Sample records for average interplanetary magnetic

  1. Average high latitude magnetic field - Variation with interplanetary sector and with season. II

    NASA Technical Reports Server (NTRS)

    Langel, R.; Brown, N.

    1974-01-01

    Average high-latitude magnetic-field data from northern observatories are examined for three ranges of magnetic disturbance level, Kp = 1- to 1+, 2- to 3+ and greater than or equal to 4-. Except for 0 to 0800 hr MLT, 55 to 78 deg invariant latitude, during away interplanetary magnetic field sectors, the variations between season and sector have the same characteristics at all Kp ranges. Because the amplitude of sector differences is much larger at sunlit local times than in the midnight sector, it is concluded that the current system of Svalgaard (1973) is not adequate to describe the sector variations in magnetic disturbance. Other current systems are discussed briefly. The disturbance morphology and seasonal variation at all Kp levels confirms the results of previous studies which indicate that latitudinally broad current systems and nonionospheric sources are present in addition to latitudinally narrow electrojet currents.

  2. Determination of best average time interval of the interplanetary magnetic field for aplication in space weather forecasting

    NASA Astrophysics Data System (ADS)

    da Silva, M. R.; Vieira, L. E. A.; dal Lago, A.; Echer, E.; Gonzalez, W. D.; Munakata, K.; Kuwabara, T.; Schuch, N. J.

    The solar activity drives a large number of phenomena that occur in the near-earth interplanetary space and in the earth's magnetosphere, the so-called Space Weather. Among the most important phenomena of Space Weather we have the Geomagnetic Storms. In these phenomena, a great transfer of energy from the Sun and the Interplanetary Medium to the earth's magnetosphere takes place. It is well known that the galactic cosmic ray particles are also affected by the solar activity. One of the most important solar ejected structures, the Coronal Mass Ejection (CME), is the main cause of intense Geomagnetic Storms, and it is known to modulate cosmic ray intensity observed with ground detectors as they approach and pass the earth (Munakata et al., 2000). Thus ground cosmic ray observations may be used for forecasting this kind of interplanetary structures. By analyzing the cosmic ray intensities measured in various directions in space by the International Muon Detector Network, together with the Interplanetary Magnetic Field (IMF) data observed by the Advanced Composition Explorer Satellite (ACE), the Loss Cone precursor can be seen some 6 to 9 hours prior to an interplanetary disturbance reaching the Earth Magnetosphere and then causing a geomagnetic storm. As the direction of the IMF is an important parameter in this forecasting scheme, this work has the objective of determining the best average time interval of the interplanetary magnetic field to be used together with the high-energy cosmic ray observations. We use ACE IMF observations from 1998 to 2001.

  3. Interplanetary Magnetic Field Lines

    NSDL National Science Digital Library

    Mendez, J.

    This web page, authored and curated by David P. Stern, provides information and a graphical exercise for students regarding the interaction between magnetic field lines and a plasma. The activity involves tracing a typical interplanetary magnetic field line, dragged out of a location on the Sun by the radial flow of the solar wind. This illustrates the way magnetic field lines are "frozen to the plasma" and the wrapping of field lines due to the rotation of the sun. This is part of the work "The Exploration of the Earth's Magnetosphere". A Spanish translation is available.

  4. Average high latitude magnetic field: Variations with interplanetary sector and with season. 2: Comparison of disturbance levels and discussion of ionospheric currents

    NASA Technical Reports Server (NTRS)

    Langel, R. A.; Brown, N.

    1973-01-01

    Average high latitude magnetic field data from northern observatories are examined for three ranges of magnetic disturbance level, Kp = 1 minus to 1+,2 minus to 3+, and or = 4 minus. Except for 0-8h MLT, 55-78 deg invariant latitude, during away interplanetary magnetic field sectors, the variations between season and sector have the the same characteristics at all Kp ranges. Because the amplitude of sector differences is much larger at sunlit local times than in the midnight sector, it is concluded that the current system of Svalgaard (1973) is not adequate to describe the sector variations in magnetic disturbance, other current systems are discussed briefly. The disturbance morphology and seasonal variation at all Kp levels confirms the results of previous studies which indicate that latitudinally broad current systems and non-ionospheric sources are present in addition to latitudinally narrow electrojet currents. Comparison of data between Kp levels indicates that the Harang discontinuity shifts toward earlier MLT with increasing Kp level.

  5. The interplanetary magnetic field. Solar origin and terrestrial effects

    Microsoft Academic Search

    John M. Wilcox

    1968-01-01

    Many observations related to the large-scale structure of the interplanetary magnetic field, its solar origin and terrestrial effects are discussed. During the period observed by spacecraft the interplanetary field was dominated by a sector structure corotating with the sun in which the field is predominantly away from the sun (on the average in the Archimedes spiral direction) for several days

  6. 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.

  7. Directional discontinuities in the interplanetary magnetic field

    Microsoft Academic Search

    Leonard F. Burlaga

    1969-01-01

    It is shown that the interplanetary magnetic field has different characteristics on different scales, and it is noted that a given physical theory may not be applicable or relevant on all scales. Four scales are defined in terms of time intervals on which the data may be viewed. Many discontinuities in the magnetic-field direction are seen on the mesoscale (˜

  8. 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.

  9. Prediction of the interplanetary magnetic field strength

    NASA Technical Reports Server (NTRS)

    Zhao, Xuepu; Hoeksema, J. Todd

    1995-01-01

    A new model of the coronal and interplanetary magnetic field can predict both the interplanetary magnetic field strength and its polarity from measurements of the photospheric magnetic field. The model includes the effects of the large-scale horizontal electric currents flowing in the inner corona, of the warped heliospheric current sheet in the upper corona, and of volume currents flowing in the region where the solar wind plasma totally controls the magnetic field. The model matches the MHD solution for a simple dipole test case better than earlier source surface and current sheet models. The strength and polarity of the radial interplanetary magnetic field component predicted for quiet time samples in each year from 1977 to 1986 agree with observations made near the Earth's orbit better than the hybrid MHD-source surface model (Wang and Sheeley, 1988). The results raise the question of whether coronal holes are the only solar source of the interplantary magnetic field in the solar wind. If some interplanetary flux originates outside coronal holes, the model can match the observed field using the accepted 1.8 saturation correction factor for lambda 5250 A magnetograph observations. Requiring open flux to come exclusively from coronal holes requires and additional factor of two.

  10. Interplanetary planar magnetic structures associated with expanding active regions

    NASA Technical Reports Server (NTRS)

    Nakagawa, Tomoko; Uchida, Yutaka

    1995-01-01

    Planar magnetic structures are interplanetary objects whose magnetic field cannot be explained by Parker's solar wind model. They are characterized by two-dimensional structure of magnetic field that are highly variable and parallel to a plane which is inclined to the ecliptic plane. They appeared independently of interplanetary compression, solar flares, active prominences nor filament disappearances, but the sources often coincided with active regions. On the other hand, it has been discovered by the Yohkoh Soft X-ray telescope that active-region corona expand outwards at speeds of a few to a few tens of km/s near the Sun. The expansions occurred repeatedly, almost continually, even in the absence of any sizable flares. In the Yohkoh Soft X-ray images, the active-region corona seems to expand out into interplanetary space. Solar sources of interplanetary planar magnetic structures observed by Sakigake were examined by Yohkoh soft X-ray telescope. During a quiet period of the Sun from January 6 to November 11, 1993, there found 5 planar magnetic structures according to the criteria (absolute value of Bn)/(absolute value of B) less than 0.1 for planarity and (dB)/(absolute value of B) greater than 0.7 for variability of magnetic field, where Bn, dB, and the absolute value of B are field component normal to a plane, standard deviation, and average of the magnitude of the magnetic field, respectively. Sources of 4 events were on low-latitude (less than 5 degrees) active regions from which loop-like structures were expanding. The coincidence, 80%, is extremely high with respect to accidental coincidence, 7%, of Sakigake windows of solar wind observation with active regions. The last source was on loop-like features which seemed to be related with a mid-latitude (20 degrees) active region.

  11. 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.

  12. 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.

  13. An interplanetary magnetic field ensemble at 1 AU

    NASA Technical Reports Server (NTRS)

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

    1986-01-01

    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 shich 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.

  14. Effects of interplanetary magnetic field on the propagation of flare-generated interplanetary shock waves.

    NASA Technical Reports Server (NTRS)

    Tam, C. K. W.; Yousefian, V.

    1972-01-01

    The effects of an interplanetary magnetic field on the propagation of flare-generated interplanetary shock waves are investigated with an approximate analytical method. It is found that the interplanetary magnetic field is relatively unimportant for strong shocks as far as the shock speed and transit time are concerned. It has more significant effects for weak shocks. However, in all the situations examined, the error committed if the magnetic field is neglected is no more than 10%. It is suggested that a model without a magnetic field gives sufficiently accurate numerical results for the propagation of flare-generated shocks.

  15. On the geomagnetic effects of solar wind interplanetary magnetic structures

    Microsoft Academic Search

    E. Echer; W. D. Gonzalez; M. V. Alves

    2006-01-01

    We present in this work a statistical study of the geoeffectiveness of the solar wind magnetic interplanetary structures over the entire observational period (1964–2003). The structures studied were magnetic clouds (MCs, 170 events), corotating interaction regions (CIRs, 727 events) and interplanetary shocks (830 events). The geoeffectiveness was assessed in terms of the geomagnetic index Kp, AE, and Dst peak values

  16. EULERIAN DECORRELATION OF FLUCTUATIONS IN THE INTERPLANETARY MAGNETIC FIELD

    SciTech Connect

    Matthaeus, W. H.; Osman, K. T. [Bartol Research Institute, Department of Physics and Astronomy, University of Delaware, DE (United States); Dasso, S. [Instituto de Astronomia y Fisica del Espacio (CONICET-UBA) and Departamento de Fisica (FCEN-UBA), Buenos Aires (Argentina); Weygand, J. M.; Kivelson, M. G. [Institute for Geophysics and Planetary Physics, University of California, Los Angeles, CA (United States)

    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.

  17. The sun and interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Smith, Edward J.

    1991-01-01

    The interplanetary magnetic field (IMF) serves as a link between the sun, the response of the earth to solar activity and variations in galactic cosmic radiation. The IMF originates as a solar-coronal magnetic field that is transported into space by the solar wind. The close connection between solar magnetic fields and the origin and structure of the solar wind is described. The solar wind forms the heliosphere, a cavity containing the magnetized solar plasma from which the interstellar plasma and field are excluded. The entry of galactic cosmic rays into the heliosphere and their strong interaction with the IMF are discussed, this topic being of primary importance to the production and temporal variations of radiogenic elements. The profound influence of the IMF on geomagnetic activity and the aurora is discussed within the context of merging or reconnection with the planetary field. The physical connection is thus established between solar magnetic fields, magnetic storms and aurora. The state of the solar wind and IMF during the Maunder minimum is considered and an explanation for the (relative) absence of sunspots and aurora is proposed. The mechanism is an interruption of the oscillatory solar dynamo, a consequent reduction in the heating of the corona, a cessation of the supersonic solar wind and a weakening or absence of southward-directed magnetic fields in the vicinity of the earth.

  18. INFLUENCE OF INTERPLANETARY MAGNETIC FIELD AND PLASMA ON GEOMAGNETIC ACTIVITY DURING QUIET-SUN CONDITIONS

    Microsoft Academic Search

    John M. Wilcox; Kenneth H. Schatten; Norman F. Ness

    1967-01-01

    Observations by the IMP 1 satellite of the interplanetary magnetic field and plasma have been compared with the 3-hour geomagnetic activity index K. The average Kis approximately a linear function of the interplanetary field magnitude B in gammas (i -- (0.33 =k 0.02)B =k 0.2). It appears significant that this relation betweenand field magnitude passes through the origin, whereas the

  19. Interplanetary magnetic field periodicity of ˜153 days

    NASA Astrophysics Data System (ADS)

    Cane, H. V.; Richardson, I. G.; von Rosenvinge, T. T.

    We report on the finding of a 153-day periodicity in the magnetic field strength and solar wind speed measured at 1 AU during the years 1978-1982. The period and the occurence epoch are consistent with the “154-day” periodicity previously reported for events occurring at the Sun. In particular, the variations in the field strength and the occurence rate of energetic (tens of MeV) solar particle events are in phase. The similar periodicities in the interplanetary field and solar phenomena are consistent with a global phenomenon. Whereas this periodicity is quite strong for the magnetic field magnitude, there is only a weak periodicity for the individual field components. The field magnitude shows essentially no periodicity at this period during the previous and following solar maxima. The lack of persistence, and of significant harmonic components of the observed periodicity, does not support the proposal of a solar “clock” mechanism. The most significant variations in the complete near-earth magnetic field data base (1963-1997) with periods of less than 200 days occur at 166 and 146 days.

  20. Magnetic field modulated dust streams from Jupiter in Interplanetary space

    E-print Network

    Hamilton, Douglas P.

    coupled to the interplanetary16 magnetic field (IMF) (Gr¨un et al., 1993, 1998; Kempf et al., 2005 phenomena shared similar properties. The saturnian20 dust streams source is not well defined yet (Kempf et

  1. 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.

  2. Recurrent structures of the interplanetary magnetic field observed by ULYSSES

    Microsoft Academic Search

    G. Erdos; A. Balogh; R. J. Forsyth; E. J. Smith

    1995-01-01

    Since its launch in October 1990, Ulysses has provided good quality magnetic field data, practically covering the whole time interval until now. We have studied the very long time scale evolution of the interplanetary magnetic field, in particlular, we have search for recurrent disturbances in the magnetic field. The magnetic field vectors have been mapped back to the Sun along

  3. 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.

  4. 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.

  5. The spiral interplanetary magnetic field: a polarity and sunspot cycle variation.

    PubMed

    Svalgaard, L; Wilcox, J M

    1974-10-01

    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 degrees , rather than 180 degrees as predicted by Parker. This effect appears to have a sunspot cycle variation. PMID:17818100

  6. New Geomagnetic Index (idv) Measuring Magnitude of Interplanetary Magnetic Field

    NASA Astrophysics Data System (ADS)

    Svalgaard, L.; Cliver, E. W.

    2003-12-01

    We present a new long-term geomagnetic index (the IDV index) which has the property that it is a proxy of the magnitude of the interplanetary magnetic field at the Earth. The index is constructed (for any given station) as the monthly (or yearly) average of the differences (taken without regard to sign) of the hourly mean values of the hour following local midnight between two consecutive days. It is similar to the classical u-measure except that the differences are between one-hour values rather than daily means. The IDV index has a strong correlation (r=0.88) with the magnitude, B, of the IMF, but is uncorrelated (r=0.09) with the solar wind speed, V. Because other indices (e.g. aa and our own IHV) are strongly correlated with BV**2, the IDV index fords a way of separating the influence of B and V and thus determining both.

  7. 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.

  8. Response of polar cap convection to the interplanetary magnetic field

    Microsoft Academic Search

    F. S. Mozer; W. D. Gonzalez

    1973-01-01

    Because the relationship between convection and the interplanetary ; magnetic fleld is of crucial importance to the understanding of the large-scale ; interaction between the solar wind and the geomagnetic field, 227 hours of polar-; cap balloon electricfield measurements were examined in search of such a ; relationship, with the conclusion that magnetic field reconnection dominates ; viscous interaction or

  9. 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.

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

    NASA Technical Reports Server (NTRS)

    Farrugia, C. J.; Freeman, M. P.; Burlaga, L. F.; Lepping, R. P.; Takahashi, K.

    1993-01-01

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

  11. A model of interplanetary and coronal magnetic fields

    Microsoft Academic Search

    Kenneth H. Schatten; John M. Wilcox; Norman F. Ness

    1969-01-01

    A model of the large-scale magnetic field structure above the photosphere uses a Green's function solution to Maxwell's equations. Sources for the magnetic field are related to the observed photospheric field and to the field computed at a ‘source’ surface about 0.6 R? above the photosphere. The large-scale interplanetary magnetic field sector pattern is related to the field pattern at

  12. INTERPLANETARY MAGNETIC FLUX DEPLETION DURING PROTRACTED SOLAR MINIMA

    SciTech Connect

    Connick, David E.; Smith, Charles W.; Schwadron, Nathan A., E-mail: davideconnick@gmail.com, E-mail: Charles.Smith@unh.edu, E-mail: N.Schwadron@unh.edu [Physics Department, Space Science Center, University of New Hampshire, Durham, NH (United States)

    2011-01-20

    We examine near-Earth solar wind observations as assembled within the Omni data set over the past 15 years that constitute the latest solar cycle. We show that the interplanetary magnetic field continues to be depleted at low latitudes throughout the protracted solar minimum reaching levels below previously predicted minima. We obtain a rate of flux removal resulting in magnetic field reduction by 0.5 nT yr{sup -1} at 1 AU when averaged over the years 2005-2009 that reduces to 0.3 nT yr{sup -1} for 2007-2009. We show that the flux removal operates on field lines that follow the nominal Parker spiral orientation predicted for open field lines and are largely unassociated with recent ejecta. We argue that the field line reduction can only be accomplished by ongoing reconnection of nominally open field lines or very old closed field lines and we contend that these two interpretations are observationally equivalent and indistinguishable.

  13. Magnetospheric convection during prolonged intervals with southward interplanetary magnetic field

    Microsoft Academic Search

    Raymond J. Walker; Maha Ashour-Abdalla; Mostafa El Alaoui; Ferdinand V. Coroniti

    2006-01-01

    We have used a global magnetohydrodynamic simulation to investigate magnetospheric convection during a prolonged interval with modest southward driving. The interval simulated occurred on 13 and 14 February 2001 during a period when the interplanetary magnetic field (IMF) remained weakly southward for over 12 hours. Early in the simulation a near-Earth neutral line located between 20 RE and 40 RE

  14. High-latitude electric fields and the three-dimensional interaction between the interplanetary and terrestrial magnetic fields

    Microsoft Academic Search

    F. S. Mozer; W. D. Gonzalez; F. Bogott; M. C. Kelley; S. Schutz

    1974-01-01

    More than 200 hours of ionospheric electric field measurements taken on balloons flown from three polar cap sites have been analyzed to determine average properties of the largescale polar cap electric field and its dependencies on the interplanetary magnetic field. The major component of this electric field was directed from dawn. to dusk and produced an average polar cap potential

  15. Interplanetary magnetic clouds at 1 AU

    Microsoft Academic Search

    L. W. Klein; L. F. Burlaga

    1982-01-01

    Magnetic clouds are defined as regions;with a radial dimension roughly-equal0.25 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,

  16. 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.

  17. 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.

  18. The control of the magnetopause by the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Russell, C. T.

    1980-01-01

    The paper examines the control of the magnetopause by the interplanetary magnetic field, noting that the solar wind pressure determines the 'zeroth-order' location of the earth's magnetopause. However, the normal stresses of the solar wind dynamic pressure are also accompanied by tangential stresses which erode the magnetopause from its equilibrium position and transport magnetic flux into the magnetotail. Finally, initial results indicate that when the magnetosheath magnetic field is southward the connection takes place in a series of flux transfer events capable of transporting 10 to the 16th Mx or more per hour.

  19. Spectral polarization analysis of the interplanetary magnetic field fluctuations

    NASA Technical Reports Server (NTRS)

    Polygiannakis, J. M.; Moussas, X.; Quenby, J. J.; Smith, E. J.

    1994-01-01

    A new computational method and algorithm, based on complex Fourier analysis, is used to derive the spectral density of plane and circularly polarized fluctuation components of the interplanetary magnetic field. Applications of the method have been made using HEOS 2 (1 AU), Pioneer 10 (5 AU), Pioneer 11 (20 AU), and International Cometary Explorer (ICE) (Giocabini-Zinner's comet) data sets. The results show the existence of circularly polarized magnetohydrodynamic (MHD) waves in all cases.

  20. 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.

  1. Magnetic reconnection in the interior of interplanetary coronal mass ejections.

    PubMed

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

    2014-07-18

    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 = ?B with ? 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. PMID:25083630

  2. Cosmic ray fluctuations parameter as indicator of interplanetary "magnetic cork"

    NASA Astrophysics Data System (ADS)

    Kozlov, V. I.; Kozlov, V. V.

    2013-02-01

    It is established, that the main contribution into dynamics of galactic cosmic ray intensity fluctuations (GCR) in a vicinity of magnetic "cork" from a shock gives a nonrandom, non-Gauss component of GCR intensity. An occurrence of correlated fluctuations is caused by following circumstance: due to laws of conservation the probability that the cosmic ray particles reflected from a magnetic cork (in the expanding magnetic field) will undergo collimations, becomes considerable. The collimation will be manifested in focusing of particles into the anisotropic beams. In this case, observations should show "scintillations" of celestial sphere in cosmic rays i.e. the" HALO" effect. Similar scintillations are the indicator of interplanetary magnetic cork. The algorithm of detection of GCR scintillations is realized in real time using "Cyber-FORSHOCK" robotized system.

  3. 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

  4. 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

  5. Dayside convection and auroral morphology during an interval of northward interplanetary magnetic eld

    E-print Network

    Boyer, Edmond

    Dayside convection and auroral morphology during an interval of northward interplanetary magnetic and ionospheric convection during an interval when the interplanetary magnetic ®eld (IMF) had predominantly radar. For an interval of IMF By 0 nT, these convection ¯ow measurements suggest the presence

  6. Radial and latitudinal variations of the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Klein, Larry W.; Burlaga, L. F.; Ness, N. F.

    1987-01-01

    This paper presents observations of the radial and latitudinal variations of the interplanetary magnetic field measured by the Voyager 1 (V1) and Voyager 2 (V2) spacecraft from mid-1977 to mid-1985. Observations of the radial variation of the large-scale magnetic field strength in the ecliptic agree with the predictions of Parker's (1958, 1963) model when temporal variations in the magnetic field and bulk speed are taken into account. The latitudinal variation of the magnetic field observed by V1 is in agreement with the predictions of Parker's model to first approximation. The magnetic field strength at higher latitudes is somewhat lower than expected on the basis of observations made in the ecliptic, but this could be due to an increase in bulk speed and/or a decrease of solar magnetic field strength with latitude. Fluctuations in the strength of the magnetic field are small compared to the large-scale field itself, and they decrease in amplitude with increasing distance approximately as R exp -1/4 . Fluctuations in the components are relatively large, and they make a significant contribution to the mean field that is not described by Parker's model.

  7. 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.

  8. Interplanetary magnetic field dependence of the suprathermal energetic neutral atoms originated in subsolar magnetopause

    NASA Astrophysics Data System (ADS)

    Ogasawara, K.; Dayeh, M. A.; Funsten, H. O.; Fuselier, S. A.; Livadiotis, G.; McComas, D. J.

    2015-02-01

    Using energetic neutral atom (ENA) emission observations of the subsolar magnetopause measured by the Interstellar Boundary Explorer (IBEX), we study the correlation between the upstream interplanetary magnetic field (IMF) conditions and the spectral index of the source ion population. Our ENA data set includes hour-averaged ENA measurements at energies between ˜0.5 and ˜6 keV obtained by the IBEX High Energy ENA imager from January 2009 to May 2011. Under the condition of quiet geomagnetic activity (SYM-H index >-20 nT), we find that the shallower spectra in the suprathermal tail of the ion population of the subsolar magnetopause is weakly correlated (correlation coefficient of -0.30) with the shock angle of the Earth's bow shock, but not correlated with parameters related to magnetic reconnection (i.e., elevation and clock angle of the interplanetary magnetic field orientation). The observed correlation suggests suprathermal ion energization from diffusive shock acceleration and thus that the suprathermal ions in the subsolar magnetopause are of shocked solar wind origin. We also argue that the roles of magnetospheric ion leakage or ion acceleration by magnetic reconnection are reduced in the magnetopause emissions compared to shock acceleration processes.

  9. High latitude electric fields an the modulations related to interplanetary magnetic field parameters

    NASA Technical Reports Server (NTRS)

    Heppner, J. P.

    1973-01-01

    The meaning and characteristics of basic and average convection (i.e., electric field) patterns are described. The continuous existence of the basic convection pattern argues against treating magnetic field merging mechanisms as the fundamental cause of magnetospheric convection. However, whether related to merging or some other mechanism, interplanetary (IP) magnetic field conditions significantly modulate the distribution, magnitudes, and boundaries of the convection pattern. A previous correlation between azimuthal angles of the IP magnetic field and asymmetries in polar cap electric field distributions as seen by OGO-6 was reviewed. A new approach was taken to reveal correlations with the north-south angle and magnitude of the IP field as well as additional features which correlate with the azimuthal angle. Both significant correlations and conditions which show a lack of correlation were found. Several aspects of the correlations appear to be particularly important.

  10. 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.

  11. Magnetic shielding of interplanetary spacecraft against solar flare radiation

    NASA Astrophysics Data System (ADS)

    Cocks, Franklin H.; Watkins, Seth

    1993-07-01

    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.

  12. 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.

  13. The interplanetary magnetic field: radial and latitudinal dependences

    E-print Network

    Khabarova, Olga V

    2013-01-01

    Results of the analysis of spacecraft measurements at 1-5.4 AU are presented within the scope of the large-scale interplanetary magnetic field (IMF) structure investigation. The work is focused on revealing of the radial IMF component (Br) variations with heliocentric distance and latitude as seen by Ulysses. It was found out that |Br| decreases as ~r^-5/3 in the ecliptic plane vicinity (10 deg. of latitude). This is consistent with the previous results obtained on the basis of five spacecraft in-ecliptic measurements (Khabarova, Obridko, 2012). The difference between the experimentally found (r^-5/3) and commonly used (r^-2) radial dependence of Br may lead to mistakes in the IMF recalculations from point to point in the heliosphere. This can be one of the main sources of the 'magnetic flux excess' effect, which is exceeding of the distantly measured magnetic flux over the values obtained through the measurements at the Earth orbit. It is shown that the radial IMF component can be considered as independent o...

  14. Polar cap magnetic variations and their relationship with the interplanetary magnetic sector structure.

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.

    1973-01-01

    The relationship between polar geomagnetic variations and the polarity of the interplanetary magnetic sectors has been studied for the quiet year 1965. It is found that during the day hours a system of ionospheric currents encircles the magnetic poles on every day. The current system may extend up to 15 deg from the pole but is strongest at 8 to 10 deg invariant colatitude. The current direction as seen from near the magnetic poles is counterclockwise during interplanetary sectors with field pointing away from the sun and clockwise during toward sectors. The current strength is dependent on season, being strongest during local summer. When the magnetic pole is on the nightside of the earth, this polar cap current is absent or very weak.

  15. Evolution of magnetic flux ropes associated with flux transfer events and interplanetary magnetic clouds

    NASA Technical Reports Server (NTRS)

    Wei, C. Q.; Lee, L. C.; Wang, S.; Akasofu, S.-I.

    1991-01-01

    Spacecraft observations suggest that flux transfer events and interplanetary magnetic clouds may be associated with magnetic flux ropes which are magnetic flux tubes containing helical magnetic field lines. In the magnetic flux ropes, the azimuthal magnetic field is superposed on the axial field. The time evolution of a localized magnetic flux rope is studied. A two-dimensional compressible MHD simulation code with a cylindrical symmetry is developed to study the wave modes associated with the evolution of flux ropes. It is found that in the initial phase both the fast magnetosonic wave and the Alfven wave are developed in the flux rope. After this initial phase, the Alfven wave becomes the dominant wave mode for the evolution of the magnetic flux rope and the radial expansion velocity of the flux rope is found to be negligible. Numerical results further show that even for a large initial azimuthal component of the magnetic field, the propagation velocity along the axial direction of the flux rope remains the Alfven velocity. It is also found that the localized magnetic flux rope tends to evolve into two separate magnetic ropes propagating in opposite directions. The simulation results are used to study the evolution of magnetic flux ropes associated with flux transfer events observed at the earth's dayside magnetopause and magnetic clouds in the interplanetary space.

  16. 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+?)?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 dimensional wave vector spectrum of magnetic field fluctuations in the solar wind is not axisymmetric about the direction of the mean magnetic field as recent observations in the ecliptic plane at 1 AU have shown.

  17. 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.

  18. 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.

  19. A Scheme for finding the Front Boundary of an Interplanetary Magnetic Cloud

    NASA Technical Reports Server (NTRS)

    Lepping, Ronald P.; Narock, Thomas W.; Wu, Chin-Chun

    2006-01-01

    We developed a scheme for finding the front boundary of an interplanetary magnetic cloud (MC) based on criteria that depend on the possible existence of any one or all of six specific solar wind features. The features that the program looks for, within +/- 2 hours of a preliminarily determined time for the front boundary, estimated either by visual inspection or by an automatic MC identification scheme, are: (1) a sufficiently large directional discontinuity in the interplanetary magnetic field (IMF), (2) existence of a magnetic hole, (3) a significant proton plasma beta drop, (4) a significant proton temperature drop, (5) a marked increase in the IMF's intensity, and (6) a significant decrease in a normalized root-mean-square deviation (RMS)of the magnetic field - where the scheme was tested using 5, 10, 15, and 20 minute averages of the relevant physical quantities, in order to find the optimum average (and RMS) to use. Other criteria, besides these six, were examined and dismissed as not reliable, e.g., plasma speed. The scheme was developed specifically for aiding in forecasting the strength and timing of a geomagnetic storm due to the passage of an interplanetary MC in real-time, but can be used in post ground-data collection for imposition of consistency in choosing a MC's front boundary. The scheme has been extensively tested, first using 80 bona fide MCs over about 9 years of WIND data, and also for 121 MC-like structures as defined by a program that automatically identifies such structures over the same period. Optimum limits for various parameters in the scheme were found by statistical studies of the WIND MCs. The resulting limits can be user-adjusted for other data sets, if desired. Final testing of the 80 MCs showed that for 50 percent of the events the boundary estimates occurred within +/-10 minutes of visually determined times, 80 percent occurred within +/-30 minutes, and 91 percent occur within +/-60 minutes, and three or more individual boundary tests were passed for 88 percent of the total MCs. The scheme and its testing will be described.

  20. Dayside Magnetopause Location During Radial Interplanetary Magnetic Field Periods

    NASA Astrophysics Data System (ADS)

    Wang, H.; Huang, T.; Shue, J. H.; Ridley, A. J.

    2014-12-01

    The present work has investigated the dayside magnetopause locations under radial interplanetary field (IMF) conditions. During 49 earthward radial IMF events from years of 2001 to 2009, Cluster satellites have crossed the dayside magnetopause for 11 times. Among them, there are 8 events occurring at mid latitudes. The observed locations of the magnetopause are compared with the widely used magnetopause model (Shue et al., 1998). The model performance exhibits local time asymmetry at mid latitudes. The observed magnetopause contracts in the prenoon while expands in the postnoon. This local time asymmetry is confirmed by GOES magnetic field observations at geosynchronous orbits. The result might confirm the bullet shape magnetopause during radial IMF period. The model-observation differences during radial IMF periods correlate well with the solar wind dynamic pressure at mid-latitudes. The present work has indicated the important role of the IMF cone angle and dipole tilt angle in the modulation of the magnetopause shape at midlatitudes. Larger IMF cone angle or smaller dipole tilt angle can make the southern magnetopause expand further outward.

  1. 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).

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

    SciTech Connect

    Khabarova, Olga; Obridko, Vladimir, E-mail: habarova@izmiran.ru [Heliophysical Laboratory, Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation RAS (IZMIRAN), Troitsk, Moscow Region 142190 (Russian Federation)

    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.

  3. Magnetic loop behind an interplanetary shock - Voyager, Helios, and IMP 8 observations

    Microsoft Academic Search

    L. Burlaga; E. Sittler; F. Mariani; R. Schwenn

    1981-01-01

    The flow behind an interplanetary shock was analyzed through the use of magnetic field and plasma data from five spacecraft, with emphasis on the magnetic cloud identified by a characteristic variation of the latitude angle of the magnetic field. The size of the cloud was found to be about 0.5 AU in radial extent and greater than 30 deg in

  4. Interplanetary magnetic field effects on the interaction of the solar wind with Venus

    SciTech Connect

    Phillips, J.L.

    1987-01-01

    The solar-wind interaction with Venus are examined, with emphasis on the role of the interplanetary magnetic field (IMF), using observations from Pioneer Venus Orbiter (PVO). The intrinsic magnetic field of Venus is much smaller than that of Earth. Based on a survey of low-altitude PVO magnetometer observations, the planetary magnetic moment is less than 8.4 x 10/sup 10/Tm/sup 3/, or roughly 1/100,000 of the terrestrial moment. As a result, the impact of changing IMF orientation on the interaction is very different at Venus than at the magnetized planets. The solar plasma interacts directly with the ionospheric plasma, which generally is able to maintain a shielding current system which constitutes an impenetrable boundary. This ionopause has an average subsolar altitude of roughly 300 km, increasing to approx. 900 km near the terminator, and is consistently higher in the dawn hemisphere than in the dusk hemisphere. This observed asymmetry is shown to results from flow aberration due to planetary motion and from orbital bias. The IMF is compressed and draped around the boundary, reaching a maximum strength just above the ionopause. This field can in certain circumstances enter the ionosphere and be carried downward by ionospheric convection. In the magnetosheath, the region between the ionosphere and the bow shock, the magnetic field has a characteristic draping pattern.

  5. Latitudinal Dependence of Cosmic Rays Modulation at 1 AU and Interplanetary-Magnetic-Field Polar Correction

    E-print Network

    Bobik, P; Boschini, M J; Consolandi, C; Della Torre, S; Gervasi, M; Grandi, D; Kudela, K; Pensotti, S; Rancoita, P G; Rozza, D; Tacconi, M

    2012-01-01

    The cosmic rays differential intensity inside the heliosphere, for energy below 30 GeV/nuc, depends on solar activity and interplanetary magnetic field polarity. This variation, termed solar modulation, is described using a 2-D (radius and colatitude) Monte Carlo approach for solving the Parker transport equation that includes diffusion, convection, magnetic drift and adiabatic energy loss. Since the whole transport is strongly related to the interplanetary magnetic field (IMF) structure, a better understanding of his description is needed in order to reproduce the cosmic rays intensity at the Earth, as well as outside the ecliptic plane. In this work an interplanetary magnetic field model including the standard description on ecliptic region and a polar correction is presented. This treatment of the IMF, implemented in the HelMod Monte Carlo code (version 2.0), was used to determine the effects on the differential intensity of Proton at 1\\,AU and allowed one to investigate how latitudinal gradients of proton...

  6. Sources of magnetic fields in recurrent interplanetary streams

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Behannon, K. W.; Hansen, S. F.; Pneuman, G. W.; Feldman, W. C.

    1977-01-01

    The sources of magnetic fields in recurrent streams were examined. Most fields and plasmas at 1 AU were related to coronal holes, and the magnetic field lines were open in those holes. Some of the magnetic 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. Magnetic field intensities in five equatorial coronal holes ranged from 2G to 18G. Average measured photospheric magnetic fields along the footprints of the corresponding unipolar fields on circular equatorial arcs at 2.5 solar radii had a similar range and average, 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.

  7. Quantitative model for the potential resulting from reconnection with an arbitrary interplanetary magnetic field

    Microsoft Academic Search

    W. D. Gonzalez; F. S. Mozer

    1974-01-01

    Considerable evidence has accumulated to suggest that many features of magnetospheric dynamics are controlled by the interaction between the interplanetary and terrestrial magnetic fields. Dungey [1961] suggested that the mechanism responsible for this interaction is magnetic field reconnection taking place at the magnetopause, where the two fields meet. The general properties of this interaction are a change in the topology

  8. A practical database method for predicting arrivals of “averageinterplanetary shocks at Earth

    Microsoft Academic Search

    X. S. Feng; Y. Zhang; W. Sun; M. Dryer; C. D. Fry; C. S. Deehr

    2009-01-01

    A practical database method for predicting the interplanetary shock arrival time at L1 point is presented here. First, a shock transit time database (hereinafter called Database-I) based on HAFv.1 (version 1 of the Hakamada-Akasofu-Fry model) is preliminarily established with hypothetical solar events. Then, on the basis of the prediction test results of 130 observed solar events during the period from

  9. The Flux of Open and Toroidal Interplanetary Magnetic Field as a Function of Heliolatitude and Solar Cycle

    Microsoft Academic Search

    David E. Connick; Charles W. Smith; Nathan A. Schwadron

    2009-01-01

    We examine 45 years of near-Earth interplanetary observations as recorded in the National Space Science Data Center OMNI data set and 18 years of observations by the Ulysses spacecraft. We find that recent claims for a 50+ year low in interplanetary magnetic field intensity are substantiated, that the low flux levels can be attributed to open magnetic field lines, and

  10. Interplanetary Magnetic Field Line Mixing Deduced from Impulsive Solar Flare Particles.

    PubMed

    Mazur; Mason; Dwyer; Giacalone; Jokipii; Stone

    2000-03-20

    We have studied fine-scale temporal variations in the arrival profiles of approximately 20 keV nucleon-1 to approximately 2 MeV nucleon-1 ions from impulsive solar flares using instrumentation on board the Advanced Composition Explorer spacecraft at 1 AU between 1997 November and 1999 July. The particle events often had short-timescale ( approximately 3 hr) variations in their intensity that occurred simultaneously across all energies and were generally not in coincidence with any local magnetic field or plasma signature. These features appear to be caused by the convection of magnetic flux tubes past the observer that are alternately filled and devoid of flare ions even though they had a common flare source at the Sun. Thus, we have used the particles to study the mixing of the interplanetary magnetic field that is due to random walk. We deduce an average timescale of 3.2 hr for these features, which corresponds to a length of approximately 0.03 AU. PMID:10702137

  11. Interplanetary medium data book

    NASA Technical Reports Server (NTRS)

    King, J. H.

    1977-01-01

    Unresolved questions on the physics of solar wind and its effects on magnetospheric processes and cosmic ray propagation were addressed with hourly averaged interplanetary plasma and magnetic 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 averaged parameters were presented in the form of digital listings and 27-day plots. The listings are contained in a separately bound appendix.

  12. The Role Played by the Interplanetary Magnetic Field Topology in the Observed intensities of Solar Energetic Particle Events

    NASA Astrophysics Data System (ADS)

    Karelitz, A. M.; Lario, D.

    2013-12-01

    The presence of large-scale solar wind structures in the interplanetary medium may affect the transport of solar energetic particles (SEPs) in the heliosphere. In particular, the interplanetary counterparts of coronal mass ejections (ICMEs) are able to modify the surrounding interplanetary medium by introducing changes in the direction and strength of the magnetic field as well as increasing the level of magnetic field turbulence. Understanding the transport of SEPs in the heliosphere can lead to the increased capability in forecasting and predicting of the intensity of future SEP events. In this study, we classify paring SEP and ICME events from the 23rd solar cycle into six different categories based on when the peak of the SEP event occurred. For example, two different categories are: (1) the SEP peak occurred when an ICME was between the Sun and the Earth and (2) the SEP peak occurred after the ICME was beyond Earth. We perform a statistical analysis of the SEP peak intensities for each class of event and according to the characteristics of the solar x-ray flare or the CME associated with the origin of the SEP event For similar properties of the associated solar flare or CME we find that, on average, events observed after the passage of an ICME have larger peak intensities than those events observed with an ICME between the Sun and Earth. Strict analysis and understanding of the influence that the dynamic interplanetary solar wind has on the peak intensity of SEPs can enable space weather operational forecasters to better predict solar energetic particle intensities based on the occurrence of previous solar activity. By forecasting solar energetic particle events spacecraft, satellites, and humans in space, can be better protected from the impact of space weather.

  13. Interplanetary magnetic field and atmospheric electric circuit influences on ground-level pressure at Vostok

    Microsoft Academic Search

    G. B. Burns; B. A. Tinsley; A. V. Frank-Kamenetsky; E. A. Bering

    2007-01-01

    The Mansurov effect, which for the Southern Hemisphere consists of a positive association between the By component (east-west) of the interplanetary magnetic field (IMF) and the ground-level pressure for stations poleward of ?80° magnetic latitude, is confirmed for Vostok (78.5°S, 106.9°E; magnetic latitude 83.6°S) using modern data. The magnitude of the association is small (0.19 hP per nT; 1.2% common

  14. Magnetic Helicity of the Parker Interplanetary Magnetic Field and Alfvén Simple Waves

    NASA Astrophysics Data System (ADS)

    Webb, G. M.; Hu, Q.; Dasgupta, B.; Zank, G. P.; Roberts, D. A.

    2011-09-01

    We discuss the relative magnetic helicity of (a) the Parker [1] interplanetary spiral magnetic field, and (b) multi-dimensional simple Alfvén waves in the solar wind. We discuss the different forms of the magnetic vector potential A using either (a) the Coulomb gauge associated with solving a Poisson equation for A, in which the current acts as a source, (b) by using the homotopy form of A or (c) using a poloidal-toroidal decomposition of the magnetic field B. For the Parker field, we show that the relative helicity for a hemispherical volume north of the current sheet is negative, and the relative helicity for a similar volume south of the current sheet is positive. The relative helicity is also calculated in terms of the linkage of the poloidal and toroidal magnetic flux. These results extend the results of Bieber et al. [2] on the magnetic helicity of the Parker field, and are related to the helicity injection rate into the solar wind determined by Berger and Ruzmaikin [3]. Similar methods are used to determine the magnetic helicity for fully nonlinear Alfvén waves in the solar wind for which the magnetic field B has a constant magnitude, and the hodograph of B moves on a sphere. The solutions have |B| = const. hodographs, similar to nonlinear Alfvén waves observed in the solar wind by Bruno et al. [4], Roberts and Goldstein [5] and Gosling et al. [6]. Both shear and 2D torsional Alfvén waves are investigated.

  15. Solar Wind and Interplanetary Magnetic Field: A Tutorial C. T. Russell

    E-print Network

    Russell, Christopher T.

    Solar Wind and Interplanetary Magnetic Field: A Tutorial C. T. Russell Institute of Geophysics at the center of the sun to its radiation into space by the photosphere, but most importantly for the solar wind controls the properties of the solar wind. In this tutorial review we examine the properties of the fields

  16. POLAR-CAP ELECTRIC FIELD DISTRIBUTIONS RELATED TO THE INTERPLANETARY MAGNETIC FIELD DIRECTION

    Microsoft Academic Search

    J. P. Heppner

    1972-01-01

    was shown that at auroral-belt latitudes in both hemispheres the electric field is consistently directed poleward in the midevening sector and equatorward in the midmorning sector (i.e., from dusk toward dawn), whereas the field at higher (polar cap) latitudes is consistently directed from dawn toward dusk. By consistently, one means independent of magnetic disturbance conditions, interplanetary field directions, and other

  17. Global hybrid simulations: Foreshock waves and cavitons under radial interplanetary magnetic field geometry

    Microsoft Academic Search

    X. Blanco-Cano; N. Omidi

    2009-01-01

    We use global hybrid (kinetic ions and fluid electrons) simulations to study the solar wind interaction with the magnetosphere for a radial ($\\\\theta$ vB = 0) interplanetary magnetic field (IMF) geometry. Global hybrid simulations provide a collective picture of processes taking place in the foreshock, bow shock, and magnetosheath. Because ions are treated as particles, these codes also give information

  18. Global hybrid simulations: Foreshock waves and cavitons under radial interplanetary magnetic field geometry

    Microsoft Academic Search

    X. Blanco-Cano; N. Omidi; C. T. Russell

    2009-01-01

    We use global hybrid (kinetic ions and fluid electrons) simulations to study the solar wind interaction with the magnetosphere for a radial ($\\\\theta$vB = 0) interplanetary magnetic field (IMF) geometry. Global hybrid simulations provide a collective picture of processes taking place in the foreshock, bow shock, and magnetosheath. Because ions are treated as particles, these codes also give information on

  19. Interplanetary Electric Field and Solar Open Magnetic Flux: no Increase Since 1926.

    NASA Astrophysics Data System (ADS)

    Le Sager, P.; Svalgaard, L.

    2003-12-01

    A correlation analysis between the interplanetary electric field and the magnetograms recorded at Godhavn (Qeqertarsuaq), a polar cap geomagnetic observatory, is performed. A direction, along which the latitudinal dependence of the geomagnetic perturbation is minimum, is found, and allows us to apply the correlation results to pre-satelitte data, back to 1926. The findings indicate no secular trend in the cross-polar cap electric field, in the interplanetary electric field, and by inference in the sun's open magnetic flux, since 1926. The result is independent of the aa geomagnetic index.

  20. Mie scattering of the interplanetary magnetic field by the whole moon

    NASA Technical Reports Server (NTRS)

    Sonett, C. P.; Colburn, D. S.

    1973-01-01

    It is known from the Apollo magnetometer experiments that significant electromagnetic induction takes place in the lunar interior. This induction is excited by fluctuations of the interplanetary magnetic field and is detected by the induced fields on the surface of the moon. These results are reviewed briefly and the formal properties of the theory are discussed. It is shown that the mathematical treatment parallels that for classical electromagnetic scattering. Further the wavelength spectrum of the fluctuations of the interplanetary magnetic field include scales consistent with the radius of the moon. The consequence is that the moon is excited in several modes. Quadrupole and possibly octupole magnetic multipoles are found in the data. The electric type radiation corresponding to transverse magnetic excitation appears suppressed and far below the detection threshold of the magnetometers.

  1. Inferring the interplanetary magnetic field by observing the polar geomagnetic field.

    NASA Technical Reports Server (NTRS)

    Wilcox, J. M.

    1972-01-01

    Svalgaard (1968, 1972) and Mansurov (1969) have shown that it is possible to infer the polarity of the interplanetary magnetic field quite reliably from observations of the diurnal variation of polar geomagnetic fields. The effect is most prominent in the vertical component of geomagnetic observatories near the geomagnetic poles during several hours near noon. The interplanetary magnetic field observed with spacecraft near the earth is very similar to the mean solar magnetic field (i.e., the sun observed as though it were a star); thus the fact that observations of the polar geomagnetic field have existed without interruption since 1926 at the Danish Meteorological Institute station at Godhavn, Greenland, means that in effect the inferred solar magnetic field during five sunspot cycles is available for analysis.-

  2. Magnetic fields of photosphere and interplanetary space: Imbalance between positive and negative polarities

    NASA Astrophysics Data System (ADS)

    Vernova, E. S.; Tyasto, M. I.; Baranov, D. G.

    2014-12-01

    Photospheric magnetic fields are studied in this work on the basis of synoptic maps from the Kitt Peak Observatory (1976-2003) and WSO (1976-2012). The imbalance between positive and negative fluxes is considered for strong magnetic fields in the sunspot zone. The imbalance sign coincides with the polar field sign in the Northern hemisphere; it depends on both the phase of the 11-year cycle and the solar cycle parity. These features of variation in the magnetic field can be explained by a strong quadrupole moment of the photospheric magnetic field, which is also seen in a change of the polarity of the interplanetary magnetic field.

  3. Response of ionosphere and thermosphere during radial interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Wang, Hui; Luehr, Hermann; Shue, Jihong

    2014-05-01

    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 average during the interest period. The CPCP (cross polar cap potential) output by AMIE and calculated from DMSP observations have average 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 magnetic 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.

  4. Statistical properties of the interplanetary microscale fluctuations. [in plasma velocity and magnetic field

    NASA Technical Reports Server (NTRS)

    Belcher, J. W.

    1975-01-01

    Results are reported for a statistical study of short-period fluctuations in the interplanetary plasma velocity and magnetic field. The data base used consists of measurements of the interplanetary plasma and magnetic 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 magnetic 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.

  5. The effect of the Interplanetary Magnetic Field (IMF) on HF radar scattering volume electron densities

    NASA Astrophysics Data System (ADS)

    Gillies, R.; Yau, A. W.; Hussey, G. C.; Sofko, G. J.

    2012-12-01

    The Cascade Small-Sat and Ionospheric Polar Explorer (CASSIOPE) satellite will be launched in late 2012 with a suite of eight scientific instruments comprising the enhanced Polar Outflow Probe (ePOP). The Radio Receiver Instrument (RRI) will be used in conjunction with Super Dual Auroral Radar Network (SuperDARN) radars for detailed studies of the radar scattering volume. The Doppler velocities that are measured by the SuperDARN radars tend to be underestimated because the refractive index in the scattering volume is not known and, therefore, not taken into account when the velocities are calculated. A technique using frequency shifts made by the SuperDARN radars to study the electron density of the radar scattering volume has been developed. These scattering volume electron density values have been calculated for various parameters from SuperDARN frequency shifting data. This study focuses on the dependence of the Interplanetary Magnetic Field (IMF) on the scattering volume electron density results. The dependence of the average scattering volume electron density at different times and locations for various IMF orientations has been determined. This study allows improvements to be made to SuperDARN velocity measurements for various conditions and provides insight into the physics of the coherent scattering process. Finally, the upcoming launch of the ePOP satellite is anticipated to further confirm these results. The instruments on ePOP satellite will provide in situ high resolution measurements of the scattering volumes of the HF radars.

  6. On the importance of interplanetary magnetic field ?By? on polar cap patch formation

    NASA Astrophysics Data System (ADS)

    Zhang, Q.-H.; Zhang, B.-C.; Liu, R.-Y.; Dunlop, M. W.; Lockwood, M.; Moen, J.; Yang, H.-G.; Hu, H.-Q.; Hu, Z.-J.; Liu, S.-L.; McCrea, I. W.; Lester, M.

    2011-05-01

    A number of poleward moving events were observed between 1130 and 1300 UT on 11 February 2004, during periods of southward interplanetary magnetic field (IMF), while the steerable antenna of the European Incoherent Scatter (EISCAT) Svalbard radar (ESR) and the Tromsø VHF radar pointed nearly northward at low elevation. In this interval, simultaneous SuperDARN CUTLASS Finland radar measurements showed poleward moving radar aurora forms (PMRAFs) which appeared very similar to the density enhancements observed by the ESR northward pointing antenna. These events appeared quasiperiodically with a period of about 10 min. Comparing the observations from the above three radars, it is inferred that there is an almost one-to-one correspondence between the poleward moving plasma concentration enhancements (PMPCEs) observed by the ESR and the VHF radar and the PMRAFs measured by the CUTLASS Finland radar. These observations are consistent with the interpretation that the polar cap patch material was generated by photoionization at subauroral latitudes and that the plasma was structured by bursts of magnetopause reconnection giving access to the polar cap. There is clear evidence that plasma structuring into patches was dependent on the variability in IMF ?By?. The duration of these events implies that the average evolution time of the newly opened flux tubes from the subauroral region to the polar cap was about 33 min.

  7. Cosmic ray north-south anisotropy: The role of the interplanetary magnetic field

    SciTech Connect

    Pomerantz, M.A.; Duggal, S.P.; Owens, A.J.; Tolba, M.F.; Tsao, C.H.

    1982-12-01

    Nucleonic intensity data from the north and south polar stations Thule and McMurdo are analyzed to determine the nature of periodicities in the north-south asymmetry of relativistic galactic cosmic rays. The 24-hour average intensity differences of individual days range from 0 to +- 1.5%, and the most prominent time variation is recurrence tendency with a period consistent with the 27-day solar rotation period. A recently developed procedure for evaluating the statistical significance of quasipersistent data has been utilized to establish the reality of the 27-day signal disclosed by superposed epoch analysis of the north-south asymmetry data. Analyses of various components of the interplanetary magnetic field reveal that the IMF component B-bar/sub ..mu../ (parallel to the nominal garden hose direction) also displays a 27-day variation with maximum amplitude. Furthermore, a significant relationship between B-bar/sub ..mu../ and the north-south asymmetry is established by Chree analysis. On the basis of this relationship, it is suggested that the 27-day variation in the north-south asymmetry arises from the B-bar/sub ..mu../ x del-bar(n) drift, where del-bar(n) represents the radial gradient of cosmic rays.

  8. Magnetic field directional discontinuities. 2: Characteristics between 0.46 and 1.0 AU. [interplanetary magnetic fields

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

    The characteristics of directional discontinuities (DD's) in the interplanetary magnetic 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 average 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 average 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.

  9. Small scale magnetic flux-averaged magnetohydrodynamics

    SciTech Connect

    Pfirsch, D. (Max-Planck-Institut fuer Plasmaphysik, EURATOM Association, D-8046 Garching (Germany)); Sudan, R.N. (Laboratory of Plasma Studies, Cornell University, Ithaca, New York 14853 (United States))

    1994-08-01

    By relaxing exact magnetic flux conservation below a scale [lambda] a system of flux-averaged magnetohydrodynamic equations are derived from Hamilton's principle with modified constraints. An energy principle can be derived from the linearized averaged system because the total system energy is conserved. This energy principle is employed to treat the resistive tearing instability and the exact growth rate is recovered when [lambda] is identified with the resistive skin depth. A necessary and sufficient stability criteria of the tearing instability with line tying at the ends for solar coronal loops is also obtained. The method is extended to both spatial and temporal averaging in Hamilton's principle. The resulting system of equations not only allows flux reconnection but introduces irreversibility for appropriate choice of the averaging function. Except for boundary contributions which are modified by the time averaging process total energy and momentum are conserved over times much longer than the averaging time [tau] but not for less than [tau]. These modified boundary contributions correspond to the existence, also, of damped waves and shock waves in this theory. Time and space averaging is applied to electron magnetohydrodynamics and in one-dimensional geometry predicts solitons and shocks in different limits.

  10. The IDV index: Its derivation and use in inferring long-term variations of the interplanetary magnetic field strength

    NASA Astrophysics Data System (ADS)

    Svalgaard, Leif; Cliver, Edward W.

    2005-12-01

    On the basis of a consideration of Bartels' historical u index of geomagnetic activity, we devise an equivalent index that we refer to as the interdiurnal variability (IDV). The IDV index has the interesting and useful property of being highly correlated with the strength of the interplanetary magnetic field (B; R2 = 0.75) and essentially unaffected by the solar wind speed (V; R2 = 0.01) as measured by spacecraft. This enables us to obtain the variation of B from 1872 to the present, providing an independent check on previously reported results for the evolution of this parameter. We find that solar cycle average B increased by ˜25% from the 1900s to the 1950s and has been lower since. If predictions for a small solar cycle 24 bear out, solar cycle average B will return to levels of ˜100 years ago during the coming cycle(s).

  11. Seeing the Sun in a New Light: Interplanetary Magnetic Field Lines

    NSDL National Science Digital Library

    David Stern

    This lesson discusses the Sun's corona, observed from spacecraft in the extreme ultra violet (EUV) and in x-rays, including coronal holes and coronal mass ejections (CME), their effect near Earth and their monitoring from space. This section also discusses related phenomena in interplanetary space and on Earth and contains an optional class exercise in which students learn about field line preservation of flows in a highly conducting plasma, and use it to graphically obtain the shapes of interplanetary magnetic field lines. They also receive information about high-energy ions and electrons accelerated by solar activity, probably from magnetic energy, and the hazard they pose to spacefarers. Students receive an introduction to NASA's great observatories, expanding the coverage of the electromagnetic spectrum by astronomers.

  12. Interplanetary magnetic field power spectra - Mean field radial or perpendicular to radial

    NASA Technical Reports Server (NTRS)

    Sari, J. W.; Valley, G. C.

    1976-01-01

    A detailed frequency analysis of Pioneer-6 interplanetary magnetic field data is carried out for 5 to 15 hour periods during which the mean interplanetary field is approximately radial or perpendicular to radial. The reason why these data sets were chosen is that by making the usual assumption that the phase speed of any wave present is much less than the mean solar wind speed, the measured frequency spectra can be interpreted in terms of the wave number parallel or perpendicular to the mean field, without such additional assumptions as isotropy or the dominance of a particular mode and without measurements of velocity and density. The details of the calculation of the magnetic field power spectra, coherencies, and correlation functions are discussed, along with results obtained directly from the data (such as spectra, slopes, anisotropies, and coherencies). The results are interpreted in terms of MHD theory, and are related to work in other areas.

  13. Comparison of inferred and observed interplanetary magnetic field polarities, 1970-1972

    NASA Technical Reports Server (NTRS)

    Wilcox, J. M.; Svalgaard, L.; Hedgecock, P. C.

    1975-01-01

    The inferred polarity (toward or away from the sun) of the interplanetary magnetic 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 interplanetary magnetic 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.

