlt">interplanetary</span> medium perturbations</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Grib, S. A.; Leora, S. N.</p> <p>2015-03-01</p> <p>We considered <span class="hlt">magnetic</span> hole-type plasma structures with a constant total pressure, which are often observed in the flux of the solar wind. The interaction between a linear <span class="hlt">magnetic</span> hole and the front of the primary or bow shock wave before the Earth's magnetosphere was studied, and the appearance of a fast shock wave in the magnetosheath and displacement of the bow shock front in the direction of the Earth's magnetosphere is described. The <span class="hlt">magnetic</span> hole in the scope of the MHD theory is considered a plasma inhomogeneity bounded by two tangential discontinuities: the front and rear boundaries. Based on the MHD theory of nonlinear interactions of solar wind discontinuity structures with a <span class="hlt">magnetic</span> hole, the appearance of new automodel and MHD shock waves inside the <span class="hlt">magnetic</span> hole is shown. The obtained results, which provide evidence of a change in the configuration of the <span class="hlt">magnetic</span> hole and a displacement of the bow shock front due to the perturbation from the solar wind, are qualitatively verified in many aspects by observations performed earlier by the Cluster and ACE spacecrafts.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19860056271&hterms=russell+saunders&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Drussell%2Bsaunders','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19860056271&hterms=russell+saunders&qs=N%3D0%26Ntk%3DAll%26Ntx%3Dmode%2Bmatchall%26Ntt%3Drussell%2Bsaunders"><span id="translatedtitle"><span class="hlt">Average</span> dimension and <span class="hlt">magnetic</span> structure of the distant Venus magnetotail</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Saunders, M. A.; Russell, C. T.</p> <p>1986-01-01</p> <p>The first major statistical investigation of the far wake of an unmagnetized object embedded in the solar wind is reported. The investigation is based on Pioneer Venus Orbiter magnetometer data from 70 crossings of the Venus wake at altitudes between 5 and 11 Venus radii during reasonably steady IMF conditions. It is found that Venus has a well-developed-tail, flaring with altitude and possibly broader in the direction parallel to the IMF cross-flow component. Tail lobe field polarities and the direction of the cross-tail field are consistent with tail accretion from the solar wind. <span class="hlt">Average</span> values for the cross-tail field (2 nT) and the distant tail flux (3 MWb) indicate that most distant tail field lines close across the center of the tail and are not rooted in the Venus ionosphere. The findings are illustrated in a three-dimensional schematic.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2016ApJ...823L..30Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2016ApJ...823L..30Z"><span id="translatedtitle"><span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field Sector from Solar Wind around Pluto (SWAP) Measurements of Heavy Ion Pickup near Pluto</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zirnstein, E. J.; McComas, D. J.; Elliott, H. A.; Weidner, S.; Valek, P. W.; Bagenal, F.; Stern, S. A.; Ennico, K.; Olkin, C. B.; Weaver, H. A.; Young, L. A.</p> <p>2016-06-01</p> <p>On 2015 July 14, the New Horizons spacecraft flew by the Pluto system. The Solar Wind Around Pluto (SWAP) instrument on board New Horizons, which detects ions in the energy per charge range ˜0.035 to 7.5 keV/q, measured the unique interaction between the solar wind and Pluto's atmosphere. Immediately after the closest approach, SWAP detected a burst of heavy ion counts when the instrument's field of view (FOV) was aligned north and south of the Sun–Pluto line and approximately normal to the solar wind flow direction, suggesting their origin as heavy neutral atoms from Pluto that were ionized and being picked up by the solar wind. The trajectories of heavy pickup ions depend on the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF). New Horizons is not equipped with a magnetometer, and we cannot directly measure the IMF. However, we can utilize SWAP's measurements and instrument FOV during this brief period of time to determine the most likely sector of the IMF that could reproduce SWAP's observations of heavy ion pickup. We find that the IMF was most likely in an outward sector, or retrograde to the planets’ motion, during the Pluto encounter, and that the heavy ions detected by SWAP are more likely {{{CH}}4}+ than {{{{N}}}2}+. This supports the existence of a methane exosphere at Pluto.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19830051481&hterms=Magnetic+memory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DMagnetic%2Bmemory','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19830051481&hterms=Magnetic+memory&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D70%26Ntt%3DMagnetic%2Bmemory"><span id="translatedtitle">Dynamical evolution of <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> fields and flows between 0.3 AU and 8.5 AU - Entrainment</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Burlaga, L. F.; Schwenn, R.; Rosenbauer, H.