  14. The relation between the polarity of the interplanetary magnetic field and the polar geomagnetic field

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.

    1973-01-01

    The relation between the azimuthal component of the interplanetary magnetic field and the polar cap geomagnetic field is discussed. The geomagnetic effects can be described as produced by an ionospheric current system encircling the magnetic 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 magnetic 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.

  15. Reconstruction and Prediction of Variations in the Open Solar Magnetic Flux and Interplanetary Conditions

    NASA Astrophysics Data System (ADS)

    Lockwood, Mike

    2013-09-01

    Historic geomagnetic activity observations have been used to reveal centennial variations in the open solar flux and the near-Earth heliospheric conditions (the interplanetary magnetic field and the solar wind speed). The various methods are in very good agreement for the past 135 years when there were sufficient reliable magnetic observatories in operation to eliminate problems due to site-specific errors and calibration drifts. This review underlines the physical principles that allow these reconstructions to be made, as well as the details of the various algorithms employed and the results obtained. Discussion is included of: the importance of the averaging timescale; the key differences between ``range'' and ``interdiurnal variability'' geomagnetic data; the need to distinguish source field sector structure from heliospherically-imposed field structure; the importance of ensuring that regressions used are statistically robust; and uncertainty analysis. The reconstru! ctions are exceedingly useful as they provide calibration between the in-situ spacecraft measurements from the past five decades and the millennial records of heliospheric behaviour deduced from measured abundances of cosmogenic radionuclides found in terrestrial reservoirs. Continuity of open solar flux, using sunspot number to quantify the emergence rate, is the basis of a number of models that have been very successful in reproducing the variation derived from geomagnetic activity. These models allow us to extend the reconstructions back to before the development of the magnetometer and to cover the Maunder minimum. Allied to the radionuclide data, the models are revealing much about how the Sun and heliosphere behaved outside of grand solar maxima and are providing a means of predicting how solar activity is likely to evolve now that the recent grand maximum (that had prevailed throughout the space age) has come to an end.

  16. Some low-altitude cusp dependencies on the interplanetary magnetic field

    Microsoft Academic Search

    Patrick T. Newell; Ching-I. Meng; David G. Sibeck; Ronald Lepping

    1989-01-01

    Although it has become well established that the low-altitude polar cusp moves equatorward during intervals of southward interplanetary magnetic field (IMF {ital B}{sub {ital z}}>0), many other important aspects of the cusp's response to IMF components are not as well investigated. An algorithm for identifying the cusp proper was applied to 12,569 high-latitude dayside passes of the DMSP F7 satellite

  17. On the existence of finite amplitude, transverse Alfven waves in the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Sari, J. W.

    1977-01-01

    Interplanetary magnetic field data from the Mariner 10 spacecraft were examined for evidence of small and finite amplitude transverse Alfven waves, general finite amplitude Alfven waves, and magnetosonic waves. No evidence for transverse Alfven waves was found. Instead, the field fluctuations were found to be dominated by the general finite amplitude Alfven wave. Such wave modes correspond to non-plane-wave solutions of the nonlinear magnetohydrodynamic equations.

  18. Advanced Propulsion for Interplanetary Flights using Magnetized Target Fusion

    Microsoft Academic Search

    Y. C. F. Thio; B. Freeze; H. Gerrish; R. C. Kirkpatrick; D. B. Landrum; G. R. Schmidt

    1998-01-01

    Magnetized target fusion is an approach in which a magnetized target plasma is compressed inertially by an imploding material wall. The use of a high energy plasma liner to provide the required implosion was recently proposed by Thio, et al. The plasma liner is formed by the merging of a number (nominally 60) of high momentum plasma jets converging towards

  19. Magnetic shielding of interplanetary spacecraft against solar flare radiation

    Microsoft Academic Search

    Franklin H. Cocks; Seth Watkins

    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

  20. Magnetohydrodynamic simulation of the interaction between two interplanetary magnetic clouds and its consequent geoeffectiveness: 2. Oblique collision

    Microsoft Academic Search

    Ming Xiong; Huinan Zheng; Shui Wang

    2009-01-01

    The numerical studies of the interplanetary coupling between multiple magnetic clouds (MCs) are continued by a 2.5-dimensional ideal magnetohydrodynamic (MHD) model in the heliospheric meridional plane. The interplanetary 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

  1. Interplanetary Magnetic Field Structure and Geomagnetic Storms during Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Maris Muntean, Georgeta; Besliu-Ionescu, Diana; Dobrica, Venera

    2015-04-01

    Interplanetary Magnetic Field (IMF) structure, determined by the solar magnetic field and its variability, is responsible for an essential part of the geomagnetic perturbations. IMF in the terrestrial orbital plane is structured into two or four sectors with opposite direction of the magnetic field, "away" and "towards" the Sun so that the Earth is passing through the opposite magnetic structures during a solar rotation (27 days). The magnetic structure of IMF is significantly varying during the 11-yr solar cycle. This paper analyses the IMF sectors in the solar cycle 24 (2009 - 2014) and the geomagnetic variability induced by the sector boundaries. High speed streams of the solar wind coincident with sector boundaries are determined. Geomagnetic storms triggered by such complex heliospheric phenomena are analysed by their main phase morphology (structures) and the energy transferred from solar wind into the terrestrial magnetosphere during the these phases.

  2. Origin of interplanetary southward magnetic fields responsible for major magnetic storms near solar maximum (1978--1979)

    Microsoft Academic Search

    Bruce T. Tsurutani; Walter D. Gonzalez; Frances Tang; Syun I. Akasofu; Edward J. Smith

    1988-01-01

    The origins of the interplanetary southward B\\/sub z\\/ which cause the 10 major (D\\/sub s\\/\\/sub t\\/<-100 nT) magnetic storms detected during the 500 days of study (August 16, 1978, to December 28, 1979) of the Gonzalez and Tsurutani (1987) work are examined in detail. A full complement of ISEE 3 plasma and field data, an 11-station AE index and the

  3. The control of auroral zone dynamics and thermodynamics by the interplanetary magnetic field dawn-dusk (Y) component

    SciTech Connect

    Sica, R.J. (Univ. of Western Ontario, London (Canada)); Hernandez, G. (Univ. of Washington, Seattle (USA)); Emery, B.A.; Roble, R.G. (National Center for Atmospheric Research, Boulder, CO (USA)); Smith, R.W.; Rees, M.H. (Univ. of Alaska, Fairbanks (USA))

    1989-09-01

    Previous theoretical and experimental studies have shown that the dawn-dusk component of the interplanetary magnetic field (IMF B{sub y}) expands the classical symmetric two-cell convection pattern toward dusk (B{sub y} negative) or toward dawn (B{sub y} positive) in the northern hemisphere, altering the ion drag forcing on the neutral atmosphere. Measurements of the neutral dynamics associated with these convection patterns have been presented primarily at magnetic latitudes greater than 70{degree} in the polar cap. In this study, nights with coincident IMF measurements have been selected from the extensive four-year auroral zone thermospheric wind and temperature data set derived from Fabry-Perot spectrometer measurements of the Doppler shifts and widths of the O({sup 1}D) 15,867 cm{sup {minus}1} (630.0 nm) emission from College, Alaska. Averages from 112 nights of measurements from College were also computed using a selection criterion that depended on the previous 2 hours of IMF measurements (case 2). This procedure yielded averages that differed at times from case 1. The wind and temperature averages for both cases show large variations with B{sub y} in the auroral zone. The wind averages for B{sub y} negative and positive are compared with National Center for Atmospheric Research thermospheric general circulation model predictions that use a B{sub y}-dependent model of ionospheric convection. The results for B{sub y} negative and positive are compared with National Center for Atmospheric Research thermospheric general circulation model predictions that use a B{sub y}-dependent model of ionospheric convection. The results for B{sub y} negative compare favorably with the averages, but there are significant differences between model calculations and averages for the B{sub y} positive case.

  4. Soft ion precipitation at very high latitudes during northward interplanetary magnetic field

    SciTech Connect

    Miyake, W.; Whalen, B.A.; Yau, A.W. [Herzberg Institute of Astrophysics, Ottawa (Canada)] [and others] [Herzberg Institute of Astrophysics, Ottawa (Canada); and others

    1994-08-01

    The authors report on satellite observations of soft ion precipitation, often in conjunction with electron precipitation, at invariant latitudes north of the auroral zones. The precipitation densities of ions were roughly 0.1/cm{sup 3}, with hundreds of eV energy, while electron energies were tens of eV with slightly higher densities. When the interplanetary magnetic field had a strong northern component, ion precipitation events could be observed at all times. There was an observed flux minimum on the flanks of the auroral oval.

  5. Contributions to the Fourth Solar Wind Conference. [interplanetary magnetic fields and medium

    NASA Technical Reports Server (NTRS)

    Acuna, M. H.; Behannon, K. W.; Burlaga, L. F.; Lepping, R.; Ness, N.; Ogilvie, K.; Pizzo, J.

    1979-01-01

    Recent results in interplanetary physics are examined. These include observations of shock waves and post-shock magnetic 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.

  6. Power spectrum analysis of periodicities in the interplanetary magnetic field polarity (1927-2002)

    NASA Astrophysics Data System (ADS)

    Echer, E.; Svalgaard, L.

    2006-05-01

    An updated analysis of periodicities present in the interplanetary magnetic field (IMF) polarity during 1927-2002 is performed in this work. Power spectral analysis was conducted using the multiple taper method. The global (whole period) spectrum showed as the main periodicities ~1 year, 27 days (solar rotation) and ~13-14 days (solar rotation 2nd harmonic). Year to year spectra showed high variability, with most years showing dominance of the 1st harmonic over the 2nd harmonic. The present results are compared with other studies found in the literature.

  7. Possible acceleration of charged particles through the reconnection of magnetic field lines in interplanetary space

    NASA Technical Reports Server (NTRS)

    Levy, E. H.; Ipavich, F. M.; Gloeckler, G.

    1974-01-01

    Prominent intensity spikes in the flux of protons and alphas with less than 0.5 MeV per charge were observed in the region several hours behind an interplanetary shock front. The small spatial scale of these events and the high anisotropy of the particle flux suggest local acceleration. The spectra of the particles, which are cut off at equal energy per charge, suggest acceleration through an electric field. The possibility is examined that these events have their origin in active magnetic neutral sheets in the shocked solar wind.

  8. Thermosphere-Ionosphere Response to Structures in the Solar Wind and Interplanetary Magnetic Field

    NASA Astrophysics Data System (ADS)

    Solomon, S. C.

    2011-12-01

    The upper atmosphere and ionosphere exhibit substantial variation in response to forcing by the solar wind and the interplanetary magnetic field. Major changes are often associated with eruptive events on the Sun, which occur more frequently at high solar activity and during the declining phase of the solar cycle. However, there has been recent appreciation of the importance of periodic fluctuations in the thermosphere-ionosphere system at lower levels of activity, and even at solar minimum. These fluctuations may be associated with regions of enhanced solar wind velocity known as high-speed streams, which are thought to be driven by regions of "open" magnetic flux in the solar corona sometimes called "coronal holes" due to their darker appearance on EUV images of the Sun. This paper presents measurement analysis and model simulations to demonstrate that thermosphere-ionosphere changes at solar minimum are indeed proportionally large, even compared with variability at solar maximum, but that the direct association with high-speed streams is overly simplistic, due to the crucial role played by the interplanetary magnetic field in magnetosphere-ionosphere coupling.

  9. Interplanetary magnetic field polarity and the size of low-pressure troughs near 180 deg W longitude

    NASA Technical Reports Server (NTRS)

    Wilcox, J. M.; Duffy, P. B.; Schatten, K. H.; Svalgaard, L.; Scherrer, P. H.; Roberts, W. O.; Olson, R. H.

    1979-01-01

    The relationship between interplanetary magnetic 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 interplanetary magnetic 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 interplanetary magnetic 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

  10. Cosmic rays, interplanetary magnetic field and Coronal mass ejections

    NASA Astrophysics Data System (ADS)

    Mishra, Rajesh Kumar; Agarwal Mishra, Rekha

    Coronal Mass Ejections are vast structures of plasma and magnetic fields that are expelled from the sun into the heliosphere. This material is detected by remote sensing and in-situ spacecraft observations. The present study deals with the influence of four types of CMEs namely Asymmetric 'Full' Halo CMEs, Partial Halo CMEs, Asymmetric and Complex 'Full' Halo CMEs and 'Full' Halo CMEs on cosmic ray neutron monitor intensity. The data of ground based neutron monitor of Moscow and CME events observed with instruments onboard and Wind spacecraft have been used in the present analysis. The method of superposed epoch (Chree) analysis has been used to the arrival times of these CMEs. It is noteworthy that the frequency of occurrence of Asymmetric 'Full' Halo CMEs is significantly high, whereas frequency of occurrence of Asymmetric and Complex 'Full' Halo CMEs is low compared to other CMEs. Significant enhancement in cosmic ray intensity is observed after 4 days of the onset of asymmetric full halo and 6 days after the onset of full halo CMEs. The fluctuations in cosmic ray intensity are more prior to the onset of both types of the CMEs. However, during Partial Halo CMEs the cosmic ray intensity peaks, 8-9 days prior to the onset of CMEs and depressed 3 days prior to the onset of CMEs, whereas in case of asymmetric and complex full CMEs, the intensity depressed 2 days prior to the onset of CMEs and enhanced 2 days after the onset of CMEs. The deviations in cosmic ray intensity are more pronounced in case for asymmetric and complex full halo CMEs compared to other CMEs. The cosmic ray intensity shows nearly good anti-correlation with IMF strength (B) during asymmetric full halo CMEs and partial halo CMEs, whereas it shows poor correlation with B during other CMEs. The IMF, B significantly decreased five days prior to the onset of asymmetric and full halo CMEs and four days after the onset of partial halo CMEs, whereas IMF strength (B) significantly enhanced 5-6 days prior and after the onset of asymmetric and complex full halo CMEs. IMF strength (B) significantly depressed 2 days prior and 4 days after the onset of full halo CMEs. However, IMF, B significantly enhanced from its minimum to maximum values in 2 days interval prior to the onset of CMEs and in 3 days interval after the onset of CMEs.

  11. The Chain Response of the Magnetospheric - and - ground Magnetic Field to Interplanetary Shocks

    NASA Astrophysics Data System (ADS)

    Sun, T.; Wang, C.; Zhang, J.; Pilipenko, V.

    2014-12-01

    In response to interplanetary (IP) shocks, magnetic field may decrease/increase (negative/positive response) in nightside magnetosphere, while at high latitudes on the ground it has two phase bipolar variations: preliminary impulse(PI) and main impulse (MI). Using global MHD simulations, we investigate the linkage between the MI phase variation on the ground and the magnetospheric negative response to an IP shock. It is revealed that although the two phenomena occur at largely-separated locations, they are physically related and form a response chain. The velocity disturbances near the flanks of the magnetopause cause the magnetic field to decrease, resulting in a dynamo which thus powers the transient field-aligned currents (FACs). These FACs further generates a pair of ionospheric current vortex, leading to MI variations on the ground. For the first time, we report here the intrinsic physically-related chain response of the magnetospheric - and - ground magnetic field to IP shocks.

  12. Magnetic Field Configuration Models and Reconstruction Methods for Interplanetary Coronal Mass Ejections

    E-print Network

    Al-Haddad, N; Savani, N P; Möstl, C; Marubashi, K; Hidalgo, M; Roussev, I I; Poedts, S; Farrugia, C J

    2012-01-01

    This study aims to provide a reference to different magnetic field models and reconstruction methods for interplanetary coronal mass ejections (ICMEs). In order to understand the differences in the outputs of those models and codes, we analyze 59 events from the Coordinated Data Analysis Workshop (CDAW) list, using four different magnetic field models and reconstruction techniques; force-free fitting (Goldstein,1983,Burlaga,1988,Lepping et al.,1990), magnetostatic reconstruction using a numerical solution to the Grad-Shafranov equation (Hu and Sonnerup, 2001), fitting to a self-similarly expanding cylindrical configuration (Marubashi and Lepping, 2007) and elliptical, non-force free fitting (Hidalgo,2003). The resulting parameters of the reconstructions for the 59 events are compared statistically, as well as in selected case studies. The ability of a method to fit or reconstruct an event is found to vary greatly: the Grad-Shafranov reconstruction is successful for most magnetic clouds (MCs) but for less than...

  13. The mean magnetic field of the sun - Method of observation and relation to the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Scherrer, P. H.; Wilcox, J. M.; Kotov, V.; Severnyi, A. B.; Howard, R.

    1977-01-01

    The mean solar magnetic field as measured in integrated light has been observed since 1968. Since 1970 it has been observed both at Hale Observatories and at the Crimean Astrophysical Observatory. The observing procedures at both observatories and their implications for mean field measurements are discussed. A comparison of the two sets of daily observations shows that similar results are obtained at both observatories. A comparison of the mean field with the interplanetary magnetic polarity shows that the IMF sector structure has the same pattern as the mean field polarity.

  14. Onset time of solar energetic particles under the influence of scattering by interplanetary magnetic turbulence

    NASA Astrophysics Data System (ADS)

    Diaz, Ismael; Zhang, Ming; Rassoul, Hamid

    When a solar flare or CME occurs, solar energetic particles (SEP) are produced and can quickly travel along the interplanetary magnetic field lines, some of which connect the sun to the earth. Because these particles are extremely hazardous to astronauts or sensitive microelectronics on spacecraft, it is an important to predict their arrival and provide a window of time when the danger will subsist. Analysis of onset time of SEP arrival has been carried out by many researchers in the community (e.g., Reames, 2009). Assuming that first arrival particles have traveled nearly scatter-free, one can determine the length of the connecting magnetic field line since the onset time will be linearly proportional to 1/v. The proportionality constant of the linear relation is the length of the field line. At Earth the nominal Parker field line length is 1.12 AU, but many onset time analyses yield larger estimates, sometimes, up to twice that length. In this paper we present a calculation of SEP onset times from a model that solves the focused transport equation that allows for particle scattering during the interplanetary transport (Zhang et. al., 2009). With typical mean free paths found in SEP observations (Bieber et al., 1994) we found that the onset time of SEP flux is delayed compared to scatter-free transport. The time delay depends on the particle rigidity. Under most reasonable ranges of mean free path and its rigidity dependence, the onset time appears to be linearly proportional to 1/v. Such a property may easily mislead researchers to think the transport is scatter-free and derive larger field line lengths than the expected Parker field line. The smaller the mean free path the longer the field line length will be derived. The model results show how interplanetary scattering can severely affect the onset times of SEP's.

  15. A study of an expanding interplanatary magnetic cloud and its interaction with the earth's magnetosphere - The interplanetary aspect

    NASA Technical Reports Server (NTRS)

    Farrugia, C. J.; Burlaga, L. F.; Osherovich, V. A.; Richardson, I. G.; Freeman, M. P.; Lepping, R. P.; Lazarus, A. J.

    1993-01-01

    High time resolution interplanetary magnetic field and plasma measurements of an interplanetary magnetic cloud and its interaction with the earth's magnetosphere on January 14/15, 1988 are interpreted and discussed. It is argued that the data are consistent with the theoretical model of magnetic clouds as flux ropes of local straight cylindrical geometry. The data also suggest that this cloud is aligned with its axis in the ecliptic plane and pointing in the east-west direction. Evidence consisting of the intensity and directional distribution of energetic particle in the magnetic cloud argues in favor of the connectedness of the magnetic field lines to the sun's surface. The intensities of about 0.5 MeV ions is rapidly enhanced and the particles stream in a collimated beam along the magnetic field preferentially from the west of the sun. The particles travel form a flare site along the cloud magnetic field lines, which are thus presumably still attached to the sun.

  16. Long-term Trends in Interplanetary Magnetic Field Strength and Solar Wind Structure during the 20th Century

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Cliver, E. W.; Cane, H. V.; White, Nicholas E. (Technical Monitor)

    2002-01-01

    Lockwood et al have recently reported an approximately 40% increase in the radial component of the interplanetary magnetic 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 average fields during solar cycle 20 (1964-1976) in comparison with surrounding cycles. For times after 1976 the average 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 averages 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.

  17. Properties of Kelvin-Helmholtz waves at the magnetopause under northward interplanetary magnetic field: Statistical study

    NASA Astrophysics Data System (ADS)

    Lin, Dong; Wang, Chi; Li, Wenya; Tang, Binbin; Guo, Xiaocheng; Peng, Zhong

    2014-09-01

    We search the plasma and magnetic field data of the Time History of Events and Macroscale Interactions during Substorms (THEMIS) probes B and C during 2008 and 2009 for observation evidences of the Kelvin-Helmholtz instability (KHI). Fourteen KHI events with rolled-up vortices are identified under the northward interplanetary magnetic field (IMF) at the low-latitude boundary layer (LLBL). We collect another 42 events reported from the observations of the Geotail, Double Star TC-1, and Cluster for a statistical study of the KH wave properties. All the 56 rolled-up KH wave events are quantitatively characterized by the dominant period, phase velocity, and the wavelength. We further explore the relationship between the KH wave period and the solar wind velocity (VSW) and the IMF clock angle. It is found that the KH period tends to be shorter under a higher VSW, and longer with a larger IMF clock angle. The spatial distribution of the KH wavelength shows a longitudinal growth with increasing distance from the subsolar point along the flank magnetopause. The statistical results provide new insights for the development of KH waves and their connection with the interplanetary conditions and deepen our understanding of the KHI at the magnetopause.

  18. Cosmic ray neutron monitor intensity in relation to Coronal Mass Ejections and Interplanetary Magnetic Field

    NASA Astrophysics Data System (ADS)

    Mishra, Rajesh Kumar; Agarwal Mishra, Rekha

    2012-07-01

    It is well known that Coronal Mass Ejections are vast structures of plasma and magnetic fields that are expelled from the sun into the heliosphere, which is detected by remote sensing and in-situ spacecraft observations. Recent work indicates that the open magnetic flux from coronal holes may be a more important driver of cosmic-ray modulation than coronal mass ejections (CMEs), which originate from closed-field regions on the Sun. Influence of four types of CMEs namely Asymmetric 'Full' Halo CMEs, Partial Halo CMEs, Asymmetric and Complex 'Full' Halo CMEs and 'Full' Halo CMEs on cosmic ray neutron monitor intensity have been investigated in this study. The data of two different ground based neutron monitors and CME events observed with instruments onboard and Wind spacecraft have been used in the present analysis. The method of superposed epoch (Chree) analysis has been used to the arrival times of these CMEs. The occurrence frequency of three different types of CMEs used in the present analysis shows complex behavior. However, significant increase in cosmic ray intensity is observed few days after the onset of asymmetric full halo and few days after the onset of full halo CMEs. The fluctuations in cosmic ray intensity are more prior to the onset of both types of the CMEs. However, during Partial Halo CMEs the cosmic ray intensity peaks, 8- 9 days prior to the onset of CMEs and depressed 3 days prior to the onset of CMEs, whereas in case of asymmetric and complex full CMEs, the intensity depressed 2 days prior to the onset of CMEs and enhanced 2 days after the onset of CMEs. The deviations in cosmic ray intensity are more pronounced in case for asymmetric and complex full halo CMEs compared to other CMEs. The cosmic ray intensity shows nearly good anti-correlation with interplanetary magnetic field strength (B) during asymmetric full halo CMEs and partial halo CMEs, whereas it shows poor correlation with B during other CMEs. The interplanetary magnetic field strength B shows significant characteristics before and after the onset of these three types of CMEs. Keywords: cosmic ray, coronal mass ejections, interplanetary magnetic field.

  19. Interplanetary magnetic field control of high-latitude activity on July 29, 1977

    NASA Technical Reports Server (NTRS)

    Zanetti, L. J.; Potemra, T. A.; Doering, J. P.; Lee, J. S.; Fennell, J. F.; Hoffman, R. A.

    1982-01-01

    Multisatellite particle and magnetic field data for the substorms of July 29, 1977, show auroral-like activity above 80 deg invariant latitude during the recovery period. The movement of auroral zone activity to high latitudes followed the substorm sequence, at which time the inferred interplanetary magnetic field (IMF) was strongly northward. Electron energy spectra indicative of a field-aligned potential drop, and the absence of supporting precipitating ions, are found at latitudes greater than 80 deg. The north-south symmetry of these observations suggests that the events are on closed field lines. It is noted the very strong northward IMF connected to the sunward tilted geomagnetic dipole field plays a role in the driving of strong Birkeland and ionospheric current systems in the northern polar regions, while eliminating them from the southern polar regions.

  20. Observation and analysis of abrupt changes in the interplanetary plasma velocity and magnetic field.

    NASA Technical Reports Server (NTRS)

    Martin, R. N.; Belcher, J. W.; Lazarus, A. J.

    1973-01-01

    This paper presents a limited study of the physical nature of abrupt changes in the interplanetary plasma velocity and magnetic 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 magnetic 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).

  1. Quantitative Imaging of the Solar Wind: CME Mass Evolution and the Interplanetary Magnetic Flux Balance

    NASA Astrophysics Data System (ADS)

    DeForest, Craig

    2012-05-01

    We recently developed post-processing techniques for heliospheric images from the STEREO spacecraft; the new data sets enable, for the first time, quantitative photometric studies of evolving wind features at distances up to 1 A.U. from the Sun. We have used the new data to trace several CMEs and magnetic disconnection events to their origins in the solar corona, and to infer the force balance and entrained magnetic flux in those features. We present recent results showing the relationship between ICME and CME anatomy, in particular the origin of an observed interplanetary flux rope and the relationship between original launched solar material and piled-up sheath material and flux in the storm at 1. A.U. We discuss implications for understanding space weather physics and predicting individual events, and point out the importance of future imaging technologies such as polarized heliospheric imaging.

  2. A global magnetohydrodynamic simulation of the magnetosheath and magnetosphere when the interplanetary magnetic field is northward

    NASA Technical Reports Server (NTRS)

    Ogino, Tatsuki; Walker, Raymond I.; Ashour-Abdalla, Maha

    1992-01-01

    We have used a new high-resolution global magnetohydrodynamic simulation model to investigate the configuration of the magnetosphere when the interplanetary magnetic field (IMF) is northward. For northward IMF the magnetospheric configuration is dominated by magnetic 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.

  3. Spatial distribution of large-scale solar magnetic fields and their relation to the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Levine, R. H.

    1979-01-01

    The spatial organization of the observed photospheric magnetic 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 interplanetary 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.

  4. Explanation for anomalous equatorial ionospheric electric fields associated with a northward turning of the interplanetary magnetic field

    Microsoft Academic Search

    M. C. Kelley; B.G. Fejer; C.A. Gonzales

    1979-01-01

    Anomalous reversals of the zonal equatorial electric field component have sometimes been observed when the interplanetary magnetic field turns northward from a steady southerly direction. We suggest that this reversal is associated with a sudden change in the convection electric field in the magnetosphere and present measurements to support this explanation. Although slower variations in the convection field are shielded

  5. Interplanetary Magnetic Field Polarity and the Size of Low-Pressure Troughs Near 180{degrees}W Longitude.

    PubMed

    Wilcox, J M; Duffy, P B; Schatten, K H; Svalgaard, L; Scherrer, P H; Roberts, W O; Olson, R H

    1979-04-01

    When the interplanetary magnetic field is directed away from the sun, the area of wintertime low-pressure (300-millibar) troughs near 180 degrees W longitude is significantly larger than when the field is toward the sun. This relation persists during most of the winters of 1951 to 1973. PMID:17816739

  6. Strong interplanetary magnetic field By-related plasma convection in the ionosphere and cusp field-aligned currents under northward

    E-print Network

    California at Berkeley, University of

    Strong interplanetary magnetic field By-related plasma convection in the ionosphere and cusp field and the assimilative mapping of ionospheric electrodynamics (AMIE) model during a prolonged interval with large procedure provides a reasonably good description of plasma circulations in the ionosphere during

  7. Waves on the dusk flank boundary layer during very northward interplanetary magnetic field conditions: Observations and simulation

    Microsoft Academic Search

    D. H. Fairfield; M. M. Kuznetsova; T. Mukai; T. Nagai; T. I. Gombosi; A. J. Ridley

    2007-01-01

    The Geotail spacecraft made an inbound passage perpendicular to the dusk equatorial magnetopause on 1 August 1998 when the interplanetary magnetic field had been very northward for more than 10 hours. As the spacecraft moved through the low-latitude boundary layer, it detected waves with ?3 min period that caused transitions between cool dense magnetosheath plasma and mixed magnetosheath and magnetosphere

  8. Magnetic and plasma response of the Earth's magnetosphere to interplanetary shock

    NASA Astrophysics Data System (ADS)

    Du, A.; Cao, X.; Wang, R.; Zhang, Y.

    2013-12-01

    In this paper, we investigate the global response of magnetosphere to interplanetary shock, and focus on the magnetic and plasma variations related to aurora. The analysis utilizes data from simultaneous observations of interplanetary 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 magnetic 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 magnetic 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).

  9. MAGNETIC VARIANCES AND PITCH-ANGLE SCATTERING TIMES UPSTREAM OF INTERPLANETARY SHOCKS

    SciTech Connect

    Perri, Silvia; Zimbardo, Gaetano, E-mail: silvia.perri@fis.unical.it, E-mail: gaetano.zimbardo@fis.unical.it [Dipartimento di Fisica, Universita della Calabria, Ponte P. Bucci, Cubo 31C, I-87036 Arcavacata di Rende (Italy)

    2012-07-20

    Recent observations of power-law time profiles of energetic particles accelerated at interplanetary shocks have shown the possibility of anomalous, superdiffusive transport for energetic particles throughout the heliosphere. Those findings call for an accurate investigation of the magnetic field fluctuation properties at the resonance frequencies upstream of the shock's fronts. Normalized magnetic 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 magnetic 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 magnetic 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 magnetic 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.

  10. The evolution of parameters of interplanetary magnetic clouds from ˜0.3 AU to 1 AU as inferred from Helios and Wind measurements

    Microsoft Academic Search

    Charles Farrugia; Martin Leitner; Helfried Biernat; Daniel Berdichevsky; Rainer Schwenn; Hiroshi Matsui; Harald Kucharek; Roy Torbert

    2004-01-01

    A class of interplanetary configurations which interact strongly with the Earth's magnetosphere are interplanetary magnetic clouds. A desideratum of space weather predictions is that they be made from data acquired by distant probes so as to guarantee as long a lead time as possible. For this to be viable, one must have accurate knowledge of how ejecta parameters evolve. To

  11. ISEE 3 observations of low-energy proton bidirectional events and their relation to isolated interplanetary magnetic structures

    NASA Technical Reports Server (NTRS)

    Marsden, R. G.; Sanderson, T. R.; Tranquille, C.; Wenzel, K.-P.; Smith, E. J.

    1987-01-01

    The paper represents the results of a comprehensive survey of low-energy proton bidirectional anisotropies and associated transient magnetic structures as observed in the 35-1600 keV energy range on ISEE-3 during the last solar maximum. The majority of observed bidirectional flow (BDF) events (more than 70 percent) are associated with isolated magnetic structures which are postulated to be an interplanetary manifestation of coronal mass ejection (CME) events. The observed BDF events can be qualitatively grouped into five classes depending on the field signature of the related magnetic structure and the association (or lack of association) with an interplanetary shock. Concerning the topology of the CME-related magnetic structures, the observations are interpreted as being consistent with a detached bubble, comprising closed loops or tightly wound helices.

  12. Comparing generic models for interplanetary shocks and magnetic clouds axis configurations at 1 AU

    NASA Astrophysics Data System (ADS)

    Janvier, M.; Dasso, S.; Démoulin, P.; Masías-Meza, J. J.; Lugaz, N.

    2015-05-01

    Interplanetary coronal mass ejections (ICMEs) are the manifestation of solar transient eruptions, which can significantly modify the plasma and magnetic conditions in the heliosphere. They are often preceded by a shock, and a magnetic flux rope is detected in situ in a third to half of them. The main aim of this study is to obtain the best quantitative shape for the flux rope axis and for the shock surface from in situ data obtained during spacecraft crossings of these structures. We first compare the orientation of the flux rope axes and shock normals obtained from independent data analyses of the same events, observed in situ at 1 AU from the Sun. Then we carry out an original statistical analysis of axes/shock normals by deriving the statistical distributions of their orientations. We fit the observed distributions using the distributions derived from several synthetic models describing these shapes. We show that the distributions of axis/shock orientations are very sensitive to their respective shape. One classical model, used to analyze interplanetary imager data, is incompatible with the in situ data. Two other models are introduced, for which the results for axis and shock normals lead to very similar shapes; the fact that the data for MCs and shocks are independent strengthens this result. The model which best fits all the data sets has an ellipsoidal shape with similar aspect ratio values for all the data sets. These derived shapes for the flux rope axis and shock surface have several potential applications. First, these shapes can be used to construct a consistent ICME model. Second, these generic shapes can be used to develop a quantitative model to analyze imager data, as well as constraining the output of numerical simulations of ICMEs. Finally, they will have implications for space weather forecasting, in particular, for forecasting the time arrival of ICMEs at the Earth.

  13. The chain response of the magnetospheric and ground magnetic field to interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Sun, T. R.; Wang, C.; Zhang, J. J.; Pilipenko, V. A.; Wang, Y.; Wang, J. Y.

    2015-01-01

    In response to interplanetary (IP) shocks, magnetic field may decrease/increase (negative/positive response) in nightside magnetosphere, while at high latitudes on the ground it has two-phase bipolar variations: preliminary impulse and main impulse (MI). Using global MHD simulations, we investigate the linkage between the MI phase variation on the ground and the magnetospheric negative response to an IP shock. It is revealed that although the two phenomena occur at largely separated locations, they are physically related and form a response chain. The velocity disturbances near the flanks of the magnetopause cause the magnetic field to decrease, resulting in a dynamo which thus powers the transient field-aligned currents (FACs). These FACs further generate a pair of ionospheric current vortex, leading to MI variations on the ground. Therefore, we report here the intrinsic physically related chain response of the magnetospheric and ground magnetic field to IP shocks, and thus link the magnetospheric sudden impulse (SI) and ground SI together.

  14. Numerical analysis and theory of oblique alfvenic solitons observed in the interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Wheeler, Harry Raphael, IV

    Recently, there have been reports of small magnetic pulses or bumps in the interplanetary magnetic field observed by various spacecraft. Most of these reports claim that these localized pulses or bumps are solitons. Solitons are weakly nonlinear localized waves that tend to retain their form as they propagate and can be observed in various media which exhibit nonlinear steepening and dispersive eects. This thesis expands the claim that these pulses or bumps are nonlinear oblique Alfven waves with soliton components, through the application of analytical techniques used in the inverse scattering transform in a numerical context and numerical integration of nonlinear partial dierential equations. One event, which was observed by the Ulysses spacecraft on February 21st, 2001, is extensively scrutinized through comparison with soliton solutions that emerge from the Derivative Nonlinear Schrodinger (DNLS) equation. The direct scattering transform of a wave prole that has corresponding morphology to the selected magnetic bump leads to the implication of a soliton component. Numerical integration of the scaled prole matching the event in the context of the DNLS leads to generation of dispersive waves and a one parameter dark soliton.

  15. Large-scale variations of the interplanetary magnetic field: Voyager 1 and 2 observations between 1-5 AU

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

    Observations by the Voyager 1 and 2 spacecraft of the interplanetary magnetic 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 averaged 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.

  16. Evidence for the occurrence and importance of reconnection between the earth's magnetic field and the interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Cowley, S. W. H.

    In line with the purpose of this session I want to begin with some appraisal. In particular I want to appraise the evidence which exists for the occurrence and importance of reconnection between the Earth's magnetospheric field and the interplanetary magnetic field (IMF). I remember talking to Jim Dungey about this subject a couple of years back, discussing particularly the controversy which had arisen concerning the interpretation of IMP 6, HEOS 2 and ISEE 1 and 2 observations at the dayside magnetopause. What Jim more or less said was that all this work was of course very interesting, but that he had really stopped worrying about the validity of the reconnection model of the magnetosphere after he had seen the results of Fairfield and Cahill [1966] in 1965. These results were the first to show that magnetospheric activity responds to southward turnings of the interplanetary field. However, most other magnetospheric physicists, being rather more of a skeptical bunch, took somewhat longer to be convinced, and have beavered away at the problem for almost another 20 years. All this activity has now resulted in a long list of items which have been cited as evidence for reconnection between the Earth's field and the IMF, much of which has been discussed at this meeting.

  17. SIGNATURE IN THE INTERPLANETARY MEDIUM FOR SUBSTORMS

    Microsoft Academic Search

    Roger L. Arnoldy

    1971-01-01

    A detailed signature for individual substorms is sought in the interplanetary medium. Hourly values of interplanetary field and plasma parameters are correlated with hourly averages of the AE index. An interplanetary variable involving the southward component of the interplanetary field in the solar magnetospheric coordinate system is shown to be singularly important for the generation of substorms. The parameter best

  18. Penetration of the Interplanetary Magnetic Field B(sub y) into Earth's Plasma Sheet

    NASA Technical Reports Server (NTRS)

    Hau, L.-N.; Erickson, G. M.

    1995-01-01

    There has been considerable recent interest in the relationship between the cross-tail magnetic field component B(sub y) and tail dynamics. The purpose of this paper is to give an overall description of the penetration of the interplanetary magnetic 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).

  19. Dependence of efficiency of magnetic storm generation on the types of interplanetary drivers.

    NASA Astrophysics Data System (ADS)

    Yermolaev, Yuri; Nikolaeva, Nadezhda; Lodkina, Irina

    2015-04-01

    To compare the coupling coefficients between the solar-wind electric field Ey and Dst (and corrected Dst*) index during the magnetic storms generated by different types of interplanetary drivers, we use the Kyoto Dst-index data, the OMNI data of solar wind plasma and magnetic 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 magnetic 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 magnetic 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 magnetic 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 magnetic 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 magnetic storms generated by different types of solar wind, Cosmic Research, 2013, Vol. 51, No. 6, pp. 401-412 3. Nikolaeva N.S., Yermolaev Yu.I., Lodkina I.G., Modeling of corrected Dst-index temporal profile on the main phase of the magnetic storms generated by different types of solar wind, Cosmic Research, 2015, Vol.53, No. 2, 81, DOI: 10.7868/S0023420615020077

  20. Saturn's dayside ultraviolet auroras: Evidence for morphological dependence on the direction of the upstream interplanetary magnetic field

    PubMed Central

    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

    2014-01-01

    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 interplanetary magnetic 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 averaged) 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 magnetic/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

  1. The magnetic flux excess effect as a consequence of non-Parker radial evolution of interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Khabarova, Olga

    2015-04-01

    The “magnetic flux excess” effect is exceeding of magnetic flux Fs=4?|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 magnetic flux Fs(r) at certain heliocentric distance r and Fs_1AU at 1 AU, which can be calculated as Fs(r)-Fs_1AU =4?·(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 magnetic field lines and consequent deviation from the Parker's model is discussed.- Khabarova Olga, and Obridko Vladimir, 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- Olga V. Khabarova, The interplanetary magnetic 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

  2. Global MHD simulation of the Kelvin-Helmholtz instability at the magnetopause for northward interplanetary magnetic field

    Microsoft Academic Search

    X. C. Guo; C. Wang; Y. Q. Hu

    2010-01-01

    The Kelvin-Helmholtz (K-H) instability is found to occur at the low-latitude magnetopause through global magnetohydrodynamic simulations during a period of northward interplanetary magnetic field. The simulation results present the global picture of the nonlinear evolution of the K-H instability at the magnetopause. At the low-latitude boundary layer (within the latitude of about 30°), vortices are generated by the K-H instability

  3. A global magnetohydrodynamic simulation of the response of the magnetosphere to a northward turning of the interplanetary magnetic field

    Microsoft Academic Search

    Tatsuki Ogino; Raymond J. Walker; Maha Ashour-Abdalla

    1994-01-01

    We have used a global magnetohydrodynamic simulation model to investigate the time series of events which occur in the magnetosphere when the interplanetary magnetic field (IMF) changes from southward to northward. Within 15 min of the northward turning the magneto-pause reconnection site moves from the subsolar point to the high-latitude tail. The high-latitude reconnection converts tail lobe field lines into

  4. Precipitation of low energy electrons at high latitudes: Effects of substorms, interplanetary magnetic field and dipole tilt angle

    NASA Technical Reports Server (NTRS)

    Burch, J. L.

    1972-01-01

    Data from the auroral particles experiment on OGO-4 were used to study effects of substorm activity, interplanetary magnetic 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 interplanetary magnetic field. (3) With times containing substorm activity or a southward interplanetary magnetic 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.

  5. The B-dot Earth Average Magnetic Field

    NASA Technical Reports Server (NTRS)

    Capo-Lugo, Pedro A.; Rakoczy, John; Sanders, Devon

    2013-01-01

    The average Earth's magnetic field is solved with complex mathematical models based on mean square integral. Depending on the selection of the Earth magnetic model, the average Earth's magnetic 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 magnetic model; but it is dependent on the magnetic 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 magnetic torquers. Finally, this technique is verified and validated using flight data from a satellite that it has been in orbit for three years.

  6. Field lines and magnetic surfaces in a two-component slab/2D model of interplanetary magnetic fluctuations

    NASA Technical Reports Server (NTRS)

    Matthaeus, W. H.; Pontius, D. H., Jr.; Gray, P. C.; Bieber, J. W.

    1995-01-01

    A two-component model for the spectrum of interplanetary magnetic 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 magnetic 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 magnetic 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.

  7. The latitudinal distributions of auroral zone electric fields and ground magnetic perturbations and their response to variations in the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Horwitz, J. L.; Doupnik, J. R.; Banks, P. M.; Kamide, Y.; Akasofu, S.-I.

    1978-01-01

    Measurements of the latitudinal distributions of electric fields obtained with the Chatanika, Alaska, incoherent radar have been employed in determining the influence of the north-south component of the interplanetary magnetic field (IMF) on the electric field pattern. Poleward (or equatorward) shifts produced by the northward (or southward) transitions of the IMF north-south component are given particular attention. The behavior of the electric field patterns and magnetic perturbations in the midnight sector during substorms near the Harang discontinuity is analyzed.

  8. Interplanetary magnetic field control of mantle precipitation and associated field-aligned currents

    NASA Technical Reports Server (NTRS)

    Xu, Dingan; Kivelson, Margaret G.; Walker, Ray J.; Newell, Patrick T.; Meng, C.-I.

    1995-01-01

    Dayside reconnection, which is particularly effective for a southward interplanetary magnetic field (IMF), allows magnetosheath particles to enter the magnetosphere where they form the plasma mantle. The motions of the reconnected flux tube produce convective flows in the ionosphere. It is known that the convection patterns in the polar cap are skewed to the dawnside for a positive IMF B(sub y) (or duskside for a negative IMF B(sub y)) in the northern polar cap. Correspondingly, one would expect to find asymmetric distributions of mantle particle precipitation, but previous results have been unclear. In this paper the correlation between B(sub y) and the distribution of mantle particle precipitation is studied for steady IMF conditions with southward IMF. Ion and electron data from the Defense Meteorological Satellite Program (DMSP) F6 and F7 satellites are used to identify the mantle region and IMP 8 is used as a solar wind monitor to characterize the IMF. We study the local time extension of mantle precipitation in the prenoon and postnoon regions. We find that, in accordance with theoretical expectations for a positive (negative) IMF B(sub y), mantle particle precipitation mainly appears in the prenoon region of the northern (southern) hemisphere. The mantle particle precipitation can extend to as early as 0600 magnetic local time (MLT) in the prenoon region but extends over a smaller local time region in the postnoon sector (we did not find mantle plasma beyond 1600 MLT in our data set although coverage is scant in this area). Magnetometer data from F7 are used to determine whether part of the region 1 current flows on open field lines. We find that at times part of the region 1 sense current extends into the region of mantle particle precipitation, and is therefore on open field lines. In other cases, region 1 currents are absent on open field lines. Most of the observed features can be readily interpreted in terms of the open magnetosphere model.

  9. MAGNETIC FIELD-LINE LENGTHS IN INTERPLANETARY CORONAL MASS EJECTIONS INFERRED FROM ENERGETIC ELECTRON EVENTS

    SciTech Connect

    Kahler, S. W. [Air Force Research Laboratory, RVBXS, 29 Randolph Rd, Hanscom AFB, MA 01731 (United States); Haggerty, D. K. [Johns Hopkins University, Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, MD 20723 (United States); Richardson, I. G., E-mail: AFRL.RVB.PA@hanscom.af.mil [Code 661, NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States)

    2011-08-01

    About one quarter of the observed interplanetary coronal mass ejections (ICMEs) are characterized by enhanced magnetic fields that smoothly rotate in direction over timescales of about 10-50 hr. These ICMEs have the appearance of magnetic flux ropes and are known as 'magnetic 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 and 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 magnetic 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 solar wind field-line lengths resulting from turbulence and found to be in good agreement.

  10. MESSENGER observations of the response of Mercury's magnetosphere to northward and southward interplanetary magnetic fields

    NASA Astrophysics Data System (ADS)

    Slavin, James

    M. H. Ac?a (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 Magnetism, 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 interplanetary magnetic 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 these southward-Bz intervals. The inbound magnetopause crossing in the magnetic field measurements is consistent with a transition from the magnetosheath into the plasma sheet. Immediately following MESSENGER's entry into the magnetosphere, rotational perturbations in the magnetic field similar to those seen at the Earth in association with large-scale plasma sheet vortices driven by Kelvin-Helmholtz waves along the magnetotail boundary at the Earth are observed. The outbound magnetopause occurred during northward IMF Bz and had the characteristics of a tangential discontinuity. These new observations have important implications for our understanding of energy transfer into Mercury's magnetosphere.

  11. Solar Sources and Geospace Consequences of Interplanetary Magnetic Clouds Observed During Solar Cycle 23

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Lepping, R. P.

    2007-01-01

    We present results of a statistical investigation of 99 magnetic clouds (MCs) observed during 1995-2005. The MC-associated coronal mass ejections (CMEs) are faster and wider on the average and originate within +/-30deg from the solar disk center. The solar sources of MCs also followed the butterfly diagram. The correlation between the magnetic 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 magnetic 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 (average speed approx. 382 km/s), had a weaker southward magnetic field (average approx. -5.2nT), and occurred mostly during the rise phase of the solar activity cycle.

  12. Observations of the interplanetary magnetic field between 0.46 and 1 A.U. by the Mariner 10 spacecraft. Ph.D. Thesis - Catholic Univ. of Am.

    NASA Technical Reports Server (NTRS)

    Behannon, K. W.

    1976-01-01

    Almost continuous measurement of the interplanetary magnetic field (IMF) at a sampling rate of 25 vectors/sec was performed by the magnetic 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 magnetic field sector. Relative fluctuations of the field in magnitude and direction were found to have large time variations, but on average the relative magnitude fluctuations were approximately constant over the range of heliocentric distance covered while the relative directional fluctuations showed a slight decrease on average with increasing distance. The occurrence rate of directional discontinuities was also found to decrease with increasing radial distance from the sun.

  13. The MHD simulation of interplanetary space and heliosphere by using the boundary conditions of time-varying magnetic field and IPS-based plasma

    Microsoft Academic Search

    K. Hayashi; M. Tokumaru; M. Kojima; K. Fujiki

    2008-01-01

    We present our new boundary treatment to introduce the temporal variation of the observation-based magnetic field and plasma parameters on the inner boundary sphere (at 30 to 50 Rs) to the MHD simulation of the interplanetary space and the simulation results. The boundary treatment to induce the time-variation of the magnetic field including the radial component is essentially same as

  14. Determination of interplanetary magnetic field strength, solar wind speed and EUV irradiance, 1890-2003

    NASA Astrophysics Data System (ADS)

    Svalgaard, Leif; Cliver, Edward W.; Lesager, Philippe

    2003-09-01

    A newly constructed long-term geomagnetic index, the interdiurnal variability (the IDV index; defined to be the unsigned difference between hourly averages of the H-component of the field near local midnight at a midlatitude station for consecutive days), has the useful property that its yearly averages are highly correlated with the solar wind magnetic field strength (B) and are independent of solar wind speed (V). Existing geomagnetic records allow us to construct IDV since 1890 and thus to determine solar wind B over that period. Once B is known, we use other long-term indices with known dependence on B and V to determine the variation of V since 1890. Average B during 1872-2003 was 6.4 nT with no long-term trend (other than a general correlation with the sunspot number) and average V for the interval 1890-2003 was 433 km/s also with no apparent trend. These results are confirmed using polar cap data available from 1926 to the present and magnetic observations of the Amundsen and Scott polar expeditions for years near 1900. Focusing on geomagnetic activity at local midnight hours cleanly separates the EUV-regulated regular variation (SR) of geomagnetic activity from the solar wind driven component, allowing us to determine EUV variability since 1901. Using older data, all these time series might be extended possibly back to the 1780s.

  15. On the nature of the in-ecliptic interplanetary magnetic field's two-humped distribution at 1AU

    E-print Network

    Khabarova, Olga

    2011-01-01

    According to classical models of the solar wind and the interplanetary magnetic field (IMF) expansion, distributions in the ecliptic plane of both the IMF at 1 AU and the radial magnetic field on the Sun are expected to be identical . We found that photospheric (as well as the solar wind source surface) magnetic field distribution is purely Gaussian, but the distribution of the in-ecliptic and radial IMF at the Earth orbit demonstrates two-humped shape. It was previously supposed that interplanetary sector structure is responsible for the latter phenomenon. Our results indicate that picture of the IMF expansion into space is more complicated than usually considered. The heliospheric current sheet and sector structure are not the only source of the effect. IMF histograms were analysed on the basis of data from different spacecraft obtained at the distances from 0.29 AU to 4 AU from the Sun. The shape of the radial IMF component distribution strongly depends on a heliocentric distance and a heliolatitude. We su...

  16. Solar wind and interplanetary magnetic field features before magnetic storm onset

    Microsoft Academic Search

    O. Khabarova; V. Pilipenko; M. J. Engebretson; E. Rudenchik

    2007-01-01

    The presented results, concerning the features of the sola r wind plasma structure as observed by spacecraft upstream of Earth, could be used for development of middle-term forecasts of magnetic storms. We have analyzed 1-hour data for 1995-2005 and a whole year of 1-min data during solar minimum (1995) and during solar maximum (2000) with 48 and 60 storms, respectively.

  17. Interplanetary magnetic field By control of prompt total electron content increases during superstorms

    NASA Astrophysics Data System (ADS)

    Mannucci, A. J.; Crowley, G.; Tsurutani, B. T.; Verkhoglyadova, O. P.; Komjathy, A.; Stephens, P.

    2014-08-01

    Large magnitude increases in ionospheric total electron content (TEC) that occur over 1-3 h on the dayside are a significant manifestation of the main phases of superstorms. For the largest superstorms of solar cycle 23 (based on the Dst index), ground networks of GPS receivers measured peak total electron content increases greater than a factor of 2 relative to quiet time TEC averaged over the broad latitude band ±40° for local times 1200-1600 LT. Near 30° latitude, the Halloween storms of October 29-30, 2003 appeared to produce storm-time TEC exceeding quiet time values by a factor of 5 within 2-3 h of storm onset, at 1300 LT. The physical cause of these large positive phase ionospheric storms is usually attributed to prompt penetration electric fields (PPEFs) initiated by Region 1 current closure through the ionosphere (Nopper and Carovillano, 1978 mechanism). An unresolved question is what determines variation of the TEC response for different superstorms. It has been suggested that the cross polar cap potential and Region 1 currents are significant factors in determining PPEF in the equatorial ionosphere, which are related to the solar wind reconnection electric field estimated by Kan-Lee and others. In this paper, we show evidence that suggests By may be a significant factor controlling the TEC response during the main phase of superstorms. We analyzed the interplanetary conditions during the period that TEC was increasing for eight superstorms. We find that increasing daytime TEC during superstorms only occurs for large reconnection electric fields when By magnitude is less than Bz. The data suggest that Bz is a far more important factor in the TEC response than the reconnection electric field. We also find that TEC decreases following its peak storm-time value for two superstorms, even though Bz remains large and By magnitudes are less than Bz. Such decreases during the geomagnetic disturbance may indicate the role of magnetospheric shielding currents, or of changes in the thermosphere that have developed over the prolonged period of large solar wind electric field. Further analysis is warranted covering a wider range of storm intensities on the role of By in affecting the daytime TEC response for a range of storm intensities.

  18. Effects of continuous solar wind pressure variations on the long-lasting penetration of the interplanetary electric field during southward interplanetary magnetic field

    Microsoft Academic Search

    Zhigang Yuan; Xiaohua Deng

    2007-01-01

    It is believed that the interplanetary electric field (IEF) can penetrate into the mid- or low-latitude ionosphere. For the penetration of the IEF, the relationship between the solar wind pressure and the penetrated electric field in the equatorial ionosphere is yet an unsolved topic. With observations of the IEF, solar wind pressure obtained from the Wind satellite, and the geomagnetic

  19. Local and nonlocal geometry of interplanetary coronal mass ejections: Galactic cosmic ray (GCR) short-period variations and magnetic field modeling

    Microsoft Academic Search

    J. J. Quenby; T. Mulligan; J. B. Blake; J. E. Mazur; D. Shaul

    2008-01-01

    Energetic galactic cosmic ray (GCR) particles, arriving within the solar system, are modulated by the overall interplanetary field carried in the solar wind. Localized disturbances related to solar activity cause further reduction in intensity, the largest being Forbush decreases in which fluxes can fall ?20% over a few days. Understanding Forbush decreases leads to a better understanding of the magnetic

  20. Kelvin-Helmholtz vortices observed by THEMIS at the duskside of the magnetopause under southward interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Yan, G. Q.; Mozer, F. S.; Shen, C.; Chen, T.; Parks, G. K.; Cai, C. L.; McFadden, J. P.

    2014-07-01

    The Time History of Events and Macroscale Interactions during Substorms (THEMIS) observed several magnetopause crossings periodically at the duskside of magnetopause under southward interplanetary magnetic field (IMF), with significant sunward returning flows inside the magnetopause. The vortex features of the flows and the periodic enhancements in the calculated vorticity normal to the spacecraft plane could be found in the observation. The distortion of the magnetopause, the periodic features of vortex flows, the tailward propagation, and the evaluation of Kelvin-Helmholtz instability (KHI) condition support the evidence of the Kelvin-Helmholtz vortices produced by the velocity shear at the duskside of magnetopause. Based on three-point simultaneous observations of the flow, the vorticity was calculated to be about 0.15 s-1, similar to previous results. The tailward propagation of the vortices along the flank magnetopause was estimated to be about 292 km/s. The circular-induced electric field of several mV/m was deduced perpendicular to the magnetic field when the magnetic field compression occurred at the edges of the vortices.

  1. Ionospheric convection response to slow, strong variations in a Northward interplanetary magnetic field: A case study for January 14, 1988

    NASA Technical Reports Server (NTRS)

    Knipp, D. J.; Emery, B. A.; Richmond, A. D.; Crooker, N. U.; Hairston, M. R.; Cumnock, J. A.; Denig, W. F.; Rich, F. J.; De La Beaujardiere, O.; Ruohoniemi, J. M.

    1993-01-01

    We analyze ionospheric convection patterns over the polar regions during the passage of an interplanetary magnetic cloud on January 14, 1988, when the interplanetary magnetic field (IMF) rotated slowly in direction and had a large amplitude. Using the assimilative mapping of ionospheric electrodynamics (AMIE) procedure, we combine simultaneous observations of ionspheric drifts and magnetic perturbations from many different instruments into consistent patterns of high-latitude electrodynamics, focusing on the period of northward IMF. By combining satellite data with ground-based observations, we have generated one of the most comprehensive data sets yet assembled and used it to produce convection maps for both hemispheres. We present evidence that a lobe convection cell was embedded within normal merging convection during a period when the IMF B(sub y) and B(sub z) components were large and positive. As the IMF became predominantly northward, a strong reversed convection pattern (afternoon-to-morning potential drop of around 100 kV) appeared in the southern (summer) polar cap, while convection in the northern (winter) hemisphere became weak and disordered with a dawn-to-dust potential drop of the order of 30 kV. These patterns persisted for about 3 hours, until the IMF rotated significantly toward the west. We interpret this behavior in terms of a recently proposed merging model for northward IMF under solstice conditions, for which lobe field lines from the hemisphere tilted toward the Sun (summer hemisphere) drape over the dayside magnetosphere, producing reverse convection in the summer hemisphere and impeding direct contact between the solar wind and field lines connected to the winter polar cap. The positive IMF B(sub x) component present at this time could have contributed to the observed hemispheric asymmetry. Reverse convection in the summer hemisphere broke down rapidly after the ratio absolute value of B(sub y)/B(sub z) exceeded unity, while convection in the winter hemisphere strengthened. A dominant dawn-to-dusk potential drop was established in both hemispheres when the magnitude of B(sub y) exceeded that of B(sub z) with potential drops of the order of 100 kV, even while B(sub z) remained northward. The latter transition to southward B(sub z) produced a gradual intensification of the convection, but a greater qualitative change occurred at the transition through absolute value of B(sub y)/B(sub z) = 1 than at at the transition through B(sub z) = 0. The various convection patterns we derive under northward IMF conditions illustrate all possibilities previously discussed in the literature: nearly single-cell and multicell, distorted and symmetric, ordered and unordered, and sunward and antisunward.

  2. Dynamical evolution of interplanetary magnetic fields and flows between 0.3 AU and 8.5 AU: Entrainment

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Schwenn, R.; Rosenbauer, H.

    1983-01-01

    The radial evolution of interplanetary flows and associated magnetic 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 magnetic polarity, are brought together to form a single new structure.

  3. Radiation shielding of astronauts in interplanetary flights: the CREAM surveyor to Mars and the magnetic lens system for a spaceship.

    PubMed

    Spillantini, P; Taccetti, F; Papini, P; Rossi, L; Casolino, M

    2001-01-01

    The radiation absorbed by astronauts during interplanetary 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 magnetic 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 magnetic lenses for protecting the crew of a spaceship. PMID:11776989

  4. Magnetic loop behind an interplanetary shock: Voyager, Helios and IMP-8 observations

    NASA Technical Reports Server (NTRS)

    Burlaga, L.; Sittler, E.; Mariani, F.; Schwenn, R.

    1981-01-01

    The shock was followed by a turbulent sheath in which there were large fluctuations in both the strength and direction of the magnetic field. This in turn was followed by a region (magnetic cloud) in which the magnetic field vectors were observed to change by rotating nearly parallel to a plane, consistent with the passage of a magnetic 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 magnetic field.

  5. Rate of erosion of dayside magnetic flux based on a quantitative study of the dependence of polar cusp latitude on the interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Burch, J. L.

    1973-01-01

    In a consideration of only those periods when the delay time from the interplanetary observing position to the magnetosphere is less than 5 minutes, it is found that, irrespective of substorm activity: (1) The 45 minute average value of interplanetary B(z) predicts the latitudes of the poleward and equatorward boundaries of polar cusp electron precipitation with rms errors of 1.34 deg and 1.16 deg respectively; (2) Both boundaries more equatorward by about 5 deg as B(z) varies from 1 to -6 gammas, the cusp remaining about 40 deg wide; (3) The amount of flux added to the polar cap is about 9.2 percent of the total southward flux impingent on the magnetosphere in the previous 45 minutes; (4) As B(z) becomes more positive, the equatorward boundary moves only slightly more poleward (1/2 deg between B(z) = 2 gammas and B(z) = 6 gammas, while the poleward boundary moves significantly toward higher latitudes, resulting in a cusp approximately 7 deg wide for B(z) = 6 gammas.

  6. Dynamical evolution of interplanetary magnetic fields and flows between 0.3 AU and 8.5 AU - Entrainment

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Schwenn, R.; Rosenbauer, H.

    1983-01-01

    An analysis is presented of the radial evolution of interplanetary flows and associated magnetic 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.

  7. Cosmic ray modulation by interplanetary disturbances

    Microsoft Academic Search

    Carlos Roberto Braga; Alisson Dal Lago; Nelson Jorge Schuch; Marlos da Silva; Ezequiel Echer; Walter Demítrio Gonzalez Alarcon; Kazuoki Munakata; Takao Kuwabara; Chihiro Kato; John W. Bieber

    2010-01-01

    Interplanetary disturbances such as ICMEs (Interplanetary Coronal Mass Ejections) and CIRs (Corotating Interaction Regions), modulate high-energy cosmic rays reaching the Earth. Prior to the arrival of the disturbances at the Earth, ground based high-energy muon detectors can detect precursory effects in cosmic-ray anisotropy, such as precursory deficit and\\/or excess of intensity along the sunward IMF (Interplanetary Magnetic Field) direction. With

  8. Interplanetary medium data book: Supplement 3A, 1977-1985

    NASA Technical Reports Server (NTRS)

    Couzens, David A.; King, Joseph H.

    1986-01-01

    Supplement 3 of the Interplanetary Medium Data Book contains a detailed discussion of a data set compilation of hourly averaged interplanetary plasma and magnetic field parameters. The discussion addresses data sources, systematic and random differences, time shifting of ISEE 3 data, and plasma normalizations. Supplement 3 also contains solar rotation plots of field and plasma parameters. Supplement 3A contains computer-generated listings of selected parameters from the composite data set. These parameters are bulk speed (km/sec), density (per cu cm), temperature (in units of 1000 K) and the IMF parameters: average magnitude, latitude and longitude angles of the vector made up of the average GSE components, GSM Cartesian components, and the vector standard deviation. The units of field magnitude, components, and standard deviation are gammas, while the units of field direction angles and degrees.

  9. Interplanetary magnetic field control of the Venus magnetosheath field and bow shock location

    NASA Technical Reports Server (NTRS)

    Phillips, J. L.; Luhmann, J. G.; Russell, C. T.; Alexander, C. J.

    1986-01-01

    Six Venus years of Pioneer Venus Orbiter (PVO) data are analyzed in a coordinate system which isolates magnetic effects. The field draping pattern features two lobes easily identifiable even in the near planet region. The magnetosheath magnetic magnitude has a hemispherical asymmetry controlled by the IMF orientation in a manner suggesting preferrential ion pickup in one hemisphere. This result complements recent findings that the bow shock position is responsive to IMF direction. Examination of the ionopause position to evaluate ionospheric effects on the overall asymmetry of thfe Venus-solar wind interaction produces negative but not conclusive results.

  10. Upstream shocks and interplanetary magnetic cloud speed and expansion: Sun, WIND, and Earth observations

    Microsoft Academic Search

    R. P. Lepping; D. Berdichevsky; A. Szabo; A. J. Lazarus; B. J. Thompson

    2002-01-01

    Identifications have been made of the probable sources on the Sun (from SOHO data), where possible, of the magnetic clouds observed by WIND near Earth over the span of about 4 years (1995–1998), i.e., mainly during the quiet solar phase. The timing of the probable source transients at the Sun allow the estimations of transit times from the Sun to

  11. Magnetically-Channeled SIEC Array (MCSA) Fusion Device for Interplanetary Missions

    Microsoft Academic Search

    G. H. Miley; R. Stubbers; J. Webber; H. Momota

    2004-01-01

    A radical new Inertial Electrostatic Confinement (IEC) concept, the Magnetically-Channeled Spherical-IEC Array (MCSA) fusion propulsion system, was proposed earlier for use in the high performance Space Ship II fusion propulsion ship (Burton, 2003). This ship was designed for a fast manned round trip mission to Jupiter. The MCSA fusion power plant represents a key enabling technology needed for this mission.

  12. Mean Interplanetary Magnetic Field Measurement Using the ARGO-YBJ Experiment

    Microsoft Academic Search

    G. Aielli; C. Bacci; B. Bartoli; P. Bernardini; X. J. Bi; C. Bleve; I. Bolognino; P. Branchini; A. Budano; S. Bussino; A. K. Calabrese Melcarne; P. Camarri; Z. Cao; A. Cappa; R. Cardarelli; S. Catalanotti; C. Cattaneo; P. Celio; S. Z. Chen; T. L. Chen; Y. Chen; P. Creti; S. W. Cui; B. Z. Dai; G. D'Alí Staiti; Danzengluobu; M. Dattoli; I. De Mitri; B. D'Ettorre Piazzoli; M. De Vincenzi; T. Di Girolamo; X. H. Ding; G. Di Sciascio; C. F. Feng; Zhaoyang Feng; Zhenyong Feng; F. Galeazzi; P. Galeotti; R. Gargana; E. Giroletti; Q. B. Gou; Y. Q. Guo; H. H. He; Haibing Hu; Hongbo Hu; Q. Huang; M. Iacovacci; R. Iuppa; I. James; H. Y. Jia; Labaciren; H. J. Li; J. Y. Li; X. X. Li; B. Liberti; G. Liguori; C. Liu; M. Y. Liu; J. Liu; H. Lu; X. H. Ma; G. Mancarella; S. M. Mari; G. Marsella; D. Martello; S. Mastroianni; X. R. Meng; P. Montini; C. C. Ning; A. Pagliaro; M. Panareo; L. Perrone; P. Pistilli; X. B. Qu; E. Rossi; F. Ruggieri; L. Saggese; P. Salvini; R. Santonico; P. R. Shen; X. D. Sheng; F. Shi; C. Stanescu; A. Surdo; Y. H. Tan; P. Vallania; S. Vernetto; C. Vigorito; B. Wang; H. Wang; C. Y. Wu; H. R. Wu; B. Xu; L. Xue; Y. X. Yan; Q. Y. Yang; X. C. Yang; Z. G. Yao; A. F. Yuan; M. Zha; H. M. Zhang; JiLong Zhang; JianLi Zhang; L. Zhang; P. Zhang; X. Y. Zhang; Y. Zhang; Zhaxisangzhu; X. X. Zhou; F. R. Zhu; Q. Q. Zhu; G. Zizzi

    2011-01-01

    The Sun blocks cosmic-ray particles from outside the solar system, forming a detectable shadow in the sky map of cosmic rays detected by the ARGO-YBJ experiment in Tibet. Because the cosmic-ray particles are positively charged, the magnetic field between the Sun and the Earth deflects them from straight trajectories and results in a shift of the shadow from the true

  13. Venus ionospheric tail rays - Spatial distributions and interplanetary magnetic field control

    NASA Technical Reports Server (NTRS)

    Ong, M.; Luhmann, J. G.; Russell, C. T.; Strangeway, R. J.; Brace, L. H.

    1991-01-01

    The overall properties of Venus ionospheric tail rays (such as density, spatial extent, and distribution) and their relationship to the draped magnetic field configuration behind the planet were investigated using measurements obtained by the Pioneer Venus Orbiter Langmuir probe, a magnetometer, and a plasma-wave detector. The results suggest that tail rays are a normal feature of the steady solar wind interaction with Venus and are not generally associated with a central tail plasma sheet. The statistics of the tail rays occurrence point toward the existence of a distributed terminator ionosphere source, consistent with findings of Brace et al. (1990).

  14. Mean Interplanetary Magnetic Field Measurement Using the ARGO-YBJ Experiment

    E-print Network

    G. Aielli; C. Bacci; B. Bartoli; P. Bernardini; X. J. Bi; C. Bleve; P. Branchini; A. Budano; S. Bussino; A. K. Calabrese Melcarne; P. Camarri; Z. Cao; A. Cappa; R. Cardarelli; S. Catalanotti; C. Cattaneo; P. Celio; S. Z. Chen; T. L. Chen; Y. Chen; P. Creti; S. W. Cui; B. Z. Dai; G. D'Alí Staiti; Danzengluobu; M. Dattoli; I. De Mitri; B. D'Ettorre Piazzoli; M. De Vincenzi; T. Di Girolamo; X. H. Ding; G. Di Sciascio; C. F. Feng; Z. Y. Feng; Zhenyong Feng; F. Galeazzi; P. Galeotti; R. Gargana; Q. B. Gou; Y. Q. Guo; H. H. He; Haibing Hu; Hongbo Hu; Q. Huang; M. Iacovacci; R. Iuppa; I. James; H. Y. Jia; Labaciren; H. J. Li; J. Y. Li; X. X. Li; B. Liberti; G. Liguori; C. Liu; C. Q. Liu; M. Y. Liu; J. Liu; H. Lu; X. H. Ma; G. Mancarella; S. M. Mari; G. Marsella; D. Martello; S. Mastroianni; X. R. Meng; P. Montini; C. C. Ning; A. Pagliaro; M. Panareo; L. Perrone; P. Pistilli; X. B. Qu; E. Rossi; F. Ruggieri; L. Saggese; P. Salvini; R. Santonico; P. R. Shen; X. D. Sheng; F. Shi; C. Stanescu; A. Surdo; Y. H. Tan; P. Vallania; S. Vernetto; C. Vigorito; B. Wang; H. Wang; C. Y. Wu; H. R. Wu; Z. G. Yao; B. Xu; L. Xue; Y. X. Yan; Q. Y. Yang; X. C. Yang; A. F. Yuan; M. Zha; H. M. Zhang; JiLong Zhang; JianLi Zhang; L. Zhang; P. Zhang; X. Y. Zhang; Y. Zhang; Zhaxisangzhu; Zhaxiciren; X. X. Zhou; F. R. Zhu; Q. Q. Zhu; G. Zizzi

    2011-01-22

    The sun blocks cosmic ray particles from outside the solar system, forming a detectable shadow in the sky map of cosmic rays detected by the ARGO-YBJ experiment in Tibet. Because the cosmic ray particles are positive charged, the magnetic field between the sun and the earth deflects them from straight trajectories and results in a shift of the shadow from the true location of the sun. Here we show that the shift measures the intensity of the field which is transported by the solar wind from the sun to the earth.

  15. Mean Interplanetary Magnetic Field Measurement Using the ARGO-YBJ Experiment

    E-print Network

    Aielli, G; Bartoli, B; Bernardini, P; Bi, X J; Bleve, C; Branchini, P; Budano, A; Bussino, S; Melcarne, A K Calabrese; Camarri, P; Cao, Z; Cappa, A; Cardarelli, R; Catalanotti, S; Cattaneo, C; Celio, P; Chen, S Z; Chen, T L; Chen, Y; Creti, P; Cui, S W; Dai, B Z; Staiti, G D'Alí; Danzengluobu,; Dattoli, M; De Mitri, I; Piazzoli, B D'Ettorre; De Vincenzi, M; Di Girolamo, T; Ding, X H; Di Sciascio, G; Feng, C F; Feng, Z Y; Feng, Zhenyong; Galeazzi, F; Galeotti, P; Gargana, R; Gou, Q B; Guo, Y Q; He, H H; Hu, Haibing; Hu, Hongbo; Huang, Q; Iacovacci, M; Iuppa, R; James, I; Jia, H Y; Labaciren,; Li, H J; Li, J Y; Li, X X; Liberti, B; Liguori, G; Liu, C; Liu, C Q; Liu, M Y; Liu, J; Lu, H; Ma, X H; Mancarella, G; Mari, S M; Marsella, G; Martello, D; Mastroianni, S; Meng, X R; Montini, P; Ning, C C; Pagliaro, A; Panareo, M; Perrone, L; Pistilli, P; Qu, X B; Rossi, E; Ruggieri, F; Saggese, L; Salvini, P; Santonico, R; Shen, P R; Sheng, X D; Shi, F; Stanescu, C; Surdo, A; Tan, Y H; Vallania, P; Vernetto, S; Vigorito, C; Wang, B; Wang, H; Wu, C Y; Wu, H R; Yao, Z G; Xu, B; Xue, L; Yan, Y X; Yang, Q Y; Yang, X C; Yuan, A F; Zha, M; Zhang, H M; Zhang, JiLong; Zhang, JianLi; Zhang, L; Zhang, P; Zhang, X Y; Zhang, Y; Zhaxisangzhu,; Zhaxiciren,; Zhou, X X; Zhu, F R; Zhu, Q Q; Zizzi, G

    2011-01-01

    The sun blocks cosmic ray particles from outside the solar system, forming a detectable shadow in the sky map of cosmic rays detected by the ARGO-YBJ experiment in Tibet. Because the cosmic ray particles are positive charged, the magnetic field between the sun and the earth deflects them from straight trajectories and results in a shift of the shadow from the true location of the sun. Here we show that the shift measures the intensity of the field which is transported by the solar wind from the sun to the earth.

  16. Coronal and interplanetary magnetic fields inferred from band-splitting of type II bursts

    NASA Astrophysics Data System (ADS)

    Vršnak, B.; Magdaleni?, J.; Aurass, H.; Mann, G.

    2002-12-01

    Adopting that the band-splitting of type II bursts is a consequence of the plasma emission from the upstream and downstream shock region, the band-split reveals the shock Mach number. On the other hand, the shock speed can be inferred from the frequency drift. Combining these two parameters the Alfvén velocity and the magnetic field in the ambient plasma can be estimated. The results of such an analysis applied to 44 type II bursts recorded from decimetric to kilometric wavelengths are presented. The inferred magnetic field decreases as R-2 beyond the radial distance of 1.5 solar radii (R > 1.5) if the two-fold Saito density model is applied at R < 10 and Leblanc model beyond R ? 30. In that case the Alfvén velocity shows a shallow local minimum of vA ? 400 km s-1 at 2 < R < 3 and a broad local maximum of vA ? 500 km s-1 at 4 < R < 6.

  17. INTERVALS OF RADIAL INTERPLANETARY MAGNETIC FIELDS AT 1 AU, THEIR ASSOCIATION WITH RAREFACTION REGIONS, AND THEIR APPARENT MAGNETIC FOOT POINTS AT THE SUN

    SciTech Connect

    Orlove, Steven T.; Smith, Charles W.; Vasquez, Bernard J.; Schwadron, Nathan A. [Physics Department and Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH (United States); Skoug, Ruth M. [Los Alamos National Laboratory, MS D466, Los Alamos, NM 87545 (United States); Zurbuchen, Thomas H.; Zhao Liang, E-mail: stx33@wildcats.unh.edu, E-mail: Charles.Smith@unh.edu, E-mail: Bernie.Vasquez@unh.edu, E-mail: N.Schwadron@unh.edu, E-mail: rskoug@lanl.gov, E-mail: thomasz@umich.edu, E-mail: lzh@umich.edu [Department of Atmospheric, Oceanic and Space Science, University of Michigan, Ann Arbor, MI (United States)

    2013-09-01

    We have examined 226 intervals of nearly radial interplanetary magnetic field orientations at 1 AU lasting in excess of 6 hr. They are found within rarefaction regions as are the previously reported high-latitude observations. We show that these rarefactions typically do not involve high-speed wind such as that seen by Ulysses at high latitudes during solar minimum. We have examined both the wind speeds and the thermal ion composition before, during and after the rarefaction in an effort to establish the source of the flow that leads to the formation of the rarefaction. We find that the bulk of the measurements, both fast- and slow-wind intervals, possess both wind speeds and thermal ion compositions that suggest they come from typical low-latitude sources that are nominally considered slow-wind sources. In other words, we find relatively little evidence of polar coronal hole sources even when we examine the faster wind ahead of the rarefaction regions. While this is in contrast to high-latitude observations, we argue that this is to be expected of low-latitude observations where polar coronal hole sources are less prevalent. As with the previous high-latitude observations, we contend that the best explanation for these periods of radial magnetic field is interchange reconnection between two sources of different wind speed.

  18. Interplanetary magnetic field By and auroral conductance effects on high-latitude ionospheric convection patterns

    NASA Astrophysics Data System (ADS)

    Tanaka, T.

    2001-11-01

    The dependence of the ionospheric electric potential (convection) on the interplanetary magnetic field (IMF) and the ionospheric conductivity is investigated to understand the generation of convection patterns in the framework of the solar wind-magnetosphere-ionosphere (S-M-I) coupling scheme and the merging concept. A numerical magnetohydrodynamic (MHD) simulation is adopted for the study of the present problem. To achieve a high resolution in the ionosphere, the MHD calculation employs the finite volume (FV) total-variation diminishing (TVD) scheme with an unstructured grid system. The two-cell convection patterns reproduced from simulation are shown for several cases under the southward IMF condition during the growth-phase interval. In the investigation of these results, special attention is paid to the analysis of mirror symmetry in the convection patterns with respect to the IMF By. On the dayside in the Northern Hemisphere, IMF By- (By+) generates flow deflection on newly opened field lines toward the dusk (dawn) without a severe violation of the mirror symmetry. While the mirror symmetry of the convection pattern is maintained even on the nightside when the ionospheric conductivity is uniform, it is not maintained on the nightside when the ionospheric conductivity is nonuniform. A realistic ionospheric conductivity modifies the convection pattern in the Northern (Southern) Hemisphere so as to emphasize distinctive features seen for IMF By+ (By-) under a uniform conductivity, and the reproduced convection patterns coincide with the observation quite well including fine signatures on the nightside, both for IMF By- and By+. Because of the nonuniform conductivity, cell centers of convection are shifted to the earlier magnetic local times, and the antisunward flow in the northern polar cap is nearly aligned with noon-midnight meridian for IMF By-, while the flow in the northern polar cap has a significant inclination from prenoon to premidnight for IMF By+. These convection patterns can be understood by considering the effect due to the Hall current closure of the region-1 field-aligned current. The analysis for the dependence of nightside convection on IMF By and ionospheric conductivity shows that the Harang discontinuity is attributed partially to the structure of magnetospheric driver but mainly to the effect of nonuniform auroral conductivity. As a consequence, it is more adequate to say that convection patterns are more or less caused by the synthesized effect of more than one process rather than a single elementary process. Reproduced convection patterns in this paper show a particular coincidence with satellite observations summarized by adopting the pattern-recognition-based approach.

  19. By-controlled convection and field-aligned currents near midnight auroral oval for northward interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Taguchi, S.; Sugiura, M.; Iyemori, T.; Winningham, J. D.; Slavin, J. A.

    1994-01-01

    Using the Dynamics Explorer (DE) 2 magnetic and electric field and plasma data, B(sub y)- controlled convection and field-aligned currents in the midnight sector for northward interplanetary magnetic field (IMF) are examined. The results of an analysis of the electric field data show that when IMF is stable and when its magnitude is large, a coherent B(sub y)-controlled convection exists near the midnight auroral oval in the ionosphere having adequate conductivities. When B(sub y) is negative, the convection consists of a westward (eastward) plasma flow at the lower latitudes and an eastward (westward) plasma flow at the higher latitudes in the midnight sector in the northern (southern) ionosphere. When B(sub y) is positive, the flow directions are reversed. The distribution of the field-aligned currents associated with the B(sub y)-controlled convection, in most cases, shows a three-sheet structure. In accordance with the convection the directions of the three sheets are dependent on the sign of B(sub y). The location of disappearance of the precipitating intense electrons having energies of a few keV is close to the convection reversal surface. However, the more detailed relationship between the electron precipitation boundary and the convection reversal surface depends on the case. In some cases the precipitating electrons extend beyond the convection reversal surface, and in others the poleward boundary terminates at a latitude lower than the reversal surface. Previous studies suggest that the poleward boundary of the electrons having energies of a few keV is not necessarily coincident with an open/closed bounary. Thus the open/closed boundary may be at a latitude higher than the poleward boundary of the electron precipitation, or it may be at a latitude lower than the poleward boundary of the electron precipitation. We discuss relationships between the open/closed boundary and the convection reversal surface. When as a possible choice we adopt a view that the open/closed boundary agrees with the convection reversal surface, we can explain qualitatively the configuration of the B(sub y)-controlled convection on the open and close field line regions by proposing a mapping modified in accordance with IMF B(sub y).

  20. Heliocentric distance and temporal dependence of the interplanetary density-magnetic field magnitude correlation

    NASA Technical Reports Server (NTRS)

    Roberts, D. A.

    1990-01-01

    The Helios, IMP 8, ISEE 3, ad Voyager 2 spacecraft are used to examine the solar cycle and heliocentric distance dependence of the correlation between density n and magnetic field magnitude B in the solar wind. Previous work had suggested that this correlation becomes progressively more negative with heliocentric distance out to 9.5 AU. Here it is shown that this evolution is not a solar cycle effect, and that the correlations become even more strongly negative at heliocentric distance larger than 9.5 AU. There is considerable variability in the distributions of the correlations at a given heliocentric distance, but this is not simply related to the solar cycle. Examination of the evolution of correlations between density and speed suggest that most of the structures responsible for evolution in the anticorrelation between n and B are not slow-mode waves, but rather pressure balance structures. The latter consist of both coherent structures such as tangential discontinuities and the more generally pervasive 'pseudosound' which may include the coherent structures as a subset.

  1. Denoising by Averaging Reconstructed Images: Application to Magnetic Resonance Images

    Microsoft Academic Search

    Jianhua Luo; Yuemin Zhu; Isabelle E. Magnin

    2009-01-01

    A novel denoising approach is proposed that is based on averaging reconstructed images. The approach first divides the spectrum of the image to be denoised into different parts. From every such partial spectrum is then reconstructed an image using a 2-D singularity function analysis model. By expressing each of the reconstructed images as the sum of the same noise-free image

  2. The Influence Gradient Drift in the Interplanetary Magnetic field (IMF) on the Spectra of Solar Energetic Protons (SEP) at Earth as a Function of Heliographic Latitude

    NASA Astrophysics Data System (ADS)

    Franklin, D. M.; Falconer, D. A.; Adams, J. H., Jr.

    2014-12-01

    Solar Energetic Particles (SEP) consists of Protons, Electrons and Ions accelerated in Solar flares and/or Coronal Mass Ejections (CME's). Current models for the interplanetary transport of SEPs neglect the effect of magnetic gradient drift because other effects are thought to dominate. This may not be the case for high energy SEPs. We report an experimental test for evidence of magnetic gradient drift using high energy proton data from large SEPs from Goddard Medium Energy (GME) on IMP-8 and the Energetic Particle System (EPS) on GOES. We identified the SEPs with measured proton fluxes above 50 MeV and measured their spectra. We also identified the hemispheric coordinates of the sites where these events originated. We compared the event-integrated proton differential energy spectra from the northern and southern hemispheres of the sun to search for difference that could be ascribed to the effects of magnetic gradient drift. The results of this comparison will be presented.

  3. Prediction of magnetic orientation in driver gas associated -Bz events. [in interplanetary medium observed at earth when solar source is identified

    NASA Technical Reports Server (NTRS)

    Hoeksema, J. T.; Zhao, Xuepu

    1992-01-01

    The source regions of five strong -Bz events detected at 1 AU for which solar sources were identified by Tang et al. (1989) and Tsurutani et al. (1992) are investigated in order to determine whether the magnetic orientation of driver gas in the interplanetary medium observed at the earth can be predicted when its solar source is identified. Three -Bz events were traced to flare-associated coronal mass ejections (CMEs), one to an eruptive prominence associated CME, and one to three possible solar sources. The computed magnetic orientations at the candidate 'release height' (the height where the front of a CME ceases to accelerate) above the flare sites associated with CMEs show the existence of the expected southward field component. It is concluded that the magnetic orientation in flare-associated CME generated driver gas may be predictable.

  4. Magnetic island formation between large-scale flow vortices at an undulating postnoon magnetopause for northward interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Eriksson, S.; Hasegawa, H.; Teh, W.-L.; Sonnerup, B. U. Ö.; McFadden, J. P.; Glassmeier, K.-H.; Le Contel, O.; Angelopoulos, V.; Cully, C. M.; Larson, D. E.; Ergun, R. E.; Roux, A.; Carlson, C. W.

    2009-02-01

    Time History of Events and Macroscale Interactions during Substorms multispacecraft observations are presented for a ~2-h-long postnoon magnetopause event on 8 June 2007 that for the first time indicate that the trailing (sunward) edges of Kelvin-Helmholtz (KH) waves are commonly related to small-scale <0.56 R E magnetic islands or flux transfer events (FTE) during the growth phase of these surface waves. The FTEs typically show a characteristic bipolar B N structure with enhanced total pressure at their center. Most of the small-scale FTEs are not related to any major plasma acceleration. TH-A observations of one small FTE at a transition from the low-latitude boundary layer (LLBL) into a magnetosheath plasma depletion layer were reconstructed using separate techniques that together confirm the presence of a magnetic island within the LLBL adjacent to the magnetopause. The island was associated with a small plasma vortex and both features appeared between two large-scale (~1 R E long and 2000 km wide) plasma vortices. We propose that the observed magnetic islands may have been generated from a time-varying reconnection process in a low ion plasma beta (? i < 0.2) and low 8.3° field shear environment at the sunward edge of the growing KH waves where the local magnetopause current sheet may be compressed by the converging flow of the large-scale plasma vortices as suggested by numerical simulations of the KH instability.

  5. Anisotropy of the solar network magnetic field around the average supergranule

    NASA Astrophysics Data System (ADS)

    Langfellner, J.; Gizon, L.; Birch, A. C.

    2015-07-01

    Supergranules in the quiet Sun are outlined by a web-like structure of enhanced magnetic field strength, the so-called magnetic network. We aim to map the magnetic network field around the average supergranule near disk center. We use observations of the line-of-sight component of the magnetic field from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). The average supergranule is constructed by coaligning and averaging over 3000 individual supergranules. We determine the positions of the supergranules with an image segmentation algorithm that we apply to maps of the horizontal flow divergence measured using time-distance helioseismology. In the center of the average supergranule, the magnetic (intranetwork) field is weaker by about 2.2 Gauss than the background value (3.5 Gauss), whereas it is enhanced in the surrounding ring of horizontal inflows (by about 0.6 Gauss on average). We find that this network field is significantly stronger west (prograde) of the average supergranule than in the east (by about 0.3 Gauss). With time-distance helioseismology, we find a similar anisotropy. The observed anisotropy of the magnetic field adds to the mysterious dynamical properties of solar supergranulation.

  6. Upper Thermosphere Winds and Temperatures in the Geomagnetic Polar Cap: Solar Cycle, Geomagnetic Activity, and Interplanetary Magnetic Field Dependencies

    NASA Technical Reports Server (NTRS)

    Killeen, T. L.; Won, Y.-I.; Niciejewski, R. J.; Burns, A. G.

    1995-01-01

    Ground-based Fabry-Perot interferometers located at Thule, Greenland (76.5 deg. N, 69.0 deg. W, lambda = 86 deg.) and at Sondre Stromfjord, Greenland (67.0 deg. N, 50.9 deg. W, lambda = 74 deg.) have monitored the upper thermospheric (approx. 240-km altitude) neutral wind and temperature over the northern hemisphere geomagnetic polar cap since 1983 and 1985, respectively. The thermospheric observations are obtained by determining the Doppler characteristics of the (OI) 15,867-K (630.0-nm) emission of atomic oxygen. The instruments operate on a routine, automatic, (mostly) untended basis during the winter observing seasons, with data coverage limited only by cloud cover and (occasional) instrument failures. This unique database of geomagnetic polar cap measurements now extends over the complete range of solar activity. We present an analysis of the measurements made between 1985 (near solar minimum) and 1991 (near solar maximum), as part of a long-term study of geomagnetic polar cap thermospheric climatology. The measurements from a total of 902 nights of observations are compared with the predictions of two semiempirical models: the Vector Spherical Harmonic (VSH) model of Killeen et al. (1987) and the Horizontal Wind Model (HWM) of Hedin et al. (1991). The results are also analyzed using calculations of thermospheric momentum forcing terms from the Thermosphere-ionosphere General Circulation Model TGCM) of the National Center for Atmospheric Research (NCAR). The experimental results show that upper thermospheric winds in the geomagnetic polar cap have a fundamental diurnal character, with typical wind speeds of about 200 m/s at solar minimum, rising to up to about 800 m/s at solar maximum, depending on geomagnetic activity level. These winds generally blow in the antisunward direction, but are interrupted by episodes of modified wind velocity and altered direction often associated with changes in the orientation of the Interplanetary Magnetic Field (IMF). The central polar cap (greater than approx. 80 magnetic latitude) antisunward wind speed is found to be a strong function of both solar and geomagnetic activity. The polar cap temperatures show variations in both solar and geomagnetic activity, with temperatures near 800 K for low K(sub p) and F(sub 10.7) and greater than about 2000 K for high K(sub p) and F(sub 10.7). The observed temperatures are significantly greater than those predicted by the mass spectrometer/incoherent scatter model for high activity conditions. Theoretical analysis based on the NCAR TIGCM indicates that the antisunward upper thermospheric winds, driven by upstream ion drag, basically 'coast' across the polar cap. The relatively small changes in wind velocity and direction within the polar cap are induced by a combination of forcing terms of commensurate magnitude, including the nonlinear advection term, the Coriolis term, and the pressure gradient force term. The polar cap thennospheric thermal balance is dominated by horizontal advection, and adiabatic and thermal conduction terms.

  7. Anisotropy of the solar network magnetic field around the average supergranule

    E-print Network

    Langfellner, J; Birch, A C

    2015-01-01

    Supergranules in the quiet Sun are outlined by a web-like structure of enhanced magnetic field strength, the so-called magnetic network. We aim to map the magnetic network field around the average supergranule near disk center. We use observations of the line-of-sight component of the magnetic field from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO). The average supergranule is constructed by coaligning and averaging over 3000 individual supergranules. We determine the positions of the supergranules with an image segmentation algorithm that we apply on maps of the horizontal flow divergence measured using time-distance helioseismology. In the center of the average supergranule the magnetic (intranetwork) field is weaker by about 2.2 Gauss than the background value (3.5 Gauss), whereas it is enhanced in the surrounding ring of horizontal inflows (by about 0.6 Gauss on average). We find that this network field is significantly stronger west (prograde) of the average sup...

  8. The averaged dynamics of the hydrogen atom in crossed electric and magnetic fields

    E-print Network

    The averaged dynamics of the hydrogen atom in crossed electric and magnetic fields as a perturbed­0430, USA July 13, 2000 Abstract We treat the classical dynamics of the hydrogen atom in perpendicular action--angle variables, we separate the different time scales of the motion. The method of averaging

  9. Magnetic field hourly averages from the Rome-GSFC experiment aboard Helios 1 and Helio 2

    NASA Technical Reports Server (NTRS)

    Mariani, F.; Ness, N. F.; Bavassano, B.; Bruno, R.; Buccellato, R.; Burlaga, L. F.; Cantarano, S.; Scearce, C. S.; Terenzi, R.; Villante, U.

    1987-01-01

    Plots of all the hourly averages computed from the solar magnetic field measurements obtained during the mission are given separately for Helios 1 and Helios 2. The magnitude and the direction of the averaged field are plotted versus the number of solar rotations as seen from Helios, counted from launch.

  10. Adiabatic and nonadiabatic responses of the radiation belt relativistic electrons to the external changes in solar wind dynamic pressure and interplanetary magnetic field

    NASA Astrophysics Data System (ADS)

    Li, L.

    2013-12-01

    By removing the influences of 'magnetopause shadowing' (r0>6.6RE) and geomagnetic activities, we investigated statistically the responses of magnetic field and relativistic (>0.5MeV) electrons at geosynchronous orbit to 201 interplanetary perturbations during 6 years from 2003 (solar maximum) to 2008 (solar minimum). The statistical results indicate that during geomagnetically quiet times (HSYM ?-30nT, and AE<200nT), ~47.3% changes in the geosynchronous magnetic field and relativistic electron fluxes are caused by the combined actions of the enhancement of solar wind dynamic pressure (Pd) and the southward turning of interplanetary magnetic field (IMF) (?Pd>0.4 nPa, and IMF Bz<0 nT), and only ~18.4% changes are due to single dynamic pressure increase (?Pd >0.4 nPa, but IMF Bz>0 nT), and ~34.3% changes are due to single southward turning of IMF (IMF Bz<0 nT, but |?Pd|<0.4 nPa). Although the responses of magnetic field and relativistic electrons to the southward turning of IMF are weaker than their responses to the dynamic pressure increase, the southward turning of IMF can cause the dawn-dusk asymmetric perturbations that the magnetic field and the relativistic electrons tend to increase on the dawnside (LT~00:00-12:00) but decrease on the duskside (LT~13:00-23:00). Furthermore, the variation of relativistic electron fluxes is adiabatically controlled by the magnitude and elevation angle changes of magnetic field during the single IMF southward turnings. However, the variation of relativistic electron fluxes is independent of the change in magnetic field in some compression regions during the enhancement of solar wind dynamic pressure (including the single pressure increases and the combined external perturbations), indicating that nonadiabatic dynamic processes of relativistic electrons occur there. Acknowledgments. This work is supported by NSFC (grants 41074119 and 40604018). Liuyuan Li is grateful to the staffs working for the data from GOES 8-12 satellites and OMNI database in CDAWeb.

  11. The interplanetary modulation and transport of Jovian electrons

    NASA Technical Reports Server (NTRS)

    Conlon, T. F.

    1978-01-01

    Based on simultaneous measurements by Pioneer 11 of the 3-6 MeV Jovian electron flux, interplanetary magnetic field magnitude, and solar wind speed, the interplanetary transport of energetic particles is studied. It is found that corotating interaction regions (CIR's) greatly inhibit electron transport across the average field direction. Cross-field transport is also influenced by the degree of compression of the solar wind since CIR's are areas of compressed solar wind plasma. The propagation of Jovian electrons is studied by a model that includes the effects of CIR's. The model tests whether or not the three-dimensional convection-diffusion theory adequately describes the cross-field transport of electrons. The model is also valid for Jovian electron observations from earth-orbiting satellites. The model may be further applied to 1 AU from the sun where it is found that the cross-field diffusion of electrons explains why Jovian electrons are detected at the earth even during periods when the interplanetary magnetic field does not connect the earth directly to Jupiter.

  12. Asymmetry in the Rosenberg-Coleman effect around solar minimum revealed by wavelet analysis of the interplanetary magnetic field polarity data (1927-2002)

    NASA Astrophysics Data System (ADS)

    Echer, E.; Svalgaard, L.

    2004-06-01

    Interplanetary magnetic field (IMF) polarity data for the years 1927-2002 were studied by wavelet analysis technique, which permits the identification of non-steady features in the IMF polarity data. It was found that the annual variation in the IMF polarity (the Rosenberg-Coleman effect) is present only during the rise phase of solar cycles. This result is confirmed by the observed Bx (radial) solar wind measurements since 1964. This asymmetry could be caused by a more stable and flat heliospheric current sheet being present only in the rise phase of solar cycles, with co-rotating high speed streams disturbing it during the descending phases. This finding bears on the generally accepted explanation of the 22-year geomagnetic activity cycle.

  13. Interplanetary circumstances of quasi-perpendicular interplanetary shocks in 1996–2005

    Microsoft Academic Search

    I. G. Richardson; H. V. Cane

    2010-01-01

    The angle ($\\\\theta$Bn) between the normal to an interplanetary shock front and the upstream magnetic field direction, though often thought of as a property “of the shock,” is also determined by the configuration of the magnetic field immediately upstream of the shock. We investigate the interplanetary circumstances of 105 near-Earth quasi-perpendicular shocks during 1996–2005 identified by $\\\\theta$Bn ? 80° and\\/or

  14. Anomalous aspects of magnetosheath flow and of the shape and oscillations of the magnetopause during an interval of strongly northward interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Chen, Sheng-Hsien; Kivelson, Margaret G.; Gosling, Jack T.; Walker, Raymond T.; Lazarus, Allan J.

    1992-01-01

    On 15 Feb. 1978, the orientation of the interplanetary magnetic field (IMF) remained steadily northward for more than 12 hours. The ISEE 1 and 2 spacecraft were located near apogee on the dawn side flank of the magnetotail. IMP 8 was almost symmetrically located in the magnetosheath on the dusk flank and IMP 7 was upstream in the solar wind. Using plasma and magnetic field data, we show the following: (1) the magnetosheath flow speed on the flanks of the magnetotail steadily exceeded the solar wind speed by 20 percent; (2) surface waves with approximately a 5-min period and very non-sinusoidal waveform were persistently present on the dawn magnetopause and waves of similar period were present in the dusk magnetosheath; and (3) the magnetotail ceased to flare at an antisunward distance of 15 R(sub E). We propose that the acceleration of the magnetosheath flow is achieved by magnetic tension in the draped field configuration for northward IMF and that the reduction of tail flaring is consistent with a decreased amount of open magnetic flux and a larger standoff distance of the subsolar magnetopause. Results of a three-dimensional magnetohydrodynamic simulation support this phenomenological model.

  15. Interplanetary Disturbances Affecting Space Weather

    NASA Astrophysics Data System (ADS)

    Wimmer-Schweingruber, Robert F.

    2014-01-01

    The Sun somehow accelerates the solar wind, an incessant stream of plasma originating in coronal holes and some, as yet unidentified, regions. Occasionally, coronal, and possibly sub-photospheric structures, conspire to energize a spectacular eruption from the Sun which we call a coronal mass ejection (CME). These can leave the Sun at very high speeds and travel through the interplanetary medium, resulting in a large-scale disturbance of the ambient background plasma. These interplanetary CMEs (ICMEs) can drive shocks which in turn accelerate particles, but also have a distinct intrinsic magnetic structure which is capable of disturbing the Earth's magnetic field and causing significant geomagnetic effects. They also affect other planets, so they can and do contribute to space weather throughout the heliosphere. This paper presents a historical review of early space weather studies, a modern-day example, and discusses space weather throughout the heliosphere.

  16. Erratum to "Solar Sources and Geospace Consequences of Interplanetary Magnetic Clouds Observed During Solar Cycle 23-Paper 1" [J. Atmos. Sol.-Terr. Phys. 70(2-4) (2008) 245-253

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Lepping, R. P.

    2009-01-01

    One of the figures (Fig. 4) in "Solar sources and geospace consequences of interplanetary magnetic Clouds observed during solar cycle 23 -- Paper 1" by Gopalswamy et al. (2008, JASTP, Vol. 70, Issues 2-4, February 2008, pp. 245-253) is incorrect because of a software error in t he routine that was used to make the plot. The source positions of various magnetic cloud (MC) types are therefore not plotted correctly.

  17. Systematic averaging interval effects on solar wind statistics

    NASA Astrophysics Data System (ADS)

    Isaacs, J. J.; Tessein, J. A.; Matthaeus, W. H.

    2015-02-01

    The choice of interval of averaging in computing statistics of solar wind fluctuations is known to be a sensitive issue in which the need for adequate sampling statistics must be balanced with the complications of establishing an ensemble, given that the solar wind admits inhomogeneity, structure, and variability at its sources. Here we examine the quantitative dependence of interval of averaging (sample size) on estimates of basic statistics such as means, variances, and anisotropies of the measured interplanetary magnetic field.

  18. Properties of a large-scale interplanetary loop structure as deduced from low-energy proton anisotropy and magnetic field measurements

    NASA Technical Reports Server (NTRS)

    Tranquille, C.; Sanderson, T. R.; Marsden, R. G.; Wenzel, K.-P.; Smith, E. J.

    1987-01-01

    Correlated particle and magnetic field measurements by the ISEE 3 spacecraft are presented for the loop structure behind the interplanetary traveling shock event of Nov. 12, 1978. Following the passage of the turbulent shock region, strong bidirectional streaming of low-energy protons is observed for approximately 6 hours, corresponding to a loop thickness of about 0.07 AU. This region is also characterized by a low relative variance of the magnetic field, a depressed proton intensity, and a reduction in the magnetic power spectral density. Using quasi-linear theory applied to a slab model, a value of 3 AU is derived for the mean free path during the passage of the closed loop. It is inferred from this observation that the proton regime associated with the loop structure is experiencing scatter-free transport and that either the length of the loop is approximately 3 AU between the sun and the earth or else the protons are being reflected at both ends of a smaller loop.

  19. The Earth's magnetosphere is 165 R(sub E) long: Self-consistent currents, convection, magnetospheric structure, and processes for northward interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Fedder, J. A.; Lyon, J. G.

    1995-01-01

    The subject of this paper is a self-consistent, magnetohydrodynamic numerical realization for the Earth's magnetosphere which is in a quasi-steady dynamic equilibrium for a due northward interplanetary magnetic field (IMF). Although a few hours of steady northward IMF are required for this asymptotic state to be set up, it should still be of considerable theoretical interest because it constitutes a 'ground state' for the solar wind-magnetosphere interaction. Moreover, particular features of this ground state magnetosphere should be observable even under less extreme solar wind conditions. Certain characteristics of this magnetosphere, namely, NBZ Birkeland currents, four-cell ionospheric convection, a relatively weak cross-polar potential, and a prominent flow boundary layer, are widely expected. Other characteristics, such as no open tail lobes, no Earth-connected magnetic flux beyond 155 R(sub E) downstream, magnetic merging in a closed topology at the cusps, and a 'tadpole' shaped magnetospheric boundary, might not be expected. In this paper, we will present the evidence for this unusual but interesting magnetospheric equilibrium. We will also discuss our present understanding of this singular state.

  20. Nonlocal plasma turbulence associated with interplanetary shocks

    NASA Technical Reports Server (NTRS)

    Kennel, C. F.; Coroniti, F. V.; Scarf, F. L.; Smith, E. J.; Gurnett, D. A.

    1982-01-01

    Regions of plasma turbulence extending several tenths of an astronomical unit upstream or downstream of interplanetary shocks have been detected by the plasma wave instrument on ISEE 3. Highly impulsive electric field bursts at 1-10 kHz were found (hours upstream of quasi-parallel interplanetary shocks) whose average and peak amplitudes occasionally increased until the shock crossing, when they were suppressed. A 0.1-1 kHz electric field component was enhanced at nearly all shocks, and persisted downstream. A smooth, high-frequency continuum near and above the local electron plasma frequency was enhanced at, and persisted downstream of, every interplanetary shock studied. While no single interplanetary shock showed every effect, the ensemble of shocks contained at least one example of each type of plasma wave found upstream of the earth's bow shock.

  1. Signal injection and averaging for position estimation of Permanent-Magnet Synchronous Motors

    E-print Network

    Jebai, Al Kassem; Martin, Philippe; Rouchon, Pierre

    2012-01-01

    Sensorless control of Permanent-Magnet Synchronous Motors at low velocity remains a challenging task. A now well-established method consists in injecting a high-frequency signal and use the rotor saliency, both geometric and magnetic-saturation induced. This paper proposes a clear and original analysis based on second-order averaging of how to recover the position information from signal injection; this analysis blends well with a general model of magnetic saturation. It also experimentally demonstrates the relevance for position estimation of a simple parametric saturation model recently introduced by the authors.

  2. Investigation of influence of hypomagnetic conditions closely similar to interplanetary magnetic filed on behavioral and vegetative reactions of higher mammals

    NASA Astrophysics Data System (ADS)

    Krivova, Natalie; Trukhanov, Kiril; Zamotshina, Tatyana; Zaeva, Olga; Khodanovich, Marina; Misina, Tatyana; Tukhvatulin, Ravil; Suhko, Valery

    To study the influence of long being under reduced magnetic field on behavioral and vegetative reactions of higher mammals the white rat males were put into the 700-1000 times reduced geomagnetic field (50-70 nT) for 25 days. Such field was obtained by using automatic compensation of the horizontal and vertical components of the GMF at a frequencies up to 10 Hz by means of solenoids of the experimental magnetic system. Control animals were located in the same room under usual laboratory GMF conditions (52 uT). Two days before the experiment the behavioral reactions were studied in the "open field" by means of a set of tests, characterizing the level of emotionality, moving and orientational-investigative activities of the animals under conditions of unimpeded behavior. 60 white underbred rat males with the initial body mass of 200 g were divided into three clusters. Animals with average indices were selected for the experiment. We have judged behavioral reaction disturbances of the rats under hypomagnetic conditions using videotape recordings carried out in the entire course of the chronic experiment. According to the obtained results during the period of maximum activity (from 230 to 330 a.m.) the number of interrelations between the individuals increased appreciably for experimental rats including interrelations with aggressive character. This was real during all 25 days of observation. We observed a certain dynamics of this index differed from that of the control group. We have also analyzed the final period of observation from the 21th to the 25th days. In this period we studied the 24 hours' dynamics of interrelations which were noted during 5 minutes in every hour around the clock. In the control group the number of interrelation was at a constantly low level. For experimental animals the number of interrelations was higher in the night hours than in the day ones. Moreover it exceeded the similar indexes observed from the 1st to the 20th day. For example from 300 to 305 a.m. on the 23th day we recorded 27 contacts of aggressive character between the individuals. So, in hypomagnetic field conditions the irritability of the animals' central nervous system grows, that expresses itself in the increase of contacts of aggressive and non-aggressive character between the individuals. Also we have carried out the Spirman correlation analysis between studied indices of moving activity and chemiluminescence of blood plasma and urine, electrolytic composition of urine and muscles. For control animals the quantity of correlation connections between electrolyte concentrations in studied substrata was higher than for experimental animals. The physiological sense of these correlation connections is discussed.

  3. Penetration of the interplanetary magnetic field B(sub y) magnetosheath plasma into the magnetosphere: Implications for the predominant magnetopause merging site

    NASA Technical Reports Server (NTRS)

    Newell, Patrick T.; Sibeck, David G.; Meng, Ching-I

    1995-01-01

    Magnetosheath plasma peertated into the magnetospere creating the particle cusp, and similarly the interplanetary magnetic field (IMF) B(sub y) component penetrates the magnetopause. We reexamine the phenomenology of such penetration to investigate implications for the magnetopause merging site. Three models are popular: (1) the 'antiparallel' model, in which merging occurs where the local magnetic shear is largest (usually high magnetic latitude); (2) a tilted merging line passing through the subsolar point but extending to very high latitudes; or (3) a tilted merging line passing through the subsolar point in which most merging occurs within a few Earth radii of the equatorial plane and local noon (subsolar merging). It is difficult to distinguish between the first two models, but the third implies some very different predictions. We show that properties of the particle cusp imply that plasma injection into the magnetosphere occurs most often at high magnetic latitudes. In particular, we note the following: (1) The altitude of the merging site inferred from midaltitude cusp ion pitch angle dispersion is typically 8-12 R(sub E). (2) The highest ion energy observable when moving poleward through the cusp drops long before the bulk of the cusp plasma is reached, implying that ions are swimming upstream against the sheath flow shortly after merging. (3) Low-energy ions are less able to enter the winter cusp than the summer cusp. (4) The local time behavior of the cusp as a function of B(sub y) and B(sub z) corroborates predictions of the high-latitude merging models. We also reconsider the penetration of the IMF B(sub y) component onto closed dayside field lines. Our approach, in which closed field lines ove to fill in flux voids created by asymmetric magnetopause flux erosion, shows that strich subsolar merging cannot account for the observations.

  4. Identification of prominence ejecta by the proton distribution function and magnetic fine structure in interplanetary coronal mass ejections in the inner heliosphere

    NASA Astrophysics Data System (ADS)

    Yao, Shuo; Marsch, Eckart; Tu, Chuan-Yi; Schwenn, Rainer

    2010-05-01

    This work presents in situ solar wind observations of three magnetic clouds (MCs) that contain cold high-density material when Helios 2 was located at 0.3 AU on 9 May 1979, 0.5 AU on 30 March 1976, and 0.7 AU on 24 December 1978. In the cold high-density regions embedded in the interplanetary coronal mass ejections we find (1) that the number density of protons is higher than in other regions inside the magnetic cloud, (2) the possible existence of He+, (3) that the thermal velocity distribution functions are more isotropic and appear to be colder than in the other regions of the MC, and the proton temperature is lower than that of the ambient plasma, and (4) that the associated magnetic field configuration can for all three MC events be identified as a flux rope. This cold high-density region is located at the polarity inversion line in the center of the bipolar structure of the MC magnetic field (consistent with previous solar observation work that found that a prominence lies over the neutral line of the related bipolar solar magnetic field). Specifically, for the first magnetic cloud event on 8 May 1979, a coronal mass ejection (CME) was related to an eruptive prominence previously reported as a result of the observation of Solwind (P78-1). Therefore, we identify the cold and dense region in the MC as the prominence material. It is the first time that prominence ejecta were identified by both the plasma and magnetic field features inside 1 AU, and it is also the first time that the thermal ion velocity distribution functions were used to investigate the microstate of the prominence material. Moreover, from our three cases, we also found that this material tended to fall behind the magnetic cloud and become smaller as it propagated farther away from the Sun, which confirms speculations in previous work. Overall, our in situ observations are consistent with three-part CME models.

  5. Implementing the Interplanetary Internet

    E-print Network

    Wood, Lloyd

    Implementing the Interplanetary Internet differing approaches Lloyd Wood Surrey Space Centre guest lecture Tuesday 17 February 2009. #12;22Interplanetary Internet ­ Lloyd Wood How did it all begin?How did Internet ­ Lloyd Wood VintVintVintVint sets up an Internet Society SIGsets up an Internet Society SIGsets

  6. The First in situ Observation of Kelvin-Helmholtz Waves at High-Latitude Magnetopause during Strongly Dawnward Interplanetary Magnetic Field Conditions

    NASA Technical Reports Server (NTRS)

    Hwang, K.-J.; Goldstein, M. L.; Kuznetsova, M. M.; Wang, Y.; Vinas, A. F.; Sibeck, D. G.

    2012-01-01

    We report the first in situ observation of high-latitude magnetopause (near the northern duskward cusp) Kelvin-Helmholtz waves (KHW) by Cluster on January 12, 2003, under strongly dawnward interplanetary magnetic field (IMF) conditions. The fluctuations unstable to Kelvin-Helmholtz instability (KHI) are found to propagate mostly tailward, i.e., along the direction almost 90 deg. to both the magnetosheath and geomagnetic fields, which lowers the threshold of the KHI. The magnetic configuration across the boundary layer near the northern duskward cusp region during dawnward IMF is similar to that in the low-latitude boundary layer under northward IMF, in that (1) both magnetosheath and magnetospheric fields across the local boundary layer constitute the lowest magnetic shear and (2) the tailward propagation of the KHW is perpendicular to both fields. Approximately 3-hour-long periods of the KHW during dawnward IMF are followed by the rapid expansion of the dayside magnetosphere associated with the passage of an IMF discontinuity that characterizes an abrupt change in IMF cone angle, Phi = acos (B(sub x) / absolute value of Beta), from approx. 90 to approx. 10. Cluster, which was on its outbound trajectory, continued observing the boundary waves at the northern evening-side magnetopause during sunward IMF conditions following the passage of the IMF discontinuity. By comparing the signatures of boundary fluctuations before and after the IMF discontinuity, we report that the frequencies of the most unstable KH modes increased after the discontinuity passed. This result demonstrates that differences in IMF orientations (especially in f) are associated with the properties of KHW at the high-latitude magnetopause due to variations in thickness of the boundary layer, and/or width of the KH-unstable band on the surface of the dayside magnetopause.

  7. The first in situ observation of Kelvin-Helmholtz waves at high-latitude magnetopause during strongly dawnward interplanetary magnetic field conditions

    NASA Astrophysics Data System (ADS)

    Hwang, K.-J.; Goldstein, M. L.; Kuznetsova, M. M.; Wang, Y.; ViñAs, A. F.; Sibeck, D. G.

    2012-08-01

    We report the first in situ observation of high-latitude magnetopause (near the northern duskward cusp) Kelvin-Helmholtz waves (KHW) by Cluster on January 12, 2003, under strongly dawnward interplanetary magnetic field (IMF) conditions. The fluctuations unstable to Kelvin-Helmholtz instability (KHI) are found to propagate mostly tailward, i.e., along the direction almost 90° to both the magnetosheath and geomagnetic fields, which lowers the threshold of the KHI. The magnetic configuration across the boundary layer near the northern duskward cusp region during dawnward IMF is similar to that in the low-latitude boundary layer under northward IMF, in that (1) both magnetosheath and magnetospheric fields across the local boundary layer constitute the lowest magnetic shear and (2) the tailward propagation of the KHW is perpendicular to both fields. Approximately 3-hour-long periods of the KHW during dawnward IMF are followed by the rapid expansion of the dayside magnetosphere associated with the passage of an IMF discontinuity that characterizes an abrupt change in IMF cone angle,? = acosBxB, from ˜90° to ˜10°. Cluster, which was on its outbound trajectory, continued observing the boundary waves at the northern evening-side magnetopause during sunward IMF conditions following the passage of the IMF discontinuity. By comparing the signatures of boundary fluctuations before and after the IMF discontinuity, we report that the frequencies of the most unstable KH modes increased after the discontinuity passed. This result demonstrates that differences in IMF orientations (especially in?) are associated with the properties of KHW at the high-latitude magnetopause due to variations in thickness of the boundary layer, and/or width of the KH-unstable band on the surface of the dayside magnetopause.