</p> <p>1983-01-01</p> <p>An analysis is presented of the radial evolution of <span class="hlt">interplanetary</span> flows and associated <span class="hlt">magnetic</span> fields between 0.3 AU and 8.5 AU using data from Helios 1 and B Voyager 1, respectively. The results indicate that in moving to 8 AU the largest corotating streams swept up the slower flows and shocks into a relatively thin region in which they coalesced to form a single large-amplitude compression. As a result of this process, referred to as entrainment, memory of the sources and flow configurations near the sun is lost, while small-scale features are erased as the flows move outward and energy is transferred from small scales to large scales.It is concluded that in the outer solar system the structure of the solar wind may be dominated by large scale pressure waves separated by several AU, while beyond several AU most of the compression waves are no longer driven by streams, and the compression waves expand freely. At large distances (greater than 25 AU) these compression waves will have interacted extensively with one another producing another state of the solar wind, with fewer large-scale nonuniformities and more small-scale nonuniformities.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015P%26SS..117...15L','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015P%26SS..117...15L"><span id="translatedtitle">Solar wind interaction effects on the <span class="hlt">magnetic</span> fields around Mars: Consequences for <span class="hlt">interplanetary</span> and crustal field measurements</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Luhmann, J. G.; Ma, Y.-J.; Brain, D. A.; Ulusen, D.; Lillis, R. J.; Halekas, J. S.; Espley, J. R.</p> <p>2015-11-01</p> <p>The first unambiguous detections of the crustal remanent <span class="hlt">magnetic</span> fields of Mars were obtained by Mars Global Surveyor (MGS) during its initial orbits around Mars, which probed altitudes to within ∼110 km of the surface. However, the majority of its measurements were carried out around 400 km altitude, fixed 2 a.m. to 2 p.m. local time, mapping orbit. While the general character and planetary origins of the localized crustal fields were clearly revealed by the mapping survey data, their effects on the solar wind interaction could not be investigated in much detail because of the limited mapping orbit sampling. Previous analyses (Brain et al., 2006) of the field measurements on the dayside nevertheless provided an idea of the extent to which the interaction of the solar wind and planetary fields leads to non-ideal field draping at the mapping altitude. In this study we use numerical simulations of the global solar wind interaction with Mars as an aid to interpreting that observed non-ideal behavior. In addition, motivated by models for different <span class="hlt">interplanetary</span> field orientations, we investigate the effects of induced and reconnected (planetary and external) fields on the Martian field's properties derived at the MGS mapping orbit altitude. The results suggest that inference of the planetary low order moments is compromised by their influence. In particular, the intrinsic dipole contribution may differ from that in the current models because the induced component is so dominant.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li class="active"><span>12</span></li> <li><a href="#" onclick='return showDiv("page_13");'>13</a></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_12 --> <div id="page_13" class="hiddenDiv"> <div class="row"> <div class="col-sm-12"> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div> </div> <div class="row"> <div class="col-sm-12"> <ol class="result-class" start="241"> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015JGRA..120.4519Z','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015JGRA..120.4519Z"><span id="translatedtitle">Direct observations of the full Dungey convection cycle in the polar ionosphere for southward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field conditions</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Zhang, Q.-H.; Lockwood, M.; Foster, J. C.; Zhang, S.-R.; Zhang, B.-C.; McCrea, I. W.; Moen, J.; Lester, M.; Ruohoniemi, J. M.</p> <p>2015-06-01</p> <p>Tracking the formation and full evolution of polar cap ionization patches in the polar ionosphere, we directly observe the full Dungey convection cycle for southward <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) conditions. This enables us to study how the Dungey cycle influences the patches' evolution. The patches were initially segmented from the dayside storm enhanced density plume at the equatorward edge of the cusp, by the expansion and contraction of the polar cap boundary due to pulsed dayside magnetopause reconnection, as indicated by in situ Time History of Events and Macroscale Interactions during Substorms (THEMIS) observations. Convection led to the patches entering the polar cap and being transported antisunward, while being continuously monitored by the globally distributed arrays of GPS receivers and Super Dual Auroral Radar Network radars. Changes in convection over time resulted in the patches following a range of trajectories, each of which differed somewhat from the classical twin-cell convection streamlines. Pulsed nightside reconnection, occurring as part of the magnetospheric substorm cycle, modulated the exit of the patches from the polar cap, as confirmed by coordinated observations of the magnetometer at Tromsø and European Incoherent Scatter Tromsø UHF radar. After exiting the polar cap, the patches broke up into a number of plasma blobs and returned sunward in the auroral return flow of the dawn and/or dusk convection cell. The full circulation time was about 3 h.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/21448705','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/21448705"><span id="translatedtitle">EVOLUTION OF A CORONAL MASS EJECTION AND ITS <span class="hlt">MAGNETIC</span> FIELD IN <span class="hlt">INTERPLANETARY</span> SPACE</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Kunkel, V.; Chen, J.</p> <p>2010-06-01</p> <p>This Letter presents the first theoretical study of the dynamics of a coronal mass ejection (CME) observed by STEREO-A/B. The CME was continuously tracked by SECCHI-A, providing position-time data from eruption to 1 AU. The ejecta was intersected by STEREO-B at 1 AU, where the <span class="hlt">magnetic</span> field and plasma parameters were measured. The observed CME trajectory and the evolution of the CME <span class="hlt">magnetic</span> field are modeled using the semianalytic erupting flux-rope model. It is shown that the best-fit theoretical solution is in good agreement-within 1% of the measured CME trajectory in the 1 AU field of view-and is consistent with the in situ <span class="hlt">magnetic</span> field and plasma data at 1 AU.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19850051368&hterms=System+Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DSystem%2BSolar','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19850051368&hterms=System+Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D40%26Ntt%3DSystem%2BSolar"><span id="translatedtitle">Theoretical interpretation of the observed <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field radial variation in the outer solar system</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Suess, S. T.; Thomas, B. T.; Nerney, S. F.</p> <p>1985-01-01</p> <p>Observations of the azimuthal component of the IMF are evaluated through the use of an MHD model which shows the effect of <span class="hlt">magnetic</span> flux tubes opening in the outer solar system. It is demonstrated that the inferred meridional transport of <span class="hlt">magnetic</span> flux is consistent with predictions by the MHD model. The computed azimuthal and radial <span class="hlt">magnetic</span> flux deficits are almost identical to the observations. It is suggested that the simplest interpretation of the observations is that meridional flows are created by a direct body force on the plasma. This is consistent with the analytic model of Nerney and Suess (1975), in which such flux deficits in the IMF arise naturally from the meridional gradient in the spiralling field.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://ntrs.nasa.gov/search.jsp?R=19890056315&hterms=heat+Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dheat%2BSolar','NASA-TRS'); return false;" href="http://ntrs.nasa.gov/search.jsp?R=19890056315&hterms=heat+Solar&qs=Ntx%3Dmode%2Bmatchall%26Ntk%3DAll%26N%3D0%26No%3D60%26Ntt%3Dheat%2BSolar"><span id="translatedtitle">Electron heat flux dropouts in the solar wind - Evidence for <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field reconnection?</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Mccomas, D. J.; Gosling, J. T.; Phillips, J. L.; Bame, S. J.; Luhmann, J. G.; Smith, E. J.</p> <p>1989-01-01</p> <p>An examination of ISEE-3 data from 1978 reveal 25 electron heat flux dropout events ranging in duration from 20 min to over 11 hours. The heat flux dropouts are found to occur in association with high plasma densities, low plasma velocities, low ion and electron temperatures, and low <span class="hlt">magnetic</span> field magnitudes. It is suggested that the heat flux dropout intervals may indicate that the spacecraft is sampling plasma regimes which are <span class="hlt">magnetically</span> disconnected from the sun and instead are connected to the outer heliosphere at both ends.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/19840005008','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/19840005008"><span id="translatedtitle"><span class="hlt">Interplanetary</span> Alfvenic fluctuations: A statistical study of the directional variations of the <span class="hlt">magnetic</span> field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>Bavassano, B.; Mariani, F.</p> <p>1983-01-01</p> <p><span class="hlt">Magnetic</span> field data from HELIOS 1 and 2 are used to test a stochastic model for Alfvenic fluctuations recently proposed. A reasonable matching between observations and predictions is found. A rough estimate of the correlation length of the observed fluctuations is inferred.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2013AGUFMSM41B2238W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2013AGUFMSM41B2238W"><span id="translatedtitle">Field-Aligned Current Reconfiguration and Magnetospheric Response to an Impulse in the <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field BY Component</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Wilder, F. D.; Eriksson, S.; Korth, H.; Hairston, M. R.; Baker, J. B.; Heinselman, C. J.