  8. Use of induction linacs with nonlinear magnetic drive as high average power accelerators

    SciTech Connect

    Birx, D.L.; Cook, E.G.; Hawkins, S.A.; Newton, M.A.; Poor, S.E.; Reginato, L.L.; Schmidt, J.A.; Smith, M.W.

    1984-08-20

    The marriage of induction linac technology with Nonlinear Magnetic Modulators has produced some unique capabilities. It appears possible to produce electron beams with average currents measured in amperes, at gradients exceeding 1 Mev/meter, and with power efficiencies approaching 50%. A 2 MeV, 5 kA electron accelerator is under construction at Lawrence Livermore National Laboratory (LLNL) to allow us to demonstrate some of these concepts. Progress on this project is reported here.

  9. Interplanetary sector structure: 1970--1972

    Microsoft Academic Search

    D. H. Fairfield; N. F. Ness

    1974-01-01

    This paper extends the spacecraft observations of interplanetary magnetic field sector structure from 1962 to 1966 [Ness and Wilcox, 1967], 1966 to 1969 [Wilcox and Colburn, 1969, 1970, 1972] through the declining years of the solar cycle, 1970, 1971, and 1972. The data are presented in Figures 1-3 in the traditional format. The dark shading superimposed on the Bartel's planetary

  10. Solar-interplanetary modeling: 3-D solar wind solutions in prescribed non-radial magnetic field geometries

    Microsoft Academic Search

    B. R. Durney; G. W. Pneuman

    1975-01-01

    A model is presented which describes the 3-dimensional non-radial solar wind expansion between the Sun and the Earth in a specified magnetic field configuration subject to synoptically observed plasma properties at the coronal base. In this paper, the field is taken to be potential in the inner corona based upon the Mt. Wilson magnetograph observations and radial beyond a certain

  11. Dawn-dusk (y) component of the interplanetary magnetic field and the local time of the Harang discontinuity

    Microsoft Academic Search

    A. S. Rodger; M. J. Brown; M. Pinnock; D. A. Simmons; S. W. H. Cowley

    1984-01-01

    The simple method presently used to obtain the time at which the meridian of a subauroral magnetic observatory crosses that of the Harang discontinuity is based on an examination of magnetograms to determine the time's variation with the dawn-dusk (y) component of the IMF, or B(y). It is noted that the time at which the Harang discontinuity is identified in

  12. An Alternative Interpretation of the Relationship between the Inferred Open Solar Flux and the Interplanetary Magnetic Field

    Microsoft Academic Search

    Pete Riley

    2007-01-01

    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 magnetic 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

  13. An interplanetary planar magnetic structure oriented at a large (about 80 deg) angle to the Parker spiral

    NASA Technical Reports Server (NTRS)

    Farrugia, M. W.; Dunlop, M. W.; Geurts, F.; Balogh, A.; Southwood, D. J.; Bryant, D. A.; Neugebauer, M.

    1990-01-01

    Magnetic field structures in the solar wind, characterized by a variation of the field vectors within a plane inclined to the ecliptic ('Planar Magnetic Structures', PMSs), were reported recently (Nakagawa et al., 1989). These PMSs have the property that the plane of variation of the field also contains the nominal Parker spiral direction. An observation of a PMS where the direction of the line of intersection of the plane of field variation with the ecliptic plane makes a large (about 80 deg) angle to the Parker spiral direction is presented. Furthermore, the angular variables of the field (1) vary over a restricted range, and (2) are linearly related. The latter property is related to the former. Currently proposed models for the origin of PMS, inasmuch as they require field configurations which retain strict alignment with the Parker spiral direction from formation to observation, are probably incomplete.

  14. Band-splitting of coronal and interplanetary type II bursts. II. Coronal magnetic field and Alfvén velocity

    NASA Astrophysics Data System (ADS)

    Vršnak, B.; Magdaleni?, J.; Aurass, H.; Mann, G.

    2002-12-01

    Type II radio bursts recorded in the metric wavelength range are excited by MHD shocks traveling through the solar corona. They often expose the fundamental and harmonic emission band, both frequently being split in two parallel lanes that show a similar frequency drift and intensity behaviour. Our previous paper showed that band-splitting of such characteristics is a consequence of the plasma emission from the upstream and downstream shock regions. Consequently, the split can be used to evaluate the density jump at the shock front and to estimate the shock Mach number, which in combination with the shock speed inferred from the frequency drift provides an estimate of the Alfvén velocity and the magnetic field in the ambient plasma. In this paper such a procedure is applied to 18 metric type II bursts with the fundamental band starting frequencies up to 270 MHz. The obtained values show a minimum of the Alfvén velocity at the heliocentric distance R~ 2 amounting to vA~ 400-500 km s-1. It then increases achieving a local maximum of vA~ 450-700 km s-1 at R~ 2.5. The implications regarding the process of formation and decay of MHD shocks in the corona are discussed. The coronal magnetic field in the range 1.3magnetic field in the range 1magnetic field is dominated by active region fields, whereas above H=1 it becomes radial, behaving roughly as B=2x R-2 with a plausible value of B~ 5 nT at 1 a.u.

  15. Wave properties near the subsolar magnetopause - Pc 3-4 energy coupling for northward interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Song, P.; Russell, C. T.; Strangeway, R. J.; Wygant, J. R.; Cattell, C. A.; Fitzenreiter, R. J.; Anderson, R. R.

    1993-01-01

    Strong slow mode waves in the Pc 3-4 frequency range are found in the magnetosheath close to the magnetopause. We have studied these waves at one of the ISEE subsolar magnetopause crossings using the magnetic field, electric field, and plasma measurements. We use the pressure balance at the magnetopause to calibrate the Fast Plasma Experiment data versus the magnetometer data. When we perform such a calibration and renormalization, we find that the slow mode structures are not in pressure balance and small scale fluctuations in the total pressure still remain in the Pc 3-4 range. Energy in the total pressure fluctuations can be transmitted through the magnetopause by boundary motions. The Poynting flux calculated from the electric and magnetic field measurements suggests that a net Poynting flux is transmitted into the magnetopause. The two independent measurements show a similar energy transmission coefficient. The transmitted energy flux is about 18 percent of the magnetic energy flux of the waves in the magnetosheath. Part of this transmitted energy is lost in the sheath transition layer before it enters the closed field line region. The waves reaching the boundary layer decay rapidly. Little wave power is transmitted into the magnetosphere.

  16. Average photospheric poloidal and toroidal magnetic field components near solar minimum

    NASA Technical Reports Server (NTRS)

    Duvall, T. L., Jr.; Scherrer, P. H.; Svalgaard, L.; Wilcox, J. M.

    1979-01-01

    Average (over longitude and time) photospheric magnetic field components are derived from 3-min Stanford magnetograms made near the solar minimum of cycle 21. The average magnetograph signal is found to behave as the projection of a vector for measurements made across the disk. The poloidal field exhibits the familiar dipolar structure near the poles, with a measured signal in the line Fe I 5250 A of about 1 G. At low latitudes the poloidal field has the polarity of the poles, but is of reduced magnitude (about 0.1 G). A net photospheric toroidal field with a broad latitudinal extent is found. The polarity of the toroidal field is opposite in the northern and southern hemispheres and has the same sense as subsurface flux tubes giving rise to active regions of solar cycle 21. These observations are used to discuss large-scale electric currents crossing the photosphere and angular momentum loss to the solar wind.

  17. An MHD simulation of the effects of the interplanetary magnetic field By component on the interaction of the solar wind with the earth's magnetosphere during southward interplanetary magnetic field

    NASA Technical Reports Server (NTRS)

    Ogino, T.; Walker, R. J.; Ashour-Abdalla, M.; Dawson, J. M.

    1986-01-01

    The interaction between the solar wind and the earth's magnetosphere has been studied by using a time-dependent three-dimensional MHD model in which the IMF pointed in several directions between dawnward and southward. When the IMF is dawnward, the dayside cusp and the tail lobes shift toward the morningside in the northern magnetosphere. The plasma sheet rotates toward the north on the dawnside of the tail and toward the south on the duskside. For an increasing southward IMF component, the plasma sheet becomes thinner and subsequently wavy because of patchy or localized tail reconnection. At the same time, the tail field-aligned currents have a filamentary layered structure. When projected onto the northern polar cap, the filamentary field-aligned currents are located in the same area as the region 1 currents, with a pattern similar to that associated with auroral surges. Magnetic reconnection also occurs on the dayside magnetopause for southward IMF.

  18. High precision lightning measurements using coherent averaging of long-distance magnetic fields

    NASA Astrophysics Data System (ADS)

    Weinert, J. L.; Cummer, S. A.

    2014-12-01

    Measurement of magnetic fields produced by lightning has many advantages over other methods of lightning characterization. Because low frequency magnetic fields produced by lightning decay slowly with distance, magnetic field measurements can be performed at large distances, often in the range of thousands of kilometers. As we have shown previously, coherent time-aligned averaging of similar lightning events can overcome many limiting factors associated with magnetic field measurements at large distances, such as sensitivity, as well as both environmental and sensor noise. Using such a method, it is possible to achieve as broadband noise level of tens of femtotesla, allowing for the detection of signals produced by current moments of a few hundred amp-kilometers. In this work, we present the results of investigation of lightning from four thunderstorms from summer 2013, each located several hundreds of kilometers from the measurement location. Cloud-to-ground (CG) events of both positive and negative polarities are compared between storms, allowing precise, quantitative measurement of flash processes with relatively small current moments, such as continuing currents and leader development. By comparing events from several storms, some conclusions about consistency of processes for both positive and negative CG flashes can be made.

  19. The relationship of the large-scale solar field to the interplanetary magnetic field - What will Ulysses find?

    NASA Technical Reports Server (NTRS)

    Hoeksema, J. T.

    1986-01-01

    Using photospheric magnetic field observations obtained at the Stanford Wilcox Solar Observatory, results from a potential field model for the present solar cycle are given, and qualitative predictions of the IMF that Ulysses may encounter are presented. Results indicate that the IMF consists of large regions of opposite polarity separated by a neutral sheet (NS) (extended to at least 50 deg) and a four-sector structure near solar minimum (produced by small quadripolar NS warps). The latitudinal extent of the NS increases following minimum and the structure near maximum includes multiple NSs, while a simplified IMF is found during the declining phase.

  20. A structurally-controllable spin filter in a ?-doped magnetically modulated semiconductor nanostructure with zero average magnetic field

    NASA Astrophysics Data System (ADS)

    Shen, Li-Hua; Ma, Wen-Yue; Zhang, Gui-Lian; Yang, Shi-Peng

    2015-07-01

    We report on a theoretical investigation of spin-polarized transport in a ?-doped magnetically modulated semiconductor nanostructure, which can be experimentally realized by depositing a ferromagnetic stripe on the top of a semiconductor heterostructure and by using the atomic layer doping technique such as molecular beam epitaxy (MBE). It is shown that although such a nanostructure has a zero average magnetic filed, a sizable spin polarization exists due to the Zeeman splitting mechanism. It is also shown that the degree of spin polarization varies sensitively with the weight and/or position of the ?-doping. Therefore, one can conveniently tailor the behaviour of the spin-polarized electron by tuning the ? -doping, and such a device can be employed as a controllable spin filter for spintronics.

  1. On the Estimate of Frequency Break and Spectral Index at Ion Scales for Interplanetary Magnetic Field Fluctuations

    NASA Astrophysics Data System (ADS)

    Telloni, D.; Bruno, R.; Trenchi, L.

    2014-12-01

    We exploited radial alignments between MESSENGER and WIND spacecraft to study: 1) the radial dependence of the spectral break located at the border between fluid and kinetic regimes; 2) the dependence, if any, of the spectral slope, around the frequency break, on the type of wind, either fast or slow.We found that this spectral break moves to lower and lower frequencies as heliocentric distance increases, following a power-law dependence. Moreover, we found evidence that a cyclotron-resonant dissipation mechanism must participate into the spectral energy cascade together with other possible kinetic noncyclotron-resonant mechanisms.On the other hand, the spectral slope shows a large variability between -3.75 and -1.75 with an average value around -2.8 and a robust tendency for this parameter to be steeper within the trailing edge of high speed streams and to be flatter within the subsequent slower wind, following a gradual transition between these two states. The value of the spectral index seems to depend firmly on the power associated to the fluctuations within the inertial range, higher the power steeper the slope. Research partially supported by the Agenzia Spaziale Italiana, contract ASI/INAF I/013/12/0 and by the European Community's Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 313038/STORM

  2. Magnetic field measurements at Jupiter by Voyagers 1 and 2: Daily plots of 48 second averages

    NASA Technical Reports Server (NTRS)

    Lepping, R. P.; Silverstein, M. J.; Ness, N. F.

    1981-01-01

    A series of 24 hour summary plots of the magnetic field, in 48-s average form, measured in the vicinity of Jupiter by the magnetometers onboard Voyagers 1 and 2 are presented. The Voyager 1 data cover the period from 27 February 1979 (day = 58) to 23 March (day = 82) inclusive, and the Voyager 2 data cover the period from 2 July 1979 (day = 183) to 14 August (day = 226) inclusive. Closest approach to the planet occurred on days 64 (AT 1205 UT) and 190 (AT 2230 UT) for Voyagers 1 and 2, respectively. Also included are: a description of the characteristics of the magnetometers, a brief description of the near-planet trajectories of the two spacecraft, a listing of the bow shock and magnetopause crossing times, and a bibliography containing Voyager-Jupiter related papers and reports.

  3. Averaging out magnetic forces with fast rf-sweeps in an optical trap for metastable chromium atoms

    E-print Network

    Q. Beaufils; R. Chicireanu; A. Pouderous; W. de Souza Melo; B. Laburthe-Tolra; E. Maréchal; L. Vernac; J. C. Keller; O. Gorceix

    2007-11-05

    We introduce a novel type of time-averaged trap, in which the internal state of the atoms is rapidly modulated to modify magnetic trapping potentials. In our experiment, fast radiofrequency (rf) linear sweeps flip the spin of atoms at a fast rate, which averages out magnetic forces. We use this procedure to optimize the accumulation of metastable chomium atoms into an optical dipole trap from a magneto-optical trap. The potential experienced by the metastable atoms is identical to the bare optical dipole potential, so that this procedure allows for trapping all magnetic sublevels, hence increasing by up to 80 percent the final number of accumulated atoms.

  4. Interplanetary orbit determination

    Microsoft Academic Search

    K. H. Rourke; N. Jerath; C. H. Acton; W. G. Breckenridge; J. K. Campbell; C. S. Christensen; A. J. Donegan; H. M. Koble; N. A. Mottinger; G. C. Rinker

    1979-01-01

    A general description of the Viking interplanetary orbit determination activity extending from launch to Mars encounter is given. The emphasis is on the technical fundamentals of the problem, basic strategies and data types used, quantitative results, and specific conclusions derived from the inflight experience. Special attention is given to the use of the spacecraft-based optical measurements and their first application

  5. Interplanetary magnetic field structure and solar wind parameters as inferred from solar magnetic field observations and by using a numerical 2-D MHD model

    Microsoft Academic Search

    A. V. Usmanov

    1993-01-01

    An attempt is made to infer parameters of the solar corona and the solar wind by means of a numerical, self-consistent MHD simulation. Boundary conditions for the magnetic field are given from the observations of the large-scale magnetic field at the Sun. A two-region, planar (the ecliptic plane is assumed) model for the solar wind flow is considered. Region I

  6. Cosmic ray modulation by interplanetary disturbances

    NASA Astrophysics Data System (ADS)

    Braga, Carlos Roberto; Dal Lago, Alisson; Schuch, Nelson Jorge; da Silva, Marlos; Echer, Ezequiel; Demítrio Gonzalez Alarcon, Walter; Munakata, Kazuoki; Kuwabara, Takao; Kato, Chihiro; Bieber, John W.

    Interplanetary disturbances such as ICMEs (Interplanetary Coronal Mass Ejections) and CIRs (Corotating Interaction Regions), modulate high-energy cosmic rays reaching the Earth. Prior to the arrival of the disturbances at the Earth, ground based high-energy muon detectors can detect precursory effects in cosmic-ray anisotropy, such as precursory deficit and/or excess of intensity along the sunward IMF (Interplanetary Magnetic Field) direction. With suitable analyses, these precursors are found typically around 8 hours prior to the disturbance arrival at the Earth. The objective of this work is to analyze these precursors by using the Global Muon Detector Network (GMDN), an international network formed by four multidirectional muon detectors viewing a full range of the pitch angle measured from the sunward IMF direction. By analyzing the variation of the count rate global distribution of the observed intensity (instead of analyzing the count rate) precursory signatures can be enhanced when compared with analyses of count rates. For some events, it is possible to make almost a global distribution map of cosmic ray density using all the directional channels of the detectors. Precursory signature is generally accompanied by the interplanetary shock, but there are also some signatures not associated with the shock.

  7. Observations of interactions between interplanetary and geomagnetic fields

    NASA Technical Reports Server (NTRS)

    Burch, J. L.

    1973-01-01

    Magnetospheric effects associated with variations of the north-south component of the interplanetary magnetic field are examined in light of recent recent experimental and theoretical results. Although the occurrence of magnetospheric substorms is statistically related to periods of southward interplanetary magnetic field, the details of the interaction are not understood. In particular, attempts to separate effects resulting directly from the interaction between the interplanetary and geomagnetic fields from those associated with substorms have produced conflicting results. The transfer of magnetic flux from the dayside to the nightside magnetosphere is evidenced by equatorward motion of the polar cusp and increases of the magnetic energy density in the lobes of the geomagnetic tail. The formation of a macroscopic X-type neutral line at tail distances less than 35 R sub E appears to be a substorm phenomenon.

  8. Distinct shock acceleration processes — Evaluation of the magnetic trap dimensions formed upstream of an interplanetary shock using measurements of the ulysses spacecraft

    Microsoft Academic Search

    P. K. Marhavilas; E. T. Sarris; G. C. Anagnostopoulos; P. C. Trochoutsos

    2003-01-01

    We analyze the acceleration signatures of energetic ions (E > 50 keV) and electrons (E > 30 keV) being observed on day 256 of the year 1992 UT, in the vicinity of the surface of a fast-mode quasi-perpendicular interplanetary hydromagnetic shock, using fine time resolution measurements by the HI-SCALE instrument onboard the Ulysses spacecraft,(s\\/c). The observations present strong evidence for

  9. Distinct shock acceleration processes - Evaluation of the magnetic trap dimensions formed upstream of an interplanetary shock using measurements of the ulysses spacecraft

    Microsoft Academic Search

    P. K. Marhavilas; E. T. Sarris; G. C. Anagnostopoulos; P. C. Trochoutsos

    2003-01-01

    We analyze the acceleration signatures of energetic ions (E > 50 keV) and electrons (E > 30 keV) being observed on day 256 of the year 1992 UT, in the vicinity of the surface of a fast-mode quasi-perpendicular interplanetary hydromagnetic shock, using fine time resolution measurements by the HI-SCALE instrument onboard the Ulysses spacecraft,(s\\/c). The observations present strong evidence for

  10. Interplanetary charged particle environments

    NASA Technical Reports Server (NTRS)

    Divine, T. N.

    1973-01-01

    Current state-of-the-art knowledge of the solar wind, solar particle events, and galactic cosmic rays is reviewed for the development of space vehicle design criteria based on these interplanetary environments. These criteria are described quantitatively in terms of intensity, flux and fluence, and their dependences on time, position and energy, and the associated probabilities and related parameters, for electrons, protons and other ions.

  11. Particle Acceleration at Interplanetary Shocks

    E-print Network

    Matthew G. Baring; Errol J. Summerlin

    2008-07-07

    The acceleration of interstellar pick-up ions as well as solar wind species has been observed at a multitude of interplanetary (IP) shocks by different spacecraft. This paper expands upon previous work modeling the phase space distributions of accelerated ions associated with the shock event encountered on day 292 of 1991 by the Ulysses mission at 4.5 AU. A kinetic Monte Carlo simulation is employed here to model the diffusive acceleration process. This exposition presents recent developments pertaining to the incorporation into the simulation of the diffusive characteristics incurred by field line wandering (FLW), according to the work of Giacalone and Jokipii. For a pure field-line wandering construct, it is determined that the upstream spatial ramp scales are too short to accommodate the HI-SCALE flux increases for 200 keV protons, and that the distribution function for H+ somewhat underpopulates the combined SWICS/HI-SCALE spectra at the shock. This contrasts our earlier theory/data comparison where it was demonstrated that diffusive transport in highly turbulent fields according to kinetic theory can successfully account for both the proton distributions and upstream ramp scales, using a single turbulence parameter. The principal conclusion here is that, in a FLW scenario, the transport of ions across the mean magnetic field is slightly less efficient than is required to effectively trap energetic ions within a few Larmor radii of the shock layer and thereby precipitate efficient acceleration. This highlights the contrast between ion transport in highly turbulent shock environs and remote, less-disturbed interplanetary regions.

  12. Multi-Spacecraft Observations of Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Smith, C. W.; Tokar, R. L.; Skoug, R. M.; Szabo, A.

    1999-01-01

    Using multi-spacecraft observations primarily from ACE and WIND and from IMP 8 and Geotail when available, the 3-dimensional structure of interplanetary shocks on the hundred Earth radii scale will be discussed. The complete magnetic field, and solar wind ion and electron data sets were used to fit the shocks with a full non-linear least squares fitting "Rankine-Hugoniot" technique yielding the local shock surface normals and speeds with associated uncertainties. Multi-spacecraft results reveal that on the distance scale of ACE's L1 halo orbit the shocks deviate from a simple planar geometry. This result has important consequences for the prediction of the exact arrival times of interplanetary shocks at the Earth's magnetosphere, and hence, on the reliability of space weather predictions. It also has implications on the coherence scale of solar wind structures and their evolution from the Sun to Earth.

  13. Multi-Spacecraft Observations of Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Szabo, A.; Smith, C. W.; Tokar, R. L.; Skoug, R. M.

    1999-01-01

    Using multi-spacecraft observations primarily from ACE and WIND, and from IMP 8 and Geotail when available, the 3-dimensional structure of interplanetary shocks on the hundred Earth radii scale will be discussed. The complete magnetic field, and solar wind ion and electron data sets were used to fit the shocks with a full non-linear least squares fit "Rankine-Hugoniot" technique yielding the local shock surface normals and speeds with associated uncertainties. Multi-spacecraft results reveal that on the distance scale of ACE's L1 halo orbit the shocks deviate significantly from a simple planar geometry. This result has important consequences for the prediction of the exact arrival times of interplanetary shocks at the Earth's magnetosphere, and hence, on the reliability of space weather predictions. It also has implications on the coherence scale of solar wind structures and their evolution from the Sun to Earth.

  14. A correlative study of SSC's, interplanetary shocks, and solar activity

    NASA Technical Reports Server (NTRS)

    Chao, J. K.; Lepping, R. P.

    1973-01-01

    A total of 93 SSC's were examined during the four year period from 1968 to 1971 at and near the peak of the solar activity cycle. Of the 93 SSC's 81 could be associated with solar activity, such as solar flares and radio bursts of Type II and Type IV. The mean propagation speeds of these flare-associated events ranged from 400 to 1000 km/sec with an average speed of 600-700 km/sec. Disturbances associated with 48 of the SSC's have been studied in detail using the corresponding interplanetary (IP) magnetic field, and plasma data when they were available. It was found that 41 of the 48 disturbances corresponded to IP shock waves, and the remaining seven events were tangential discontinuities. Thirty percent of the IP shocks had thick structure (i.e. the magnetic field jump across the shock occurred over a distance much greater than 50 proton Larmor radii). Also given is a statistical study of the gross geometry of a typical or average shock surface based on multiple spacecraft sightings and their relative orientation with respect to the solar flare. It is suggested that a typical shock front propagating out from the sun at l AU has a radius of curvature on the order of l AU. Also given are some general properties of oblique IP flare-shocks.

  15. The averaged dynamics of the hydrogen atom in crossed electric and magnetic fields as a perturbed Kepler problem

    E-print Network

    Nils Berglund; Turgay Uzer

    2000-07-13

    We treat the classical dynamics of the hydrogen atom in perpendicular electric and magnetic fields as a celestial mechanics problem. By expressing the Hamiltonian in appropriate action-angle variables, we separate the different time scales of the motion. The method of averaging then allows us to reduce the system to two degrees of freedom, and to classify the most important periodic orbits.

  16. Relationship between the near-Earth interplanetary field and the coronal source flux: Dependence on timescale

    E-print Network

    Lockwood, Mike

    independent of latitude. This has allowed quantification of the total open solar flux from near-Earth observations of the interplanetary magnetic field. The open flux can also be estimated from photospheric of flux emerging at higher heliographic latitudes. INDEX TERMS: 2164 Interplanetary Physics: Solar wind

  17. KINETIC PROPERTIES OF INTERPLANETARY MATTER

    Microsoft Academic Search

    E Parker

    1962-01-01

    Estimates of the kinetic and transport properties of the interplanetary ; medium are reviewed. It is pointed out that the effective mean free paths of ; interplanetary ions and electrons are effectively small compared to the scale of ; the system, either because of Coulomb collisions or dynamical instability of the ; gas. Numerical expressions are given for the mean

  18. A Cost Effective Sensorless Control Method for Permanent Magnet Synchronous Motors Based on Average Terminal Voltage

    Microsoft Academic Search

    Cheng-Hu Chen; Wei-Chih Tai; Ming-Yang Cheng

    2006-01-01

    This paper presents the design, analysis, and implementation of a high performance and cost effective sensorless control scheme for the extensively used brushless DC motors (BLDCM), permanent magnet synchronous motors (PMSM), and interior permanent magnet synchronous motors (IPMSM). In the proposed approach, instead of sensing the non-excited back emf or injecting the additional high frequency switching signals, the commutation signals

  19. Observations of interplanetary shocks with multiple spacecraft

    NASA Astrophysics Data System (ADS)

    Kajdi?, Primož; Blanco-Cano, Xochitl; Lavraud, Benoit

    2015-04-01

    Interplanetary (IP) shocks in the heliosphere are often driven by Coronal Mass Ejections and Stream Interaction Regions. They are one of the main accelerators of suprathermal and energetic particles in the interplanetary space. The acceleration mechanisms of these collisionless shocks depend on their Mach numbers and also on the angle between the upstream interplanetary magnetic field and the local normal to the shock. It has been recognized in the past that the latter varies along the shock surface. Observations with multiple spacecraft have shown that the local shock normal is oriented differently at different points in space. However this has been done for spacecraft separations of at least several Earth radii. Here we present observations of IP shocks with multiple spacecraft and missions for much smaller inter-spacecraft separations. In the case of observations with Cluster mission, these separations can be as small as 40 km. Even on these scales we find that the observed shock profiles may be slightly different. We have elaborated a catalog of ~80 shocks observed with two or more spacecraft in orbit around Earth. Here we present this catalog as well as some of the most interesting case events.

  20. Propagation anisotropies of solar flare protons and electrons at low energies in interplanetary space.

    NASA Technical Reports Server (NTRS)

    Pyle, K. R.

    1973-01-01

    Flux anisotropies in interplanetary space were investigated for protons with E greater than 0.66 MeV and electrons with E greater than 400 keV. Data were taken from the University of Chicago charged-particle telescope aboard the deep-space probe Pioneer 7 and from the Goddard Space Flight Center magnetometer aboard the same spacecraft. Flux anisotropies lying to the east of the average interplanetary magnetic field direction were first reported by McCracken et al. (1971), late in a solar particle event, for proton energies greater than 7.5 MeV. This work extends this investigation to much lower proton energies, studies the proton and electron anisotropies during both early and late phases of a particle event, and makes use of detailed magnetic field data. The investigation consists of two parts, a study of many periods taken at random during solar events, for both protons and electrons, and a detailed analysis of one period, early in an event, during which the magnetic field was near the solar direction.

  1. Reply to the comment by M. Lockwood et al. on ``The IDV index: Its derivation and use in inferring long-term variations of the interplanetary magnetic field''

    NASA Astrophysics Data System (ADS)

    Svalgaard, L.; Cliver, E. W.

    2006-09-01

    From an analysis of geomagnetic and solar wind data, [1999] (hereinafter referred to as LSW99) reported that the solar coronal magnetic field had increased by more than a factor of two during the last century. If true, this would be an important discovery. Recently, [2005] (hereinafter referred to as SC05) reported an analysis based on our newly developed interdiurnal variability (IDV) index of geomagnetic activity which indicated that cycle averages of the solar field varied no more than ˜25% over the same time interval and are now decreasing. Here, we answer the criticisms of [2006] (hereinafter referred to as LRFS06) to our paper. In sum, we find their objections without merit. If our prediction that the next solar cycle will be the smallest in 100 years [, 2005] bears out, this debate may be settled by direct solar wind measurements within the next few years. In the following sections we respond to the various points raised by LRFS06: percentage change, Br versus B, regression technique (including the effect of missing data), and analysis procedure.

  2. Large-amplitude Alfvén waves in the interplanetary medium, 2

    Microsoft Academic Search

    J. W. Belcher; Leverett Davis

    1971-01-01

    An extensive study of the dynamic nonshock properties of the microscale fluctuations (scale lengths of 0.01 AU and less) in the interplanetary medium was made by using plasma and magnetic field data from Mariner 5 (Venus 1967). The observational results of the study-are: (1) Large- amplitude, nonsinusoidal Mfvn waves propagating outward from the sun with a broad wave- length range

  3. The Interplanetary Exchange of Photosynthesis

    Microsoft Academic Search

    Charles S. Cockell

    2008-01-01

    Panspermia, the transfer of organisms from one planet to another, either through interplanetary or interstellar space, remains\\u000a speculation. However, its potential can be experimentally tested. Conceptually, it is island biogeography on an interplanetary\\u000a or interstellar scale. Of special interest is the possibility of the transfer of oxygenic photosynthesis between one planet\\u000a and another, as it can initiate large scale biospheric

  4. Laser-fusion rocket for interplanetary propulsion

    SciTech Connect

    Hyde, R.A.

    1983-09-27

    A rocket powered by fusion microexplosions is well suited for quick interplanetary travel. Fusion pellets are sequentially injected into a magnetic thrust chamber. There, focused energy from a fusion Driver is used to implode and ignite them. Upon exploding, the plasma debris expands into the surrounding magnetic field and is redirected by it, producing thrust. This paper discusses the desired features and operation of the fusion pellet, its Driver, and magnetic thrust chamber. A rocket design is presented which uses slightly tritium-enriched deuterium as the fusion fuel, a high temperature KrF laser as the Driver, and a thrust chamber consisting of a single superconducting current loop protected from the pellet by a radiation shield. This rocket can be operated with a power-to-mass ratio of 110 W gm/sup -1/, which permits missions ranging from occasional 9 day VIP service to Mars, to routine 1 year, 1500 ton, Plutonian cargo runs.

  5. Proceedings of the Symposium on the Study of the Sun and Interplanetary Medium in Three Dimensions. [space mission planning and interplanetary trajectories by NASA and ESA to better observe the sun and solar system

    NASA Technical Reports Server (NTRS)

    Fisk, L. A. (editor); Axford, W. I. (editor)

    1976-01-01

    A series of papers are presented from a symposium attended by over 200 European and American scientists to examine the importance of exploring the interplanetary medium and the sun by out-of-the-ecliptic space missions. The likely scientific returns of these missions in the areas of solar, interplanetary, and cosmic ray physics is examined. Theoretical models of the solar wind and its interaction with interplanetary magnetic fields are given.

  6. Search Coil vs. Fluxgate Magnetometer Measurements at Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Wilson, L.B., III

    2012-01-01

    We present magnetic field observations at interplanetary shocks comparing two different sample rates showing significantly different results. Fluxgate magnetometer measurements show relatively laminar supercritical shock transitions at roughly 11 samples/s. Search coil magnetometer measurements at 1875 samples/s, however, show large amplitude (dB/B as large as 2) fluctuations that are not resolved by the fluxgate magnetometer. We show that these fluctuations, identified as whistler mode waves, would produce a significant perturbation to the shock transition region changing the interpretation from laminar to turbulent. Thus, previous observations of supercritical interplanetary shocks classified as laminar may have been under sampled.

  7. Perturbation solution of the bounce-averaged Fokker-Planck equation for an electrostatic magnetic mirror

    SciTech Connect

    Zerguini, T.H.

    1983-07-01

    Sloshing ion distributions are a crucial feature in the end cells of recent tandem mirror reactor designs. They provide the ambipolar potentials that confine central ions and often have the function of making the electron thermal barrier with a potential shape that traps enough cold ions at the midplane for the stabilization of loss cone modes. A perturbation method is developed to find solutions of sloshing-ion distributions. This method uses an expansion in the ratio of electrostatic potential to average ion energy to simplify the bounce-averaged Fokker-Planck equation. The zero'th order equation obtained is separated into equations for the angular and velocity-dependent parts of the distribution function. An analytical solution of the angular equation is derived for small charge-exchange to ionization ratios. For any value of this ratio finite element techniques, which provide rapid numerical solutions for parametric studies of sloshing ions, are used to derive the angular and the velocity distribution functions. The density ratio and the ambipolar potential, as functions of axial distance, are computed from the angular distribution function. There is excellent agreement with results from the Lawrence Livermore National Laboratory bounce-averaged Fokker-Planck code with as much as 500 times less CRAY-1 computer time.

  8. Analisys of interplanetary structures associated with cosmic ray precursory anisotropies and intense geomagnetic storms

    NASA Astrophysics Data System (ADS)

    Savian, J. F.; da Silva, M. R.; Signori, M. R.; Andrioli, V. F.; dal Lago, A.; Eduardo, L.; Vieira, A.; Munakata, K.; Gonzalez, W. D.; Schuch, N. J.

    Throughout the 11 year solar cycle a number of energetic phenomena such as "flares" and coronal mass ejections (CME) give rise at earth to the so-called magnetic storms. These storms are characterized by a decrease in the H component of terrestrial magnetic field, lasting some dozens of hours. They are associated to interplanetary structures whose interplanetary magnetic field component in the Z direction (Bz) is southward, i.e., antiparalell to the earth's magnetic field direction. Thus, the interplanetary magnetic field interconnects with the geomagnetic field causing energy to be transported inwards. Some of these structures are associated with precursory anisotropy observed in ground cosmic ray data (muons). The objective of this work is to use a set of intense geomagnetic storm events (Dst<-100nT), already studied by Munakata et al (2000) in terms of cosmic ray signatures, and identify their interplanetary structures using observations made by ACE, Wind and IMP-8 satellites. We use the following interplanetary data: plasma (solar wind speed , density and temperature of protons), interplanetary magnetic field (B, Bx, By, Bz), observed by IMP-8, WIND and ACE satellites, and Dst index from Kyoto to characterize the storms.

  9. Perturbation solution of the bounce-averaged Fokker-Planck equation in magnetic mirrors

    SciTech Connect

    Zerguini, T.H.

    1983-01-01

    Sloshing-ion distributions are a crucial feature in the end cells of Tandem Mirror Reactor designs. They provide the ambipolar potential that confines central-cell ions and often have the function of creating the electron thermal barrier with a potential shape that traps enough cold ions at the midplane for the stabilization of loss-cone modes. A perturbation method is developed to find solutions of sloshing ion distributions. This method uses an expansion in the ratio of electrostatic potential to average ion energy to simplify the bounce averaged Fokker-Planck equation. The zero-th order equation obtained is separated into equations for the angular- and velocity-dependent parts of the distribution function. An analytical solution of the angular equation is derived for small charge-exchange to ionization ratios. For any value of this ratio finite-element techniques, which provide rapid numerical solutions for parametric studies of sloshing ions, are used to derive the zero-th order angular and velocity equations. The first-order two-dimensional equation was also expanded into finite-element hat functions. Application of Galerkin's method gives a linear system of equations where all matrix and source elements are calculated analytically.

  10. Electromagnetic Whistler Precursors at Supercritical Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III

    2012-01-01

    We present observations of electromagnetic precursor waves, identified as whistler mode waves, at supercritical interplanetary shocks using the Wind search coil magnetometer. The precursors propagate obliquely with respect to the local magnetic field, shock normal vector, solar wind velocity, and they are not phase standing structures. All are right-hand polarized with respect to the magnetic field (spacecraft frame), and all but one are right-hand polarized with respect to the shock normal vector in the normal incidence frame. Particle distributions show signatures of specularly reflected gyrating ions, which may be a source of free energy for the observed modes. In one event, we simultaneously observe perpendicular ion heating and parallel electron acceleration, consistent with wave heating/acceleration due to these waves.

  11. Multi-Spacecraft Observations of Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Szabo, Adam

    2005-01-01

    Multi-spacecraft solar wind observations reveal that many interplanetary shocks deviate significantly from exact planarity on scale length of the magnetospheric cross section. A number of different IP shock observations with four spacecraft will be presented to demonstrate quantitatively the angular deviations between shock normals obtained from 4-spacecraft methods, using only the time and position information of shock observations but assuming a exactly planar geometry, and those obtained from a non-linear least squares fitting of the "Rankine-Hugoniot" conservation equations at each spacecraft. Moreover, the curvature of the shock fronts is strongly related to its driver, typically magnetic clouds. It will be demonstrated that small and slower moving magnetic clouds drive shocks with significantly more irregular surface geometries.

  12. Interplanetary Microlaser Transponders

    NASA Technical Reports Server (NTRS)

    Degnan, John J.

    1999-01-01

    The feasibility of an asynchronous (i.e. independently firing) interplanetary laser transponder, capable of ranging between Earth and Mars and using the automated SLR2000 Satellite Laser Ranging (SLR) system as an Earth base station, has been suggested. Since that time, we have received a small amount of discretionary funding to further explore the transponder concept and to develop and test an engineering breadboard. Candidate operational scenarios for acquiring and tracking the opposite laser terminal over interplanetary distances have been developed, and breadboard engineering parameters were chosen to reflect the requirements of an Earth-Mars link Laboratory tests have been devised to simulate the Earth- Mars link between two independent SLR2000 transceivers and to demonstrate the transfer of range and time in single photon mode. The present paper reviews the concept of the asynchronous microlaser transponder, the transponder breadboard design, an operational scenario recently developed for an asteroid rendezvous, and the laboratory test setup. The optical head of the transponder breadboard fits within a cylinder roughly 15 cm in diameter and 32 cm in length and is mounted in a commercial two axis gimbal driven by two computer-controlled stepper motors which allows the receiver optical axis to be centered on a simulated Earth image. The optical head is built around a small optical bench which supports a 14.7 cm diameter refractive telescope, a prototype 2 kHz SLR2000 microlaser transmitter, a quadrant microchannel plate photomultiplier (MCP/PMT), a CCD array camera, spatial and spectral filters, assorted lenses and mirrors, and protective covers and sun shields. The microlaser is end-pumped by a fiber-coupled diode laser array. An annular mirror is employed as a passive transmit/receive (T/R) switch in an aperture-sharing arrangement wherein the transmitted beam passes through the central hole and illuminates only the central 2.5 cm of the common telescope (adequate to achieve a 10 arcsecond full laser beam divergence) while the receiver uses the remainder of the 14.7 cm aperture. Additional electronic instrumentation includes the diode pump array and associated heat sink and current drivers, rubidium frequency standard, timing distribution module, range gate generator, a recently developed all-digital correlation range receiver, and system computer. Acquisition of the opposite transponder terminal requires a search within a three-dimensional volume determined by the initial pointing uncertainty and a maximum 500 microsecond uncertainty in the laser time of fire at the opposite terminal for totally uncorrelated Earth and spacecraft clocks. The angular search is aided by a sensitive CCD array capable of imaging the Earth, Moon, and surrounding stars within the nominal + 0.5 degree cone of uncertainty associated with the initial pointing of a spacecraft body or microwave communications dish.

  13. Refractory minerals in interplanetary dust.

    PubMed

    Christoffersen, R; Buseck, P R

    1986-10-31

    A newly studied interplanetary dust particle contains a unique set of minerals that closely resembles assemblages in the refractory, calcium- and aluminum-rich inclusions in carbonaceous chondrite meteorites. The set of minerals includes diopside, magnesium- aluminum spinel, anorthite, perovskite, and fassaite. Only fassaite has previously been identified in interplanetary dust particles. Diopside and spinel occur in complex symplectic intergrowths that may have formed by a reaction between condensed melilite and the solar nebula gas. The particle represents a new link between interplanetary dust particles and carbonaceous chondrites; however, the compositions of its two most abundant refractory phases, diopside and spinel, differ in detail from corresponding minerals in calcium- and aluminum-rich inclusions. PMID:17835566

  14. Evolution and interaction of large interplanetary streams

    NASA Technical Reports Server (NTRS)

    Whang, Y. C.; Burlaga, L. F.

    1985-01-01

    A computer simulation for the evolution and interaction of large interplanetary streams based on multi-spacecraft observations and an unsteady, one-dimensional MHD model is presented. Two events, each observed by two or more spacecraft separated by a distance of the order of 10 AU, were studied. The first simulation is based on the plasma and magnetic field observations made by two radially-aligned spacecraft. The second simulation is based on an event observed first by Helios-1 in May 1980 near 0.6 AU and later by Voyager-1 in June 1980 at 8.1 AU. These examples show that the dynamical evolution of large-scale solar wind structures is dominated by the shock process, including the formation, collision, and merging of shocks. The interaction of shocks with stream structures also causes a drastic decrease in the amplitude of the solar wind speed variation with increasing heliocentric distance, and as a result of interactions there is a large variation of shock-strengths and shock-speeds. The simulation results shed light on the interpretation for the interaction and evolution of large interplanetary streams. Observations were made along a few limited trajectories, but simulation results can supplement these by providing the detailed evolution process for large-scale solar wind structures in the vast region not directly observed. The use of a quantitative nonlinear simulation model including shock merging process is crucial in the interpretation of data obtained in the outer heliosphere.

  15. Effect of the latitudinal distribution of temperature at the coronal base on the interplanetary magnetic field configuration and the solar wind flow

    Microsoft Academic Search

    Bo Li; Shadia Rifai Habbal; Xing Li; Chris Mountford

    2005-01-01

    Received 22 July 2005; revised 13 September 2005; accepted 26 October 2005; published 30 December 2005. (1) Using a two-dimensional MHD model of the corona and solar wind, we investigate the role of the temperature distribution with latitude at the coronal base on the global magnetic field configuration and solar wind properties at 1 AU. The latitudinal distribution of temperature

  16. Effect of the latitudinal distribution of temperature at the coronal base on the interplanetary magnetic field configuration and the solar wind flow

    Microsoft Academic Search

    Bo Li; Shadia Rifai Habbal; Xing Li; Chris Mountford

    2005-01-01

    Using a two-dimensional MHD model of the corona and solar wind, we investigate the role of the temperature distribution with latitude at the coronal base on the global magnetic field configuration and solar wind properties at 1 AU. The latitudinal distribution of temperature is aimed at modeling the transition in electron temperature at the Sun from a polar coronal hole

  17. Magnetohydrodynamic modeling of interplanetary CMEs

    Microsoft Academic Search

    Pete Riley; Jon A. Linker; Zoran Mikic; Dusan Odstrcil

    2004-01-01

    Heliospheric models of coronal mass ejection (CME) propagation and evolution provide an important insight into the dynamics of CMEs and are a valuable tool for interpretating interplanetary in situ observations. Moreover, they represent a virtual laboratory for exploring conditions and regions of space that are not conveniently or currently accessible by spacecraft. We summarize our recent advances in modeling the

  18. An In Vivo Three-Dimensional Magnetic Resonance Imaging-Based Averaged Brain Collection of the Neonatal Piglet (Sus scrofa)

    PubMed Central

    Conrad, Matthew S.; Sutton, Bradley P.; Dilger, Ryan N.; Johnson, Rodney W.

    2014-01-01

    Due to the fact that morphology and perinatal growth of the piglet brain is similar to humans, use of the piglet as a translational animal model for neurodevelopmental studies is increasing. Magnetic resonance imaging (MRI) can be a powerful tool to study neurodevelopment in piglets, but many of the MRI resources have been produced for adult humans. Here, we present an average in vivo MRI-based atlas specific for the 4-week-old piglet. In addition, we have developed probabilistic tissue classification maps. These tools can be used with brain mapping software packages (e.g. SPM and FSL) to aid in voxel-based morphometry and image analysis techniques. The atlas enables efficient study of neurodevelopment in a highly tractable translational animal with brain growth and development similar to humans. PMID:25254955

  19. An in vivo three-dimensional magnetic resonance imaging-based averaged brain collection of the neonatal piglet (Sus scrofa).

    PubMed

    Conrad, Matthew S; Sutton, Bradley P; Dilger, Ryan N; Johnson, Rodney W

    2014-01-01

    Due to the fact that morphology and perinatal growth of the piglet brain is similar to humans, use of the piglet as a translational animal model for neurodevelopmental studies is increasing. Magnetic resonance imaging (MRI) can be a powerful tool to study neurodevelopment in piglets, but many of the MRI resources have been produced for adult humans. Here, we present an average in vivo MRI-based atlas specific for the 4-week-old piglet. In addition, we have developed probabilistic tissue classification maps. These tools can be used with brain mapping software packages (e.g. SPM and FSL) to aid in voxel-based morphometry and image analysis techniques. The atlas enables efficient study of neurodevelopment in a highly tractable translational animal with brain growth and development similar to humans. PMID:25254955

  20. Interplanetary Circumstances of Quasi-Perpendicular Interplanetary Shocks in 1996-2005

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Cane, H. V.

    2010-01-01

    The angle (theta(sub Bn)) between the normal to an interplanetary shock front and the upstream magnetic field direction, though often thought of as a property "of the shock," is also determined by the configuration of the magnetic field immediately upstream of the shock. We investigate the interplanetary circumstances of 105 near-Earth quasi-perpendicular shocks during 1996-2005 identified by theta(sub Bn) greater than or equal to 80 degrees and/or by evidence of shock drift particle acceleration. Around 87% of these shocks were driven by interplanetary coronal mass ejections (ICMEs); the remainder were probably the forward shocks of corotating interaction regions. For around half of the shocks, the upstream field was approximately perpendicular to the radial direction, either east-west or west-east or highly inclined to the ecliptic. Such field directions will give quasi-perpendicular configurations for radially propagating shocks. Around 30% of the shocks were propagating through, or closely followed, ICMEs at the time of observation. Another quarter were propagating through the heliospheric plasma sheet (HPS), and a further quarter occurred in slow solar wind that did not have characteristics of the HPS. Around 11% were observed in high-speed streams, and 7% in the sheaths following other shocks. The fraction of shocks found in high-speed streams is around a third of that expected based on the fraction of the time when such streams were observed at Earth. Quasi-perpendicular shocks are found traveling through ICMEs around 2-3 times more frequently than expected. In addition, shocks propagating through ICMEs are more likely to have larger values of theta(sub Bn) than shocks outside ICMEs.

  1. THREE-DIMENSIONAL FEATURES OF THE OUTER HELIOSPHERE DUE TO COUPLING BETWEEN THE INTERSTELLAR AND INTERPLANETARY MAGNETIC FIELDS. III. THE EFFECTS OF SOLAR ROTATION AND ACTIVITY CYCLE

    SciTech Connect

    Pogorelov, Nikolai V.; Borovikov, Sergey N.; Zank, Gary P. [Physics Department and Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, 320 Sparkman Dr., Huntsville, AL 35805 (United States); Ogino, Tatsuki [Solar-Terrestrial Environment Laboratory, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi, 464-8601 (Japan)], E-mail: Nikolai.Pogorelov@uah.edu, E-mail: snb0003@uah.edu, E-mail: zank@cspar.uah.edu, E-mail: ogino@stelab.nagoya-u.ac.jp

    2009-05-10

    We investigate the effects of the 11 year solar cycle and 25 day rotation period of the Sun on the interaction of the solar wind (SW) with the local interstellar medium (LISM). Our models take into account the partially ionized character of the LISM and include momentum and energy transfer between the ionized and neutral components. We assume that the interstellar magnetic field vector belongs to the hydrogen deflection plane as discovered in the SOHO SWAN experiment. This plane is inclined at an angle of about 60 deg. toward the ecliptic plane of the Sun, as suggested in recent publications relating the local interstellar cloud properties to the radio emission observed by Voyager 1. It is assumed that the latitudinal extent of the boundary between the slow and fast SW regions, as well as the angle between the Sun's rotation and magnetic-dipole axes, are periodic functions of time, while the polarity of the interstellar magnetic field changes sign every 11 years at the solar maximum. The global variation of the SW-LISM interaction pattern, the excursions of the termination shock and the heliopause, and parameter distributions in certain directions are investigated. The analysis of the behavior of the wavy heliospheric current sheet in the supersonic SW region shows the importance of neutral atoms on its dynamics.

  2. MAGNETOHYDRODYNAMIC SIMULATIONS OF INTERPLANETARY CORONAL MASS EJECTIONS

    SciTech Connect

    Lionello, Roberto; Downs, Cooper; Linker, Jon A.; Török, Tibor; Riley, Pete; Miki?, Zoran, E-mail: lionel@predsci.com, E-mail: cdowns@predsci.com, E-mail: linker@predsci.com, E-mail: tibor@predsci.com, E-mail: pete@predsci.com, E-mail: mikic@predsci.com [Predictive Science, Inc., 9990 Mesa Rim Road, Suite 170, San Diego, CA 92121-2910 (United States)

    2013-11-01

    We describe a new MHD model for the propagation of interplanetary coronal mass ejections (ICMEs) in the solar wind. Accurately following the propagation of ICMEs is important for determining space weather conditions. Our model solves the MHD equations in spherical coordinates from a lower boundary above the critical point to Earth and beyond. On this spherical surface, we prescribe the magnetic field, velocity, density, and temperature calculated typically directly from a coronal MHD model as time-dependent boundary conditions. However, any model that can provide such quantities either in the inertial or rotating frame of the Sun is suitable. We present two validations of the technique employed in our new model and a more realistic simulation of the propagation of an ICME from the Sun to Earth.

  3. An Empirical Relationship Between Interplanetary Conditions and Dst

    Microsoft Academic Search

    R. K. Burton; R. L. McPherron; C. T. Russell

    1975-01-01

    An algorithm is presented for predicting the ground-based Dst index solely from a knowledge of the velocity and density of the solar wind and the north-south solar magnetospheric component of the interplanetary magnetic field. The three key elements of this model are an adjustment for solar wind dynamic pressure, an injection rate linearly proportional to the dawn-to-dusk component of the

  4. Interplanetary origin of multiple-dip geomagnetic storms

    Microsoft Academic Search

    J. Zhang; I. G. Richardson; D. F. Webb

    2008-01-01

    In this paper, we have systematically investigated the interplanetary drivers of major dips during intense (Dst ? ?100 nT) geomagnetic storms in 1996–2006. A major dip is defined as a temporary decrease in Dst index with amplitude larger than 14.5 nT. Multiple dips result in a storm if regions of geoeffective solar wind with strong southward magnetic fields are separated

  5. Interplanetary Dust Particles

    NASA Astrophysics Data System (ADS)

    Bradley, J. P.

    2003-12-01

    One of the fundamental goals of the study of meteorites is to understand how the solar system and planetary systems around other stars formed. It is known that the solar system formed from pre-existing (presolar) interstellar dust grains and gas. The grains originally formed in the circumstellar outflows of other stars. They were modified to various degrees, ranging from negligible modification to complete destruction and reformation during their ˜108 yr lifetimes in the interstellar medium (ISM) (Seab, 1987; Mathis, 1993). Finally, they were incorporated into the solar system. Submicrometer-sized silicates and carbonaceous material are believed to be the most common grains in the ISM ( Mathis, 1993; Sandford, 1996), but it is not known how much of this presolar particulate matter was incorporated into the solar system, to what extent it has survived, and how it might be distinguished from solar system grains. In order to better understand the process of solar system formation, it is important to identify and analyze these solid grains. Since all of the alteration processes that modified solids in the solar nebula presumably had strong radial gradients, the logical place to find presolar grains is in small primitive bodies like comets and asteroids that have undergone little, if any, parent-body alteration.Trace quantities of refractory presolar grains (e.g., SiC and Al2O3) survive in the matrices of the most primitive carbon-rich chondritic meteorites (Anders and Zinner, 1993; Bernatowicz and Zinner, 1996; Bernatowicz and Walker, 1997; Hoppe and Zinner, 2000; see Chapter 1.02). Chondritic meteorites are believed to be from the asteroid belt, a narrow region between 2.5 and 3.5 astronomical units (AU) that marks the transition from the terrestrial planets to the giant gas-rich planets. The spectral properties of the asteroids suggest a gradation in properties with some inner and main belt C and S asteroids (the source region of most meteorites and polar micrometeorites) containing layer silicates indicative of parent-body aqueous alteration and the more distant anhydrous P and D asteroids exhibiting no evidence of (aqueous) alteration (Gradie and Tedesco, 1982). This gradation in spectral properties presumably extends several hundred AU out to the Kuiper belt, the source region of most short-period comets, where the distinction between comets and outer asteroids may simply be one of the orbital parameters ( Luu, 1993; Brownlee, 1994; Jessberger et al., 2001). The mineralogy and petrography of meteorites provides direct confirmation of aqueous alteration, melting, fractionation, and thermal metamorphism among the inner asteroids ( Zolensky and McSween, 1988; Farinella et al., 1993; Brearley and Jones, 1998). Because the most common grains in the ISM (silicates and carbonaceous matter) are not as refractory as those found in meteorites, it is unlikely that they have survived in significant quantities in meteorites. Despite a prolonged search, not a single presolar silicate grain has yet been identified in any meteorite.Interplanetary dust particles (IDPs) are the smallest and most fine-grained meteoritic objects available for laboratory investigation (Figure 1). In contrast to meteorites, IDPs are derived from a broad range of dust-producing bodies extending from the inner main belt of the asteroids to the Kuiper belt (Flynn, 1996, 1990; Dermott et al., 1994; Liou et al., 1996). After release from their asteroidal or cometary parent bodies the orbits of IDPs evolve by Poynting-Robertson (PR) drag (the combined influence of light pressure and radiation drag) ( Dermott et al., 2001). Irrespective of the location of their parent bodies nearly all IDPs under the influence of PR drag can eventually reach Earth-crossing orbits. IDPs are collected in the stratosphere at 20-25 km altitude using NASA ER2 aircraft ( Sandford, 1987; Warren and Zolensky, 1994). Laboratory measurements of implanted rare gases, solar flare tracks ( Figure 2), and isotope abundances have confirmed that the collected particles are indeed extraterrestrial

  6. No increase of the interplanetary electric field since 1926

    NASA Astrophysics Data System (ADS)

    Le Sager, Philippe; Svalgaard, Leif

    2004-07-01

    The long-term variation of the interplanetary electric field is inferred back to 1926 from a correlation analysis with the magnetograms recorded at Godhavn and Thule, two polar cap geomagnetic observatories. The method is reliable because of the large dependence of the magnetic perturbation on the cross-polar cap electric field, i.e., the penetration and mapping of the interplanetary electric field into the magnetosphere-ionosphere system. This dependence is isolated by minimizing Sq and the Svalgaard-Mansurov effect. Both appear when an observatory moves closer to the polar cap boundary and are found to be a minimum in a direction almost perpendicular to the magnetic north. Strictly speaking, no secular trend in the solar wind-magnetosphere large-scale coupling is indicated for the past 77 years. This suggests that there is no secular trend in the interplanetary electric field and by inference in the Sun's open magnetic flux and in the solar wind speed. The method is independent of the aa geomagnetic index and the sunspot cycle characteristics.

  7. On Relation of the Rigidity Spectrum of 11-YEAR Variation of the Galactic Cosmic Ray Intensity and the Interplanetary Magnetic Field Turbulence

    NASA Astrophysics Data System (ADS)

    Iskra, Krzysztof; Siluszyk, Marek

    We use data of neutron monitors and IMF components Bx, By and Bz to study a dependence of the rigidity spectrum exponent gamma (deltaD(R)/D(R)=AR (-gamma) ) of the Galactic Cosmic Rays (GCR) intensity variations on IMF turbulence, characterized by the exponent ? of the power spectral density (PSD) of the IMF turbulence (PSD =af (-nu) , f is frequency). A high inversely correlations between temporal changes of (gamma and nu _{x}), (gamma and nu _{y}), and (gamma and nu _{z}) observed in 1977-1989 (A>0) do not depend whether the nu _{x} , nu _{y} and nu _{z} are calculated for alternated of resonant frequency of the IMF turbulence versus solar activity or for constant B and V _{sw} corresponding to average resonant frequency range responsible for scattering of GCR particles to which neutron monitors respond; consequently, nu _{x} , nu _{y} and nu _{z} are basically unchangeable when a range of frequency Deltaf=3x10 (-6) Hz is sliding versus time corresponding to the changes of resonant frequency of the IMF’s turbulence during 1977-1989. At the same time for the solar cycles 20 and 22 a clear inverse correlation between gamma and nu _{y} takes place for shifted frequency range versus solar activity corresponding to the alternation of resonant frequencies of turbulence of the IMF. For A<0 epochs a dependence of gamma upon nu _{y}is sharp comparing with A>0 epochs. Similar relationship is observed for regression of (gamma on nu _{z}) and (gamma on nu _{x})

  8. THREE-DIMENSIONAL FEATURES OF THE OUTER HELIOSPHERE DUE TO COUPLING BETWEEN THE INTERSTELLAR AND INTERPLANETARY MAGNETIC FIELDS. IV. SOLAR CYCLE MODEL BASED ON ULYSSES OBSERVATIONS

    SciTech Connect

    Pogorelov, N. V.; Zank, G. P. [Department of Physics, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Suess, S. T. [National Space Science and Technology Center, Huntsville, AL 35805 (United States); Borovikov, S. N. [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, 320 Sparkman Dr., Huntsville, AL 35805 (United States); Ebert, R. W.; McComas, D. J., E-mail: np0002@uah.edu [Southwest Research Institute, San Antonio, TX 78227 (United States)

    2013-07-20

    The solar cycle has a profound influence on the solar wind (SW) interaction with the local interstellar medium (LISM) on more than one timescales. Also, there are substantial differences in individual solar cycle lengths and SW behavior within them. The presence of a slow SW belt, with a variable latitudinal extent changing within each solar cycle from rather small angles to 90 Degree-Sign , separated from the fast wind that originates at coronal holes substantially affects plasma in the inner heliosheath (IHS)-the SW region between the termination shock (TS) and the heliopause (HP). The solar cycle may be the reason why the complicated flow structure is observed in the IHS by Voyager 1. In this paper, we show that a substantial decrease in the SW ram pressure observed by Ulysses between the TS crossings by Voyager 1 and 2 contributes significantly to the difference in the heliocentric distances at which these crossings occurred. The Ulysses spacecraft is the source of valuable information about the three-dimensional and time-dependent properties of the SW. Its unique fast latitudinal scans of the SW regions make it possible to create a solar cycle model based on the spacecraft in situ measurements. On the basis of our analysis of the Ulysses data over the entire life of the mission, we generated time-dependent boundary conditions at 10 AU from the Sun and applied our MHD-neutral model to perform a numerical simulation of the SW-LISM interaction. We analyzed the global variations in the interaction pattern, the excursions of the TS and the HP, and the details of the plasma and magnetic field distributions in the IHS. Numerical results are compared with Voyager data as functions of time in the spacecraft frame. We discuss solar cycle effects which may be reasons for the recent decrease in the TS particles (ions accelerated to anomalous cosmic-ray energies) flux observed by Voyager 1.

  9. Three-dimensional Features of the Outer Heliosphere due to Coupling between the Interstellar and Interplanetary Magnetic Fields. IV. Solar Cycle Model Based on Ulysses Observations

    NASA Astrophysics Data System (ADS)

    Pogorelov, N. V.; Suess, S. T.; Borovikov, S. N.; Ebert, R. W.; McComas, D. J.; Zank, G. P.

    2013-07-01

    The solar cycle has a profound influence on the solar wind (SW) interaction with the local interstellar medium (LISM) on more than one timescales. Also, there are substantial differences in individual solar cycle lengths and SW behavior within them. The presence of a slow SW belt, with a variable latitudinal extent changing within each solar cycle from rather small angles to 90°, separated from the fast wind that originates at coronal holes substantially affects plasma in the inner heliosheath (IHS)—the SW region between the termination shock (TS) and the heliopause (HP). The solar cycle may be the reason why the complicated flow structure is observed in the IHS by Voyager 1. In this paper, we show that a substantial decrease in the SW ram pressure observed by Ulysses between the TS crossings by Voyager 1 and 2 contributes significantly to the difference in the heliocentric distances at which these crossings occurred. The Ulysses spacecraft is the source of valuable information about the three-dimensional and time-dependent properties of the SW. Its unique fast latitudinal scans of the SW regions make it possible to create a solar cycle model based on the spacecraft in situ measurements. On the basis of our analysis of the Ulysses data over the entire life of the mission, we generated time-dependent boundary conditions at 10 AU from the Sun and applied our MHD-neutral model to perform a numerical simulation of the SW-LISM interaction. We analyzed the global variations in the interaction pattern, the excursions of the TS and the HP, and the details of the plasma and magnetic field distributions in the IHS. Numerical results are compared with Voyager data as functions of time in the spacecraft frame. We discuss solar cycle effects which may be reasons for the recent decrease in the TS particles (ions accelerated to anomalous cosmic-ray energies) flux observed by Voyager 1.

  10. Solar and interplanetary control of the location of the Venus bow shock

    SciTech Connect

    Russell, C.T.; Chou, E.; Luhmann, J.G. (Univ. of California, Los Angeles (USA)); Gazis, P. (NASA Ames Research Center, Moffett Field, CA (USA)); Brace, L.H.; Hoegy, W.R. (NASA Goddard Space Flight Center, Greenbelt, MD (USA))

    1988-06-01

    The Venus box shock location has been measured at nearly 2,000 shock crossings, and its dependence on solar EUV, solar wind conditions, and the interplanetary magnetic field determined. The shock position at the terminator varies from about 2.14 Venus radii at solar minimum to 2.40 Venus radii at solar maximum.The location of the shock varies little with solar wind dynamic pressure but strongly with solar wind Mach number. The shock is farthest from Venus on the side of the planet in which newly created ions gyrate away from the ionosphere. When the interplanetary magnetic field is perpendicular to the flow, the cross section of the shock is quite elliptical. This effect appears to be due to the anisotropic propagation of the fast magnetosonic wave. When the interplanetary magnetic field is aligned with the flow, the box shock cross section is circular and only weakly sensitive to changing EUV flux.

  11. Atypical Particle Heating at a Supercritical Interplanetary Shock

    NASA Technical Reports Server (NTRS)

    Wilson, Lynn B., III

    2010-01-01

    We present the first observations at an interplanetary shock of large amplitude (> 100 mV/m pk-pk) solitary waves and large amplitude (approx.30 mV/m pk-pk) waves exhibiting characteristics consistent with electron Bernstein waves. The Bernstein-like waves show enhanced power at integer and half-integer harmonics of the cyclotron frequency with a broadened power spectrum at higher frequencies, consistent with the electron cyclotron drift instability. The Bernstein-like waves are obliquely polarized with respect to the magnetic field but parallel to the shock normal direction. Strong particle heating is observed in both the electrons and ions. The observed heating and waveforms are likely due to instabilities driven by the free energy provided by reflected ions at this supercritical interplanetary shock. These results offer new insights into collisionless shock dissipation and wave-particle interactions in the solar wind.

  12. Active shielding for long duration interplanetary manned missions

    NASA Astrophysics Data System (ADS)

    Spillantini, Piero

    2010-04-01

    For long duration interplanetary manned missions the protection of astronauts from cosmic radiation is an unavoidable problem that has been considered by many space agencies. In Europe, during 2002-2004, the European Space Agency supported two research programs on this thematic: one was the constitution of a dedicated study group (on the thematic 'Shielding from cosmic radiation for interplanetary missions: active and passive methods') in the framework of the 'life and physical sciences' report, and the other an industrial study concerning the 'radiation exposure and mission strategies for interplanetary manned missions to Moon and Mars'. Both programs concluded that, outside the protection of the magnetosphere and in the presence of the most intense and energetic solar events, the protection cannot rely solely on the mechanical structures of the spacecraft, but a temporary shelter must be provided. Because of the limited mass budget, the shelter should be based on the use of superconducting magnetic systems. For long duration missions the astronauts must be protected from the much more energetic galactic cosmic rays during the whole mission period. This requires the protection of a large habitat where they could live and work, and not the temporary protection of a small volume shelter. With passive absorbers unable to play any significant role, the use of active shielding is mandatory. The possibilities offered by superconducting magnets are discussed, and recommendations are made about the needed R&D. The technical developments that have occurred in the meanwhile and the evolving panorama of possible near future interplanetary missions, require revising the pioneering studies of the last decades and the adoption of a strategy that considers long lasting human permanence in 'deep' space, moreover not only for a relatively small number of dedicated astronauts but also for citizens conducting there 'normal' activities.

  13. On interplanetary coronal mass ejection identification at 1 AU

    NASA Astrophysics Data System (ADS)

    Mulligan, T.; Russell, C. T.; Gosling, J. T.

    1999-06-01

    Coronal mass ejections are believed to be produced in the corona from closed magnetic regions not previously participating in the solar wind expansion. At 1 AU their interplanetary counterparts (ICMEs) generally have a number of distinct plasma and field signatures that distinguish them from the ambient solar wind. These include heat flux dropouts, bi-directional streaming, enhanced alpha particle events, times of depressed proton temperatures, intervals of distorted or enhanced magnetic field, and times of large magnetic field rotations characteristic of magnetic clouds. The first three of these signatures are phenomena that occur at some point within the ICME, but do not necessarily persist throughout the entire ICME. The large scale magnetic field rotations, distortions and enhancements, and the proton temperature depressions tend to mark more accurately the beginning and end of the ICME proper. We examine herein the reliability with which each of these markers identifies ICMEs utilizing ISEE-3 data from 1978-1980.

  14. Different “average” nuclear magnetic resonance relaxation times for correlation with fluid-flow permeability and irreducible water saturation in water-saturated sandstones

    Microsoft Academic Search

    G. C. Borgia; R. J. S. Brown; P. Fantazzini

    1997-01-01

    Fluid-flow properties of porous media, such as permeability k and irreducible water saturation Swi, can be estimated from water 1H nuclear magnetic resonance (NMR) relaxation data, but there are basic questions regarding data processing and interpretation. We found that Swi and k are better estimated if different forms of “average” relaxation time are used. NMR longitudinal relaxation data for a

  15. Interplanetary Lyman-beta emissions

    NASA Technical Reports Server (NTRS)

    Paresce, F.

    1973-01-01

    Derivation of the intensity of the diffuse hydrogen Lyman-beta glow at 1025 A which is due to resonance scattering of the solar H I 1025 A line by interstellar and interplanetary hydrogen. Two sources of neutral hydrogen are considered: the local interstellar medium interacting with the solar system, and the dust deionization of the H(+) component of the solar wind. It is shown that if the dust geometrical factor is less than or equal to five quintillionths per cm, observations of backscattered Lyman-beta radiation will provide a unique determination of the density and temperature of the local interstellar medium.

  16. Propagation of normal and faster CMEs in the interplanetary medium

    NASA Astrophysics Data System (ADS)

    Mujiber Rahman, A.; Shanmugaraju, A.; Umapathy, S.

    2013-09-01

    We have analyzed 101 Coronal Mass Ejection (CME) events and their associated interplanetary CMEs (ICMEs) and interplanetary (IP) shocks observed during the period 1997-2005 from the list given by Mujiber Rahman et al. (2012). The aim of the present work is to correlate the interplanetary parameters such as, the speeds of IP shocks and ICMEs, CME transit time and their relation with CME parameters near the Sun. Mainly, a group of 10 faster CME events (VINT > 2200 km/s) are compared with a list of 91 normal events of Manoharan et al. (2004). From the distribution diagrams of CME, ICME and IP shock speeds, we note that a large number of events tends to narrow towards the ambient (i.e., background) solar wind speed (?500 km/s) in agreement with the literature. Also, we found that the IP shock speed and the average ICME speed measured at 1 AU are well correlated. In addition, the IP shock speed is found to be slightly higher than the ICME speed. While the normal events show CME travel time in the range of ?40-80 h with a mean value of 65 h, the faster events have lower transit time with a mean value of 40 h. The effect of solar wind drag is studied using the correlation of CME acceleration with interplanetary (IP) acceleration and with other parameters of ICMEs. While the mean acceleration values of normal and faster CMEs in the LASCO FOV are 1 m/s2, 18 m/s2, they are -1.5 m/s2 and -14 m/s2 in the interplanetary medium, respectively. The relation between CME speed and IP acceleration for normal and faster events are found to agree with that of Lindsay et al. (1999) and Gopalswamy et al. (2001) except slight deviations for the faster events. It is also seen that the faster events with less travel time face higher negative acceleration (>-10 m/s2) in the interplanetary medium up to 1 AU.

  17. Geometrical Relationship Between Interplanetary Flux Ropes and Their Solar Sources

    NASA Astrophysics Data System (ADS)

    Marubashi, K.; Akiyama, S.; Yashiro, S.; Gopalswamy, N.; Cho, K.-S.; Park, Y.-D.

    2015-05-01

    We investigated the physical connection between interplanetary flux ropes (IFRs) near Earth and coronal mass ejections (CMEs) by comparing the magnetic field structures of IFRs and CME source regions. The analysis is based on the list of 54 pairs of ICMEs (interplanetary coronal mass ejections) and CMEs that are taken to be the most probable solar source events. We first attempted to identify the flux rope structure in each of the 54 ICMEs by fitting models with a cylinder and torus magnetic field geometry, both with a force-free field structure. This analysis determined the possible geometries of the identified flux ropes. Then we compared the flux rope geometries with the magnetic field structure of the solar source regions. We obtained the following results: (1) Flux rope structures are seen in 51 ICMEs out of the 54. The result implies that all ICMEs have an intrinsic flux rope structure, if the three exceptional cases are attributed to unfavorable observation conditions. (2) It is possible to find flux rope geometries with the main axis orientation close to the orientation of the magnetic polarity inversion line (PIL) in the solar source regions, the differences being less than 25°. (3) The helicity sign of an IFR is strongly controlled by the location of the solar source: flux ropes with positive (negative) helicity are associated with sources in the southern (northern) hemisphere (six exceptions were found). (4) Over two-thirds of the sources in the northern hemisphere are concentrated along PILs with orientations of 45° ± 30° (measured clockwise from the east), and over two-thirds in the southern hemisphere along PILs with orientations of 135° ± 30°, both corresponding to the Hale boundaries. These results strongly support the idea that a flux rope with the main axis parallel to the PIL erupts in a CME and that the erupted flux rope propagates through the interplanetary space with its orientation maintained and is observed as an IFR.

  18. Solar events and their influence on the interplanetary medium

    NASA Technical Reports Server (NTRS)

    Joselyn, Joann

    1987-01-01

    Aspects of a workshop on Solar events and their influence on the interplanetary medium, held in September 1986, are reviewed, the goal of which was to foster interactions among colleagues, leading to an improved understanding of the unified relationship between solar events and interplanetary disturbances. The workshop consisted of three working groups: (1) flares, eruptives, and other near-Sun activity; (2) coronal mass ejections; and (3) interplanetary events. Each group discussed topics distributed in advance. The flares-eruptives group members agreed that pre-event energy is stored in stressed/sheared magnetic fields, but could not agree that flares and other eruptive events (e.g., eruptive solar prominences) are aspects of the same physical phenomenon. In the coronal mass ejection group, general agreement was reached on the presence of prominences in CMEs, and that they have a significant three-dimensional structure. Some topics identified for further research were the aftermath of CMEs (streamer deflections, transient coronal holes, possible disconnections), identification of the leading edge of CMEs, and studies of the range and prevalence of CME mass sizes and energies.

  19. A near-IR line of Mn I as a diagnostic tool of the average magnetic energy in the solar photosphere

    E-print Network

    A. Asensio Ramos; M. J. Martinez Gonzalez; A. Lopez Ariste; J. Trujillo Bueno; M. Collados

    2006-12-14

    We report on spectropolarimetric observations of a near-IR line of Mn I located at 15262.702 A whose intensity and polarization profiles are very sensitive to the presence of hyperfine structure. A theoretical investigation of the magnetic sensitivity of this line to the magnetic field uncovers several interesting properties. The most important one is that the presence of strong Paschen-Back perturbations due to the hyperfine structure produces an intensity line profile whose shape changes according to the absolute value of the magnetic field strength. A line ratio technique is developed from the intrinsic variations of the line profile. This line ratio technique is applied to spectropolarimetric observations of the quiet solar photosphere in order to explore the probability distribution function of the magnetic field strength. Particular attention is given to the quietest area of the observed field of view, which was encircled by an enhanced network region. A detailed theoretical investigation shows that the inferred distribution yields information on the average magnetic field strength and the spatial scale at which the magnetic field is organized. A first estimation gives ~250 G for the mean field strength and a tentative value of ~0.45" for the spatial scale at which the observed magnetic field is horizontally organized.

  20. Impact angle control of interplanetary shock geoeffectiveness

    NASA Astrophysics Data System (ADS)

    Oliveira, D. M.; Raeder, J.

    2014-10-01

    We use Open Geospace General Circulation Model global MHD simulations to study the nightside magnetospheric, magnetotail, and ionospheric responses to interplanetary (IP) fast forward shocks. Three cases are presented in this study: two inclined oblique shocks, hereafter IOS-1 and IOS-2, where the latter has a Mach number twice stronger than the former. Both shocks have impact angles of 30° in relation to the Sun-Earth line. Lastly, we choose a frontal perpendicular shock, FPS, whose shock normal is along the Sun-Earth line, with the same Mach number as IOS-1. We find that, in the IOS-1 case, due to the north-south asymmetry, the magnetotail is deflected southward, leading to a mild compression. The geomagnetic activity observed in the nightside ionosphere is then weak. On the other hand, in the head-on case, the FPS compresses the magnetotail from both sides symmetrically. This compression triggers a substorm allowing a larger amount of stored energy in the magnetotail to be released to the nightside ionosphere, resulting in stronger geomagnetic activity. By comparing IOS-2 and FPS, we find that, despite the IOS-2 having a larger Mach number, the FPS leads to a larger geomagnetic response in the nightside ionosphere. As a result, we conclude that IP shocks with similar upstream conditions, such as magnetic field, speed, density, and Mach number, can have different geoeffectiveness, depending on their shock normal orientation.

  1. Infrared emission from interplanetary dust

    NASA Astrophysics Data System (ADS)

    Temi, P.; de Bernardis, P.; Masi, S.; Moreno, G.; Salama, A.

    1989-02-01

    Standard models of the interplanetary dust emission fail to account satisfactorily for IR observations. A new model of the dust, based on very simple assumptions on the grain structure (spherical and homogeneous) and chemical composition (astronomical silicates, graphite, blackbodies) is developed. Updated values of the refractive indexes have been included in the analysis. The predictions of the model (absolute values of the fluxes, spectral shape, elongation dependence of the emission) have then been compared with all the available IR observations performed by the ARGO (balloon-borne experiment by University of Rome), AFGL and Zodiacal Infrared Project (ZIP) (rocket experiments by Air Force Geophysics Laboratory, Bedford, Mass.), and IRAS satellite. Good agreement is found when homogeneous data sets from single experiments (e.g., ZIP and ARGO) are considered separately.

  2. Shielding Structures for Interplanetary Human Mission

    NASA Astrophysics Data System (ADS)

    Tracino, Emanuele; Lobascio, Cesare

    2012-07-01

    Since the end of Apollo missions, human spaceflight has been limited to the Low Earth Orbit (LEO), inside the protective magnetic field of the Earth, because astronauts are, to the largest degree, protected from the harsh radiation environment of the interplanetary space. However, this situation will change when space exploration missions beyond LEO will become the real challenge of the human exploration program. The feasibility of these missions in the solar system is thus strongly connected to the capability to mitigate the radiation-induced biological effects on the crew during the journey and the permanence on the intended planet surface. Inside the International Space Station (ISS), the volumes in which the crew spends most of the time, namely the crew quarters are the only parts that implement dedicated additional radiation shielding made of polyethylene tiles designed for mitigating SPE effects. Furthermore, specific radiation shielding materials are often added to the described configuration to shield crew quarters or the entire habitat example of these materials are polyethylene, liquid hydrogen, etc. but, increasing the size of the exploration vehicles to bring humans beyond LEO, and without the magnetosphere protection, such approach is unsustainable because the mass involved is a huge limiting factor with the actual launcher engine technology. Moreover, shielding against GCR with materials that have a low probability of nuclear interactions and in parallel a high ionizing energy loss is not always the best solution. In particular there is the risk to increase the LET of ions arriving at the spacecraft shell, increasing their Radio-Biological Effectiveness. Besides, the production of secondary nuclei by projectile and target fragmentation is an important issue when performing an engineering assessment of materials to be used for radiation shielding. The goal of this work is to analyze different shielding solutions to increase as much as possible the radiation shielding power of the interplanetary habitat structures, like the spacecraft shell, minimizing the amount of mass used. From the radiation protection point of view the spacecraft shell is an interesting spacecraft system because it surrounds almost homogeneously all the habitat and it is typically composed by the Micrometeorites and Debris Protection Systems (MDPS), the Multilayer Insulation (MLI) for thermal control purposes, and the primary structure that offers the pressure containment functionality. Nevertheless, the spacecraft internal outfitting is important to evaluate the different shielded areas in the habitat. Using Geant4 Monte Carlo simulations toolkit through GRAS (Geant4 Radiation Analysis for Space) tool, different spacecraft structures will be analyzed for their shielding behavior in terms of fluxes, dose reduction and radiation quality, and for their implementation in a real pressurized module. Effects on astronauts and electronic equipments will be also assessed with respect to the standard aluminum structures.

  3. The interaction of a magnetic cloud with the Earth - Ionospheric convection in the Northern and Southern Hemispheres for a wide range of quasi-steady interplanetary magnetic field conditions

    NASA Technical Reports Server (NTRS)

    Freeman, M. P.; Farrugia, C. J.; Burlaga, L. F.; Hairston, M. R.; Greenspan, M. E.; Ruohoniemi, J. M.; Lepping, R. P.

    1993-01-01

    Observations are presented of the ionospheric convection in cross sections of the polar cap and auroral zone as part of the study of the interaction of the Earth's magnetosphere with the magnetic cloud of January 13-15, 1988. For strongly northward IMF, the convection in the Southern Hemisphere is characterized by a two-cell convection pattern comfined to high latitudes with sunward flow over the pole. The strength of the flows is comparable to that later seen under southward IMF. Superimposed on this convection pattern there are clear dawn-dusk asymmetries associated with a one-cell convection component whose sense depends on the polarity of the magnetic cloud's large east-west magnetic field component. When the cloud's magnetic field turns southward, the convection is characterized by a two-cell pattern extending to lower latitude with antisunward flow over the pole. There is no evident interhemispheric difference in the structure and strength of the convection. Superimposed dawn-dusk asymmetries in the flow patterns are observed which are only in part attributable to the east-west component of the magnetic field.

  4. On the anisotropies of interplanetary low-energy proton intensities

    NASA Technical Reports Server (NTRS)

    Pesses, M. E.; Sarris, E. T.

    1975-01-01

    Explorer 35 proton anisotropic flux data (proton energies between 0.3 and 6.3 MeV) and simultaneous magnetic field measurements were used to supply more information on the propagation characteristics of low-energy protons in the interplanetary medium. During the rising portions of the proton events, large field-aligned anisotropies were observed. During the decaying part of the proton events, either radial anisotropy or near-isotropy was noticed. In addition, certain observations made during the decaying part of the proton events revealed anisotropies deviating significantly from the radial direction.

  5. Interplanetary medium data book, supplement 4, 1985-1988

    NASA Technical Reports Server (NTRS)

    King, Joseph H.

    1989-01-01

    An extension is presented of the series of Interplanetary Medium Data Books and supplements which have been issued by the National Space Science Data Center since 1977. This volume contains solar wind magnetic field (IMF) and plasma data from the IMP 8 spacecraft for 1985 to 1988, and 1985 IMF data from the Czechoslovakian Soviet Prognoz 10 spacecraft. The normalization of the MIT plasma density and temperature, which has been discussed at length in previous volumes, is implemented as before, using the same normalization constants for 1985 to 1988 data as for the earlier data.

  6. The Ring Current Response to Solar and Interplanetary Storm Drivers

    NASA Astrophysics Data System (ADS)

    Mouikis, C.; Kistler, L. M.; Bingham, S.; Kronberg, E. A.; Gkioulidou, M.; Huang, C. L.; Farrugia, C. J.

    2014-12-01

    The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), corotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure, in turn, change the global magnetic field, controlling the transport of the radiation belts. To quantitatively determine the field changes during a storm throughout the magnetosphere, it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. Because the measured ring current energy spectra depend not only on local processes, but also on the history of the ions along their entire drift path, measurements of ring current energy spectra at two or more locations can be used to strongly constrain the time dependent magnetic and electric fields. In this study we use data predominantly from the Cluster and the Van Allen Probes, covering more than a full solar cycle (from 2001 to 2014). For the period 2001-2012, the Cluster CODIF and RAPID measurements of the inner magnetosphere are the primary data set used to monitor the storm time ring current variability. After 2012, the Cluster data set complements the data from the Van Allen Probes HOPE and RBSPICE instruments, providing additional measurements from different MLT and L shells. Selected storms from this periods, allow us to study the ring current dynamics and pressure changes, as a function of L shell, magnetic local time, and the type of interplanetary disturbances.

  7. Radial speeds of an extreme Interplanetary Coronal Mass Ejection and its shock

    NASA Astrophysics Data System (ADS)

    Kajdic, Primoz; Gonzalez Esparza, Juan-Americo; Aguilar Rodriguez, Ernesto; Corona-Romero, Pedro

    2014-05-01

    During the current solar cycle, our star has been less active when compared to the previous cycles. This is reflected in lower sunspot numbers but also in a lesser number of observed Coronal Mass Ejections (CME) and their interplanetary counterparts (ICME). However, lower solar activity does not necessarily mean less powerful events. Here we study propagation of an ICME that was detected by the STEREO A spacecraft on July 23, 2012. This was the most extreme event observed since the beginning of the space era. The magnetic field inside this ICME reached maximum value of 109 nT. The average ICME transit speed at 1 AU was 1910 kms-1, while its average speed on the way to 1 AU was 2125 kms-1. The ICME drove a fast-mode shock that preceded it. At the shock the plasma speed rose to 2250 kms-1. We study the propagation of the shock and of the ICME itself by using the radio data from the STEREO WAVES (S/WAVES) onboard of the STEREO A spacecraft. Since the shock emitted Type II radio emission, we are able to reconstruct its speed at various heliocentric distances. We also compare the measured velocities and arrival times of the shock and of the ejecta with predictions from numerical models.

  8. Ogo 5 Observations of Upstream Waves in the Interplanetary Medium: Discrete Wave Packets

    Microsoft Academic Search

    C. T. Russell; D. D. Childers; P. J. Coleman

    1971-01-01

    One class of waves observed in the interplanetary medium within several earth radii of the earth's bow shock consists of discrete wave packets with amplitudes that are a significant fraction of the background magnetic field. In the spacecraft frame, these wave packets have periods of about 2.5 sec, grow rapidly in time and decay more slowly, and are left-handed with

  9. Interplanetary coronal mass ejections in the near-Earth solar wind during 1996-2002

    Microsoft Academic Search

    H. V. Cane; I. G. Richardson

    2003-01-01

    We summarize the occurrence of interplanetary coronal mass ejections (ICMEs) in the near-Earth solar wind during 1996-2002, corresponding to the increasing and maximum phases of solar cycle 23. In particular, we give a detailed list of such events. This list, based on in situ observations, is not confined to subsets of ICMEs, such as ``magnetic clouds'' or those preceded by

  10. Operating CFDP in the Interplanetary Internet

    NASA Technical Reports Server (NTRS)

    Burleigh, S.

    2002-01-01

    This paper examines the design elements of CCSDS File Delivery Protocol and Interplanetary Internet technologies that will simplify their integration and discusses the resulting new capabilities, such as efficient transmission of large files via multiple relay satellites operating in parallel.

  11. Volatiles in interplanetary dust particles: a review.

    PubMed

    Gibson, E K

    1992-03-25

    The paper presents a review of the volatiles found within interplanetary dust particles. These particles have been shown to represent primitive material from early in the solar system's formation and also may contain records of stellar processes. The organogenic elements (i.e., H, C, N, O, and S) are among the most abundant elements in our solar system, and their abundances, distributions, and isotopic compositions in early solar system materials permit workers to better understand the processes operating early in the evolutionary history of solar system materials. Interplanetary dust particles have a range of elemental compositions, but generally they have been shown to be similar to carbonaceous chondrites, the solar photosphere, Comet Halley's chondritic cores, and matrix materials of chondritic chondrites. Recovery and analysis of interplanetary dust particles have opened new opportunities for analysis of primitive materials, although interplanetary dust particles represent major challenges to the analyst because of their small size. PMID:11537855

  12. TPS Ablator Technologies for Interplanetary Spacecraft

    NASA Technical Reports Server (NTRS)

    Curry, Donald M.

    2004-01-01

    This slide presentation reviews the status of Thermal Protection System (TPS) Ablator technologies and the preparation for use in interplanetary spacecraft. NASA does not have adequate TPS ablatives and sufficient selection for planned missions. It includes a comparison of shuttle and interplanetary TPS requirements, the status of mainline TPS charring ablator materials, a summary of JSC SBIR accomplishments in developing advanced charring ablators and the benefits of SBIR Ablator/fabrication technology.

  13. Plasma and energetic particle structure upstream of a quasi-parallel interplanetary shock

    SciTech Connect

    Kennel, C.F.; Scarf, F.L.; Coroniti, F.V.; Russell, C.T.; Wenzel, K.; Sanderson, T.R.; Van Nes, P.; Feldman, W.C.; Parks, G.K.; Smith, E.J.; Tsurutani, B.T.; Mozer, F.S.; Temerin, M.; Anderson, R.R.; Scudder, J.D.; Scholer, M.

    1984-07-01

    This paper assembles ISEE 1, 2, and 3 observations of the interplanetary magnetic and electric fields, plasma, magnetohydrodynamic waves, electromagnetic and electrostatic plasma waves, 1- to 6-keV protons and electrons, and >30-keV/Q ions for the interplanetary shock of November 12, 1978. The shock was high speed (640 km s/sup -1/), supercritical, quasi-parallel, and an efficient accelerator of energetic protons. The flux of >35-keV protons increased by a factor of 15 in the last 45 min and 270 R/sub E/ before shock encounter. The >10-keV proton energy density approached that of the magnetic field and thermal plasma upstream of the shock. The shock was inside a closed magnetic structure that was connected at both ends to the shock. The intensity of ion acoustic and low-frequency MHD waves increased inside the closed magnetic bubble.

  14. Particle Acceleration at Interplanetary Shocks

    E-print Network

    Baring, Matthew G

    2008-01-01

    The acceleration of interstellar pick-up ions as well as solar wind species has been observed at a multitude of interplanetary (IP) shocks by different spacecraft. This paper expands upon previous work modeling the phase space distributions of accelerated ions associated with the shock event encountered on day 292 of 1991 by the Ulysses mission at 4.5 AU. A kinetic Monte Carlo simulation is employed here to model the diffusive acceleration process. This exposition presents recent developments pertaining to the incorporation into the simulation of the diffusive characteristics incurred by field line wandering (FLW), according to the work of Giacalone and Jokipii. For a pure field-line wandering construct, it is determined that the upstream spatial ramp scales are too short to accommodate the HI-SCALE flux increases for 200 keV protons, and that the distribution function for H+ somewhat underpopulates the combined SWICS/HI-SCALE spectra at the shock. This contrasts our earlier theory/data comparison where it wa...

  15. Quaternion Averaging

    NASA Technical Reports Server (NTRS)

    Markley, F. Landis; Cheng, Yang; Crassidis, John L.; Oshman, Yaakov

    2007-01-01

    Many applications require an algorithm that averages quaternions in an optimal manner. For example, when combining the quaternion outputs of multiple star trackers having this output capability, it is desirable to properly average the quaternions without recomputing the attitude from the the raw star tracker data. Other applications requiring some sort of optimal quaternion averaging include particle filtering and multiple-model adaptive estimation, where weighted quaternions are used to determine the quaternion estimate. For spacecraft attitude estimation applications, derives an optimal averaging scheme to compute the average of a set of weighted attitude matrices using the singular value decomposition method. Focusing on a 4-dimensional quaternion Gaussian distribution on the unit hypersphere, provides an approach to computing the average quaternion by minimizing a quaternion cost function that is equivalent to the attitude matrix cost function Motivated by and extending its results, this Note derives an algorithm that deterniines an optimal average quaternion from a set of scalar- or matrix-weighted quaternions. Rirthermore, a sufficient condition for the uniqueness of the average quaternion, and the equivalence of the mininiization problem, stated herein, to maximum likelihood estimation, are shown.

  16. INTERPLANETARY SHOCKS LACKING TYPE II RADIO BURSTS

    SciTech Connect

    Gopalswamy, N.; Kaiser, M. L. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Xie, H.; Maekelae, P.; Akiyama, S. [Catholic University of America, Washington, DC 20064 (United States); Yashiro, S. [Interferometrics, Herndon, VA 20170 (United States); Howard, R. A. [Naval Research Laboratory, Washington, DC 20375 (United States); Bougeret, J.-L., E-mail: nat.gopalswamy@nasa.go [Paris Observatory, Meudon (France)

    2010-02-20

    We report on the radio-emission characteristics of 222 interplanetary (IP) shocks detected by spacecraft at Sun-Earth L1 during solar cycle 23 (1996 to 2006, inclusive). A surprisingly large fraction of the IP shocks ({approx}34%) was radio quiet (RQ; i.e., the shocks lacked type II radio bursts). We examined the properties of coronal mass ejections (CMEs) and soft X-ray flares associated with such RQ shocks and compared them with those of the radio-loud (RL) shocks. The CMEs associated with the RQ shocks were generally slow (average speed {approx}535 km s{sup -1}) and only {approx}40% of the CMEs were halos. The corresponding numbers for CMEs associated with RL shocks were 1237 km s{sup -1} and 72%, respectively. Thus, the CME kinetic energy seems to be the deciding factor in the radio-emission properties of shocks. The lower kinetic energy of CMEs associated with RQ shocks is also suggested by the lower peak soft X-ray flux of the associated flares (C3.4 versus M4.7 for RL shocks). CMEs associated with RQ CMEs were generally accelerating within the coronagraph field of view (average acceleration {approx}+6.8 m s{sup -2}), while those associated with RL shocks were decelerating (average acceleration {approx}-3.5 m s{sup -2}). This suggests that many of the RQ shocks formed at large distances from the Sun, typically beyond 10 Rs, consistent with the absence of metric and decameter-hectometric (DH) type II radio bursts. A small fraction of RL shocks had type II radio emission solely in the kilometric (km) wavelength domain. Interestingly, the kinematics of the CMEs associated with the km type II bursts is similar to those of RQ shocks, except that the former are slightly more energetic. Comparison of the shock Mach numbers at 1 AU shows that the RQ shocks are mostly subcritical, suggesting that they were not efficient in accelerating electrons. The Mach number values also indicate that most of these are quasi-perpendicular shocks. The radio-quietness is predominant in the rise phase and decreases through the maximum and declining phases of solar cycle 23. About 18% of the IP shocks do not have discernible ejecta behind them. These shocks are due to CMEs moving at large angles from the Sun-Earth line and hence are not blast waves. The solar sources of the shock-driving CMEs follow the sunspot butterfly diagram, consistent with the higher-energy requirement for driving shocks.

  17. Interplanetary Shocks Lacking Type 2 Radio Bursts

    NASA Technical Reports Server (NTRS)

    Gopalswamy, N.; Xie, H.; Maekela, P.; Akiyama, S.; Yashiro, S.; Kaiser, M. L.; Howard, R. A.; Bougeret, J.-L.

    2010-01-01

    We report on the radio-emission characteristics of 222 interplanetary (IP) shocks detected by spacecraft at Sun-Earth L1 during solar cycle 23 (1996 to 2006, inclusive). A surprisingly large fraction of the IP shocks (approximately 34%) was radio quiet (RQ; i.e., the shocks lacked type II radio bursts). We examined the properties of coronal mass ejections (CMEs) and soft X-ray flares associated with such RQ shocks and compared them with those of the radio-loud (RL) shocks. The CMEs associated with the RQ shocks were generally slow (average speed approximately 535 km/s) and only approximately 40% of the CMEs were halos. The corresponding numbers for CMEs associated with RL shocks were 1237 km/s and 72%, respectively. Thus, the CME kinetic energy seems to be the deciding factor in the radio-emission properties of shocks. The lower kinetic energy of CMEs associated with RQ shocks is also suggested by the lower peak soft X-ray flux of the associated flares (C3.4 versus M4.7 for RL shocks). CMEs associated with RQ CMEs were generally accelerating within the coronagraph field of view (average acceleration approximately +6.8 m/s (exp 2)), while those associated with RL shocks were decelerating (average acceleration approximately 3.5 m/s (exp 2)). This suggests that many of the RQ shocks formed at large distances from the Sun, typically beyond 10 Rs, consistent with the absence of metric and decameter-hectometric (DH) type II radio bursts. A small fraction of RL shocks had type II radio emission solely in the kilometric (km) wavelength domain. Interestingly, the kinematics of the CMEs associated with the km type II bursts is similar to those of RQ shocks, except that the former are slightly more energetic. Comparison of the shock Mach numbers at 1 AU shows that the RQ shocks are mostly subcritical, suggesting that they were not efficient in accelerating electrons. The Mach number values also indicate that most of these are quasi-perpendicular shocks. The radio-quietness is predominant in the rise phase and decreases through the maximum and declining phases of solar cycle 23. About 18% of the IP shocks do not have discernible ejecta behind them. These shocks are due to CMEs moving at large angles from the Sun-Earth line and hence are not blast waves. The solar sources of the shock-driving CMEs follow the sunspot butterfly diagram, consistent with the higher-energy requirement for driving shocks.

  18. LDEF Interplanetary Dust Experiment (IDE) results

    NASA Technical Reports Server (NTRS)

    Oliver, John P.; Singer, S. F.; Weinberg, J. L.; Simon, C. G.; Cooke, W. J.; Kassel, P. C.; Kinard, W. H.; Mulholland, J. D.; Wortman, J. J.

    1995-01-01

    The Interplanetary Dust Experiment (IDE) provided high time resolution detection of microparticle impacts on the Long Duration Exposure Facility satellite. Particles, in the diameter range from 0.2 microns to several hundred microns, were detected impacting on six orthogonal surfaces of the gravity-gradient stabilized LDEF spacecraft. The total sensitive surface area was about one square meter, distributed between LDEF rows 3 (Wake or West), 6 (South), 9 (Ram or East), 12 (North), as well as the Space and Earth ends of LDEF. The time of each impact is known to an accuracy that corresponds to better than one degree in orbital longitude. Because LDEF was gravity-gradient stabilized and magnetically damped, the direction of the normal to each detector panel is precisely known for each impact. The 11 1/2 month tape-recorded data set represents the most extensive record gathered of the number, orbital location, and incidence direction for microparticle impacts in low Earth orbit. Perhaps the most striking result from IDE was the discovery that microparticle impacts, especially on the Ram, South, and North surfaces, were highly episodic. Most such impacts occurred in localized regions of the orbit for dozens or even hundreds of orbits in what we have termed Multiple Orbit Event Sequences (MOES). In addition, more than a dozen intense and short-lived 'spikes' were seen in which impact fluxes exceeded the background by several orders of magnitude. These events were distributed in a highly non-uniform fashion in time and terrestrial longitude and latitude.

  19. Intensity of tropospheric circulation associated with solar magnetic sector boundary transits

    NASA Technical Reports Server (NTRS)

    Wilcox, J. M.; Scherrer, P. H.; Svalgaard, L.

    1979-01-01

    The fractional decrease in the vorticity area index associated with transits past the earth of interplanetary magnetic sector boundaries increase as the value of vorticity used to compute the index increases. This suggests that after the boundary transit there is an approximately uniform reduction in all the values of vorticity that are not less than 0.00020/sec. In low altitudes and large absolute vorticities not less than 0.00020/sec the average change in the vorticity area index approaches 50%.

  20. International Launch Vehicle Selection for Interplanetary Travel

    NASA Technical Reports Server (NTRS)

    Ferrone, Kristine; Nguyen, Lori T.

    2010-01-01

    In developing a mission strategy for interplanetary travel, the first step is to consider launch capabilities which provide the basis for fundamental parameters of the mission. This investigation focuses on the numerous launch vehicles of various characteristics available and in development internationally with respect to upmass, launch site, payload shroud size, fuel type, cost, and launch frequency. This presentation will describe launch vehicles available and in development worldwide, then carefully detail a selection process for choosing appropriate vehicles for interplanetary missions focusing on international collaboration, risk management, and minimization of cost. The vehicles that fit the established criteria will be discussed in detail with emphasis on the specifications and limitations related to interplanetary travel. The final menu of options will include recommendations for overall mission design and strategy.

  1. Development of shocks waves in the solar corona and the interplanetary space

    NASA Astrophysics Data System (ADS)

    Mann, G.; Klassen, A.; Aurass, H.; Classen, H. T.

    2003-09-01

    At the Sun shock waves are produced either by flares or by coronal mass ejections and are regarded to be the source of solar energetic particle events. The propagation of a disturbance away from an active region through the corona into the interplanetary space is considered by evaluating the radial behaviour of the Alfvén speed. The magnetic field of an active region is modelled by a magnetic dipole superimposed on that of the quiet Sun. Such a magnetic field structure leads to a local mimimum of the Alfvén speed in the middle of the corona and a maximum of 740 km/s at a radial distance of 6 solar radii from the center of the Sun. The occurrence of these extrema of the Alfvén speed has consequences for the formation and development of shock waves in the corona and interplanetary space.

  2. LDEF Interplanetary Dust Experiment - Techniques for identification and study of long-lived orbital debris clouds

    NASA Technical Reports Server (NTRS)

    Singer, S. F.; Oliver, J. P.; Weinberg, J. L.; Cooke, W. J.; Montague, N. L.; Mulholland, J. D.; Wortman, J. J.; Kassel, P. C.; Kinard, W. H.

    1991-01-01

    The Long Duration Exposure Facility (LDEF) is a 12-sided, 4.3-m-diameter, 9.1-m-long cylinder designed and built by NASA Langley to carry experiments for extended periods in space. The LDEF was first placed in orbit by the Shuttle Challenger on 7 April 1984 and recovered by the Shuttle Columbia in January 1990, only days before it was expected to burn up in the earth's atmosphere. The Interplanetary Dust Experiment (IDE) was designed to detect impacts of extra-terrestrial particles and orbital debris. The IDE detectors (which covered about 1 sq m of the surface of LDEF) were sensitive to particles ranging in size from about 0.2 to 100 microns. Data were recorded for 11.5 months before the supply of magnetic tape was exhausted. Examination of the LDEF IDE dataset shows that impacts often occurred in 'bursts', during which numerous impacts occurred in a short time (typically 3-5 min) at a rate much greater than the average impact rate. In several cases, such events reoccurred each time the LDEF returned to the same point in its orbit. Such multi-orbit event sequences were found to extend for as many as 25 or more orbits.

  3. The solar/interplanetary event of 14 April 1994 observed by Yohkoh/SXT

    NASA Technical Reports Server (NTRS)

    Alexander, D.; Harvey, K. L.; Hudson, H. S.; Hoeksema, J. T.; Zhao, X.

    1995-01-01

    The polar crown event of April 14 1994 is one of the largest scale eruptive events observed by the Yohkoh/SXT. Associated with the formation of an arcade of soft X-ray loops at the Sun was the detection of an interplanetary forward/reverse shock event by the Ulysses spacecraft some 4-7 days later. The relationship between the coronal and interplanetary signatures of these events is important if we are to address fully the initialization and consequent acceleration of interplanetary phenomena, such as CMEs and counter-streaming electrons, originating at the Sun. From detailed analysis of the energetics of the arcade formed during the eruption of April 14 1994, we find peak temperatures and emission measures of approximately 5MK and approximately 10(exp 48)cm(exp -3) respectively. The total thermal content of the arcade loop structure observed in soft X-rays is calculated to be some 5 x 10(exp 29) ergs. The development of these parameters as the event proceeds and their relationship to the dynamics of the eruption are investigated. Although spanning a longitudinal range of some 150 degrees the April 14 event displayed the typical helmet streamer structure normally associated with coronal mass ejections These helmet streamers are thought to be related to the global solar magnetic field through the heliospheric current sheet (HCS). The arcade formation, together with the eruption of material into interplanetary space, signifies a large-scale reconfiguration of the coronal magnetic field. We examine the effects of the formation of such a coronal arcade structure on the HCS and discuss the dynamics involved with the passage of a large scale disturbance through the interplanetary magnetic field.

  4. Mars Science Laboratory Interplanetary Navigation Performance

    NASA Technical Reports Server (NTRS)

    Martin-Mur, Tomas J.; Kruizinga, Gerhard; Wong, Mau

    2013-01-01

    The Mars Science Laboratory spacecraft, carrying the Curiosity rover to Mars, hit the top of the Martian atmosphere just 200 meters from where it had been predicted more than six days earlier, and 2.6 million kilometers away. This un-expected level of accuracy was achieved by a combination of factors including: spacecraft performance, tracking data processing, dynamical modeling choices, and navigation filter setup. This paper will describe our best understanding of what were the factors that contributed to this excellent interplanetary trajectory prediction performance. The accurate interplanetary navigation contributed to the very precise landing performance, and to the overall success of the mission.

  5. Radiation exposure and Mission Strategies for Interplanetary Manned Missions (REMSIM)

    Microsoft Academic Search

    C. Cougnet; N. B. Crosby; S. Eckersley; C. Foullon; V. Guarnieri; S. Guatelli; D. Heynderickx; A. Holmes-Siedle; C. Lobascio; S. Masiello; P. Nieminen; G. Parisi; P. Parodi; M. A. Perino; M. G. Pia; R. Rampini; P. Spillantini; V. Tamburini; E. Tracino

    2004-01-01

    .  Cosmic radiation is an important problem for human interplanetary missions. The “Radiation Exposure and Mission Strategies for Interplanetary Manned Missions–REMSIM” study is summarised here. They are related to current strategies and countermeasures to ensure the protection of astronauts from radiation during interplanetary missions, with specific reference to: radiation environment and its variability; radiation effects on the crew; transfer trajectories and

  6. Performance of a Bounce-Averaged Global Model of Super-Thermal Electron Transport in the Earth's Magnetic Field

    NASA Technical Reports Server (NTRS)

    McGuire, Tim

    1998-01-01

    In this paper, we report the results of our recent research on the application of a multiprocessor Cray T916 supercomputer in modeling super-thermal electron transport in the earth's magnetic field. In general, this mathematical model requires numerical solution of a system of partial differential equations. The code we use for this model is moderately vectorized. By using Amdahl's Law for vector processors, it can be verified that the code is about 60% vectorized on a Cray computer. Speedup factors on the order of 2.5 were obtained compared to the unvectorized code. In the following sections, we discuss the methodology of improving the code. In addition to our goal of optimizing the code for solution on the Cray computer, we had the goal of scalability in mind. Scalability combines the concepts of portabilty with near-linear speedup. Specifically, a scalable program is one whose performance is portable across many different architectures with differing numbers of processors for many different problem sizes. Though we have access to a Cray at this time, the goal was to also have code which would run well on a variety of architectures.

  7. Average configuration of the distant (less than 220-earth-radii) magnetotail - Initial ISEE-3 magnetic field results

    NASA Technical Reports Server (NTRS)

    Slavin, J. A.; Tsurutani, B. T.; Smith, E. J.; Jones, D. E.; Sibeck, D. G.

    1983-01-01

    Magnetic field measurements from the first two passes of the ISEE-3 GEOTAIL Mission have been used to study the structure of the trans-lunar tail. Good agreement was found between the ISEE-3 magnetopause crossings and the Explorer 33, 35 model of Howe and Binsack (1972). Neutral sheet location was well ordered by the hinged current sheet models based upon near earth measurements. Between X = -20 and -120 earth radii the radius of the tail increases by about 30 percent while the lobe field strength decreases by approximately 60 percent. Beyond X = -100 to -1200 earth radii the tail diameter and lobe field magnitude become nearly constant at terminal values of approximately 60 earth radii and 9 nT, respectively. The distance at which the tail was observed to cease flaring, 100-120 earth radii, is in close agreement with the predictions of the analytic tail model of Coroniti and Kennel (1972). Overall, the findings of this study suggest that the magnetotail retains much of its near earth structure out to X = -220 earth radii.

  8. Interplanetary approach optical navigation with applications

    Microsoft Academic Search

    N. Jerath

    1976-01-01

    The use of optical data from onboard television cameras for the navigation of interplanetary spacecraft during the planet approach phase is investigated. Three optical data types are investigated: (1) the planet limb with auxiliary celestial references; (2) the satellite-star; and (3) the planet star two camera methods. Analysis and modelling issues related to the nature and information content of the

  9. INTERPLANETARY TYPE III RADIOBURSTS AND RELATIVISTIC ELECTRONS

    E-print Network

    Steinhoff, Heinz-Jürgen

    INTERPLANETARY TYPE III RADIOBURSTS AND RELATIVISTIC ELECTRONS S. HUCKE*, M.-B. KALLENRODE, and compared the antenna temperature TA of the 466 kHz type III bursts measured by the SBH instrument on ISEE 3 with the fluxes of ~ 0.5 MeV electrons measured by HELIOS. For 51 flare-associated kilometric type III bursts

  10. Mars Odyssey Joins the Third Interplanetary Network

    Microsoft Academic Search

    K. Hurley; I. Mitrofanov; A. Kozyrev; M. Litvak; A. Sanin V. Grinkov; S. Charyshnikov; W. Boynton; C. Fellows; K. Harshman; D. Hamara; C. Shinohara; R. Starr; T. Cline

    2006-01-01

    The Mars Odyssey spacecraft carries two experiments that are capable of detecting cosmic gamma-ray bursts and soft gamma repeaters. Since 2001 April they have detected over 275 bursts and, in conjunction with the other spacecraft of the interplanetary network, localized many of them rapidly and precisely enough to allow sensitive multiwavelength counterpart searches. We present the Mars Odyssey mission and

  11. Apollo and the Space Race! Interplanetary Travel!

    E-print Network

    Stengel, Robert F.

    Seminar 6! Apollo and the Space Race! Interplanetary Travel! FRS 104, Princeton University! Robert" !! Project Rover, 1960s "" !! Nuclear rockets" !! High specific impulse" !! Safety concerns" !! Atmospheric to image makers" !! Apollo: Greatest peace-time commitment by Congress in history" !! McNamara: Strict

  12. Interplanetary monitoring platform engineering history and achievements

    NASA Technical Reports Server (NTRS)

    Butler, P. M.

    1980-01-01

    In the fall of 1979, last of ten Interplanetary Monitoring Platform Satellite (IMP) missions ended a ten year series of flights dedicated to obtaining new knowledge of the radiation effects in outer space and of solar phenomena during a period of maximum solar flare activity. The technological achievements and scientific accomplishments from the IMP program are described.

  13. The Interplanetary GRB Network: A Status Report

    Microsoft Academic Search

    T. L. Cline; K. Hurley; J. Laros; E. Mazets; S. Golenetskii; J. Trombka; S. Barthelmy; M. Feroci; F. Frontera

    2000-01-01

    Interplanetary spacecraft have been used with orbiting satellites to precisely localize gamma ray transients for nearly 25 years, making possible both early GRB and SGR discoveries and enabling a number of recent GRB-associated afterglow observations. This technique was pursued by the creative modifications of experiments generally planned with other goals, an existential mode at best. The latest achievement is the

  14. Average Names

    NSDL National Science Digital Library

    2014-09-19

    In this activity, learners compare the number of letters in the names of the people in their families or group of friends. Learners write out the names in graph paper, with one letter in each square, and cut out the names. Learners sort the names from shortest to longest and then find the average length of the names by cutting and scrambling up the letters. This activity guide contains sample questions to ask, literary connections, extensions, and alignment to local and national standards.

  15. Differences in the quasi-biennial oscillation and quasi-triennial oscillation characteristics of the solar, interplanetary, and terrestrial parameters

    NASA Astrophysics Data System (ADS)

    Kane, R. P.

    2005-01-01

    The 12-month running means (12 m) and the parameter (12-36 m) representing the quasi-biennial oscillation (QBO) and quasi-triennial oscillation (QTO) were examined and spectrally analyzed for several solar, interplanetary, and terrestrial parameters. Solar indices (including solar open magnetic flux in solar latitudes <45°) had a QBO in the form of double peaks separated by ˜2-3 years during sunspot maximum years and smaller waves in other phases of the sunspot cycle. In the interplanetary space a similar structure was seen only in interplanetary total magnetic field B. Interplanetary N and V had long-term variations different from solar variations. For ground-level solar proton events as well as all solar proton events observed in satellites and for geomagnetic Dst and Ap, a partial relationship with V (solar wind) is indicated. Cosmic rays observed on Earth seem to have peaks matching with those of solar indices. In the terrestrial atmosphere, stratospheric wind has a predominant QBO similar to solar indices, but the sequence is more uniform than that of the QBO of solar indices. The El Niño-Southern Oscillation (ENSO) indices (T-D) and Pacific sea surface temperature have overall characteristics different from those of stratospheric winds or solar indices. Thus there seem to be probably at least four QBO-QTO regimes, namely those of (1) solar indices at low solar latitudes, (2) interplanetary parameters near Earth, (3) terrestrial low-latitude stratospheric zonal winds, and (4) terrestrial ENSO phenomena.

  16. Extreme interplanetary rotational discontinuities at 1 AU

    NASA Astrophysics Data System (ADS)

    Lepping, R. P.; Wu, C.-C.

    2005-11-01

    This study is concerned with the identification and description of a special subset of four Wind interplanetary rotational discontinuities (from an earlier study of 134 directional discontinuities by Lepping et al. (2003)) with some "extreme" characteristics, in the sense that every case has (1) an almost planar current sheet surface, (2) a very large discontinuity angle (?), (3) at least moderately strong normal field components (>0.8 nT), and (4) the overall set has a very broad range of transition layer thicknesses, with one being as thick as 50 RE and another at the other extreme being 1.6 RE, most being much thicker than are usually studied. Each example has a well-determined surface normal (n) according to minimum variance analysis and corroborated via time delay checking of the discontinuity with observations at IMP 8 by employing the local surface planarity. From the variance analyses, most of these cases had unusually large ratios of intermediate-to-minimum eigenvalues (?I/?min), being on average 32 for three cases (with a fourth being much larger), indicating compact current sheet transition zones, another (the fifth) extreme property. For many years there has been a controversy as to the relative distribution of rotational (RDs) to tangential discontinuities (TDs) in the solar wind at 1 AU (and elsewhere, such as between the Sun and Earth), even to the point where some authors have suggested that RDs with large ?Bn?s are probably not generated or, if generated, are unstable and therefore very rare. Some of this disagreement apparently has been due to the different selection criteria used, e.g., some allowed eigenvalue ratios (?I/?min) to be almost an order of magnitude lower than 32 in estimating n, usually introducing unacceptable error in n and therefore also in ?Bn?. However, we suggest that RDs may not be so rare at 1 AU, but good quality cases (where ?Bn? confidently exceeds the error in ?Bn?) appear to be uncommon, and further, cases of large ?Bn? may indeed be rare. Finally, the issue of estimating the number of RDs-to-TDs was revisited using the full 134 events of the original Lepping et al. (2003) study (which utilized the RDs' propagation speeds for this estimation, an unconventional approach) but now by considering only normal field components, the more conventional approach. This resulted in slightly different conclusions, depending on specific assumptions used, making the unconventional approach suspect.