</p> <p>2013-12-01</p> <p>When the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) is dawnward or duskward, <span class="hlt">magnetic</span> merging between the IMF and the geomagnetic field occurs near the cusp on the dayside flanks of the magnetosphere. During these intervals, flow channels in the ionosphere with velocities in excess of 2 km/s have been observed, which can deposit large amounts of energy into the high-latitude thermosphere. In this study, we analyze an interval on 5 April 2010 where there was a strong dawnward impulse in the IMF, followed by a gradual decay in IMF magnitude at constant clock angle. Data from the Sondrestrom incoherent scatter radar and the DMSP spacecraft were used to investigate ionospheric convection during this interval, and data from the Active Magnetospheric and Planetary Electrodynamics Response Experiment (AMPERE) were used to investigate the associated Field-Aligned Current (FAC) system. Additionally, data from AMPERE were used to investigate the time response of the dawn-side FAC pair. We find there is a delay of approximately 1.25 hours between the arrival of the dawnward IMF impulse at the magnetopause and strength of the dawnward FAC pair, which is comparable to substorm growth and expansion time scales under southward IMF. Additionally, we find at the time of the peak FAC, there is evidence of a reconfiguring four-sheet FAC system in the morning local time sector of the ionosphere. Additionally, we find an inverse correlation between the dawn FAC strength and both the solar wind Alfvénic Mach number and the SYM-H index. No statistically significant correlation between the FAC strength and the solar wind dynamic pressure was found.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://www.osti.gov/scitech/biblio/5839089','SCIGOV-STC'); return false;" href="http://www.osti.gov/scitech/biblio/5839089"><span id="translatedtitle">The <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field B sub y -dependent field-aligned current in the dayside polar cap under quiet conditions</span></a></p> <p><a target="_blank" href="http://www.osti.gov/scitech">SciTech Connect</a></p> <p>Yamauchi, M. Kyoto Univ. ); Araki, T. )</p> <p>1989-03-01</p> <p>Spatial distribution and temporal variation of the <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) B{sub y}-dependent cusp region field-aligned currents (FACs) during quiet periods were studied by use of <span class="hlt">magnetic</span> data observed by Magsat. The analysis was made for 11 events (each event lasts more than one and a half days) when the IMF B{sub y} component was steadily large and B{sub x} was relatively small ({vert bar}B{sub z}{vert bar} < {vert bar}B{sub y}{vert bar}). Results of the analysis of total 62 half-day periods for the IMF B{sub y}-dependent cusp region FAC are summarized as follows: (1) the IMF B{sub y}-dependent cusp region FAC is located at around 86{degree}-87{degree} invariant latitude local noon, which is more poleward than the location of the IMF B{sub z}-dependent cusp region FAC; (2) the current density of this FAC is greater than previous studies ({ge} 4 {mu}A/m{sup 2} for IMF B{sub y} = 6 nT); (3) there are two time scales for the IMF B{sub y}-dependent cusp region FAC to appear: the initial rise of the current is on a short time scale, {approximately} 10 min, and it is followed by a gradual increase on a time scale of several hours to a half day; (4) the seasonal change of this FAC is greater than that of the nightside region 1 or region 2 FACs; (5) the IMF B{sub z}-dependent cusp region FAC is not well observed around the cusp when the IMF B{sub y}-dependent cusp region FAC is intense.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://hdl.handle.net/2060/20140009617','NASA-TRS'); return false;" href="http://hdl.handle.net/2060/20140009617"><span id="translatedtitle">Turbulence in a Global Magnetohydrodynamic Simulation of the Earth's Magnetosphere during Northward and Southward <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field</span></a></p> <p><a target="_blank" href="http://ntrs.nasa.gov/search.jsp">NASA Technical Reports Server (NTRS)</a></p> <p>El-Alaoui, M.; Richard, R. L.; Ashour-Abdalla, M.; Walker, R. J.; Goldstein, M. L.</p> <p>2012-01-01</p> <p>We report the results of MHD simulations of Earth's magnetosphere for idealized steady solar wind plasma and <span class="hlt">interplanetary</span> <span class="hlt">magnetic</span> field (IMF) conditions. The simulations feature purely northward and southward <span class="hlt">magnetic</span> fields and were designed to study turbulence in the magnetotail plasma sheet. We found that the power spectral densities (PSDs) for both northward and southward IMF had the characteristics of turbulent flow. In both cases, the PSDs showed the three scale ranges expected from theory: the energy-containing scale, the inertial range, and the dissipative range. The results were generally consistent with in-situ observations and theoretical predictions. While the two cases studied, northward and southward IMF, had some similar characteristics, there were significant differences as well. For southward IMF, localized