  17. Fine-scale characteristics of interplanetary sector boundaries

    NASA Technical Reports Server (NTRS)

    Behannon, K. W.; Neubauer, F. M.; Barnstorf, H.

    1981-01-01

    The study examines the structure of the interplanetary sector boundaries observed by Helios 1 within sector transition regions during the time interval from December 1974 to April 1975. The transition regions are found to be complex in character, consisting of intermediate average field orientations in some cases as well as a number of large-angle directional discontinuities (DDs). It is suggested that the observed DDs represent multiple traversals of the global heliospheric current sheet caused by local fluctuations in the position of the sheet. There is evidence that such fluctuations are sometimes produced by wavelike motions or surface corrugations of scale length 0.05-0.1 AU, superimposed on the large-scale structure.

  18. Numerical Modeling of Interplanetary Coronal Mass Ejections and Comparison with Heliospheric Images

    E-print Network

    Lugaz, N; 10.1016/j.jastp.2010.08.016

    2010-01-01

    Interplanetary coronal mass ejections (ICMEs) have complex magnetic and density structures, which is the result of their interaction with the structured solar wind and with previous eruptions. ICMEs are revealed by in situ measurements and in the past five years, through remote-sensing observations by heliospheric imagers. However, to understand and analyze these observations often requires the use of numerical modeling. It is because no instruments can yet provide a simple view of ICMEs in two or three dimensions. Numerical simulations can be used to determine the origin of a complex ejecta observed near Earth, or to analyze the origin, speed and extent of density structures observed remotely. Here, we review and discuss recent efforts to use numerical simulations of ICMEs to investigate the magnetic topology, density structure, energetics and kinematics of ICMEs in the interplanetary space. After reviewing existing numerical models of ICMEs, we first focus on numerical modeling in support of the SMEI and ST...

  19. The VISTA spacecraft: Advantages of ICF (Inertial Confinement Fusion) for interplanetary fusions propulsion applications

    NASA Technical Reports Server (NTRS)

    Orth, Charles D.; Klein, Gail; Sercel, Joel; Hoffman, Nate; Murray, Kathy; Chang-Diaz, Franklin

    1987-01-01

    Inertial Confinement Fusion (ICF) is an attractive engine power source for interplanetary manned spacecraft, especially for near-term missions requiring minimum flight duration, because ICF has inherent high power-to-mass ratios and high specific impulses. We have developed a new vehicle concept called VISTA that uses ICF and is capable of round-trip manned missions to Mars in 100 days using A.D. 2020 technology. We describe VISTA's engine operation, discuss associated plasma issues, and describe the advantages of DT fuel for near-term applications. Although ICF is potentially superior to non-fusion technologies for near-term interplanetary transport, the performance capabilities of VISTA cannot be meaningfully compared with those of magnetic-fusion systems because of the lack of a comparable study of the magnetic-fusion systems. We urge that such a study be conducted.

  20. Multi-Spacecraft Observations of Interplanetary Shocks Near Earth

    NASA Astrophysics Data System (ADS)

    Kajdic, P.; Blanco-Cano, X.; Lavraud, B.

    2014-12-01

    Space missions around Earth have been continuously monitoring solar wind and interplanetary magnetic field for many years now. They have detected a large number of interplanetary (IP) shocks. These have been observed with multiple spacecraft at separations ranging from 103 km to several 105. Comparing observations of IP shocks at different locations in space can provide us with important insights on micro-physical processes that take place near or within the shock transitions. We have compiled a database of about 50 IP shocks detected between 2001 and 2014 with several missions. In the first part of our research we calculated local normals of IP shocks by using different one-spacecraft methods and also the 4-spacecraft method, when possible. In some cases we were able to compare the results of the latter method for different inter-spacecraft separations. This is the first time that comparison of IP shock profiles is also performed systematically on small inter-spacecraft separations of several 100 km (Cluster and Themis observations). Shock normals obtained by using different spacecraft configurations may differ. We find that spacecraft observe different shock profiles even when the their separations are only ~1000 km and the detection times differ by less than a second. The four-spacecraft method is less reliable when the detection times are small, since the changing shock profiles and uncertainties related to timing of the shock arrivals may distort the calculations. We also study regions upstream and downstream of IP shocks - we analyze the properties of suprathermal particles and magnetic perturbations there.

  1. Identification of Interplanetary Coronal Mass Ejections at 1 AU Using Multiple Solar Wind Plasma Composition Anomalies

    NASA Technical Reports Server (NTRS)

    Richardson, I. G.; Cane, H. V.

    2004-01-01

    We investigate the use of multiple simultaneous solar wind plasma compositional anomalies, relative to the composition of the ambient solar wind, for identifying interplanetary coronal mass ejection (ICME) plasma. We first summarize the characteristics of several solar wind plasma composition signatures (O(+7)/O(+6), Mg/O, Ne/O, Fe charge states, He/p) observed by the ACE and WIND spacecraft within the ICMEs during 1996 - 2002 identsed by Cane and Richardson. We then develop a set of simple criteria that may be used to identify such compositional anomalies, and hence potential ICMEs. To distinguish these anomalies from the normal variations seen in ambient solar wind composition, which depend on the wind speed, we compare observed compositional signatures with those 'expected' in ambient solar wind with the same solar wind speed. This method identifies anomalies more effectively than the use of fixed thresholds. The occurrence rates of individual composition anomalies within ICMEs range from approx. 70% for enhanced iron and oxygen charge states to approx. 30% for enhanced He/p (> 0.06) and Ne/O, and are generally higher in magnetic clouds than other ICMEs. Intervals of multiple anomalies are usually associated with ICMEs, and provide a basis for the identification of the majority of ICMEs. We estimate that Cane and Richardson, who did not refer to composition data, probably identitied approx. 90% of the ICMEs present. However, around 10% of their ICMEs have weak compositional anomalies, suggesting that the presence of such signatures does not provide a necessary requirement for an ICME. We note a remarkably similar correlation between the Mg/O and O(7)/O(6) ratios in hourly-averaged data both within ICMEs and the ambient solar wind. This 'universal' relationship suggests that a similar process (such as minor ion heating by waves inside coronal magnetic field loops) produces the first-ionization potential bias and ion freezing-in temperatures in the source regions of both ICMEs and the ambient solar wind.

  2. Plasma propulsion for interplanetary flight

    Microsoft Academic Search

    Franklin R. Chang-Díaz

    2006-01-01

    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is a high-power propulsion concept using radio waves to create and accelerate plasma in a magnetic nozzle. Important features are its high and variable exhaust velocity, which greatly enhances performance. A NASA-led, research team is developing this technology in the U.S. Recent advances include demonstration of efficient propellant utilization in its helicon plasma

  3. Solar and interplanetary control of the location of the Venus bow shock

    Microsoft Academic Search

    C.T. Russell; E. Chou; J. G. Luhmann; P. Gazis; L. H. Brace; W. R. Hoegy

    1988-01-01

    The Venus box shock location has been measured at nearly 2,000 shock crossings, and its dependence on solar EUV, solar wind conditions, and the interplanetary magnetic field determined. The shock position at the terminator varies from about 2.14 Venus radii at solar minimum to 2.40 Venus radii at solar maximum.The location of the shock varies little with solar wind dynamic

  4. Upper limit concentrations of trapped xenon in individual interplanetary dust particles from the stratosphere

    Microsoft Academic Search

    K. Kehm; S. Crowther; J. D. Gilmour; R. K. Mohapatra; C. M. Hohenberg

    2009-01-01

    The Xe contents in 25 individual stratospheric interplanetary dust particles were measured in two different laboratories using focused laser micro-gas extraction and (1) a conventional low-blank magnetic sector mass spectrometer (Washington University), and (2) a resonance ionization time of flight mass spectrometer (RELAX-University of Manchester). Data from both laboratories yielded a remarkably similar upper-limit 132Xe concentration in the IDPs (<2.7,

  5. Fullerenes and interplanetary dust at the Permian-Triassic boundary.

    PubMed

    Poreda, Robert J; Becker, Luann

    2003-01-01

    We recently presented new evidence that an impact occurred approximately 250 million years ago at the Permian-Triassic boundary (PTB), triggering the most severe mass extinction in the history of life on Earth. We used a new extraterrestrial tracer, fullerene, a third carbon carrier of noble gases besides diamond and graphite. By exploiting the unique properties of this molecule to trap noble gases inside of its caged structure (helium, neon, argon), the origin of the fullerenes can be determined. Here, we present new evidence for fullerenes with extraterrestrial noble gases in the PTB at Graphite Peak, Antarctica, similar to PTB fullerenes from Meishan, China and Sasayama, Japan. In addition, we isolated a (3)He-rich magnetic carrier phase in three fractions from the Graphite Peak section. The noble gases in this magnetic fraction were similar to zero-age deep-sea interplanetary dust particles (IDPs) and some magnetic grains isolated from the Cretaceous-Tertiary boundary. The helium and neon isotopic compositions for both the bulk Graphite Peak sediments and an isolated magnetic fraction from the bulk material are consistent with solar-type gases measured in zero-age deep-sea sediments and point to a common source, namely, the flux of IDPs to the Earth's surface. In this instance, the IDP noble gas signature for the bulk sediment can be uniquely decoupled from fullerene, demonstrating that two separate tracers are present (direct flux of IDPs for (3)He vs. giant impact for fullerene). PMID:12804366

  6. Toroidal Plasma Thruster for Interplanetary and Interstellar Space Flights

    SciTech Connect

    N.N. Gorelenkov; L.E. Zakharov; and M.V. Gorelenkova

    2001-07-11

    This work involves a conceptual assessment for using the toroidal fusion reactor for deep space interplanetary and interstellar missions. Toroidal thermonuclear fusion reactors, such as tokamaks and stellarators, are unique for space propulsion, allowing for a design with the magnetic configuration localized inside toroidal magnetic field coils. Plasma energetic ions, including charged fusion products, can escape such a closed configuration at certain conditions, a result of the vertical drift in toroidal rippled magnetic field. Escaping particles can be used for direct propulsion (since toroidal drift is directed one way vertically) or to create and heat externally confined plasma, so that the latter can be used for propulsion. Deuterium-tritium fusion neutrons with an energy of 14.1 MeV also can be used for direct propulsion. A special design allows neutrons to escape the shield and the blanket of the tokamak. This provides a direct (partial) conversion of the fusion energy into the directed motion of the propellant. In contrast to other fusion concepts proposed for space propulsion, this concept utilizes the natural drift motion of charged particles out of the closed magnetic field configuration.

  7. Different {open_quotes}average{close_quotes} nuclear magnetic resonance relaxation times for correlation with fluid-flow permeability and irreducible water saturation in water-saturated sandstones

    SciTech Connect

    Borgia, G.C. [University of Bologna, Dipartimento di Ingegneria Chimica, Mineraria, e Delle Tecnolgie Ambientali, Viale Risorgimento 2, 40136 Bologna (Italy)] [University of Bologna, Dipartimento di Ingegneria Chimica, Mineraria, e Delle Tecnolgie Ambientali, Viale Risorgimento 2, 40136 Bologna (Italy); Brown, R.J. [515 W. 11th Street, Claremont, California 91711-3721 (United States)] [515 W. 11th Street, Claremont, California 91711-3721 (United States); Fantazzini, P. [University of Bologna, Dipartimento of Physics, Via Irnerio 46, 40126 Bologna (Italy)] [University of Bologna, Dipartimento of Physics, Via Irnerio 46, 40126 Bologna (Italy)

    1997-11-01

    Fluid-flow properties of porous media, such as permeability k and irreducible water saturation S{sub wi}, can be estimated from water {sup 1}H nuclear magnetic resonance (NMR) relaxation data, but there are basic questions regarding data processing and interpretation. We found that S{sub wi} and k are better estimated if different forms of {open_quotes}average{close_quotes} relaxation time are used. NMR longitudinal relaxation data for a suite of 106 water-saturated clean sandstones were used. Sandstones represent a specialized class of porous media, where even for small porosity, substantially all pore space is connected. The sandstones exhibit distributions of relaxation times ranging over factors from at least 10 to more than 10{sup 3}. We tried several forms of {open_quotes}average{close_quotes} relaxation time T. One family of Ts is {l_angle}T{sup p}{r_angle}{sup 1/p}, where limp{r_arrow}0 gives the geometric mean. The best estimator we found for S{sub wi} uses a form of average relaxation time {ital only}, rather than relaxation time cutoff. The time used can be any of several forms of T, giving more emphasis to {ital short times} than the geometric mean does. On the contrary, the best T for estimating permeability without other information is precisely the geometric mean. The best estimates of permeability came from fits of ln(k/{phi}) using Ts with emphasis at {ital slightly longer times}. While S{sub wi} is better estimated by using all the data points (starting from our minimum 0.4 ms), k is better estimated by starting at a few ms, that is by ignoring a {ital non-negligible} fraction of the signal for some samples. These results can be obtained also by using computations that do not need to invert multiexponential relaxation data, and good results are obtained even with only a few data points. (Abstract Truncated)

  8. Interplanetary Shock Waves and Large-Scale Structures: Ulysses' Observations in and out of the Ecliptic Plane

    NASA Technical Reports Server (NTRS)

    Gonzalez-Esparza, J. A.; Balogh, A.; Forsyth, R. J.; Neugebauer, M.; Smith, E. J.; Phillips, J. L.

    1995-01-01

    A study is presented of 153 fast shock waves and their relation to other large-scale features in the solar wind: corotating interaction regions (CIRs), interplanetary counterparts of coronal mass ejections (ICMEs) and the magnetic sector structure, observed by Ulysses from October 1990 to the south solar pass in the summer of 1994.

  9. Solar rotating magnetic dipole?. [around axis perpendicular to rotation axis of the sun

    NASA Technical Reports Server (NTRS)

    Antonucci, E.

    1974-01-01

    A magnetic dipole rotating around an axis perpendicular to the rotation axis of the sun can account for the characteristics of the surface large-scale solar magnetic fields through the solar cycle. The polarity patterns of the interplanetary magnetic field, predictable from this model, agree with the observed interplanetary magnetic sector structure.

  10. A catalog of interplanetary type III storms

    NASA Technical Reports Server (NTRS)

    Kayser, S. E.; Bougeret, J.-L.; Fainberg, J.; Stone, R. G.

    1988-01-01

    A catalog describing the characteristics of all the interplanetary type III storms observed at kilometric wavelengths by the radio astronomy experiment on the ISEE-3 spacecraft between September 1978 and October 1982 is presented. Three-dimensional trajectories have been determined for about one-third of these storms using radio techniques. Solar coordinate and solar wind parameters derived from the trajectories are also tabulated. A statistical summary of the data is included.

  11. Interplanetary approach optical navigation with applications

    Microsoft Academic Search

    N. Jerath

    1978-01-01

    The use of optical data from onboard television cameras for the navigation of interplanetary spacecraft during the planet approach phase is investigated. Three optical data types were studied: the planet limb with auxiliary celestial references, the satellite-star, and the planet-star two-camera methods. Analysis and modelling issues related to the nature and information content of the optical methods were examined. Dynamic

  12. Optimum solar-sail interplanetary trajectories

    NASA Technical Reports Server (NTRS)

    Sauer, C. G., Jr.

    1976-01-01

    A description is given of the optimization of solar-sail interplanetary trajectories. The optimization procedure is based on the calculus of variations. Attention is given to aspects of thrust optimization, optimization criteria, a terrestrial planet rendezvous, the Venus and Mars rendezvous, the Mercury rendezvous, and an asteroid roundtrip mission. The investigation shows that a solar-sail spacecraft represents a viable option for the exploration of the solar system in the future.

  13. Technology of experiments measuring interplanetary dust

    Microsoft Academic Search

    H. Dodeck

    1975-01-01

    Onboard the solar probe Helios, interplanetary dust particles are detected by a micrometeoroid detector based upon impact ionization. Chemical analysis is performed by a time-of-flight spectrometer. Special provisions were necessary to provide waste-heat dissipation from the eliptic sensor. The essential requirement of the zodiacal-light experiment is the suppression of straylight by a factor of 10 to the -15th power to

  14. Integrated shielding systems for manned interplanetary spaceflight

    NASA Astrophysics Data System (ADS)

    George, Jeffrey A.

    1992-01-01

    The radiation environment encountered by manned interplanetary missions can have a severe impact on both vehicle design and mission performance. This study investigates the potential impact of radiation protection on interplanetary vehicle design for a manned Mars mission. A systems approach was used to investigate the radiation protection requirements of the sum interplanetary environment. Radiation budgets were developed which result in minimum integrated shielding system masses for both nuclear and non-nuclear powered missions. A variety of system configurations and geometries were assessed over a range of dose constraints. For an annual dose equivalent rate limit of 50 rem/yr, an environmental shielding system composed of a habitat shield and storm shelter was found to result in the lowest total mass. For a limit of 65 rem/yr, a system composed of a sleeping quarters shield was least massive, and resulted in significantly reduced system mass. At a limit of 75 rem/yr, a storm shelter alone was found to be sufficient, and exhibited a further mass reduction. Optimal shielding system results for 10 MWe nuclear powered missions were found to follow along similar lines, with the addition of a reactor shadow shield. A solar minimum galactic cosmic ray spectrum and one anomalously large solar particle event during the course of a two year mission were assumed. Water was assumed for environmental radiation shielding.

  15. The rate of separation of magnetic lines of force in a random magnetic field.

    NASA Technical Reports Server (NTRS)

    Jokipii, J. R.

    1973-01-01

    The mixing of magnetic lines of force, as represented by their rate of separation, as a function of distance along the magnetic field, is considered with emphasis on neighboring lines of force. This effect is particularly important in understanding the transport of charged particles perpendicular to the average magnetic field. The calculation is carried out in the approximation that the separation changes by an amount small compared with the correlation scale normal to the field, in a distance along the field of a few correlation scales. It is found that the rate of separation is very sensitive to the precise form of the power spectrum. Application to the interplanetary and interstellar magnetic fields is discussed, and it is shown that in some cases field lines, much closer together than the correlation scale, separate at a rate which is effectively as rapid as if they were many correlation lengths apart.

  16. CAWSES November 7-8, 2004, Superstorm: Complex Solar and Interplanetary Features in the Post-Solar Maximum Phase

    NASA Technical Reports Server (NTRS)

    Tsurutani, Bruce T.; Echer, Ezequiel; Guarnieri, Fernando L.; Kozyra, J. U.

    2008-01-01

    The complex interplanetary structures during 7 to 8 Nov 2004 are analyzed to identify their properties as well as resultant geomagnetic effects and the solar origins. Three fast forward shocks, three directional discontinuities and two reverse waves were detected and analyzed in detail. The three fast forward shocks 'pump' up the interplanetary magnetic field from a value of approx.4 nT to 44 nT. However, the fields after the shocks were northward, and magnetic storms did not result. The three ram pressure increases were associated with major sudden impulses (SI + s) at Earth. A magnetic cloud followed the third forward shock and the southward Bz associated with the latter was responsible for the superstorm. Two reverse waves were detected, one at the edge and one near the center of the magnetic cloud (MC). It is suspected that these 'waves' were once reverse shocks which were becoming evanescent when they propagated into the low plasma beta MC. The second reverse wave caused a decrease in the southward component of the IMF and initiated the storm recovery phase. It is determined that flares located at large longitudinal distances from the subsolar point were the most likely causes of the first two shocks without associated magnetic clouds. It is thus unlikely that the shocks were 'blast waves' or that magnetic reconnection eroded away the two associated MCs. This interplanetary/solar event is an example of the extremely complex magnetic storms which can occur in the post-solar maximum phase.

  17. Partially ejected flux ropes: Implications for interplanetary coronal mass ejections

    NASA Astrophysics Data System (ADS)

    Gibson, S. E.; Fan, Y.

    2008-09-01

    Connecting interplanetary coronal mass ejections (ICMEs) to their solar pre-eruption source requires a clear understanding of how that source may have evolved during eruption. Gibson and Fan (2006a) have presented a three-dimensional numerical magnetohydrodynamic simulation of a CME, which showed how, in the course of eruption, a coronal flux rope may writhe and reconnect both internally and with surrounding fields in a manner that leads to a partial ejection of only part of the rope as a CME. In this paper, we will explicitly describe how the evolution during eruption found in that simulation leads to alterations of the magnetic connectivity, helicity, orientation, and topology of the ejected portion of the rope so that it differs significantly from that of the pre-eruption rope. Moreover, because a significant part of the magnetic helicity remains behind in the lower portion of the rope that survives the eruption, the region is likely to experience further eruptions. These changes would complicate how ICMEs embedded in the solar wind relate to their solar source. In particular, the location and evolution of transient coronal holes, topology of magnetic clouds ("tethered spheromak"), and likelihood of interacting ICMEs would differ significantly from what would be predicted for a CME which did not undergo writhing and partial ejection during eruption.

  18. An unusual interplanetary event - Encounter with a comet?

    NASA Technical Reports Server (NTRS)

    Russell, C. T.; Luhmann, J. G.; Barnes, A.; Mihalov, J. D.; Elphic, R. C.

    1983-01-01

    The possibility that the slow rise to a sharp maximum and then decay surrounding a strong current sheet observed in the Venus magnetic field 0.72 AU from the sun was caused by passage of Venus through the wake of an active comet is examined. Data were also gathered by the ISEE 3 satellite magnetometer at 0.99 AU 25 h, 20 min later, a delay corresponding to the transit time for the solar wind. No shock structures bounded the phenomenon. The data indicate the presence of a small body in a much larger field of interaction and the magnetometer, solar wind probe, and electron temperature probe support a behavior similar to a planetary magnetosheath. The observed He structure in interplanetary space ruled out a solar wind source, while consideration of the magnetic equator and magnetic pole suggest that an unknown comet passed through the region between the sun and Venus at a distance where the effects would not be detected at earth.

  19. Correlations between sunspot numbers, interplanetary parameters and geomagnetic trends over solar cycles 21-23

    NASA Astrophysics Data System (ADS)

    Arora, Kusumita; Chandrasekhar, N. Phani; Nagarajan, Nandini; Singh, Ankit

    2014-07-01

    We have analysed correlations between sunspot numbers, solar wind, ion density, interplanetary magnetic field vis-à-vis magnetic activity. Planetary geomagnetic index (Ap) and local residual measure of magnetic activity (I?H) from low-latitude Magnetic Observatory, CSIR-NGRI, Hyderabad (IMO-HYB) spanning solar cycles 21-23 are used for this study. Using correlation coefficients between and wavelet decomposition of sunspot numbers, interplanetary parameters and measures of magnetic activity, the complex and time varying nature of these inter-relationships are brought out. The overall influence of sunspot number could be separated and combined episodic effects of other solar parameters could be distinguished. The demonstrated correlation or lack of it, between measures of magnetic activity (Ap and I?H), and all the parameters of solar activity, presented here corroborate established mechanisms as well as delineated clearly the relative impact of different solar mechanisms over phases of three solar cycles. The possible role of non-sunspot related activity from high latitude regions of the sun is indicated.

  20. Long Duration Exposure Facility (LDEF) attitude measurements of the Interplanetary Dust Experiment

    NASA Technical Reports Server (NTRS)

    Kassel, Philip C., Jr.; Motley, William R., III; Singer, S. Fred; Mulholland, J. Derral; Oliver, John P.; Weinberg, Jerry L.; Cooke, William J.; Wortman, Jim J.

    1993-01-01

    Analysis of the data from the Long Duration Exposure Facility (LDEF) Interplanetary Dust Experiment (IDE) sun sensors has allowed a confirmation of the attitude of LDEF during its first year in orbit. Eight observations of the yaw angle at specific times were made and are tabulated in this paper. These values range from 4.3 to 12.4 deg with maximum uncertainty of plus or minus 2.0 deg and an average of 7.9 deg. No specific measurements of pitch or roll were made but the data indicates that LDEF had an average pitch down attitude of less than 0.7 deg.

  1. Characteristics of interplanetary type II radio emission and the relationship to shock and plasma properties

    NASA Technical Reports Server (NTRS)

    Lengyel-Frey, D.; Stone, R. G.

    1989-01-01

    A large sample of type II events is the basis of the present study of the properties of interplanetary type II bursts' radio-emission properties. Type II spectra seem to be composed of fundamental and harmonic components of plasma emission, where the intensity of the fundamental component increases relative to the harmonic as the burst evolves with heliocentric distance; burst average flux density increases as a power of the associated shock's average velocity. Solar wind density structures may have a significant influence on type II bandwidths.

  2. Measurements of line-averaged electron density of pulsed plasmas using a He-Ne laser interferometer in a magnetized coaxial plasma gun device

    NASA Astrophysics Data System (ADS)

    Iwamoto, D.; Sakuma, I.; Kitagawa, Y.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

    2012-10-01

    In next step of fusion devices such as ITER, lifetime of plasma-facing materials (PFMs) is strongly affected by transient heat and particle loads during type I edge localized modes (ELMs) and disruption. To clarify damage characteristics of the PFMs, transient heat and particle loads have been simulated by using a plasma gun device. We have performed simulation experiments by using a magnetized coaxial plasma gun (MCPG) device at University of Hyogo. The line-averaged electron density measured by a He-Ne interferometer is 2x10^21 m-3 in a drift tube. The plasma velocity measured by a time of flight technique and ion Doppler spectrometer was 70 km/s, corresponding to the ion energy of 100 eV for helium. Thus, the ion flux density is 1.4x10^26 m-2s-1. On the other hand, the MCPG is connected to a target chamber for material irradiation experiments. It is important to measure plasma parameters in front of target materials in the target chamber. In particular, a vapor cloud layer in front of the target material produced by the pulsed plasma irradiation has to be characterized in order to understand surface damage of PFMs under ELM-like plasma bombardment. In the conference, preliminary results of application of the He-Ne laser interferometer for the above experiment will be shown.

  3. Emission of whistler-mode waves and diffusion of electrons around interplanetary shocks

    SciTech Connect

    Pierre, F.; Solomon, J.; Cornilleau-Wehrlin, N.; Canu, P.; Scime, E. E.; Phillips, J. L.; Balogh, A.; Forsyth, R. J. [IAS/CNRS/Univ. Paris 11, Orsay (France); CETP/CNRS, Velizy (France); CETP/CNRS, Velizy (France); Physics Dpt., West Virginia University, Morgantown, West Virginia (United States); Los Alamos National Laboratory, Los Alamos, New Mexico (United States); Imperial College of Science and Technology, London (United Kingdom)

    1996-07-20

    We present a study of whistler-mode wave generation and wave particle interaction in the vicinity of interplanetary shocks in the ecliptic plane, as observed by the Ulysses spacecraft. Generally the whistler-mode waves (measured in the frequency range 0.22-448 Hz) are observed downstream of the shocks where they persist for some hours. From the electron distribution functions (EDF) in the energy range 1.6 to 862 eV, we compute the temperature anisotropy and the wave growth rate of the electromagnetic electron cyclotron instability for the case of parallel propagation of the waves with respect to the interplanetary magnetic field (IMF) B. In general, in agreement with the wave measurements, the instability grows only downstream of the shock fronts. Following the wave activity, velocity space diffusion of the electrons results in a marginally stable state with sporadic fluctuations.

  4. Emission of whistler-mode waves and diffusion of electrons around interplanetary shocks

    SciTech Connect

    Pierre, F.; Solomon, J. [IAS/CNRS/Univ. Paris 11, Orsay (France)]|[CETP/CNRS, Velizy (France); Cornilleau-Wehrlin, N.; Canu, P. [CETP/CNRS, Velizy (France); Scime, E.E. [Physics Dpt., West Virginia University, Morgantown, West Virginia (United States of America); Phillips, J.L. [Los Alamos National Laboratory, Los Alamos, New Mexico (United States of America); Balogh, A.; Forsyth, R.J. [Imperial College of Science and Technology, London (England)

    1996-07-01

    We present a study of whistler-mode wave generation and wave particle interaction in the vicinity of interplanetary shocks in the ecliptic plane, as observed by the Ulysses spacecraft. Generally the whistler-mode waves (measured in the frequency range 0.22{endash}448 Hz) are observed downstream of the shocks where they persist for some hours. From the electron distribution functions (EDF) in the energy range 1.6 to 862 eV, we compute the temperature anisotropy and the wave growth rate of the electromagnetic electron cyclotron instability for the case of parallel propagation of the waves with respect to the interplanetary magnetic field (IMF) {bold B}. In general, in agreement with the wave measurements, the instability grows only downstream of the shock fronts. Following the wave activity, velocity space diffusion of the electrons results in a marginally stable state with sporadic fluctuations. {copyright} {ital 1996 American Institute of Physics.}

  5. Interplanetary particle transport simulation for warning system for aviation exposure to solar energetic particles

    E-print Network

    Kubo, Yûki; Sato, Tatsuhiko

    2015-01-01

    Solar energetic particles (SEPs) are one of the extreme space weather phenomena. A huge SEP event increases the radiation dose received by aircrews, who should be warned of such events as early as possible. We developed a warning system for aviation exposure to SEPs. This article describes one component of the system, which calculates the temporal evolution of the SEP intensity and the spectrum immediately outside the terrestrial magnetosphere. To achieve this, we performed numerical simulations of SEP transport in interplanetary space, in which interplanetary SEP transport is described by the focused transport equation. We developed a new simulation code to solve the equation using a set of stochastic differential equations. In the code, the focused transport equation is expressed in a magnetic field line coordinate system, which is a non-orthogonal curvilinear coordinate system. An inverse Gaussian distribution is employed as the injection profile of SEPs at an inner boundary located near the Sun. We applie...

  6. Large-Amplitude Electrostatic Waves Observed at a Supercritical Interplanetary Shock

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III; Cattell, C. A.; Kellogg, P. J.; Goetz, K.; Kersten, K.; Kasper, J. C.; Szabo, A.; Wilber, M.

    2010-01-01

    We present the first observations at an interplanetary shock of large-amplitude (> 100 mV/m pk-pk) solitary waves and large-amplitude (approx.30 mV/m pk-pk) waves exhibiting characteristics consistent with electron Bernstein waves. The Bernstein-like waves show enhanced power at integer and half-integer harmonics of the cyclotron frequency with a broadened power spectrum at higher frequencies, consistent with the electron cyclotron drift instability. The Bernstein-like waves are obliquely polarized with respect to the magnetic field but parallel to the shock normal direction. Strong particle heating is observed in both the electrons and ions. The observed heating and waveforms are likely due to instabilities driven by the free energy provided by reflected ions at this supercritical interplanetary shock. These results offer new insights into collisionless shock dissipation and wave-particle interactions in the solar wind.

  7. Large-amplitude electrostatic waves observed at a supercritical interplanetary shock

    NASA Astrophysics Data System (ADS)

    Wilson, L. B., III; Cattell, C. A.; Kellogg, P. J.; Goetz, K.; Kersten, K.; Kasper, J. C.; Szabo, A.; Wilber, M.

    2010-12-01

    We present the first observations at an interplanetary shock of large-amplitude (> 100 mV/m pk-pk) solitary waves and large-amplitude (˜30 mV/m pk-pk) waves exhibiting characteristics consistent with electron Bernstein waves. The Bernstein-like waves show enhanced power at integer and half-integer harmonics of the cyclotron frequency with a broadened power spectrum at higher frequencies, consistent with the electron cyclotron drift instability. The Bernstein-like waves are obliquely polarized with respect to the magnetic field but parallel to the shock normal direction. Strong particle heating is observed in both the electrons and ions. The observed heating and waveforms are likely due to instabilities driven by the free energy provided by reflected ions at this supercritical interplanetary shock. These results offer new insights into collisionless shock dissipation and wave-particle interactions in the solar wind.

  8. The interplanetary shock event of November 11/12 1978 - A comprehensive test of acceleration theory

    NASA Technical Reports Server (NTRS)

    Wenzel, K.-P.; Sanderson, T. R.; Van Nes, P.; Kennel, C. F.; Scarf, F. L.; Coroniti, F. V.; Russell, C. T.; Parks, G. K.; Smith, E. J.; Feldman, W. C.

    1983-01-01

    A comprehensive study of the November 11, 12, 1978 shock event based on energetic particle, solar wind, magnetic field and wave data from the ISEE-3, -1 and -2 spacecraft has been undertaken both from the energetic and the collisionless shock point of view. The energy density of 10-50 keV protons accelerated by the shock is found to be equivalent to the upstream magnetic field energy density. The observations are in quantitative agreement with Lee's (1983) self consistent theory for the excitation of hydromagnetic waves and the acceleration of ions upstream of interplanetary shocks.

  9. Penetration electric fields and global ionospheric disturbances during super magnetic storms

    Microsoft Academic Search

    C. Huang; J. Foster; A. Coster; P. Erickson; W. Rideout; L. Goncharenko; M. Colerico

    2006-01-01

    Magnetic storms represent the largest disturbances in the magnetosphere and ionosphere The interplanetary magnetic field IMF is generally southward during the main phase of magnetic storms and the interplanetary electric field can penetrate to the low-latitude ionosphere for many hours without decay Penetration electric fields play a very important role in the storm-time redistribution of the global ionospheric plasma We

  10. Observations of Electromagnetic Whistler Precursors at Supercritical Interplanetary Shocks

    NASA Technical Reports Server (NTRS)

    Wilson, L. B., III; Koval, A.; Szabo, Adam; Breneman, A.; Cattell, C. A.; Goetz, K.; Kellogg, P. J.; Kersten, K.; Kasper, J. C.; Maruca, B. A.; Pulupa, M.

    2012-01-01

    We present observations of electromagnetic precursor waves, identified as whistler mode waves, at supercritical interplanetary shocks using the Wind search coil magnetometer. The precursors propagate obliquely with respect to the local magnetic field, shock normal vector, solar wind velocity, and they are not phase standing structures. All are right-hand polarized with respect to the magnetic field (spacecraft frame), and all but one are right-hand polarized with respect to the shock normal vector in the normal incidence frame. They have rest frame frequencies f(sub ci) < f much < f(sub ce) and wave numbers 0.02 approx < k rho (sub ce) approx <. 5.0. Particle distributions show signatures of specularly reflected gyrating ions, which may be a source of free energy for the observed modes. In one event, we simultaneously observe perpendicular ion heating and parallel electron acceleration, consistent with wave heating/acceleration due to these waves. Al though the precursors can have delta B/B(sub o) as large as 2, fluxgate magnetometer measurements show relatively laminar shock transitions in three of the four events.

  11. Discovery of nuclear tracks in interplanetary dust

    NASA Technical Reports Server (NTRS)

    Bradley, J. P.; Brownlee, D. E.; Fraundorf, P.

    1984-01-01

    Nuclear tracks have been identified in interplanetary dust particles (IDP's) collected from the stratosphere. The presence of tracks unambiguously confirms the extraterrestrial nature of IDP's, and the high track densities (10 to the 10th to 10 to the 11th per square centimeter) suggest an exposure age of approximately 10,000 years within the inner solar system. Tracks also provide an upper temperature limit for the heating of IDP's during atmospheric entry, thereby making it possible to distinguish between pristine and thermally modified micrometeorites.

  12. Nonthermal Radiation Processes in Interplanetary Plasmas

    NASA Astrophysics Data System (ADS)

    Chian, A. C. L.

    1990-11-01

    RESUMEN. En la interacci6n de haces de electrones energeticos con plasmas interplanetarios, se excitan ondas intensas de Langmuir debido a inestabilidad del haz de plasma. Las ondas Langmuir a su vez interaccio nan con fluctuaciones de densidad de baja frecuencia para producir radiaciones. Si la longitud de las ondas de Langmujr exceden las condicio nes del umbral, se puede efectuar la conversi5n de modo no lineal a on- das electromagneticas a traves de inestabilidades parametricas. As se puede excitar en un plasma inestabilidades parametricas electromagneticas impulsadas por ondas intensas de Langmuir: (1) inestabilidades de decaimiento/fusi5n electromagnetica impulsadas por una bomba de Lang- muir que viaja; (2) inestabilidades dobles electromagneticas de decai- miento/fusi5n impulsadas por dos bombas de Langrnuir directamente opues- tas; y (3) inestabilidades de dos corrientes oscilatorias electromagne- ticas impulsadas por dos bombas de Langmuir de corrientes contrarias. Se concluye que las inestabilidades parametricas electromagneticas in- ducidas por las ondas de Langmuir son las fuentes posibles de radiacio- nes no termicas en plasmas interplanetarios. ABSTRACT: Nonthermal radio emissions near the local electron plasma frequency have been detected in various regions of interplanetary plasmas: solar wind, upstream of planetary bow shock, and heliopause. Energetic electron beams accelerated by solar flares, planetary bow shocks, and the terminal shock of heliosphere provide the energy source for these radio emissions. Thus, it is expected that similar nonthermal radiation processes may be responsible for the generation of these radio emissions. As energetic electron beams interact with interplanetary plasmas, intense Langmuir waves are excited due to a beam-plasma instability. The Langmuir waves then interact with low-frequency density fluctuations to produce radiations near the local electron plasma frequency. If Langmuir waves are of sufficiently large amplitude to exceed the thresfiold conditions, nonlinear mode conversion electromagnetic waves can be effected through parametric instabilities. A number of electromagnetic parametric instabilities driven by intense Langmuir waves can be excited in a plasma: (1) electromagnetic decay/fusion instabilities driven by a traveling Langmuir pump; (2) double electromagnetic decay/fusion instabilities driven by two oppositely directed Langmuir pumps; and (3) electromagnetic oscillating two-stream instabilities driven by two counterstreaming Langmuir pumps. It is concluded that the electromagnetic parametric instabilities induced by Langmuir waves are likely sources of nonthermal radiations in interplanetary plasmas. Keq ( : INTERPLANETARY MEDIUM - PLASMAS

  13. Extreme Historic and Solar cycle 23 Geomagnetic Storm events and their Interplanetary characteristics over Indian Sector

    NASA Astrophysics Data System (ADS)

    Kumar, Sandeep; Ram Sudarsanam, Tulasi; Veenadhari, Bhasakara; Kadam, B. D.; Mukherjee, Shyamoli

    Geomagnetic storms are large disturbances in the magnetosphere often persisting for several days or more. During geomagnetic storms the magnetic field measured at the earth’s surface is perturbed by strong electric currents flowing within both the magnetosphere and the ionosphere. Ground magnetic and satellite measurements provide a unique database in understanding space weather. The solar cycle 23 evidenced some major geomagnetic storms. Some severe and moderate geomagnetic storms of solar cycle 23 will be studied using magnetic and satellite data. We performed superposed epoch analysis of these storms to study their ground magnetic and interplanetary characteristics. The geomagnetic data from Colaba Magnetic Observatory (Geog. Long. 72(°) 49’E, Lat. 18(°) 5’ N) consisted of systematic hourly eye observations from 1847 to 1872 in continuation of the earlier series of observations at Colaba since 1841. The extreme space weather events recorded on Colaba observatory will be discussed. We compared solar cycle 23 storms with historical geomagnetic storms recorded at Colaba to estimate their interplanetary characteristics.

  14. Reflected ions at interplanetary shocks J. D. Richardson1

    E-print Network

    Richardson, John

    Click Here for Full Article Reflected ions at interplanetary shocks J. D. Richardson1 Received 21 are responsible for shock dissipation beyond 35 AU. We make the first study of reflected ions in ICME sheaths downstream of interplanetary shocks observed by Voyager 2 from 1­80 AU. A reflected ion population

  15. Active shielding for long duration interplanetary manned missions

    Microsoft Academic Search

    Piero Spillantini

    2010-01-01

    For long duration interplanetary manned missions the protection of astronauts from cosmic radiation is an unavoidable problem that has been considered by many space agencies. In Europe, during 2002–2004, the European Space Agency supported two research programs on this thematic: one was the constitution of a dedicated study group (on the thematic ‘Shielding from cosmic radiation for interplanetary missions: active

  16. Solar Protons above 500 MeV in the Sun's Atmosphere and in Interplanetary Space

    NASA Astrophysics Data System (ADS)

    Tylka, Allan J.; Share, Gerald H.; Dietrich, William F.; Murphy, Ronald J.; Keong Ng, Chee; Shea, Margaret A.; Smart, Don F.

    2014-05-01

    At least two distinct acceleration mechanisms produce energetic particles at or near the Sun: (1) acceleration at coronal sites of magnetic reconnection, generally associated with flares and (2) acceleration at shocks driven by fast coronal mass ejections (CMEs). Both mechanisms can accelerate protons to well beyond 500 MeV. Moreover, when a very large solar energetic particle (SEP) event is observed in interplanetary space, both a large flare and the launch of a fast CME are observed nearly simultaneously (unless the flare occurs behind a limb). Numerous studies have tried to sort out how these two phenomena contribute to the energetic particle population. To date, there is no consensus on this issue, particularly at the highest energies, where the release of particles from the neighborhood of the Sun generally persists for only a short period of time. Although the maximum of Cycle 24 has been notably deficient in producing high-energy SEPs, new instrumentation has provided powerful new insights into these questions. Fermi provides routine measurements of solar gamma-rays above 100 MeV, from which the number of >500 MeV protons interacting in the solar-atmosphere can be deduced, separately in the impulsive phase of the flare (lasting minutes and coincident with hard x-ray emission) and in the frequently observed extended phase (which can persist for many hours and whose origin is under debate). Simultaneously, other satellites and ground-based neutron monitors provide measurements of these high-energy protons in interplanetary space, the modeling of which is greatly strengthened by the STEREO's observations of the large-scale heliospheric distribution of SEPs. We report results for seven events in which the time-integrated number of >500 MeV protons at the Sun and in interplanetary space have been independently extracted. We find that >500 MeV protons in the impulsive phase of the flare typically constitute a percent or less of the protons in IP space, without any clear correlation to the number of >500 MeV protons in interplanetary space. By contrast, the number of >500 MeV protons in the extended phase of the flare is typically ~5-10% of the number in interplanetary space and is well correlated with it. These results suggest that (1) the impulsive phase of the flare does not make a significant contribution to the interplanetary population at these very high energies and (2) the extended-phase gamma-ray emissions are likely due to shock-accelerated protons precipitating down onto the solar atmosphere.

  17. Evolution of turbulence through interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Pitna, Alexander; Safrankova, Jana; Nemecek, Zdenek; Nemec, Frantisek; Prech, Lubomir; Chen, Christopher H. K.; Zastenker, Georgy N.

    2015-04-01

    The solar wind plasma is a turbulent medium in which Alfvenic MHD turbulence is assumed to be a prime candidate for a transfer of large scale variations into smaller spatial scales, up to the ion kinetic scale related to a thermal gyroradius or an ion inertial length. Interplanetary shocks are naturally occurring in the solar wind and provide a unique opportunity to compare a relatively quiet solar wind upstream with the shocked plasma downstream. The BMSW instrument onboard the Spektr-R spacecraft has detected tens of interplanetary (IP) shocks in a course of the 2011-2014 years. The high-time resolution (31 ms) of the ion flux, density and solar wind speed measurements allows us to study spectral properties in the transition region between MHD and kinetic scales. We have found that the overall power of the ion flow fluctuations at all spatial scales increases roughly ten times. The spectral slope of the power spectra in the kinetic range (3-8 Hz) is steeper downstream IP shocks than in the upstream solar wind. If the fluctuation level increases the power law decay of ion kinetic structures gradually changes to the exponential decay already reported for turbulence in interstellar plasmas.

  18. Jovian modulation of interplanetary electrons as observed with Voyagers 1 and 2

    NASA Technical Reports Server (NTRS)

    Schardt, A. W.; Mcdonald, F. B.; Trainor, J. H.

    1982-01-01

    The release of magnetospheric electrons from Jupiter into interplanetary space is modulated by the Jovian rotation period. The Voyager 1 and 2 observations showed that the modulation period agrees on the average with the synodic period of Jupiter (9h 55m 33.12s), but over intervals of weeks it can differ from the synodic period by several minutes. The lack of exact synchronization is attributed to changes of the plasma population in the Jovian magnetosphere. The Jovian modulation appears to be a persistent feature of the interaction between the solar wind and the magnetosphere and the disappearance of the modulation away from Jupiter is attributed to interplanetary propagation conditions. This leads to the following limits on the diffuse coefficient for interplanetary electrons: kappa perpendicular is or = 8 x 10 to the 19th power sq cm/s and kappa parallel is or = 10 to the 21st power sq cm/s. Modulation was still detectable at 3.8 A.U. behind Jupiter in the far magnetotail. This requires a mean free path in the tail 0.75 A.U. and good field connection along the tail to Jupiter.

  19. Superposed epoch analyses of HILDCAAs and their interplanetary drivers: Solar cycle and seasonal dependences

    NASA Astrophysics Data System (ADS)

    Hajra, Rajkumar; Echer, Ezequiel; Tsurutani, Bruce T.; Gonzalez, Walter D.

    2014-12-01

    We study the solar cycle and seasonal dependences of high-intensity, long-duration, continuous AE activity (HILDCAA) events and associated solar wind/interplanetary external drivers for ~ 3 1/2 solar cycle period, from 1975 to 2011. 99 HILDCAAs which had simultaneous solar wind/interplanetary data are considered in the present analyses. The peak occurrence frequency of HILDCAAs was found to be in the descending phase of the solar cycle. These events had the strongest time-integrated AE intensities and were coincident with peak occurrences of high-speed solar wind streams. The event initiations were statistically coincident with high-to-slow speed stream interactions, compressions in the solar wind plasma and interplanetary magnetic field (IMF). The latter were corotating interaction regions (CIRs). The signatures of related CIRs were most prominent for the events occurring during the descending and solar minimum phases of the solar cycles. For these events, the solar wind speed increased by ~41% and ~57% across the CIRs, respectively. There was weak or no stream-stream interaction or CIR structure during the ascending and solar maximum phases. HILDCAAs occurring during spring and fall seasons were found to occur preferentially in negative and positive IMF sector regions (toward and away from the Sun), respectively.

  20. PROPAGATION AND EVOLUTION OF THE JUNE 1st 2008 CME IN THE INTERPLANETARY MEDIUM

    NASA Astrophysics Data System (ADS)

    Nieves-Chinchilla, T.; Lamb, D. A.; Davila, J. M.; Vinas, A. F.; Moestl, C.; Hidalgo, M. A.; Farrugia, C. J.; Malandraki, O.; Dresing, N.; Gómez-Herrero, R.

    2009-12-01

    In this work we present a study of the coronal mass ejection (CME) of June 1st of 2008 in the interplanetary medium. This event has been extensively studied by others because of its favorable geometry and the possible consequences of its peculiar initiation for space weather forecasting. We show an analysis of the evolution of the CME in the interplanetary medium in order to shed some light on the propagation mechanism of the ICME. We have determined the typical shock associated characteristics of the ICME in order to understand the propagation properties. Using two different non force-free models of the magnetic cloud allows us to incorporate expansion of the cloud. We use in-situ measurements from STEREO B/IMPACT to characterize the ICME. In addition, we use images from STEREO A/SECCHI-HI to analyze the propagation and visual evolution of the associated flux rope in the interplanetary medium. We compare and contrast these observations with the results of the analytical models.

  1. Commercially-driven human interplanetary propulsion systems: Rationale, concept, technology, and performance requirements

    SciTech Connect

    Williams, C.H.; Borowski, S.K. [NASA Lewis Research Center, MS 500-201, 21000 Brookpark Road, Cleveland, Ohio 44135 (United States)

    1996-03-01

    Previous studies of human interplanetary missions are largely characterized by long trip times, limited performance capabilities, and enormous costs. Until these missions become dramatically more {open_quote}{open_quote}commercial-friendly{close_quote}{close_quote}, their funding source and rationale will be restricted to national governments and their political/scientific interests respectively. A rationale is discussed for human interplanetary space exploration predicated on the private sector. Space propulsion system requirements are identified for interplanetary transfer times of no more than a few weeks/months to and between the major outer planets. Nuclear fusion is identified as the minimum requisite space propulsion technology. A conceptual design is described and evolutionary catalyzed-DD to DHe{sup 3} fuel cycles are proposed. Magnetic nozzles for direct thrust generation and quantifying the operational aspects of the energy exchange mechanisms between high energy reaction products and neutral propellants are identified as two of the many key supporting technologies essential to satisfying system performance requirements. Government support of focused, breakthrough technologies is recommended at funding levels appropriate to other ongoing federal research. {copyright} {ital 1996 American Institute of Physics.}

  2. The amplitudes of interplanetary fluctuations - Stream structure, heliocentric distance, and frequency dependence

    NASA Technical Reports Server (NTRS)

    Roberts, D. A.; Goldstein, M. L.; Klein, L. W.

    1990-01-01

    A study is presented of the heliocentric distance, frequency, and stream structure dependence of the amplitudes of interplanetary fluctuations in the velocity and magnetic field from 0.3 to nearly 20 AU and for spacecraft-frame periods of 10 days to a few hours. Evidence is presented that, at a given heliocentric distance, the amplitude of the magnetic field fluctuations is proportional to the magnitude of the field, nearly independently of the solar wind speed. The radial evolution of magnetic fluctuations is shown to be nearly consistent with WKB expectations except at smaller scales in the inner heliosphere and at the largest scales in the outer heliosphere. While the large-scale velocity fluctuations are kinetic energy-dominated in the inner heliosphere due to the presence of streams, the magnetic fluctuation energy eventually comes to be slightly dominant over the kinetic energy at all scales. The theoretical implications of the results are considered.

  3. Interplanetary meteoroid debris in LDEF metal craters

    NASA Technical Reports Server (NTRS)

    Brownlee, D. E.; Horz, F.; Bradley, J.

    1992-01-01

    The extraterrestrial meteoroid residue found lining craters in the Long Duration Exposure Facility (LDEF) aluminum and gold targets is highly variable in both quantity and type. In typical craters only a minor amount of residue is found and for these craters it is evident that most of the impacting projectile was ejected during crater formation. Less than 10 percent of the craters greater than 100 microns contain abundant residue consistent with survival of a major fraction of the projectile. In these cases the residue can be seen optically as a dark liner and it can easily be analyzed by SEM-EDX techniques. Because they are rare, the craters with abundant residue must be a biased sampling of the meteoroids reaching the earth. Factors that favor residue retention are low impact velocity and material properties such as high melting point. In general, the SEM-EDX observations of crater residues are consistent with the properties of chondritic meteorites and interplanetary dust particles collected in the stratosphere. Except for impacts by particles dominated by single minerals such as FeS and olivine, most of the residue compositions are in broad agreement with the major element compositions of chondrites. In most cases the residue is a thin liner on the crater floor and these craters are difficult to quantitatively analyze by EDX techniques because the electron beam excites both residue and underlying metal substrate. In favorable cases, the liner is thick and composed of vesicular glass with imbedded FeNi, sulfide and silicate grains. In the best cases of meteoroid preservation, the crater is lined with large numbers of unmelted mineral grains. The projectiles fragmented into micron sized pieces but the fragments survived without melting. In one case, the grains contain linear defects that appear to be solar flare tracks. Solar flare tracks are common properties of small interplanetary particles and their preservation during impact implies that the fragments were not heated above 600 C. We are investigating the meteoroid fragments in LDEF metal craters to determine the properties of interplanetary dust and to determine if there are meteoroid types that are overlooked or otherwise undetected in cosmic dust collections obtained from the stratosphere and polar ice.

  4. Plasma and Magnetic Field Inside Magnetic Clouds: a Global Study

    Microsoft Academic Search

    C. Cid; M. A. Hidalgo; T. Nieves-Chinchilla; J. Sequeiros; A. F. Viñas

    2002-01-01

    Data observed during spacecraft encounters with magnetic clouds have been extensively analyzed in the literature. Moreover, several models have been proposed for the magnetic topology of these events, and fitted to the observations. Although these interplanetary events present well-defined plasma features, none of those models have included a simultaneous analysis of magnetic field and plasma data. Using as a starting

  5. Variations of the helium content across interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Cagas, Petr; Safrankova, Jana; Nemecek, Zdenek; Prech, Lubomir; Zastenker, Georgy N.

    2015-04-01

    Changes of the abundance of heavy species observed in the solar wind are usually attributed to spacecraft encounters with streams emanating from different places and altitudes in the source region and their further evolution is considered as being negligible. These conclusions are based on the analysis of highly averaged data and much less attention was devoted to variations on the time scale of seconds. The BMSW instrument onboard the Spektr-R spacecraft provides high-time resolution measurements of the helium and proton fluxes and proton velocity, density, and temperature that are suitable for investigations of rapid variations. In this paper, we compare measurements of variations of the helium content across interplanetary (IP) shocks in two points (Spektr-R and Wind) separated about 200 RE with a focus on the changes of helium abundance on this scale. The case study shows that the proton density exhibits a smooth profile after the IP shock in the data of both spacecraft, but the helium content is highly variable. Our analysis provides a clear evidence that the abrupt changes of the helium content are caused by the turbulence excited by the IP shock. It is important to note that the changes of protons and helium content are not correlated, thus the helium enhancements cannot be attributed to compressional MHD waves because both species vary independently.

  6. Forecasting space weather: Predicting interplanetary shocks using neural networks

    NASA Astrophysics Data System (ADS)

    Vandegriff, Jon; Wagstaff, Kiri; Ho, George; Plauger, Janice

    We are developing a system to predict the arrival of interplanetary (IP) shocks at the Earth. These events are routinely detected by the Electron, Proton, and Alpha Monitor (EPAM) instrument aboard NASA's ACE spacecraft, which is positioned at Lagrange Point 1 (L1). In this work, we use historical EPAM data to train an IP shock forecasting algorithm. Our approach centers on the observation that these shocks are often preceded by identifiable signatures in the energetic particle intensity data. Using EPAM data, we trained an artificial neural network to predict the time remaining until the shock arrival. After training this algorithm on 37 events, it was able to forecast the arrival time for 19 previously unseen events. The average uncertainty in the prediction 24 h in advance was 8.9 h, while the uncertainty improved to 4.6 h when the event was 12 h away. This system is accessible online, where it provides predictions of shock arrival times using real-time EPAM data.

  7. Comparisons of interplanetary type III storm footpoints with solar features

    NASA Technical Reports Server (NTRS)

    Kayser, Susan E.; Bougeret, Jean-Louis; Fainberg, Joseph; Stone, Robert G.

    1987-01-01

    The trajectories of 38 type III storms in the interplanetary medium have been deduced from ISEE-3 radio observations and extrapolated back to the sun to determine the Carrington coordinates of their footpoints. The analysis assumes radial motion of the solar wind, and the trajectories are projected radially back toward the surface for the last few solar radii. To identify the storm sources, the footpoints were compared to a variety of solar features: to the large-scale neutral line at the base of the current sheet, to active regions, to the small-scale neutral lines and H-alpha filaments which trace out active regions, and to coronal holes. Most of the footpoints were found to lie near active regions, in agreement with metric storm locations. There is a weak correlation with H-alpha filaments, no apparent association with the current sheet, and an anticorrelation with coronal holes. There is a small excess of storms in the leading half of magnetic sectors.

  8. PARTICLE ENERGY SPECTRA AT TRAVELING INTERPLANETARY SHOCK WAVES

    SciTech Connect

    Reames, Donald V., E-mail: dvreames@umd.edu [Institute for Physical Science and Technology, University of Maryland, College Park, MD 20742 (United States)

    2012-09-20

    We have searched for evidence of significant shock acceleration of He ions of {approx}1-10 MeV amu{sup -1} in situ at 258 interplanetary traveling shock waves observed by the Wind spacecraft. We find that the probability of observing significant acceleration, and the particle intensity observed, depends strongly upon the shock speed and less strongly upon the shock compression ratio. For most of the 39 fast shocks with significant acceleration, the observed spectral index agrees with either that calculated from the shock compression ratio or with the spectral index of the upstream background, when the latter spectrum is harder, as expected from diffusive shock theory. In many events the spectra are observed to roll downward at higher energies, as expected from Ellison-Ramaty and from Lee shock-acceleration theories. The dearth of acceleration at {approx}85% of the shocks is explained by (1) a low shock speed, (2) a low shock compression ratio, and (3) a low value of the shock-normal angle with the magnetic field, which may cause the energy spectra that roll downward at energies below our observational threshold. Quasi-parallel shock waves are rarely able to produce measurable acceleration at 1 AU. The dependence of intensity on shock speed, seen here at local shocks, mirrors the dependence found previously for the peak intensities in large solar energetic-particle events upon speeds of the associated coronal mass ejections which drive the shocks.

  9. Interplanetary medium data book, supplement 5, 1988-1993

    NASA Technical Reports Server (NTRS)

    King, Joseph H.; Papitashvili, Natalia E.

    1994-01-01

    This publication represents an extension of the series of Interplanetary Medium Data Books and supplements that have been issued by the National Space Science Data Center since 1977. This volume contains solar wind magnetic field and plasma data from the IMP 8 spacecraft for 1988 through the end of 1993. The normalization of the MIT plasma density and temperature, which has been discussed at length in previous volumes, is implemented as before, using the same normalization constants for 1988-1993 data as for the earlier data. Owing to a combination of non-continuity of IMP 8 telemetry acquisition and IMP's being out of the solar wind for about 40 percent of its orbit, the annual solar wind coverage for 1988-1993 is 40 plus or minus 5 percent. The plots and listings of this supplement are in essentially the same format as in previous supplements. Days for which neither IMF nor plasma data were available for any hours are omitted from the listings.

  10. Rotational bursting of interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Paddack, S. J.; Rhee, J. W.

    1976-01-01

    Rotationally induced bursting of interplanetary dust particles by a windmill effect stemming from solar radiation pressure, and eventual elimination of the particles from the solar system, is discussed. A life span on the order of 100,000 years for stony meteoritic material or tektite glass with radii of about 1 cm is arrived at for this process. A life span of a million years is computed for particles containing Fe, Ni, or Al with spin damping effects taken into cognizance. This depletion mechanism operates at a rate two orders of magnitude greater than that of the Poynting-Robertson effect in the case of nonmetallic particles and one order of magnitude greater in the case of metallic particles.

  11. Interplanetary space transport using inertial fusion propulsion

    SciTech Connect

    Orth, C.D.

    1998-04-20

    In this paper, we indicate how the great advantages that ICF offers for interplanetary propulsion can be accomplished with the VISTA spacecraft concept. The performance of VISTA is expected to surpass that from other realistic technologies for Mars missions if the energy gain achievable for ICF targets is above several hundred. Based on the good performance expected from the U. S. National Ignition Facility (NIF), the requirements for VISTA should be well within the realm of possibility if creative target concepts such as the fast ignitor can be developed. We also indicate that a 6000-ton VISTA can visit any planet in the solar system and return to Earth in about 7 years or less without any significant physiological hazards to astronauts. In concept, VISTA provides such short-duration missions, especially to Mars, that the hazards from cosmic radiation and zero gravity can be reduced to insignificant levels. VISTA therefore represents a significant step forward for space-propulsion concepts.

  12. Interplanetary Coronal Mass Ejections detected by HAWC

    NASA Astrophysics Data System (ADS)

    Lara, Alejandro

    The High Altitude Water Cherenkov (HAWC) observatory is being constructed at the volcano Sierra Negra (4100 m a.s.l.) in Mexico. HAWC’s primary purpose is the study of both: galactic and extra-galactic sources of high energy gamma rays. HAWC will consist of 300 large water Cherenkov detectors (WCD), instrumented with 1200 photo-multipliers. The Data taking has already started while construction continues, with the completion projected for late 2014. The HAWC counting rate will be sensitive to cosmic rays with energies above the geomagnetic cutoff of the site (˜ 8 GV). In particular, HAWC will detect solar energetic particles known as Ground Level Enhancements (GLEs), and the effects of Coronal Mass Ejections on the galactic cosmic ray flux, known as Forbush Decreases. In this paper, we present a description of the instrument and its response to interplanetary coronal mass ejections, and other solar wind large scale structures, observed during the August-December 2013 period.

  13. Interplanetary approach optical navigation with applications

    NASA Technical Reports Server (NTRS)

    Jerath, N.

    1978-01-01

    The use of optical data from onboard television cameras for the navigation of interplanetary spacecraft during the planet approach phase is investigated. Three optical data types were studied: the planet limb with auxiliary celestial references, the satellite-star, and the planet-star two-camera methods. Analysis and modelling issues related to the nature and information content of the optical methods were examined. Dynamic and measurement system modelling, data sequence design, measurement extraction, model estimation and orbit determination, as relating optical navigation, are discussed, and the various error sources were analyzed. The methodology developed was applied to the Mariner 9 and the Viking Mars missions. Navigation accuracies were evaluated at the control and knowledge points, with particular emphasis devoted to the combined use of radio and optical data. A parametric probability analysis technique was developed to evaluate navigation performance as a function of system reliabilities.

  14. The WIND magnetic field investigation

    Microsoft Academic Search

    R. P. Lepping; M. H. Ac?na; L. F. Burlaga; W. M. Farrell; J. A. Slavin; K. H. Schatten; F. Mariani; N. F. Ness; F. M. Neubauer; Y. C. Whang; J. B. Byrnes; R. S. Kennon; P. V. Panetta; J. Scheifele; E. M. Worley

    1995-01-01

    The magnetic field experiment on WIND will provide data for studies of a broad range of scales of structures and fluctuation characteristics of the interplanetary magnetic field throughout the mission, and, where appropriate, relate them to the statics and dynamics of the magnetosphere. The basic instrument of the Magnetic Field Investigation (MFI) is a boom-mounted dual triaxial fluxgate magnetometer and

  15. Overview of cosmic rays, solar and interplanetary physics research (1987-1990)

    NASA Technical Reports Server (NTRS)

    Jokipii, J. R.

    1991-01-01

    A brief survey of recent U.S. investigations in the field of heliospheric plasmas and their manifestations is presented, introducing the following collection of detailed reviews (accessions A91-46959 to A91-46964). Topics examined include the large-scale structure of interplanetary plasmas, models of Galactic cosmic-ray production and propagation, solar-wind turbulence, long-period solar-terrestrial variability, the possible relation between solar-neutrino counts and the sunspot cycle, X-ray studies of solar flares and their implications for solar processes, and the near-sun magnetic field.

  16. On the use of Godhavn H component as an indicator of the interplanetary sector polarity

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.

    1975-01-01

    An objective method of inferring the polarity of the interplanetary magnetic field using the H component at Godhavn is presented. The objectively inferred polarities are compared with a subjective index inferred earlier (Svalgaard, 1972b). It is concluded that no significant difference exists between the two methods. The inferred polarities derived from Godhavn H are biased by the Sq-p signature in the sense that during summer, prolonged intervals of geomagnetic calm will result in inferred away polarity regardless of the actual sector polarity. This bias does not significantly alter the large-scale structure of the inferred sector structure.

  17. On the use of Godhavn H-component as an indicator of the interplanetary sector polarity

    NASA Technical Reports Server (NTRS)

    Svalgaard, L.

    1974-01-01

    An objective method of inferring the polarity of the interplanetary magnetic field using the H-component at Godhavn is presented. The objectively inferred polarities are compared with a subjective index inferred earlier. It is concluded that no significant difference exists between the two methods. The inferred polarities derived from Godhavn H is biased by the (slp) sub q signature in the sense that during summer prolonged intervals of geomagnetic calm will result in inferred Away polarity regardless of the actual sector polarity. This bias does not significantly alter the large scale structure of the inferred sector structure.

  18. Energetic particles at interplanetary shock waves - The April 29, 1978 event

    NASA Technical Reports Server (NTRS)

    Richter, A. K.; Hsieh, K. C.; Keppler, E.; Schwenn, R.; Van Hollebeke, M. A. I.; Mcdonald, F. B.; Denskat, K. U.

    1980-01-01

    On April 29, 1978 a low-energetic particle event originating from a 3B flare at N22 E38 was observed by HELIOS 1 at 0.31 AU and W 38 and by HELIOS 2 at 0.29 AU and W 67 simultaneously with an interplanetary shock wave. Using plasma and magnetic field data these shocks were classified; the time variations were examined along with the angular and spectral distributions in the ecliptic plane of the intensities of 80 or more keV ions.

  19. Evidence for confinement of low-energy cosmic rays ahead of interplanetary shock waves.

    NASA Technical Reports Server (NTRS)

    Palmeira, R. A. R.; Allum, F. R.

    1973-01-01

    Short-lived (about 15 min), low-energy proton increases associated with the passage of interplanetary shock waves have been previously reported. In the present paper, we have examined in a fine time scale (about 1 min) the concurrent particle and magnetic field data, taken by detectors on Explorer 34, for four of these events. Our results further support the view that these impulsive events are due to confinement of the solar cosmic-ray particles in the region just ahead (about 1,000,000 km) of the advancing shock front.

  20. Propagation pattern of interplanetary shock waves associated with solar proton flares

    NASA Technical Reports Server (NTRS)

    Sakurai, K.

    1973-01-01

    The two dimensional pattern of interplanetary shock waves is deduced by taking into account the solar longitude dependence of the time intervals between SSC geomagnetic storms and responsible flares. This pattern near the earth's orbit is not symmetric with respect to the meridian plane which crosses the position of the flare, and the highest speed of this wave propagation is observed in the direction about 30 degrees east of this meridian plane. The magnitude of the Forbush decreases of galactic cosmic rays also varies with the longitude positions of those flares. This is used to estimate the distribution of magnetic fields behind the shock waves.

  1. Formation and Development of Shock Waves In The Solar Corona and Interplanetary Space

    NASA Astrophysics Data System (ADS)

    Mann, G.; Klassen, A.; Aurass, H.; Classen, H.-T.

    At the Sun shock waves are produced either by flares or by coronal mass ejections and are regarded to be the source of solar energetic particle events. In the solar corona shock waves appear as type II radio bursts. The propagation of a disturbance away from an active region from the corona into the interplanetary space is considered by evaluating the radial behaviour of the Alfven speed. The magnetic field of an active region is modelled by a magnetic dipole superimposed on that of the quiet Sun. Such a magnetic field structure leads to a local minimum of the Alfvén speed in the middle of the corona and a maximum of 740 km/s at a distance of 3.8 solar radii from the center of the Sun. The occurrence of such a minimum and maximum has important consequences on the formation and development of shock waves in the corona and the interplanetary space and their ability to accelerate particles leading to a special temporal delay of the on-set of solar energetic particle events.

  2. Bulk properties of the slow and fast solar wind and interplanetary coronal mass ejections measured by Ulysses: Three polar orbits of observations

    Microsoft Academic Search

    R. W. Ebert; D. J. McComas; H. A. Elliott; R. J. Forsyth; J. T. Gosling

    2009-01-01

    We examined plasma and magnetic field observations from all three Ulysses polar orbits of the Sun to study the properties of the slow and fast solar wind and interplanetary coronal mass ejections (ICMEs). We derived equations to characterize the radial and latitudinal variations for these three types of heliospheric plasma and identify distinguishing features in their spatial variations. Most notably,

  3. Zodiacal light as an indicator of interplanetary dust

    NASA Technical Reports Server (NTRS)

    Weinberg, J. L.; Sparrow, J. G.

    1978-01-01

    The most striking feature of the night sky in the tropics is the zodiacal light, which appears as a cone in the west after sunset and in the east before sunrise. It is caused by sunlight scattered or absorbed by particles in the interplanetary medium. The zodiacal light is the only source of information about the integrated properties of the whole ensemble of interplanetary dust. The brightness and polarization in different directions and at different colors can provide information on the optical properties and spatial distribution of the scattering particles. The zodiacal light arises from two independent physical processes related to the scattering of solar continuum radiation by interplanetary dust and to thermal emission which arises from solar radiation that is absorbed by interplanetary dust and reemitted mainly at infrared wavelengths. Attention is given to observational parameters of zodiacal light, the methods of observation, errors and absolute calibration, and the observed characteristics of zodiacal light.

  4. Charging kinetics of dust in interplanetary space plasma

    NASA Astrophysics Data System (ADS)

    Misra, Shikha; Mishra, S. K.

    2013-07-01

    A theoretical kinetic model for the physical understanding of the charging of dust particles in the interplanetary space plasma has been developed. In contrast to earlier studies, the present analysis incorporates (i) uniform potential theory for complex plasmas with size distribution of the dust particles, (ii) charge, number and energy balance of the constituents and (iii) appropriate expressions for photoelectric emission from a positively charged particle with inherent charge neutrality of the interplanetary space plasma. Further utilizing the population balance equation (given by Matsoukas and Russel) for the interplanetary dust particles, the fluctuations in steady-state charge (or electric potential) has also been investigated. For the illustration purpose, the computations have been performed for the interplanetary space plasma at 1 au from the sun; for this distance, reasonably good information on the gaseous and dust components are available. As an interesting feature, the theoretical predictions are in reasonably good agreement with observations and earlier estimates.

  5. Circumstellar aluminum oxide and silicon carbide in interplanetary dust particles

    E-print Network

    notions of interplanetary dust particles as the most primitive extraterrestrial material currently of astrophysical research that connects astronomy with the laboratory study of extraterrestrial materials particles (IDPs) are a unique type of extraterrestrial material available for laboratory analysis

  6. Designing An Interplanetary Autonomous Spacecraft Navigation System Using Visible Planets 

    E-print Network

    Karimi, Reza

    2012-07-16

    A perfect duality exists between the problem of space-based orbit determination from line-of-sight measurements and the problem of designing an interplanetary autonomous navigation system. Mathematically, these two problems are equivalent. Any...

  7. TP-planet: a reliable transport protocol for interplanetary Internet

    Microsoft Academic Search

    Özgür B. Akan; Jian Fang; Ian F. Akyildiz

    2004-01-01

    The space exploration missions are crucial for acquisition of information about the space and the universe. The entire success of a mission is directly related to the satisfaction of its communications needs. For this goal, the challenges posed by the InterPlaNetary Internet need to be addressed. Current TCP protocols have very poor performance in the InterPlaNetary Internet which is characterized

  8. Plasma and energetic particle structure upstream of a quasi-parallel interplanetary shock

    NASA Technical Reports Server (NTRS)

    Kennel, C. F.; Scarf, F. L.; Coroniti, F. V.; Russell, C. T.; Wenzel, K.-P.; Sanderson, T. R.; Van Nes, P.; Smith, E. J.; Tsurutani, B. T.; Scudder, J. D.

    1984-01-01

    ISEE 1, 2 and 3 data from 1978 on interplanetary magnetic fields, shock waves and particle energetics are examined to characterize a quasi-parallel shock. The intense shock studied exhibited a 640 km/sec velocity. The data covered 1-147 keV protons and electrons and ions with energies exceeding 30 keV in regions both upstream and downstream of the shock, and also the magnitudes of ion-acoustic and MHD waves. The energetic particles and MHD waves began being detected 5 hr before the shock. Intense halo electron fluxes appeared ahead of the shock. A closed magnetic field structure was produced with a front end 700 earth radii from the shock. The energetic protons were cut off from the interior of the magnetic bubble, which contained a markedly increased density of 2-6 keV protons as well as the shock itself.

  9. Global Magnetospheric Response to an Interplanetary Shock: THEMIS Observations

    NASA Technical Reports Server (NTRS)

    Zhang, Hui; Sibeck, David G.; Zong, Q.-G.; McFadden, James P.; Larson, Davin; Glassmeier, K.-H.; Angelopoulos, V.

    2011-01-01

    We investigate the global response of geospace plasma environment to an interplanetary shock at approx. 0224 UT on May 28, 2008 from multiple THEMIS spacecraft observations in the magnetosheath (THEMIS B and C) and the mid-afternoon (THEMIS A) and dusk magnetosphere (THEMIS D and E). The interaction of the transmitted interplanetary shock with the magnetosphere has global effects. Consequently, it can affect geospace plasma significantly. After interacting with the bow shock, the interplanetary shock transmitted a fast shock and a discontinuity which propagated through the magnetosheath toward the Earth at speeds of 300 km/s and 137 km/s respectively. THEMIS A observations indicate that the plasmaspheric plume changed significantly by the interplanetary shock impact. The plasmaspheric plume density increased rapidly from 10 to 100/ cubic cm in 4 min and the ion distribution changed from isotropic to strongly anisotropic distribution. Electromagnetic ion cyclotron (EMIC) waves observed by THEMIS A are most likely excited by the anisotropic ion distributions caused by the interplanetary shock impact. To our best knowledge, this is the first direct observation of the plasmaspheric plume response to an interplanetary shock's impact. THEMIS A, but not D or E, observed a plasmaspheric plume in the dayside magnetosphere. Multiple spacecraft observations indicate that the dawn-side edge of the plasmaspheric plume was located between THEMIS A and D (or E).

  10. INITIAL RESULTS OF THE IMP I MAGNETIC FIELD EXPERIMENT

    Microsoft Academic Search

    Norman F. Ness; Clell S. Scearce; Joseph B. Seek

    1964-01-01

    The interplanetary monitoring platform Imp 1, or Explorer 18, launched on No- vember 27, 1963, has provided the first accurate measurements of interplanetary magnetic fields. The initial apogee of the satellite was 197,616 km on the sunlit side of the earth, with an apogee-earth-sun angle of 26 ø . This paper presents the initial results of the detailed meas- urements

  11. Rapporteur paper for sessions MG1, MG3 and MG4: Modulation theory, interplanetary propagation and interplanetary acceleration

    NASA Technical Reports Server (NTRS)

    Jones, F. C.

    1983-01-01

    Theories and reported results from investigations of cosmic ray modulation and acceleration are summarized. Aspects considered include microscopic or fundamental theory; gradient and curvature drifts in modulation; and interplanetary acceleration of shocks and particles.

  12. The quiet solar wind. [proton and magnetic properties

    NASA Technical Reports Server (NTRS)

    Neugebauer, M.

    1976-01-01

    Data from nine spacecraft are combined to study the properties of solar wind protons and the interplanetary magnetic field under unusual conditions that proton speed, density, and temperature variations are small over periods comparable to the solar wind expansion time. From the 14 quiet intervals studied it is determined that (1) the square root of T versus velocity relation is less steep than was calculated from long-term-averaged or 3-hour quiet data; (2) the density varies approximately as the inverse square of the velocity; however, the data scatter is large, and an alternative interpretation is that mass flux is constant for velocities over about 400 km/s, in agreement with earlier studies; (3) the magnitude of the interplanetary magnetic field is independent of solar wind speed and density; and (4) the average field direction varies with the solar wind speed as predicted by Parker's spiral model. The intercalibration of solar wind measurements by different spacecraft is discussed in an appendix.

  13. Very intense geomagnetic storms and their relation to interplanetary and solar active phenomena

    NASA Astrophysics Data System (ADS)

    Szajko, N. S.; Cristiani, G.; Mandrini, C. H.; Dal Lago, A.

    2013-05-01

    We revisit previous studies in which the characteristics of the solar and interplanetary sources of intense geomagnetic storms have been discussed. In this particular analysis, using the Dst time series, we consider the very intense geomagnetic storms that occurred during Solar Cycle 23 by setting a value of Dstmin?-200nT as threshold. After carefully examining the set of available solar and in situ observations from instruments aboard the Solar and Heliospheric Observatory (SOHO) and the Advanced Composition Explorer (ACE), complemented with data from the ground, we have identified and characterized the solar and interplanetary sources of each storm. That is to say, we determine the time, angular width, plane-of-the-sky, lateral expansion, and radial velocities of the source coronal mass ejection (CME), the type and heliographic location of the CME solar source region (including the characteristics of the sunspot groups), and the time duration of the associated flare. After this, we investigate the overall characteristics of the interplanetary (IP) main-phase storm driver, including the time arrival of the shock/disturbance at 1 AU, the type of associated IP structure/ejecta, the origin of a prolonged and enhanced southward component (Bs) of the IP field, and other characteristics related to the energy injected into the magnetosphere during the storm (i.e. the solar wind maximum convected electric field, Ey). The analyzed set consists of 20 events, some of these are complex and present two or more Dst minima that are, in general, due to consecutive solar events. The 20 storms are distributed along Solar Cycle 23 (which is a double-peak cycle) in such a way that 15% occurs during the rising phase of the cycle, 45% during both cycle maxima, and, surprisingly, 40% during the cycle descending phase. This latter set includes half of the superstorms and the only cycle extreme event. 85% of the storms are associated to full halo CMEs and 10% to partial halo events. One of the storms occurred at the time contact with SOHO was lost. The CME solar sources of all analyzed storms, but one, are active regions (ARs). The source of the remaining CME is a bipolar low-field region where a long and curved filament erupts. The ARs where the CMEs originate show, in general, high magnetic complexity; ? spots are present in 74% of the ARs, 10% are formed by several bipolar sunspot groups, and only 16% present a single bipolar sunspot group. All CMEs are associated to long duration events (LDEs), exceeding 3 h in all cases, with around 75% lasting more than 5 h. The associated flares are, in general, intense events, classified as M or X in soft X-rays; only 3 of them fall in the C class, with the one happening in the bipolar low field region hardly reaching the C level. We calculate the lateral expansion velocity for most of the CMEs. The values found exceed in all cases but one the fast solar wind speed (?750 km s-1). The average lateral expansion velocity is 2400 km s-1. The spatial distribution of the solar CME sources on the solar disk shows an evident asymmetry; while there are no sources located more eastward than 12° in longitude, there are 7 events more westward than 12°. Nevertheless, the bulk of the solar sources are located near Sun center, i.e. at less than 20° in longitude or latitude. Considering the IP structures responsible for a long and enhanced Bs, we find that 35% correspond to magnetic clouds (MCs) or ICME fields, 30% to sheath fields, and 30% to combined sheath and MC or ICME fields. For only one storm the origin of Bs is related to the back compression of an ICME by a high speed stream coming from a coronal hole in the neighborhood of the corresponding CME source region. We have also found that for this particular set of storms the linear relation between Ey and the storm intensity holds (with a correlation coefficient of 0.73). These results complement and extend those of other works in the literature.

  14. An Average Reynolds Equation for Non-Newtonian Fluid with Application to the Lubrication of the Magnetic Head-Disk Interface©

    Microsoft Academic Search

    Wang-Long Li; Cheng-I Weng; Chi-Chuan Hwang

    1997-01-01

    A closed, form of the average Reynolds equation is derived for non-Newtonian inelastic fluids with roughness effects taken into consideration. The derivation of flow factors is carried out by means of the perturbation approach with Green's function technique. A coordinate transformation is also utilized to make the equations similar with the Newtonian ones. The results of flow factors are expressed

  15. BACODINE/3rd Interplanetary Network burst localization

    SciTech Connect

    Hurley, K.; Barthelmy, S.; Butterworth, P.; Cline, T.; Sommer, M.; Boer, M.; Niel, M.; Kouveliotou, C.; Fishman, G.; Meegan, C. [University of California Space Sciences Laboratory Berkeley, California 94720-7450 (United States); NASA Goddard Space Flight Center Greenbelt, Maryland 20771 (United States); Max-Planck Institut fuer Extraterrestrische Physik, 85740 Garching (Germany); Centre d'Etude Spatiale des Rayonnements, 31029 Toulouse Cedex (France); NASA Marshall Space Flight Center Huntsville, Alabama 35812 (United States)

    1996-08-01

    Even with only two widely separated spacecraft (Ulysses and GRO), 3rd Interplanetary Network (IPN) localizations can reduce the areas of BATSE error circles by two orders of magnitude. Therefore it is useful to disseminate them as quickly as possible following BATSE bursts. We have implemented a system which transmits the light curves of BACODINE/BATSE bursts directly by e-mail to UC Berkeley immediately after detection. An automatic e-mail parser at Berkeley watches for these notices, determines the Ulysses crossing time window, and initiates a search for the burst data on the JPL computer as they are received. In ideal cases, it is possible to retrieve the Ulysses data within a few hours of a burst, generate an annulus of arrival directions, and e-mail it out to the astronomical community by local nightfall. Human operators remain in this loop, but we are developing a fully automated routine which should remove them, at least for intense events, and reduce turn-around times to an absolute minimum. We explain the current operations, the data types used, and the speed/accuracy tradeoffs.

  16. Radioisotopic heater units warm an interplanetary spacecraft

    SciTech Connect

    Franco-Ferreira, E.A. [Oak Ridge National Lab., TN (United States). Engineering Technology Div.; Rinehart, G.H. [Los Alamos National Lab., NM (United States)

    1998-01-01

    The Cassini orbiter and Huygens probe, which were successfully launched on October 15, 1997, constitute NASA`s last grand-scale interplanetary mission of this century. The mission, which consists of a four-year, close-up study of Saturn and its moons, begins in July 2004 with Cassini`s 60 orbits of Saturn and about 33 fly-bys of the large moon Titan. The Huygens probe will descend and land on Titan. Investigations will include Saturn`s atmosphere, its rings and its magnetosphere. The atmosphere and surface of Titan and other icy moons also will be characterized. Because of the great distance of Saturn from the sun, some of the instruments and equipment on both the orbiter and the probe require external heaters to maintain their temperature within normal operating ranges. These requirements are met by Light Weight Radioisotope Heater Units (LWRHUs) designed, fabricated and safety tested at Los Alamos National Laboratory, New Mexico. An improved gas tungsten arc welding procedure lowered costs and decreased processing time for heat units for the Cassini spacecraft.

  17. Raman observations on individual interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Wopenka, Brigitte

    1988-01-01

    A Raman study of 20 representative interplanetary dust particles (IDPs) belonging to different infrared spectral classes is discussed. Six different groups of Raman spectra were discerned among the IDPs studied. Groups 1-5 exhibit the Raman signature of poorly crystallized carbonaceous material, with the degree of disorder of this material increasing from group 1 (most ordered) to group 5 (least ordered). Group 1 contains IDPs that have infrared spectra characteristic of olivines, and are deuterium depleted, while those in groups 2, 3, and 4 contain less ordered carbonaceous material and are deuterium enriched, suggesting different carbonaceous carrier phases for deuterium depletions and enrichments. Groups 5 and 6 contain little or no carbonaceous material, with an abundance of deuterium. No obvious relationship was found between Raman groups and infrared classes based on the 10 micron absorption band due to silicates. Because silicates are known to be present, but are not seen, it is presumed that silicate grains are coated with and/or imbedded in carbonaceous material. Several IDPs show broad visible laser-induced photoluminescence, probably produced by a carbonaceous component.

  18. SIMONE: Interplanetary microsatellites for NEO rendezvous missions

    NASA Astrophysics Data System (ADS)

    Wells, Nigel; Walker, Roger; Green, Simon; Ball, Andrew

    2006-10-01

    The paper summarises a novel mission concept called SIMONE (smallsat intercept missions to objects near Earth), whereby a fleet of microsatellites may be deployed to individually rendezvous with a number of near Earth objects (NEOs), at very low cost. The mission enables, for the first time, the diverse properties of a range of spectral and physical type NEOs to be determined. Such data are invaluable to the scientific study, impact damage prediction, and impact countermeasure planning of NEOs. The five identical 120 kg spacecraft are designed for low-cost piggyback launch on Ariane-5 into GTO, from where each uses a gridded-ion engine to escape the Earth and ultimately to rendezvous with a different NEO target. The primary challenge with such a mission is the ability to accommodate the necessary electric propulsion, power, payload and other on-board systems within the constraints of a microsatellite. The paper describes the way in which the latest technological advancements have been selected and applied to the mission design. The SIMONE design is feasible and clearly demonstrates that the concept of an "interplanetary microsatellite" is now realisable.

  19. SIMONE: interplanetary microsatellites for NEO rendezvous missions

    NASA Astrophysics Data System (ADS)

    Wells, Nigel; Walker, Roger; Green, Simon; Ball, Andrew

    2003-11-01

    The paper summarises a novel mission concept called SIMONE (Smallsat Intercept Missions to Objects Near Earth), whereby a fleet of microsatellites may be deployed to individually rendezvous with a number of Near Earth Objects (NEOs), at very low cost. The mission enables, for the first time, the diverse properties of a range of spectral and physical type NEOs to be determined. Such data are invaluable to the scientific study, impact damage prediction, and impact countermeasure planning of NEOs. The five identical 120kg spacecraft are designed for low-cost piggyback launch on Ariane-5 into GTO, from where each uses a gridded-ion engine to escape the Earth and ultimately to rendezvous with a different NEO target. The primary challenge with such a mission is the ability to accommodate the necessary electric propulsion, power, payload and other onboard systems within the constraints of a microsatellite. The paper describes the way in which the latest technological advancements have been selected and applied to the mission design. The SIMONE design is feasible and clearly demonstrates that the concept of an "interplanetary microsatellite" is now realisable.

  20. Impact Angle Control of Interplanetary Shock Geoeffectiveness

    E-print Network

    Oliveira, D M

    2015-01-01

    We use OpenGGCM global MHD simulations to study the nightside magnetospheric, magnetotail, and ionospheric responses to interplanetary (IP) fa st forward shocks. Three cases are presented in this study: two inclined oblique shocks, here after IOS-1 and IOS-2, where the latter has a Mach number twice stronger than the former. Both shocks have impact angles of 30$^o$ in relation to the Sun-Earth line. Lastly, we choose a frontal perpendicular shock, FPS, whose shock normal is along the Sun-Earth line, with the same Mach number as IOS-1. We find that, in the IOS-1 case, due to the north-south asymmetry, the magnetotail is deflected southward, leading to a mild compression. The geomagnetic activity observed in the nightside ionosphere is then weak. On the other hand, in the head-on case, the FPS compresses the magnetotail from both sides symmetrically. This compression triggers a substorm allowing a larger amount of stored energy in the magnetotail to be released to the nightside ionosphere, resulting in stronger...

  1. Volatiles in interplanetary dust particles and aerogels

    NASA Technical Reports Server (NTRS)

    Gibson, E. K., Jr.; Harmetz, C. P.

    1991-01-01

    Volatiles measured in 25 interplanetary dust particles (IDPs) are a mixture of both indigenous materials and contaminants associated with the collection and processing of the ODPs prior to analysis. Most IDPs have been collected in the stratosphere using a silicone oil/freon mixture (20:1 ratio) coated on collector plates. Studies have shown that silicone oil, freon and hexane residues remain with the ODPs, despite attempts to clean the IDPs. Analysis of the IDPs with the LMMS-technique produces spectra with a mixture of indigeneous and contaminants components. The contamination signal can be identified and removed; however, the contamination signal may obscure some of the indigeneous component's signal. Employing spectra stripping techniques, the indigenous volatile constituents associated with the IDPs can be identified. Volatiles are similar to those measured in CI or CM carbonaceous chondrites. Collection of IDPs in low-Earth orbit utilizing a Cosmic Dust Collection Facility attached to Space Station Freedom has been proposed. The low-density material aerogel has been proposed as a collection substrate for IDPs. Our studies have concentrated on identifying volatile contaminants that are associated with aerogel. We have found that solvents used for the preparation of aerogel remain in aerogel and methods must be developed for removing the entrapped solvents before aerogels can be used for an IDP collection substrate.

  2. Raman observations on individual interplanetary dust particles

    NASA Astrophysics Data System (ADS)

    Wopenka, B.

    1988-05-01

    A Raman study of 20 representative interplanetary dust particles (IDPs) belonging to different infrared spectral classes is discussed. Six different groups of Raman spectra were discerned among the IDPs studied. Groups 1-5 exhibit the Raman signature of poorly crystallized carbonaceous material, with the degree of disorder of this material increasing from group 1 (most ordered) to group 5 (least ordered). Group 1 contains IDPs that have infrared spectra characteristic of olivines, and are deuterium depleted, while those in groups 2, 3, and 4 contain less ordered carbonaceous material and are deuterium enriched, suggesting different carbonaceous carrier phases for deuterium depletions and enrichments. Groups 5 and 6 contain little or no carbonaceous material, with an abundance of deuterium. No obvious relationship was found between Raman groups and infrared classes based on the 10 micron absorption band due to silicates. Because silicates are known to be present, but are not seen, it is presumed that silicate grains are coated with and/or imbedded in carbonaceous material. Several IDPs show broad visible laser-induced photoluminescence, probably produced by a carbonaceous component.

  3. Inward electrostatic precipitation of interplanetary particles

    NASA Technical Reports Server (NTRS)

    Rulison, Aaron J.; Flagan, Richard C.; Ahrens, Thomas J.

    1993-01-01

    An inward precipitator collects particles initially dispersed in a gas throughout either a cylindrical or spherical chamber onto a small central planchet. The instrument is effective for particle diameters greater than about 1 micron. One use is the collection of interplanetary dust particles (IDPs) which are stopped in a noble gas (xenon) by drag and ablation after perforating the wall of a thin-walled spacecraft-mounted chamber. First, the particles are positively charged for several seconds by the corona production of positive xenon ions from inward facing needles placed on the chamber wall. Then an electric field causes the particles to migrate toward the center of the instrument and onto the planchet. The collection time (on the order of hours for a 1 m radius spherical chamber) is greatly reduced by the use of optimally located screens which reapportion the electric field. Some of the electric field lines terminate on the wires of the screens so a fraction of the total number of particles in the chamber is lost. The operation of the instrument is demonstrated by experiments which show the migration of carbon soot particles with radius of approximately 1 micron in a 5 cm diameter cylindrical chamber with a single field enhancing screen toward a 3.2 mm central collection rod.

  4. Origins and Dynamics of Interplanetary Dust Particles

    NASA Technical Reports Server (NTRS)

    Dermott, Stanley F.

    2005-01-01

    This is a final report for research supported by the National Aeronautics and Space Administration issued through the Office of Space Science Planetary Geology and Geophysics Program, covering all relevant activities during its 3-year period of funding from 02/01/2002 through to 01/31/2005. The ongoing aim of the research supported through this grant, and now through a successor award, is to investigate the origin of interplanetary dust particles (IDPs) and their dynamical and collisional evolution, in order to: (1) understand the provenance of zodiacal cloud particles and their transport from their source regions to the inner solar system; (2) produce detailed models of the zodiacal cloud and its constituent components; (3) determine the origin of the dust particles accreted by the Earth; (4) ascertain the level of temporal variations in the dust environment of the inner solar system and the accretion rate of IDPs by the Earth, and evaluate potential effects on global climate; and to (5) exploit this research as a basis for interpreting the structure observed in exozodiacal clouds that may result from the collisional evolution of planetesimals and the presence of unseen planets.

  5. Orientations of LASCO Halo CMEs and Their Connection to the Flux Rope Structure of Interplanetary CMEs

    E-print Network

    V. Yurchyshyn; Q. Hu; R. P. Lepping; B. J. Lynch; J. Krall

    2007-03-23

    Coronal mass ejections (CMEs) observed near the Sun via LASCO coronographic imaging are the most important solar drivers of geomagnetic storms. ICMEs, their interplanetary, near-Earth counterparts, can be detected in-situ, for example, by the Wind and ACE spacecraft. An ICME usually exhibits a complex structure that very often includes a magnetic cloud (MC). They can be commonly modelled as magnetic flux ropes and there is observational evidence to expect that the orientation of a halo CME elongation corresponds to the orientation of the flux rope. In this study, we compare orientations of elongated CME halos and the corresponding MCs, measured by Wind and ACE spacecraft. We characterize the MC structures by using the Grad-Shafranov reconstruction technique and three MC fitting methods to obtain their axis directions. The CME tilt angles and MC fitted axis angles were compared without taking into account handedness of the underlying flux rope field and the polarity of its axial field. We report that for about 64% of CME-MC events, we found a good correspondence between the orientation angles implying that for the majority of interplanetary ejecta their orientations do not change significantly (less than 45 deg rotation) while travelling from the Sun to the near Earth environment.

  6. Quiet-Time Interplanetary Superhalo Electrons at Solar Minimum

    NASA Astrophysics Data System (ADS)

    Wang, Linghua; Lin, Robert; Salem, Chadi; Pulupa, Marc; Larson, Davin; Yoon, Peter; Luhmann, Janet

    2013-04-01

    We present a statistical survey of ~2-20 keV superhalo electrons in the solar wind measured by the SupraThermal Electron (STE) instrument onboard the two STEREO spacecraft, during quiet-time periods from March 2007 through March 2009 at solar minimum. The observed superhalo electrons have a nearly isotropic angular distribution and a power-law spectrum, f ? v-? , with ? ranging from 5 to 8.7, with nearly half between 6.5 and 7.5, and an average index of 6.69±0.90. The observed power-law spectrum varies significantly on a spatial scale of ?0.1 AU and temporal scale of ?days. The integrated density of quiet-time superhalo electrons at 2-20 keV ranges from ~10-8 cm-3 to 10-6 cm-3, about 10-9 -10-6 of the solar wind density and it, as well as the power-law spectrum shows no correlation with solar wind proton density, velocity or temperature. The density of superhalo electrons decreases by approximately one order of magnitude between early 2007 and early 2009, probably reflecting the decay of solar cycle 23 and the approach to its unusually deep activity minimum, while the power-law spectral index ? has no solar-cycle variation. These quiet-time superhalo electrons are present even in the absence of any solar activity, e.g., active regions, flares or microflares, type III radio bursts, etc., suggesting that they may be accelerated by resonant wave-particle interactions in the interplanetary medium, or by nonthermal processes related to the acceleration of the solar wind such as nanoflares.

  7. High resolution three-dimensional brain atlas using an average magnetic resonance image of 40 adult C57Bl\\/6J mice

    Microsoft Academic Search

    A. E. Dorr; J. P. Lerch; S. Spring; N. Kabani; R. M. Henkelman

    2008-01-01

    Detailed anatomical atlases can provide considerable interpretive power in studies of both human and rodent neuroanatomy. Here we describe a three-dimensional atlas of the mouse brain, manually segmented into 62 structures, based on an average of 32 ?m isotropic resolution T2-weighted, within skull images of forty 12 week old C57Bl\\/6J mice, scanned on a 7 T scanner. Individual scans were normalized, registered, and

  8. Plasma-tail activity and the interplanetary medium at Halley's Comet during Armada Week: 6-14 March 1986

    NASA Technical Reports Server (NTRS)

    Niedner, Malcolm B., Jr.; Schwingenschuh, Konrad; Hoeksema, J. Todd; Dryer, Murray; Mcintosh, Patrick S.

    1987-01-01

    The encounters of five spacecraft with Halley's Comet during 6-14 March 1986 offered a unique opportunity to calibrate the solar-wind interaction with cometary plasmas as recorded by remote wide-field and narrow-field/narrowband imaging. Perhaps not generally recognized in the comet community is the additional opportunity offered by the Halley Armada to study the structure of the solar-wind and interplanetary magnetic field (IMF) in three dimensions using five sets of data obtained over similar time intervals and heliocentric distances, but at somewhat different heliolatitudes. In fact, the two problems, i.e., comet physics and the structure of the interplanetary medium, are coupled if one wants to understand what conditions pertained at the comet between the encounters. This relationship is discussed.

  9. Constraints on the average magnetic field strength of relic radio sources 0917+75 and 1401-33 from XMM-Newton observations

    E-print Network

    C. M. Hubert Chen; D. E. Harris; Fiona A. Harrison; Peter H. Mao

    2008-01-01

    We observed two relic radio sources, 0917+75 and 1401-33, with the XMM-Newton X-ray observatory. We did not detect any X-ray emission, thermal or non-thermal, in excess of the local background level from either target. This imposes new upper limits on the X-ray flux due to inverse Compton scattering of photons from the cosmic microwave background by relativistic electrons in the relic sources, and new lower limits on the magnetic field strength from the relative strength of the radio and X-ray emission. The combination of radio and X-ray observations provides a measure of the magnetic field independent of equipartition or minimum energy assumptions. Due to increasing sensitivity of radio observations, the known population of cluster relics has been growing; however, studies of non-thermal X-ray emission from relics remain scarce. Our study adds to the small sample of relics studied in X-rays. In both relics, our field strength lower limits are slightly larger than estimates of the equipartition magnetic field.

  10. A scale-free analysis of magnetic holes in the solar wind

    E-print Network

    Stevens, M. L. (Michael Louis)

    2006-01-01

    Magnetic holes are isolated intervals of depleted interplanetary magnetic field (IMF) strength on timescales of several seconds to several hours. These intervals have been seen as often as several times per day in the ...

  11. Lunar and Planetary Science XXXV: Interplanetary Dust and Aerogel

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Contents include the following: Isotopically Primitive Interplanetary Dust Particles of Cometary Origin: Evidence from Nitrogen Isotopic Compositions. The Solar Nebula s First Accretionary Particles (FAPs) Are They Preserved in Collected Interplanetary Dust Samples? On the Origin of GEMS. An Analytical SuperSTEM for Extraterrestrial Materials Research. Sub-Micrometer Scale Minor Element Mapping in Interplanetary Dust Particles: A Test for Stratospheric Contamination. First Report of Taenite in an Asteroidal Interplanetary Dust Particle: Flash-heating Simulates Nebular Dust Evolution. FTIR Analyses of IDPs: Comparison with the InfraRed Spectra of the Interstellar Medium. Mineralogical Study of Hydrated IDPs: X-Ray Diffraction and Transmission Electron Microscopy. Focused Ion Beam Recovery and Analysis of Interplanetary Dust Particles (IDPs) and Stardust Analogues. Technique for Concentration of Carbonaceous Material from Aerogel Collectors Using HF-Vapor Etching. Synchrotron X-Ray Analysis of Captured Particle Residue in Aerogel. In-Situ Analyses of Earth Orbital Grains Trapped in Aerogel, Using Synchrotron X-Ray Microfluorescence Techniques. Igneous Rims on Micrometeorites and the Sizes of Chondrules in Main Belt Asteroids.

  12. Interplanetary MeV electrons of Jovian origin

    NASA Technical Reports Server (NTRS)

    Teegarden, B. J.; Mcdonald, F. B.; Trainor, J. H.; Webber, W. R.; Roelof, E. C.

    1974-01-01

    Observations of low energy electron increases observed in interplanetary space on Pioneer 10 are reported as it approached Jupiter. These discrete bursts were several hundred times the normal quiet-time electron flux, and became more frequent as one approached Jupiter resulting in the quasi-continuous presence of large fluxes of these electrons in interplanetary space. It is noted that the integrated flux from quiet-time electrons is comparable to the integrated ambient electron flux itself. In addition, the spectrum of electrons observed in Jupiter's magnetosphere, on Pioneer 10 in interplanetary space near Jupiter, for the quiet-time increases near the earth, and for the ambient electron spectrum are all remarkably similar. These two lines of evidence suggest the possibility that Jupiter could be the source of most of the ambient electrons at low energies.

  13. Largest geomagnetic sudden commencement (SC) and interplanetary shock

    NASA Astrophysics Data System (ADS)

    Araki, Tohru

    2015-04-01

    The long term variation of amplitude of geomagnetic sudden commencements (SCs) is examined by checking old magnetograms at Kakioka (27.5 deg. geomagnetic latitude) and Alibag (10.3 deg.) and SC lists prepared by both stations. We found that the SC occurred on March 24, 1940 was largest since 1868. The amplitude is 310 nT at Alibag and larger than 273 nT at Kakioka. The magnetogram of Cape Town (-33.3 deg) was also available for this event which shows 164 nT amplitude. This SC occurred during the main phase of a large magnetic storm which has been interested as one of space weather events. The statistical analysis shows that the occurrence probability is less than 5 % for SCs with amplitude larger than 50 nT and less than 1 % for SCs larger than 100 nT at both Kakioka and Alibag. Large amplitude SCs tend to occur in the declining phase of the sun spot cycle as is reported for magnetic storms. Siscoe et al. (1968) firstly proposed the relationship for the solar wind dynamic pressure P and SC amplitude, dH as dH = C*d(P^0.5) where d(P^0.5) shows a jump of the square root of P associated with interplanetary shocks. If we take the proportionality constant C as 15 nT/(nPa)^0.5 and the 300 nT SC amplitude (dH) needs pressure jump from 2 nPa (assumed dynamic pressure in front of the shock) to 460 nPa. If the non-linear effect for magnetospheric compression is taken into account, a larger dynamic pressure will be needed for this large amplitude SC. On the other hand, the proportionality constant, C, might become larger for larger amplitude SC because C includes effects of electric currents induced in the earth. Larger amplitude SCs have larger time variation rate by which C becomes larger and the required dynamic pressure increase becomes smaller. We do not know which of the two competing processes is dominant but we consider that the linear estimation of the required dynamic pressure described above may be valid as the first order approximation.

  14. Optical spectroscopy of interplanetary dust collected in the earth's stratosphere

    NASA Technical Reports Server (NTRS)

    Fraundorf, P.; Patel, R. I.; Shirck, J.; Walker, R. M.; Freeman, J. J.

    1980-01-01

    Optical absorption spectra of interplanetary dust particles 2-30 microns in size collected in the atmosphere at an altitude of 20 km by inertial impactors mounted on NASA U-2 aircraft are reported. Fourier transform absorption spectroscopy of crushed samples of the particles reveals a broad feature in the region 1300-800 kaysers which has also been found in meteorite and cometary dust spectra, and a weak iron crystal field absorption band at approximately 9800 kaysers, as is observed in meteorites. Work is currently in progress to separate the various components of the interplanetary dust particles in order to evaluate separately their contributions to the absorption.

  15. Congestion Avoid Movement Aware Routing Protocol in Interplanetary Backbone Networks

    NASA Astrophysics Data System (ADS)

    Sun, Haoliang; Hu, Xiaohui; Liu, Lixiang

    The existing routing protocols for the interplanetary backbone network did not consider future link connection and link congestion. A novel routing protocol named CAMARP for the interplanetary backbone network is proposed in this letter. We use wait delay to consider future link connection and make the best next hop selection. A load balancing mechanism is used to avoid congestion. The proposed method leads to a better and more efficient distribution of traffic, and also leads to lower packet drop rates and higher throughput. CAMARP demonstrates good performance in the experiment.

  16. Particle acceleration by coronal and interplanetary shock waves

    NASA Technical Reports Server (NTRS)

    Pesses, M. E.

    1982-01-01

    Utilizing many years of observation from deep space and near-earth spacecraft a theoretical understanding has evolved on how ions and electrons are accelerated in interplanetary shock waves. This understanding is now being applied to solar flare-induced shock waves propagating through the solar atmosphere. Such solar flare phenomena as gamma-ray line and neutron emissions, interplanetary energetic electron and ion events, and Type II and moving Type IV radio bursts appear understandable in terms of particle acceleration in shock waves.

  17. Jupiter Icy Moons Orbiter interplanetary injection period analysis

    NASA Technical Reports Server (NTRS)

    Kowalkowski, Theresa D.; Kangas, Julie A.; Parcher, Daniel W.

    2006-01-01

    This paper investigates the sensitivity of the planned Jupiter Icy Moons Orbiter mission to variations in interplanetary injection date, magnitude, and direction, starting in a low-Earth assembly orbit. These results are used to determine the frequency and number of injection opportunities from a processing assembly obit. It is shown that the use of a low-thrust propulsion system with a nuclear-electric power source would allow the interplanetary trajectory performance to be relatively insensitive to variations in injection conditions. This result yields many injection opportunities due to the long injection period and consecutive orbits with favorable geometry.

  18. Solar photoionization as a loss mechanism of neutral interstellar hydrogen in interplanetary space

    NASA Technical Reports Server (NTRS)

    Ogawa, H. S.; Wu, C. Y. Robert; Gangopadhyay, P.; Judge, D. L.

    1995-01-01

    Two primary loss mechanisms of interstellar neutral hydrogen in interplanetary space are resonance charge exchange ionization with solar wind protons and photoionization by solar EUV radiation. The later process has often been neglected since the average photoionization rate has been estimated to be as much as 5 to 10 times smaller than the charge exchange rate. These factors are based on ionization rates from early measurements of solar EUV and solar wind fluxes. Using revised solar EUV and solar wind fluxes measured near the ecliptic plane we have reinvestigated the ionization rates of interplanetary hydrogen. The result of our analysis indicates that indeed the photoionization rate during solar minimum can be smaller than charge exchange by a factor of 5; however, during solar maximum conditions when solar EUV fluxes are high, and solar wind fluxes are low, photoionization can be over 60% of the charge exchange rate at Earth orbit. To obtain an accurate estimate of the importance of photoionization relative to charge exchange, we have included photoionization from both the ground and metastable states of hydrogen. We find, however, that the photoionization from the metastable state does not contribute significantly to the overall photoionization rate.

  19. Carbon abundances, major element chemistry, and mineralogy of hydrated interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Keller, L. P.; Thomas, K. L.; Mckay, D. S.

    1993-01-01

    Hydrated interplanetary dust particles (IDP's) comprise a major fraction of the interplanetary dust particles collected in the stratosphere. While much is known about the mineralogy and chemistry of hydrated IDP's, little is known about the C abundance in this class of IDP's, the nature of the C-bearing phases, and how the C abundance is related to other physical properties of hydrated IDP's. Bulk compositional data (including C and O) for 11 hydrated IDP's that were subsequently examined by the transition electron microscopy (TEM) to determine their mineralogy and mineral chemistry are reported. Our analysis indicates that these hydrated IDP's are strongly enriched in C relative to the most C-rich meteorites. The average abundance of C in these hydrated IDP's is 4X CI chondrite values. The bulk compositions (including C and O) of 11 hydrated IDP's were determined by thin-window, energy-dispersive x ray (EDX) spectroscopy of the uncoated IDP's on Be substrates in the scanning electron microscopy (SEM). As a check on our C measurements, one of the IDP's (L2006H5) was embedded in glassy S, and microtome thin sections were prepared and placed onto Be substrates. Thin-film EDX analyses of multiple thin sections of L2006H5 show good agreement with the bulk value determined in the SEM. Following EDX analysis, the mineralogy and mineral chemistry of each IDP was determined by analyzing ultramicrotome thin sections in a TEM equipped with an EDX spectrometer.

  20. Conceptual Design For Interplanetary Spaceship Discovery

    NASA Astrophysics Data System (ADS)

    Benton, Mark G.

    2006-01-01

    With the recently revived national interest in Lunar and Mars missions, this design study was undertaken by the author in an attempt to satisfy the long-term space exploration vision of human travel ``to the Moon, Mars, and beyond'' with a single design or family of vehicles. This paper describes a conceptual design for an interplanetary spaceship of the not-to-distant future. It is a design that is outwardly similar to the spaceship Discovery depicted in the novel ``2001 - A Space Odyssey'' and film of the same name. Like its namesake, this spaceship could one day transport a human expedition to explore the moons of Jupiter. This spaceship Discovery is a real engineering design that is capable of being implemented using technologies that are currently at or near the state-of-the-art. The ship's main propulsion and electrical power are provided by bi-modal nuclear thermal rocket engines. Configurations are presented to satisfy four basic Design Reference Missions: (1) a high-energy mission to Jupiter's moon Callisto, (2) a high-energy mission to Mars, (3) a low-energy mission to Mars, and (4) a high-energy mission to the Moon. The spaceship design includes dual, strap-on boosters to enable the high-energy Mars and Jupiter missions. Three conceptual lander designs are presented: (1) Two types of Mars landers that utilize atmospheric and propulsive braking, and (2) a lander for Callisto or Earth's Moon that utilizes only propulsive braking. Spaceship Discovery offers many advantages for human exploration of the Solar System: (1) Nuclear propulsion enables propulsive capture and escape maneuvers at Earth and target planets, eliminating risky aero-capture maneuvers. (2) Strap-on boosters provide robust propulsive energy, enabling flexibility in mission planning, shorter transit times, expanded launch windows, and free-return abort trajectories from Mars. (3) A backup abort propulsion system enables crew aborts at multiple points in the mission. (4) Clustered NTR engines provide ``engine out'' redundancy. (5) The design efficiently implements galactic cosmic ray shielding using main propellant liquid hydrogen. (6) The design provides artificial gravity to mitigate crew physiological problems on long-duration missions. (7) The design is modular and can be launched using the proposed upgrades to the Evolved Expendable Launch Vehicles or Shuttle-derived heavy lift launch vehicles. (8) High value modules are reusable for Mars and Lunar missions. (9) The design has inherent growth capability, and can be tailored to satisfy expanding mission requirements to enable an in-family progression ``to the Moon, Mars, and beyond.''

  1. Reflectance spectroscopy of interplanetary dust particles

    NASA Astrophysics Data System (ADS)

    Bradley, J. P.; Keller, L. P.; Brownlee, D. E.; Thomas, K. L.

    1996-05-01

    Reflectance spectra were collected from chondritic interplanetary dust particles (IDPs), a polar micrometeorite, Allende (CV3) meteorite matrix, and mineral standards using a microscope spectrophotometer. Data were acquired over the 380-1100 nm wavelength range in darkfield mode using a halogen light source, particle aperturing diaphrams, and photomultiplier tube (PMT) detectors. Spectra collected from titanium oxide (Ti4O7), magnetite (Fe3O4), and Allende matrix establish that it is possible to measure indigenous reflectivities of micrometer-sized (>5 ?m in diameter) particles over the visible (VIS) wavelength range 450-800 nm. Below 450 nm, small particle effects cause a fall-off in signal into the ultraviolet (UV). Near-infrared (IR) spectra collected from olivine and pyroxene standards suggest that the ˜1 ?m absorption features of Fe-bearing silicates in IDPs can be detected using microscope spectrophotometry. Chondritic IDPs are dark objects (<15% reflectivity) over the VIS 450-800 nm range. Large (>1 ?m in diameter) embedded and adhering single mineral grains make IDPs significantly brighter, while surficial magnetite formed by frictional heating during atmospheric entry makes them darker. Most chondritic smooth (CS) IDPs, dominated by hydrated layer silicates, exhibit generally flat spectra with slight fall-off towards 800 nm, which is similar to type CI and CM meteorites and main-belt C-type asteroids. Most chondritic porous (CP) IDPs, dominated by anhydrous silicates (pyroxene and olivine), exhibit generally flat spectra with a slight rise towards 800 nm, which is similar to outer P and D asteroids. The most C-rich CP IDPs rise steeply towards 800 nm with a redness comparable to that of the outer asteroid object Pholus (Binzel, 1992). Chondritic porous IDPs are the first identified class of meteoritic materials exhibiting spectral reflectivities (between 450 and 800 nm) similar to those of P and D asteroids. Although large mineral grains, secondary magnetite, and small particle effects complicate interpretation of IDP reflectance spectra, microscope spectrophotometry appears to offer a rapid, nondestructive technique for probing the mineralogy of IDPs, comparing them with meteorites, investigating their parent body origins, and identifying IDPs that may have been strongly heated during atmospheric entry.

  2. Relationship of Interplanetary Shock Micro and Macro Characteristics: A Wind Study

    NASA Technical Reports Server (NTRS)

    Szabo, Adam; Koval, A

    2008-01-01

    The non-linear least squared MHD fitting technique of Szabo 11 9941 has been recently further refined to provide realistic confidence regions for interplanetary shock normal directions and speeds. Analyzing Wind observed interplanetary shocks from 1995 to 200 1, macro characteristics such as shock strength, Theta Bn and Mach numbers can be compared to the details of shock micro or kinetic structures. The now commonly available very high time resolution (1 1 or 22 vectors/sec) Wind magnetic field data allows the precise characterization of shock kinetic structures, such as the size of the foot, ramp, overshoot and the duration of damped oscillations on either side of the shock. Detailed comparison of the shock micro and macro characteristics will be given. This enables the elucidation of shock kinetic features, relevant for particle energization processes, for observations where high time resolution data is not available. Moreover, establishing a quantitative relationship between the shock micro and macro structures will improve the confidence level of shock fitting techniques during disturbed solar wind conditions.