reconnection was the main energy source for the turbulence. For northward IMF, remnant reconnection contributed to driving the turbulence. Boundary waves may also have contributed. In both cases, the PSD slopes had spatial distributions in the dissipative range that reflected the pattern of resistive dissipation. For southward IMF there was a trend toward steeper slopes in the dissipative range with distance down the tail. For northward IMF there was a marked dusk-dawn asymmetry with steeper slopes on the dusk side of the tail. The inertial scale PSDs had a dusk-dawn symmetry during the northward IMF interval with steeper slopes on the dawn side. This asymmetry was not found in the distribution of inertial range slopes for southward IMF. The inertial range PSD slopes were clustered around values close to the theoretical expectation for both northward and southward IMF. In the dissipative range, however, the slopes were broadly distributed and the median values were significantly different, consistent with a different distribution of resistivity.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2015AGUFMSH33A2450W','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2015AGUFMSH33A2450W"><span id="translatedtitle">Complexity Variations in the <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field between 0.4 and 5.3 AU</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Weygand, J. M.; Kivelson, M.; Velli, M.; Gekelman, W. N.; Khurana, K. K.; Angelopoulos, V.; Walker, R. J.</p> <p>2015-12-01</p> <p>We have investigated how the character of <span class="hlt">magnetic</span> fluctuations of solar wind plasma depends on radial distance from the Sun. We use measurements of the <span class="hlt">magnetic</span> field taken at different distances from the Sun by different spacecraft: Helios between 0.4 and 1 AU, ACE and Wind at about 1 AU, and Ulysses at about 5.3 AU. Data intervals are selected to contain only what appear to be random fluctuations and to exclude solar wind structures such as coronal mass ejections, co-rotating interaction regions, heliospheric current sheets, shocks, etc. With these data we calculate the Jensen-Shannon complexity as a function of permutation entropy. Jensen-Shannon complexity maps indicate if the fluctuations in the <span class="hlt">magnetic</span> fields are stochastic (low complexity and high entropy), or if they exhibit minimal or maximal complexity and lower entropy. The Jensen-Shannon complexity values determined from the spacecraft measurements evolve from moderate complexity and high entropy at 0.4 AU to lower complexity and higher entropy farther from the Sun. We interpret these data to mean that as the solar wind plasma expands outward, the <span class="hlt">magnetic</span> field fluctuations evolve from chaotic (i.e., low dimensionality, deterministic fluctuations) to turbulent (i.e., low dimensionality, non-deterministic fluctuations). By separating the <span class="hlt">magnetic</span> fluctuations into slow solar wind (<450 km/s) and fast solar wind (>550 km/s), we find that the younger solar wind (transported outward rapidly) has higher complexity than the older solar wind (transported outward slowly). These results can be tested by Solar Probe Plus to be launched in 2018.</p> </li> <li> <p><a target="_blank" onclick="trackOutboundLink('http://adsabs.harvard.edu/abs/2002EGSGA..27..577M','NASAADS'); return false;" href="http://adsabs.harvard.edu/abs/2002EGSGA..27..577M"><span id="translatedtitle">Ring Current Decay During Northward Turnings of The <span class="hlt">Interplanetary</span> <span class="hlt">Magnetic</span> Field</span></a></p> <p><a target="_blank" href="http://adsabs.harvard.edu/abstract_service.html">NASA Astrophysics Data System (ADS)</a></p> <p>Monreal MacMahon, R.; Llop, C.; Miranda, R.</p> <p></p> <p>The ring current formation and energization is thought to be the main consequence of geomagnetic storms and its strength is characterized by the Dst index which evolu- tion satisfies a simple and well-known differential equation introduced by Burton et al. (1975). Since then, several attempts and approaches have been done to study the evolution of the ring current whether introducing discrete values or continuous func- tions for the decay time involved. In this work, we study the character of the recovery phase of <span class="hlt">magnetic</span> storms in response to well defined northward turnings of the inter- planetary <span class="hlt">magnetic</span> field using our functional form of the decay time of ring current particles introduced previously.</p> </li> </ol> <div class="pull-right"> <ul class="pagination"> <li><a href="#" onclick='return showDiv("page_1");'>«</a></li> <li><a href="#" onclick='return showDiv("page_9");'>9</a></li> <li><a href="#" onclick='return showDiv("page_10");'>10</a></li> <li><a href="#" onclick='return showDiv("page_11");'>11</a></li> <li><a href="#" onclick='return showDiv("page_12");'>12</a></li> <li class="active"><span>13</span></li> <li><a href="#" onclick='return showDiv("page_13");'>»</a></li> </ul> </div> </div><!-- col-sm-12 --> </div><!-- row --> </div><!-- page_13 --> <center> <div class="footer-extlink text-muted"><small>Some links on this page may take you to non-federal websites. 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