  3. Diffusive Shock Acceleration of High-energy Charged Particles at Fast Interplanetary Shocks: A Parameter Survey

    NASA Astrophysics Data System (ADS)

    Giacalone, Joe

    2015-01-01

    We present results from numerical simulations of the acceleration of solar energetic particles (SEPs) associated with strong, fast, and radially propagating interplanetary shocks. We focus on the phase of the SEP event at the time of the shock passage at 1 AU, which is when the peak intensity at energies below a few MeV is the highest. The shocks in our study start between 2 and 10 solar radii and propagate beyond 1 AU. We study the effect of various shock and particle input parameters, such as the spatial diffusion coefficient, shock speed, solar wind speed, initial location of the shock, and shock deceleration rate, on the total integrated differential intensity, I, of SEPs with kinetic energies > 10 MeV. I is the integral over energy of the differential intensity spectrum at the time of the shock passage at 1 AU. We find that relatively small changes in the parameters can lead to significant event-to-event changes in I. For example, a factor of 2 increase in the diffusion coefficient at a given energy and spatial location, can lead to a decrease in I by as much as a factor of 50. This may help explain why there are fewer large SEP events seen during the current solar maximum compared to previous maxima. It is known that the magnitude of the interplanetary magnetic field is noticeably weaker this solar cycle than it was in the previous cycle and this will naturally lead to a somewhat larger diffusion coefficient of SEPs.

  4. Use of magnetic sails for advanced exploration missions

    NASA Technical Reports Server (NTRS)

    Andrews, Dana G.; Zubrin, Robert M.

    1990-01-01

    The magnetic sail, or magsail, is a field effect device which interacts with the ambient solar wind or interstellar medium over a considerable volume of space to generate drag and lift forces. Two theories describing the method of thrust generation are analyzed and data results are presented. The techniques for maintaining superconductor temperatures in interplanetary space are analyzed and low risk options presented. Comparisons are presented showing mission performance differences between currently proposed spacecraft using chemical and electric propulsion systems, and a Magsail propelled spacecraft capable of generating an average thrust of 250 Newtons at a radius of one A.U. The magsail also provides unique capabilities for interstellar missions, in that at relativistic speeds the magnetic field would ionize and deflect the interstellar medium producing a large drag force. This would make it an ideal brake for decelerating a spacecraft from relativistic speeds and then maneuvering within the target star system.

  5. Bi-directional streaming of solar wind electrons greater than 80 eV - ISEE evidence for a closed-field structure within the driver gas of an interplanetary shock

    NASA Technical Reports Server (NTRS)

    Bame, S. J.; Asbridge, J. R.; Feldman, W. C.; Gosling, J. T.; Zwickl, R. D.

    1981-01-01

    In near time coincidence with the arrival of helium enriched plasma driving the shock wave disturbance of November 12-13, 1978, strong bi-directional streaming of solar wind electrons greater than about 80 eV was observed with Los Alamos instrumentation on ISEE 3. The streaming persisted for many hours simultaneously parallel and anti-parallel to the interplanetary magnetic field which was directed roughly perpendicular to the sun-satellite line. This example of bidirectional streaming cannot be explained by field line connection to the earth's bow shock or the outward propagating interplanetary shock which passed ISEE 3 approximately 16 hours earlier. The event is explained if the local interplanetary field was a part of a magnetic bottle rooted at the sun or a disconnected loop propagating outward.

  6. Congestion Aware Routing Strategies for DTN-Based Interplanetary Networks

    Microsoft Academic Search

    Igor Bisio; Mario Marchese; Tomaso De Cola

    2008-01-01

    The networking and communication challenges posed by interplanetary environments make the design and the deployment of complex telecommunication infrastructures particularly difficult, especially with regard to routing and congestion control issues. To this end, the paper proposes a congestion-aware routing paradigm that applies multi attribute decision making (MADM) concepts for next-hop selection, by formulating an optimisation problem and proposing some possible

  7. DESIGN AND TEST OF A BREADBOARD INTERPLANETARY LASER TRANSPONDER

    Microsoft Academic Search

    John Degnan; Jan McGarry; Phillip Dabney; Thomas Zagwodzki; Michael Tierney; Matthew Weatherly

    2000-01-01

    At the last SLR Workshop in Shanghai, the feasibility of an asynchronous (i.e. independently firing) interplanetary laser transponder, capable of ranging between Earth and Mars and using the automated SLR2000 system as an Earth base station, was suggested. Since that time, we have received a small amount of discretionary funding to further explore the transponder concept and to develop and

  8. Solar flare neutron fluxes derived from interplanetary charged particle measurements

    Microsoft Academic Search

    P. Evenson; R. Kroeger; P. Meyer; D. Muller

    1983-01-01

    The first observation of interplanetary protons produced by the decay of solar neutrons made by Evenson et al. (1983) after a solar flare which occurred on June 3, 1982, is expanded, extending the measurement of the spectrum of the decay protons to higher energy. The spectrum of the decay protons for the June 21, 1980, neutron event observed by Chupp

  9. A Mathematical Model for Interplanetary Logistics Ms. Christine Taylor

    E-print Network

    de Weck, Olivier L.

    A Mathematical Model for Interplanetary Logistics Ms. Christine Taylor Research Assistant. A primary question for space exploration mission design is how to best design the logistics re- quired to sustain the exploration initiative. Using terrestrial logistics modeling tools that have been extended

  10. Towards an interplanetary internet: a proposed strategy for standardization

    NASA Technical Reports Server (NTRS)

    Hooke, A. J.

    2002-01-01

    This paper reviews the current set of standard data communications capabilities that exist to support advanced missions, discusses the architectural concepts for the future Interplanetary Internet, and suggests how a standardized set of space communications protocols that can grow to support future scenarios where human intelligence is widely distributed across the Solar System.

  11. Applications of presently planned interplanetary missions to testing gravitational theories

    NASA Technical Reports Server (NTRS)

    Friedman, L. D.

    1971-01-01

    A summary of the probable interplanetary missions for the 1970's is presented, which may prove useful in testing the general theory of relativity. Mission characteristics are discussed, as well as instrumentation. This last includes a low-level accelerometer and S-/X-band transponders and antennas.

  12. The impact of ion propulsion on high energy interplanetary missions

    Microsoft Academic Search

    David G Feam

    1995-01-01

    Interplanetary science missions often require a significant on-board propulsive capability, which results in the need to carry large quantities of propellant. This reduces possible payload mass, or increases the overall size, mass and cost of the mission. Ion propulsion offers an attractive means of avoiding these large propellant masses associated with chemical propulsion systems. Indeed, if a spiral orbit-raising approach

  13. Radiation Protection for Manned Interplanetary Missions - Radiation Sources, Risks, Remedies

    Microsoft Academic Search

    R. Facius; G. Reitz

    2006-01-01

    Health risks in interplanetary explorative missions differ in two major features significantly from those during the manned missions experienced so far. For one, presently available technologies lead to durations of such missions significantly longer than so far encountered - with the added complication that emergency returns are ruled out. Thus radiation exposures and hence risks for late radiation sequelae like

  14. Interplanetary space-A new laboratory for rarefied gas dynamics

    NASA Technical Reports Server (NTRS)

    Spreiter, J. R.; Rizzi, A. R.

    1974-01-01

    Interplanetary space provides simultaneously the best vacuum available to man and, because of the solar wind, a tenuous and unsteady high-speed outflow of predominantly hydrogen gas from the sun, a remarkable variety of rarefied gasdynamics phenomena, to observe. A review is provided of these phenomena, and of the way in which the present level of understanding has been achieved.

  15. Accretion of Interplanetary Dust Particles by the Earth

    Microsoft Academic Search

    Stephen J. Kortenkamp; Stanley F. Dermott

    1998-01-01

    Analyses of hypervelocity micrometeoroid impact craters preserved in lunar material and on the panels of the Long Duration Exposure Facility (LDEF) indicate that each year Earth accretes about 3 x 10^7 kg of interplanetary dust particles (IDPs) from the zodiacal cloud (E. Grun et al. 1985, Astron. Astrophys. 286, 915-924 S. G. Love and D. E. Brownlee, 1993, Science 262,

  16. Space Travel is Utter Bilge: Early Ideas on Interplanetary Exploration

    Microsoft Academic Search

    D. K. Yeomans

    2003-01-01

    Until a few decades ago, interplanetary travel was the stuff of dreams but the dreamers often turned out to be farsighted while the predictions of some eminent scientists were far too conservative. The prescient dreamers include the Russian schoolteacher, Konstanin Tsiolkovsky who, in 1883, was the first to note that only rockets could serve the needs of space travel. In

  17. The outer magnetic field

    NASA Technical Reports Server (NTRS)

    Hoeksema, J. T.; Suess, S. T.

    1990-01-01

    The magnetic field of the sun extends outward through the photosphere into the corona. The resulting coronal and interplanetary magnetic fields therefore respond to and evolve with the solar cycle, as well as on shorter and longer time scales. These fields are modeled using photospheric magnetic field observations under the assumption that the coronal field is current free, becomes radial at a 'source surface' placed at 2.5 solar radii from the center of the sun, and is passively advected by the solar wind beyond the source surface. This review covers the computation of such models and their applications to characterize the morphology, evolution, and rotation of coronal and interplanetary magnetic fields using data collected between 1976 and the present at the Wilcox Solar Observatory.

  18. Variability in Martian magnetic field topology

    NASA Astrophysics Data System (ADS)

    Brain, D. A.; Halekas, J. S.; Eastwood, J. P.; Ulusen, D.; Lillis, R. J.

    2013-12-01

    Martian crustal magnetic fields form localized mini-magnetosphere structures that extend in some regions well above the Martian ionosphere, interacting directly with the draped external interplanetary magnetic field (IMF). In some regions the crustal magnetic field lines are closed, locally shielding the ionosphere from external plasma. In other locations the crustal field lines are open, allowing exchange of plasma between the ionosphere and the surrounding plasma interaction region. The average magnetic topology as a function of geographic location has been mapped previously, using ~7 years of Mars Global Surveyor electron observations recorded at constant altitude and local time. In this previous work, pitch angle distributions of suprathermal electrons were examined for the presence of loss cones to determine whether field lines were open or closed. Here we apply the same technique to describe how magnetic topology varies with four external drivers: solar wind pressure, IMF orientation, solar EUV flux, and Martian season. We see that some locations on Mars change topology frequently depending upon external conditions, while others have a relatively static field topology.

  19. Interplanetary acceleration of coronal mass ejections

    Microsoft Academic Search

    N. Gopalswamy; A. Lara; R. P. Lepping; M. L. Kaiser; D. Berdichevsky; O. C. St. Cyr

    2000-01-01

    Using an observed relation between speeds of CMEs near the Sun and in the solar wind, we determine an ``effective'' acceleration acting on the CMEs. We found a linear relation between this effective acceleration and the initial speed of the CMEs. The acceleration is similar to that of the slow solar wind in magnitude. The average solar wind speed naturally

  20. Planetary Science Decadal Survey White Paper: Interplanetary Dust

    NASA Astrophysics Data System (ADS)

    Espy, Ashley J.; Graps, A.; Altobelli, N.; Blum, J.; Brownlee, D.; Campins, H.; Close, S.; Cooke, W.; Dermott, S.; Drolshagen, G.; Grün, E.; Hamilton, D.; Horányi, M.; Hedman, M.; Jenniskens, P.; Kehoe, T.; Kortenkamp, S.; Krüger, H.; Kuchner, M.; Liou, J.; Lisse, C.; Madsen, G.; Mann, I.; May, B.; Meyer-Vernet, N.; Nesvorny, D.; Palumbo, P.; Reach, W.; Russell, C.; Srama, R.; Sykes, M.; Trigo-Rodríguez, J.; Vaubaillon, J.; Weaver, H.; Zolensky, M.

    2009-12-01

    The goal of the interplanetary dust decadal survey white paper is to define the main questions facing the field over the next 10 years and determine what focus of reasearch, technology, and mission resources will best address these questions. Interplanetary dust particles (IDPs), largely collected near the Earth's orbit and on the Earth itself, represent the most inexpensive sample return mission from a diversity of targets. The work in this field will thus focus on the collection and analysis of these particles (which yield information on the sources producing them), and the use of observations and dynamically modeling of the dust cloud (which helps link the IDPs to their sources). The main science questions in the study of interplanetary dust that will guide research efforts are as follows: What is the detailed composition of interplanetary dust? How are interplanetary dust particles generated, how do they evolve dynamically, and what are the dominant loss mechanisms? What are the relative contributions of dust particles from each source to the zodiacal cloud as a whole? What is the global structure of the cloud and how does it compare to exo-zodiacal clouds? In order to address these main science questions, the community needs continued R&A support of investigations into the nature of dust in the solar system. Specific areas of focus for research and technology support are: continued collection and analysis IDPs, support for ground- and space-based observing facilities and instruments, support for dynamical modeling, and support for development of technologies for improvement in IDP collection and analysis. Mission emphasis over the next decade is on New Frontiers or Flagship-class missions to the outer solar system ? with instruments capable of studying the outer cloud and Discovery class near-Earth space facilities to take advantage of the full range of IDPs in the vicinity.

  1. INTERPLANETARY ASPECTS OF CMES David F. Webb

    E-print Network

    Webb, David F.

    (Burlaga and Russell, 2001), from the ACE and Wind spacecraft near Earth and Ulysses, NEAR, Nozomi by other SOHO coronal instruments, especially EIT, UVCS and CDS, and the TRACE and Yohkoh spacecraft The coronal magnetic elds and plasma from CMEs can be detected by remote sensing and in-situ spacecraft

  2. Seed population for about 1 MeV per nucleon heavy ions accelerated by interplanetary shocks

    NASA Technical Reports Server (NTRS)

    Tan, L. C.; Mason, G. M.; Klecker, B.; Hovestadt, D.

    1989-01-01

    Data obtained between 1977 and 1982 by the ISEE 1 and ISEE 3 satellites on the composition of heavy ions of about 1 MeV per nucleon, accelerated in interplanetary shock events which followed solar flare events, are examined. It was found that the average relative abundances for C, O, and Fe in the shock events were very close to those found for energetic ions in the solar flares, suggesting that, at these energies, the shock accelerated particles have the solar energetic particles as their seed population. This hypothesis is supported by the fact that the Fe/O ratio in the solar particle events is very strongly correlated with the Fe/O ratio in associated diffusive shock events.

  3. Interplanetary material as a guide to the composition of interstellar grains

    NASA Astrophysics Data System (ADS)

    Jones, A. P.; Williams, D. A.

    1987-01-01

    A compositional model for interstellar magnesium-iron silicate and iron-containing grains is derived under the constraint of elemental depletions, and using the composition of primitive solar system material as a paradigm of the interstellar particles. The solar system material invoked includes both chondritic porous aggregate interplanetary dust particles and unequilibrated ordinary chondritic meteorites. It is shown that the interstellar silicate grains are olivine rich (olivine-to-pyroxene grain mass ratio of greater than 0.8) and are iron rich (magnesium-to-iron atomic ratio of greater than 0.65). Iron not incorporated into silicates is assumed to be depleted into the iron sulphide pyrrhotite which makes up less than 6 percent of the refractory grain mass. The inclusion of grains of this magnetic sulphide into aggregate interstellar grains can explain the alignment of the grains responsible for the polarization in the visual.

  4. A temporary earth co-orbital linked to interplanetary field enhancements

    NASA Astrophysics Data System (ADS)

    Connors, M.; Russell, C. T.; Lai, H. R.

    2014-09-01

    Near-Earth asteroid 138175 (2000 EE104) will soon be temporarily resonant with Earth, but has a much longer residence in an orbit which features a trapping behaviour with frequent Earth and Venus encounters. The object has been identified as a possible source of material for interplanetary field enhancements, a magnetic phenomenon in the solar wind inferred to be due to dust arising from secondary collisions with 10-m scale objects injected into its path. Its horseshoe libration will be reversed by a very close encounter with Venus in 2251 CE. We characterize the orbit of this asteroid, model the dispersion of the primary collision products along its path, and discuss the non-gravitational motion of secondary dust in the solar wind.

  5. Consequences of using nonlinear particle trajectories to compute spatial diffusion coefficients. [for cosmic ray propagation in interstellar and interplanetary space

    NASA Technical Reports Server (NTRS)

    Goldstein, M. L.

    1977-01-01

    In a study of cosmic ray propagation in interstellar and interplanetary space, a perturbed orbit resonant scattering theory for pitch angle diffusion in a slab model of magnetostatic turbulence is slightly generalized and used to compute the diffusion coefficient for spatial propagation parallel to the mean magnetic field. This diffusion coefficient has been useful for describing the solar modulation of the galactic cosmic rays, and for explaining the diffusive phase in solar flares in which the initial anisotropy of the particle distribution decays to isotropy.

  6. Interplanetary particles and fields, November 22 - December 6, 1977: Helios, Voyager, and IMP observations between 0.6 AU and 1.6 AU

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Lepping, R. P.; Weber, R.; Armstrong, T.; Goodrich, C.; Sullivan, J.; Gurnett, D.; Kellogg, P.; Keppler, E.; Mariani, F.

    1979-01-01

    The principal interplanetary events observed are described and analyzed. Three flow systems were observed: (1) a corotating stream and a stream interface associated with a coronal hole; (2) a shock wave and an energetic particle event associated with a 2-B flare; and (3) an isolated shock wave of uncertain origin. Data from 28 experiments and 6 spacecraft provide measurements of solar wind plasma, magnetic fields, plasma waves, radio waves, energetic electrons, and low energy protons.

  7. Formation and development of shock waves in the solar corona and the near-Sun interplanetary space

    NASA Astrophysics Data System (ADS)

    Mann, G.; Klassen, A.; Aurass, H.; Classen, H.-T.

    2003-03-01

    At the Sun, shock waves are produced either by flares and/or by coronal mass ejections (CMEs) and are regarded as the source of solar energetic particle events. They can be able to generate solar type II radio bursts. The non-radial propagation of a disturbance is considered away from an active region through the corona into the interplanetary space by evaluating the spatial behaviour of the Alfvén speed. The magnetic field of an active region is modelled by a magnetic dipole superimposed on that of the quiet Sun. Such a magnetic field structure leads to a local minimum of the Alfvén speed in the range 1.2-1.8 solar radii in the corona as well as a maximum of 740 km s-1 at a distance of 3.8 solar radii. The occurrence of such local extrema has important consequences for the formation and development of shock waves in the corona and the near-Sun interplanetary space and their ability to accelerate particles. It leads to a temporal delay of the onset of solar energetic particle events with respect to both the initial energy release (flare) and the onset of the solar type II radio burst.

  8. The Interplanetary Internet: A Communications Infrastructure for Mars Exploration

    NASA Astrophysics Data System (ADS)

    Burleigh, S.; Cerf, V.; Durst, R.; Fall, K.; Hooke, A.; Scott, K.; Weiss, H.

    2002-01-01

    A successful program of Mars Exploration will depend heavily on a robust and dependable space communications infrastructure that is well integrated with the terrestrial Internet. In the same way that the underpinnings of the Internet are the standardized "TCP/IP" suite of protocols, an "Interplanetary Internet" will need a similar set of capabilities that can support reliable communications across vast distances and highly stressed communications environments. For the past twenty years, the Consultative Committee for Space Data Systems (CCSDS) has been developing standardized long- haul space link communications techniques that are now in use by over two hundred missions within the international space community. New CCSDS developments, shortly to be infused into Mars missions, include a proximity link standard and a store-and- forward file transfer protocol. As part of its `Next Generation Internet' initiative, the U.S. Defense Advanced Projects Agency (DARPA) recently supported an architectural study of a future "InterPlaNetary Internet" (IPN). The IPN architecture assumes that in short-delay environments - such as on and around Mars - standard Internet technologies will be adapted to the locally harsh environment and deployed within surface vehicles and orbiting relays. A long-haul interplanetary backbone network that includes Deep Space Network (DSN) gateways into the terrestrial Internet will interconnect these distributed internets that are scattered across the Solar System. Just as TCP/IP unites the Earth's "network of networks" to become the Internet, a new suite of protocols known as "Bundling" will enable the IPN to become a "network of internets" to support true interplanetary dialog. An InterPlaNetary Internet Research Group has been established within the Internet community to coordinate this research and NASA has begun to support the further development of the IPN architecture and the Bundling protocols. A strategy is being developed whereby the current set of standard CCSDS data communications protocols can be incrementally evolved so that true InterPlaNetary Internet operations are feasible by the end of the decade. The strategy - which is already in progress via the deployment of Mars relay links - needs individual missions to each contribute increments of capability so that a standard communications infrastructure can rapidly accrete. This paper will describe the IPN architectural concepts, discuss the current set of standard data communications capabilities that exist to support Mars exploration and review the proposed new developments. We will also postulate that the concept is scalable and can grow to support future scenarios where human intelligence is widely distributed across the Solar System and day-to-day communications dialog among planets is routine. 1 2 3 4 5

  9. Remarks on transport theories of interplanetary fluctuations

    NASA Technical Reports Server (NTRS)

    Zhou, YE; Matthaeus, William H.

    1990-01-01

    The structure of a transport theory presented by Zhou and Matthaeus (1989), in which coupling of 'inward' and 'outward'-type fluctuations appears in the leading order, is studied. Allowance is made for the dynamic behavior of the 'fast' scale variables, which are averaged over to obtain slow-scale transport equations. The relationship of the two-scale transport models to transport models derived from the WKB approximation (Jeffreys and Jeffreys, 1980: Weinberg 1962; Dewar, 1970) as it has been applied to the solar wind MHD wave problem (Parker, 1965; Hollweg, 1973, 1974) is discussed.

  10. Forward modelling to determine the observational signatures of white-light imaging and interplanetary scintillation for the propagation of an interplanetary shock in the ecliptic plane

    Microsoft Academic Search

    Ming Xiong; A. R. Breen; M. M. Bisi; M. J. Owens; R. A. Fallows; G. D. Dorrian; J. A. Davies; P. Thomasson

    2011-01-01

    Recent coordinated observations of interplanetary scintillation (IPS) from the EISCAT, MERLIN, and STELab, and stereoscopic white-light imaging from the two heliospheric imagers (HIs) onboard the twin STEREO spacecraft are significant to continuously track the propagation and evolution of solar eruptions throughout interplanetary space. In order to obtain a better understanding of the observational signatures in these two remote-sensing techniques, the

  11. Rotational bursting of interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Paddack, S. J.; Rhee, J. W.

    1974-01-01

    Solar radiation pressure is discussed as a cause of rotational bursting, and of eventual elimination of asymmetric dust particles from the solar system, by a windmill effect. The predicted life span with this process for metallic particles with radii of 0.00001 to 0.01 cm ranges from 10 to 10,000 years. The effects of magnetic spin damping were considered. This depletion mechanism works faster than the traditional Poynting-Robertson effect by approximately one order of magnitude for metallic particles and about two orders of magnitude for nonmetallic particles.

  12. Rotational bursting of interplanetary dust particles

    NASA Technical Reports Server (NTRS)

    Paddack, S. J.; Rhee, J. W.

    1975-01-01

    Solar radiation pressure can cause rotational bursting and eventual elimination from the solar system of asymmetric dust particles by a windmill effect. The life span against this process for metallic particles with radii of 0.00001-0.01 cm ranges from 10 to 10,000 years. The effects of magnetic spin damping have been considered in this estimate. This depletion mechanism works faster than the traditional Poynting-Robertson effect by approximately one order of magnitude for metallic particles and about two-orders of magnitude for nonmetallic particles.

  13. Infrared spectroscopy of interplanetary dust in the laboratory

    NASA Technical Reports Server (NTRS)

    Fraundorf, P.; Patel, R. I.; Freeman, J. J.

    1981-01-01

    A mount containing three crushed chondritic interplanetary dust particles (IDPs) collected in the earth's stratosphere and subjected to infrared spectroscopic measurements shows features near 1000 and 500/cm, suggesting crystalline pyroxene rather than crystalline olivine, amorphous olivine, or meteoritic clay minerals. Chondritic IDP structural diversity and atmospheric heating effects must be considered when comparing this spectrum with interplanetary and cometary dust astrophysical spectra. TEM and infrared observations of one member of the rare subset of IDPs resembling hydrated carbonaceous chondrite matrix material shows a close infrared spectrum resemblance between 4000 and 400/cm to the C2 meteorite Murchison. TEM observations suggest that this class of particles may be used as an atmospheric entry heating-process thermometer.

  14. Fractal signatures in analogs of interplanetary dust particles

    NASA Astrophysics Data System (ADS)

    Katyal, Nisha; Banerjee, Varsha; Puri, Sanjay

    2014-10-01

    Interplanetary dust particles (IDPs) are an important constituent of the earths stratosphere, interstellar and interplanetary medium, cometary comae and tails, etc. Their physical and optical characteristics are significantly influenced by the morphology of silicate aggregates which form the core in IDPs. In this paper we reinterpret scattering data from laboratory analogs of cosmic silicate aggregates created by Volten et al. (2007) [1] to extract their morphological features. By evaluating the structure factor, we find that the aggregates are mass fractals with a mass fractal dimension dm?1.75. The same fractal dimension also characterizes clusters obtained from diffusion limited aggregation (DLA). This suggests that the analogs are formed by an irreversible aggregation of stochastically transported silicate particles.

  15. Dynamic modeling of coronal and interplanetary responses to solar events

    NASA Technical Reports Server (NTRS)

    Wu, S. T.; Nakagawa, Y.; Dryer, M.

    1977-01-01

    Recent progress in the dynamic modeling of responses of the corona and interplanetary medium to solar events (such as surges, eruptive prominences, flares, etc.) is reviewed. In particular, coronal transients and wave phenomena are discussed in some detail including pertinent mathematical requirements. Within the context of hydrodynamics and magnetohydrodynamics, a summary of both one- and two-dimensional time-dependent models is presented. A comparison of theoretical results with ground-based optical, radio, ATM Skylab observations, Pioneer 9 and Pioneer 10 solar wind observations is also presented. It is illustrated that: (1) substantial progress has been made in the theoretical (i.e., numerical) modeling of coronal and interplanetary responses within the last few years; (2) two-dimensional, time-dependent modeling is needed to examine the details of nonlinear wave coupling; and (3) theoretical results of modeling appear to reproduce physical consequences successfully.

  16. Study of Travelling Interplanetary Phenomena (STIP) workshop travel

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    1986-01-01

    Thirty six abstracts are provided from the SCOSTEP/STIP Symposium on Retrospective Analyses and Future Coordinated Intervals held in Switzerland on June 10 to 12, 1985. Six American scientists participated in the symposium and their abstracts are also included. The titles of their papers are: (1) An analysis of near surface and coronal activity during STIP interval 12, by T. E. Gergely; (2) Helios images of STIP intervals 6, B. V. Jackson; (3) Results from the analysis of solar and interplanetary observations during STIP interval 7, S. R. Kane; (4) STIP interval 19, E. Cliver; (5) Hydrodynamic buoyancy force in the solar atmosphere, T. Yeh; and (6) A combined MHD modes for the energy and momentum transport from solar surface to interplanetary space, S. T. Wu.

  17. The Current Performance of the Third Interplanetary Network

    E-print Network

    Hurley, K; Mitrofanov, I G; Mazets, E; Golenetskii, S V; Frontera, F; Montanari, E; Guidorzi, C; Feroci, M

    2003-01-01

    The 3rd Interplanetary Network (IPN) has been operating since April 2001 with two distant spacecraft, Ulysses and Mars Odyssey, and numerous near-Earth spacecraft, such as BeppoSAX, Wind, and HETE-II. Mars Odyssey is presently in orbit about Mars, and the network has detected approximately 30 cosmic, SGR, and solar bursts. We discuss the results obtained to date and use them to predict the future performance of the network.

  18. The Current Performance of the Third Interplanetary Network

    E-print Network

    K. Hurley; T. Cline; I. Mitrofanov; E. Mazets; S. Golenetskii; F. Frontera; E. Montanari; C. Guidorzi; M. Feroci

    2002-01-22

    The 3rd Interplanetary Network (IPN) has been operating since April 2001 with two distant spacecraft, Ulysses and Mars Odyssey, and numerous near-Earth spacecraft, such as BeppoSAX, Wind, and HETE-II. Mars Odyssey is presently in orbit about Mars, and the network has detected approximately 30 cosmic, SGR, and solar bursts. We discuss the results obtained to date and use them to predict the future performance of the network.

  19. MEXART Measurements of Radio Sources. Interplanetary Scintillation Array in Mexico

    NASA Astrophysics Data System (ADS)

    Gonzalez-Esparza, A.; Carrillo, A.; Andrade, E.; Jeyakumar, S.; Ananthakrishnan, S.; Praveenkumar, A.; Sankarasubramanian, G.; Sureshkumar, S.; Sierra, P.; Vazquez, S.; Perez-Enriquez, R.; Kurtz, S.

    2005-12-01

    The Mexican Array Radio Telescope (MEXART) consists of a 64x64 array of full-wave dipoles operating at 139.65 MHz. The primary aim of the array is to perform Interplanetary Scintillations (IPS) observations of radio sources to track large-scale solar wind perturbations within 1~AU. We describe the initial measurements of radio sources and the advances in the calibration of the antenna.

  20. High time resolution study of interplanetary parameter correlations with AE

    Microsoft Academic Search

    D. N. Baker; E. W. Jr. Hones; J. B. Payne; W. C. Feldman

    1981-01-01

    Using the earth-orbiting spacecraft IMP-8, we have performed a high time-resolution (2.5-min) study of the linear cross-correlations of a quantitative indicator of magnetospheric substorm activity, the auroral electrojet (AE) index, with several interplanetary (IP) parameters. The present study includes all available satellite data (from an eight-month period) rather than selecting a small number of substorm events, or a relatively small

  1. Workshop on the Analysis of Interplanetary Dust Particles

    NASA Technical Reports Server (NTRS)

    Zolensky, Michael E. (editor)

    1994-01-01

    Great progress has been made in the analysis of interplanetary dust particles (IDP's) over the past few years. This workshop provided a forum for the discussion of the following topics: observation and modeling of dust in the solar system, mineralogy and petrography of IDP's, processing of IDP's in the solar system and terrestrial atmosphere, comparison of IDP's to meteorites and micrometeorites, composition of IDP's, classification, and collection of IDP's.

  2. Radial distribution of meteoric particles in interplanetary space

    NASA Technical Reports Server (NTRS)

    Rhee, J. W.

    1976-01-01

    The heliocentric distribution of meteoric particles in interplanetary space is derived, with consideration of the Poynting-Robertson effect, interparticle collision processes and cometary dust injection. Radial distribution functions were derived for zodiacal dust, radar meteors and the meteoroids of mass 10 to the -9th to about 10 to the -10th g (normalized to 1 AU). The number density was found to depend on particle size.

  3. Magnetohydrodynamic modelling of interplanetary disturbances between the Sun and Earth

    Microsoft Academic Search

    M. Dryer; S. T. Wu; G. Gislason; S. M. Han; Z. K. Smith; J. F. Wang; D. F. Smart; M. A. Shea

    1984-01-01

    A time-dependent, nonplanar, two-dimensional magnetohydrodynamic computer model is used to simulate a series, separately examined, of solar flare-generated shock waves and their subsequent disturbances in interplanetary space between the Sun and the Earth's magnetosphere. The ‘canonical’ or ansatz series of shock waves include initial velocities near the Sun over the range 500 to 3500 km s-1. The ambient solar wind,

  4. Propagation of inclined interplanetary shock through the magnetosheath

    Microsoft Academic Search

    A. A. Samsonov

    2011-01-01

    Normals of most interplanetary shocks are nearly aligned with the Sun–Earth line. But some shocks, especially those connected with corotating interaction regions, are sufficiently diverted from the typical orientation near 1AU. We obtain that shocks with normal lying in the XY plane and inclined at an angle about 40°or more from the Sun–Earth line can result in sudden impulse variations

  5. Accretion of Interplanetary Dust Particles by the Earth

    Microsoft Academic Search

    Stephen J Kortenkamp; Stanley F Dermott

    1998-01-01

    Analyses of hypervelocity micrometeoroid impact craters preserved in lunar material and on the panels of the Long Duration Exposure Facility (LDEF) indicate that each year Earth accretes about 3 × 107kg of interplanetary dust particles (IDPs) from the zodiacal cloud (E. Grünet al.1985,Astron. Astrophys.286, 915–924; S. G. Love and D. E. Brownlee, 1993,Science262, 550–553). The size distributions of these lunar

  6. Asynchronous Laser Transponders for Precise Interplanetary Ranging and Time Transfer

    NASA Technical Reports Server (NTRS)

    Degnan, John J.; Smith, David E. (Technical Monitor)

    2001-01-01

    The feasibility of a two-way asynchronous (i.e. independently firing) interplanetary laser transponder pair, capable of decimeter ranging and subnanosecond time transfer from Earth to a spacecraft anywhere within the inner Solar System, is discussed. In the Introduction, we briefly discuss the current state-of-the-art in Satellite Laser Ranging (SLR) and Lunar Laser Ranging (LLR) which use single-ended range measurements to a passive optical reflector, and the limitations of this approach in ranging beyond the Moon to the planets. In Section 2 of this paper, we describe two types of transponders (echo and asynchronous), introduce the transponder link equation and the concept of "balanced" transponders, describe how range and time can be transferred between terminals, and preview the potential advantages of photon counting asynchronous transponders for interplanetary applications. In Section 3, we discuss and provide mathematical models for the various sources of noise in an interplanetary transponder link including planetary albedo, solar or lunar illumination of the local atmosphere, and laser backscatter off the local atmosphere. In Section 4, we introduce the key engineering elements of an interplanetary laser transponder and develop an operational scenario for the acquisition and tracking of the opposite terminal. In Section 5, we use the theoretical models of th previous sections to perform an Earth-Mars link analysis over a full synodic period of 780 days under the simplifying assumption of coaxial, coplanar, circular orbits. We demonstrate that, using slightly modified versions of existing space and ground based laser systems, an Earth-Mars transponder link is not only feasible but quite robust. We also demonstrate through analysis the advantages and feasibility of compact, low output power (<300 mW photon-counting transponders using NASA's developmental SLR2000 satellite laser ranging system as the Earth terminal. Section 6 provides a summary of the results and some concluding remarks regarding future applications.

  7. Resonant wave-ion interactions in the heliosphere: I. Interplanetary traveling shocks. II. Ion heating and acceleration in the extended corona

    NASA Astrophysics Data System (ADS)

    Gordon, Bruce Edward

    In Part I we present a revised version of the self- consistent theory of ion diffusive shock acceleration and associated generation of hydromagnetic waves at a planar stationary shock. Coupled wave kinetic and energetic particle transport equations are solved numerically and compared with an analytical approximation similar to that derived by Lee [1982, 1983]. The analytical approximation provides an accurate representation of both the proton distribution and the wave intensity. Excellent agreement between the predicted wave magnetic power spectral density adjacent to the shock as a function of frequency and the wave spectrum measured by ISEE 3 at the November 11 12, 1978, interplanetary traveling shock is achieved. A comparison is also made between the predicted total wave energy density and that observed upstream of Earth's bow shock by the AMPTE/IRM satellite for a statistical study of approximately 400 near-to-nose events from late 1984 and 1985. The correlation between the observed wave power and the prediction is very good with a correlation coefficient of 0.92. However, the average observed wave magnetic energy density is approximately 63% of that predicted, suggesting possible wave dissipation, which is not included in the theory. In Part II we present a semi-analytical solution of the gyrophase-averaged ion transport equation for ion distribution functions in the extended corona. We adopt the essential features of the kinetic shell model [Isenberg , 1997; 2001a, b, c; Isenberg et al., 2000, 2001] and thus, we describe the ion distribution as comprised of cyclotron-resonant and nonresonant parts. We include gravity, the ambipolar electric field, adiabatic deceleration, and magnetic mirroring, but keep the solar wind and wave phase speeds constant. The cold, electron- proton plasma dispersion relation is used to determine the wave-ion resonance condition. The actual, analytical forms of the ion distribution functions obtained are clearly not Maxwellian or bi-Maxwellian. Our solutions describe some of the non-thermal phenomena frequently observed in the extended corona: anisotropic temperature distributions, and differential streaming between protons and minor ion species. However, we fail to model the observed radial temperature dependence of protons and O5+ ions.

  8. Sensing CMEs Propagating in the Interplanetary Medium. MEXART IPS Observations

    NASA Astrophysics Data System (ADS)

    Gonzalez-Esparza, A.; Romero Hernandez, E.; Aguilar-Rodriguez, E.; Ontiveros-Hernandez, V.; Rodriguez-Martinez, M. R.; Mejia-Ambriz, J. C.

    2014-12-01

    The Mexican Array Radiotelescope (MEXART) is a ground instrument fully dedicated to perform Interplanetary Scintillation (IPS) observations to track large-scale solar wind disturbances within the Sun and the Earth. The MEXART is located at Michoacan (19 degrees 48' North, 101 degrees 41' West) and has an operation frequency of 140 MHz. The IPS technique is based on the scintillations that interplanetary disturbances (e.g., ICMEs) causes on the signal of small diameter cosmic radio sources detected by a radiotelescope. We report the tracking of the first solar disturbances detected by the instrument during the maximum of solar cycle 24. We estimated solar wind velocities and scintillation indexes (m). We present the first curves of the variation of the scintillating index with respect to the heliocentric distance for some strong radio sources using IPS observations at 140 MHZ. We identified events associated with strong scintilltaion in our data. We combine the IPS data with white light chronograph observations to identify the first CMEs in the interplanetary medium detected by the instrument.

  9. Magnetism

    NSDL National Science Digital Library

    University Corporation for Atmospheric Research Windows to the Universe team

    2007-12-12

    This webpage is part of the University Corporation for Atmospheric Research (UCAR) Windows to the Universe program. It describes the nature and configuration of magnetic fields, which are the result of moving electric charges, including how they cause magnetic objects to orient themselves along the direction of the magnetic force points, which are illustrated as lines. Magnetic field lines by convention point outwards at the north magnetic pole and inward at the south magnetic pole. The site features text, scientific illustrations and an animation. Text and vocabulary are selectable for the beginning, intermediate, or advanced reader.

  10. VECTOR MAGNETIC FIELDS OF A SOLAR POLAR REGION

    SciTech Connect

    Jin Chunlan; Wang Jingxiu, E-mail: cljin@nao.cas.cn, E-mail: wangjx@nao.cas.cn [Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012 (China)

    2011-05-01

    We study the vector magnetic fields of a solar polar region (PR) based on Solar Optical Telescope/Spectro-Polarimeter measurements. To better understand the polar magnetic properties, we compare the observed polar field with that in two solar quiet regions at the limb (QRL) and the disk center (QRD), and with that in a region of a low-latitude coronal hole (CHR). The following results are discussed: (1) The average vertical flux density of PR is 16 G, while the average horizontal flux density is 91 G. If we assume that the observed polar field suffers the same amount of limb weakening in polarization measurements as the Sun's quiet region, the average unsigned flux density in the pole would be 54 G, 60% stronger than that in the CHR. (2) The kG field in the PR occupies 6.7% of the region. The magnetic filling factor in the PR is characterized by a two-peak distribution, which appears at a field strength close to 100 G and 1000 G, respectively. (3) For the network elements, a correlation holds between the vertical and horizontal flux densities, suggesting the same physical entity is manifested by the observed stronger vertical and horizontal components. (4) The ratio of the magnetic flux in the minority polarity to that in the dominant polarity is approximately 0.5, implying that only 1/3 of the magnetic flux in the PR opens to the interplanetary space. Exemplified with CHR by a quasi-linear force-free extrapolation of the observed magnetic field, we find that the photospheric open flux is not always associated with strong vertical magnetic elements.

  11. Interplanetary propagation behavior of the fast coronal mass ejection from 23 July 2012

    NASA Astrophysics Data System (ADS)

    Temmer, Manuela; Nitta, Nariaki

    2015-04-01

    The fast coronal mass ejection (CME) from July 23, 2012 raised special attention due to its extremely short propagation time of less than 21hrs from Sun to 1 AU. In-situ data from STEREO-A revealed the arrival of a fast forward shock having a velocity of more than 2200 km/s followed by a magnetic structure with a speed of almost 1900 km/s. We present a study about the evolution of the CME in interplanetary (IP) space, separately for the shock and magnetic structure, using the drag based model to reproduce the short propagation time and high impact speed as derived from in-situ data. We find that due to an efficient magnetic reconnection process in the long-duration flare associated to the CME, the event reached a very high speed. Furthermore, the ambient density must have been exceptionally low which reduced the drag force, such that the massive CME experienced almost no deceleration. The solar wind density is found to be rather low due to the weak solar activity and might have been additionally lowered by a previous CME event.

  12. A search for the interplanetary quantity controlling the development of geomagnetic storms

    NASA Technical Reports Server (NTRS)

    Akasofu, S.-I.

    1979-01-01

    An historical account is presented concerning the evolution of our present concept of geomagnetic storms. The present concept was formulated by Chapman (1927) in his magnetic data statistical studies of 'the initial rise' (now termed the initial phase) 'and subsequent larger decrease' (now termed the main phase) in H, followed by 'slow recovery'. The concept introduced by Alfven in 1940 of guiding center motions of a charged particle in a nonuniform magnetic field (ring currents) is also discussed. By 1963 it became quite certain that the ring current, namely a storm-time Van Allen belt, is formed in the magnetosphere during the storm's main phase. The search then began for the solar wind quantity controlling the development of the main phase. The author then gives a personal account of how our concept of geomagnetic storms has advanced and how new findings based on satellite and ground-based observations have made it possible to arrive at a first-approximation expression for the interplanetary quantity controlling the development of geomagnetic storms. Since a geomagnetic storm is a magnetic manifestation of a magnetospheric storm, which is a nonlinear superposition of intense magnetospheric substorms, the main emphasis is shifted toward the understanding of magnetospheric substorms in order to arrive at the parameters controlling the development of geomagnetic storms.

  13. Statistical results for the thermospheric and geomagnetic response to interplanetary coronal mass ejections

    NASA Astrophysics Data System (ADS)

    Temmer, Manuela; Krauss, Sandro; Veronig, Astrid; Baur, Oliver; Lammer, Helmut

    2015-04-01

    During the time range August 2003 - August 2010, we find for 35 disturbances from interplanetary coronal mass ejections (ICMEs) a clear density enhancement in the thermosphere (derived from GRACE and CHAMP accelerometer measurements) by more than 150 percent compared to the pre-event level. For this sample of ICME-thermosphere events, we extract geomagnetic parameters and from the ICME, separately for the sheath and magnetic cloud component, characteristic parameters such as the impact speed, magnetic field orientation as well as strength and disturbance duration. We present a statistical analysis of various ICME parameters and their relation to geomagnetic (Dst, AE, ap, Kp, ...) as well as thermospheric response. We show, among high correlations between geomagnetic and thermospheric quantities, that the strength of the Bz component of the ICME gives the strongest relation to the neutral density enhancement. For most of the events, the strongest negative Bz component is found in the magnetic cloud of the disturbance. Furthermore, the results indicate a shock related intensification of geomagnetic storms and neutral density enhancement due to a larger Bz caused by shock compression.

  14. Operational, Real-Time, Sun-to-Earth Interplanetary Shock Predictions During Solar Cycle 23

    Microsoft Academic Search

    C. D. Fry; M. Dryer; W. Sun; C. S. Deehr; Z. Smith; S. Akasofu

    2002-01-01

    We report on our progress in predicting interplanetary shock arrival time (SAT) in real-time, using three forecast models: the Hakamada-Akasofu-Fry (HAF) modified kinematic model, the Interplanetary Shock Propagation Model (ISPM) and the Shock Time of Arrival (STOA) model. These models are run concurrently to provide real-time predictions of the arrival time at Earth of interplanetary shocks caused by solar events.

  15. Influence of the Ambient Solar Wind Flow on the Propagation Behavior of Interplanetary Coronal Mass Ejections

    NASA Astrophysics Data System (ADS)

    Temmer, Manuela; Rollett, Tanja; Möstl, Christian; Veronig, Astrid M.; Vršnak, Bojan; Odstr?il, Dusan

    2011-12-01

    We study three coronal mass ejection (CME)/interplanetary coronal mass ejection (ICME) events (2008 June 1-6, 2009 February 13-18, and 2010 April 3-5) tracked from Sun to 1 AU in remote-sensing observations of Solar Terrestrial Relations Observatory Heliospheric Imagers and in situ plasma and magnetic field measurements. We focus on the ICME propagation in interplanetary (IP) space that is governed by two forces: the propelling Lorentz force and the drag force. We address the question: which heliospheric distance range does the drag become dominant and the CME adjust to the solar wind flow. To this end, we analyze speed differences between ICMEs and the ambient solar wind flow as a function of distance. The evolution of the ambient solar wind flow is derived from ENLIL three-dimensional MHD model runs using different solar wind models, namely, Wang-Sheeley-Arge and MHD-Around-A-Sphere. Comparing the measured CME kinematics with the solar wind models, we find that the CME speed becomes adjusted to the solar wind speed at very different heliospheric distances in the three events under study: from below 30 R ?, to beyond 1 AU, depending on the CME and ambient solar wind characteristics. ENLIL can be used to derive important information about the overall structure of the background solar wind, providing more reliable results during times of low solar activity than during times of high solar activity. The results from this study enable us to obtain greater insight into the forces acting on CMEs over the IP space distance range, which is an important prerequisite for predicting their 1 AU transit times.

  16. INFLUENCE OF THE AMBIENT SOLAR WIND FLOW ON THE PROPAGATION BEHAVIOR OF INTERPLANETARY CORONAL MASS EJECTIONS

    SciTech Connect

    Temmer, Manuela; Rollett, Tanja; Moestl, Christian; Veronig, Astrid M. [Kanzelhoehe Observatory-IGAM, Institute of Physics, University of Graz, Universitaetsplatz 5, A-8010 Graz (Austria); Vrsnak, Bojan [Hvar Observatory, Faculty of Geodesy, University of Zagreb, Kaciceva 26, HR-10000 Zagreb (Croatia); Odstrcil, Dusan [Cooperative Institute for Research in Environmental Sciences, University of Colorado at Boulder, Boulder, CO (United States)

    2011-12-20

    We study three coronal mass ejection (CME)/interplanetary coronal mass ejection (ICME) events (2008 June 1-6, 2009 February 13-18, and 2010 April 3-5) tracked from Sun to 1 AU in remote-sensing observations of Solar Terrestrial Relations Observatory Heliospheric Imagers and in situ plasma and magnetic field measurements. We focus on the ICME propagation in interplanetary (IP) space that is governed by two forces: the propelling Lorentz force and the drag force. We address the question: which heliospheric distance range does the drag become dominant and the CME adjust to the solar wind flow. To this end, we analyze speed differences between ICMEs and the ambient solar wind flow as a function of distance. The evolution of the ambient solar wind flow is derived from ENLIL three-dimensional MHD model runs using different solar wind models, namely, Wang-Sheeley-Arge and MHD-Around-A-Sphere. Comparing the measured CME kinematics with the solar wind models, we find that the CME speed becomes adjusted to the solar wind speed at very different heliospheric distances in the three events under study: from below 30 R{sub Sun }, to beyond 1 AU, depending on the CME and ambient solar wind characteristics. ENLIL can be used to derive important information about the overall structure of the background solar wind, providing more reliable results during times of low solar activity than during times of high solar activity. The results from this study enable us to obtain greater insight into the forces acting on CMEs over the IP space distance range, which is an important prerequisite for predicting their 1 AU transit times.

  17. Monthly Average Temperature Modelling

    Microsoft Academic Search

    M. Andrade-Bejarano

    This research is associated with the goal of the horticultural sector of the Colombian southwest, which is to obtain climatic\\u000a information, specifically, to predict the monthly average temperature in sites where it has not been measured. The data correspond\\u000a to monthly average temperature, and were recorded in meteorological stations at Valle del Cauca, Colombia, South America.\\u000a Two components are identified

  18. Extraterrestrial magnetic fields - Achievements and opportunities

    Microsoft Academic Search

    E. J. Smith; C. P. Sonett

    1976-01-01

    The major scientific achievements associated with the measurement of magnetic fields in space over the past decade and a half are reviewed. Aspects of space technology relevant to magnetic-field observations are discussed: magnetometers and how they operate, problems arising from spacecraft-generated magnetic fields and appropriate countermeasures and on-board processing of magnetometer data. The solar wind and interplanetary magnetic field, the

  19. Interplanetary missions with the GDM propulsion system

    SciTech Connect

    Kammash, T.; Emrich, W. Jr. [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Marshall Space Flight Center, Huntsville, Alabama 35812 (United States)

    1998-01-15

    The Gasdynamic Mirror (GDM) fusion propulsion system utilizes a magnetic mirror machine in which a hot dense plasma is confined long enough to produce fusion energy while allowing a fraction of its charged particle population to escape from one end to generate thrust. The particles escaping through the opposite end have their energy converted to electric power which can be used to sustain the system in a steady state operation. With the aid of a power flow diagram the minimum demands on energy production can be established and the propulsive capability of the system can be determined by solving an appropriate set of governing equations. We apply these results to several missions within the solar system and compute the trip time by invoking a continuous burn, acceleration/deceleration type of trajectory with constant thrust and specific impulse. Ignoring gravitational effects of the planets or the sun, and neglecting the change in the Earth's position during the flight we compute the round trip time for missions from Earth to Mars, Jupiter, and Pluto using linear distances and certain payload fractions. We find that a round trip to Mars with the GDM rocket takes about 170 days while those to Jupiter and Pluto take 494 and 1566 days respectively.

  20. Solar wind control of the tail lobe magnetic field as deduced from Geotail, AMPTE/IRM, and ISEE 2 data

    NASA Astrophysics Data System (ADS)

    Tsyganenko, N. A.

    2000-03-01

    A statistical study was made of the tail lobe field response to the dynamical pressure of the incoming solar wind and to the interplanetary magnetic field, as well as its relation to the concurrent level of the Dst field. The study covers a wide range of distances between 10 and 60RE and is based on a large set of tail lobe magnetic field data, compiled from three sources: (1) Geotail magnetometer and low-energy plasma instrument data for 1993-1997, (2) AMPTE/IRM magnetometer and plasma instrument data for 1985-1986, and (3) ISEE 2 magnetometer and fast plasma experiment data for 1978-1980. The tailward variation of the tail lobe field and of its response to the solar wind and interplanetary magnetic field (IMF) conditions was studied using a regression relationship, including various combinations of the interplanetary quantities, measured by IMP 8 and Wind spacecraft. An investigation of the role of the time lag effects was made by tagging each lobe field measurement by a ``trail'' of 12 consecutive 5-min average values of the solar wind parameters and finding best fit distributions of the lagged response amplitudes in the solar-wind and IMF-related regression terms. The goal of the work is to find a set of input variables providing the highest correlation between the observed and predicted magnitude of the tail lobe field, so that their combination could be used for parameterizing the strength of the cross-tail current in the data-based magnetospheric models.

  1. On the Relationship Between Transit Velocity of Interplanetary Shocks and Solar Active Processes

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.

    1996-01-01

    Recently, it was reported that preferential relationships exist between the transit velocity V(sub T) of earthward-directed interplanetary shocks and solar active processes, in particular, eruptive filaments outside active regions (the size of the erupting filament L(sub f)) and solar flares (the value of the X-ray characteristic J). Unfortunately, statistical testing of the proposed associations was not accomplished, nor was the 'geo-effectiveness' of the events adequately described. Reported here are the results of a re-examination of the 21 eruptive filaments (SSC-EF events) and 26 X-ray flares (SSC-F events) that have been associated with storm sudden commencements (SSCs) at Earth. Simple statistical testing refutes the claim that a preferential relationship exists between V(sub T) and L(sub F), while it supports the claim that one exists between V(sub T) and J. More importantly, the inferred relationship between V(sub T) and J is found to be more complicated than previously thought. In particular, it now appears that SSC-F events may be separable into two groups, based on the value of J: a low-J group (J less than 56), in which V(sub T) varies directly with J, and a high-J group (J greater than 56), in which V(sub T) varies inversely with J. As a whole, high-J events are associated with shocks of higher average transit velocity than those of low-J events, and SSC-F events with shocks of higher average transit velocity than those of SSC-EF events. Further, high-J events tend to be of greater X-ray class ( greater than M3), longer duration (greater then 80 min), and are more likely to be associated with type II/IV radio emission (9 of 12) than low-J events. They also tend to occur in magnetically complex (gamma/delta configuration) active regions (10 of 12) that are large in area extent (area greater than 445 millionths of a solar hemisphere) on the day of flaring (9 of 12). Of the 9 solar proton events that affected the Earth's environment that were found to be associated with SSC-F events, six were high-J events. Concerning 'geo-effectiveness', there appears to be no preferential relationship between the value of the J-parameter and the most negative value of the Dst geomagnetic index Dst(min) following the SSC, which is found to usually occur at 6-14 h after SSC onset (18 of 26) and which ranged in value from -1 to -249 (having a median value of about -75). Of the 26 SSC-F events, only 14 can be associated with a Dst(min) less than or equal to -75, and of these only 7 were high-J events. Of the 14 storm-related events (i.e. Dst(min) less than or equal to -75), three have previously been identified as being either 'magnetic clouds' or 'bidirectional flows', both manifestations of earthward-directed coronal mass ejections (CMEs). Superposed epoch analyses of selected solar wind parameters and Dst during the interval of storm-related SSC-F events demonstrate that geoeffective SSC-F events tend to be associated with solar wind flows that are faster, greater in magnetic field strength, and have a rotating field which has a strong southward component shortly after SSC onset, in comparison to SSC-F events that do not have Dst(min) less than or equal to 75. Therefore, it is inferred that geoeffective SSC-F events are probably fast earthward-directed CMEs. Although no single parameter is found that can serve as a predictor of high-skill level for determining the geoeffectiveness of an SSC-F event prior to its occurrence at Earth, one finds that knowledge of the flare's hemispheric location and appearance or lack of appearance of a two-ribbon structure is sufficient to correctly predict the geoeffectiveness of 20 out of 25 of the SSC-F events (80%). Surprisingly, the association or lack of association of metric type II/IV radio emission as a characteristic for determining the geoeffectiveness of the SSC-F events proved unfruitful, as did, to a lesser extent, the duration of the X-ray emission.

  2. Forward modelling to determine the observational signatures of white-light imaging and interplanetary scintillation for the propagation of an interplanetary shock in the ecliptic plane

    Microsoft Academic Search

    Ming Xiong; A. R. Breen; M. M. Bisi; M. J. Owens; R. A. Fallows; G. D. Dorrian; J. A. Davies; P. Thomasson

    2010-01-01

    Recent coordinated observations of interplanetary scintillation (IPS) and\\u000astereoscopic heliospheric imagers (HIs) are significant to continuously track\\u000athe propagation and evolution of solar eruptions throughout interplanetary\\u000aspace. In order to obtain a better understanding of the observational\\u000asignatures in these two remote-sensing techniques, the magnetohydrodynamics of\\u000athe macro-scale interplanetary disturbance and the radio-wave scattering of the\\u000amicro-scale electron-density fluctuation are

  3. International Seminar of Magnetosphere, Ionosphere and Interplanetary Space, 2nd, Warsaw, Poland, June 21-23, 1979, Proceedings

    NASA Astrophysics Data System (ADS)

    1980-08-01

    Topics discussed include shock waves in interplanetary and near-earth plasma, the gasdynamic description of solar wind flow past planets, the isotope and charge composition of solar cosmic rays, electromagnetic coupling between the ionosphere and the magnetosphere, and the structure of the plasma sheet in the magnetospheric tail. Consideration is also given to the precipitation of charged particles during magnetic storms, the diffusion of radiation-belt electrons in quiet geomagnetic conditions, infralow-frequency fluctuations of electric and magnetic fields, and the irregular structure of the F-layer. The digital analysis of whistlers, the linear transformation of whistlers in the upper ionosphere, and ionospheric electron density during geomagnetic storms are also examined.

  4. The Interplanetary Network Supplement to the BATSE 5B Catalog of Cosmic Gamma-Ray Bursts

    E-print Network

    K. Hurley; M. S. Briggs; R. M. Kippen; C. Kouveliotou; C. Meegan; G. Fishman; T. Cline; J. Trombka; T. McClanahan; W. Boynton; R. Starr; R. McNutt; M. Boer

    2011-08-18

    We present Interplanetary Network (IPN) localization information for 343 gamma-ray bursts observed by the Burst and Transient Source Experiment (BATSE) between the end of the 4th BATSE catalog and the end of the Compton Gamma-Ray Observatory (CGRO) mission, obtained by analyzing the arrival times of these bursts at the Ulysses, Near Earth Asteroid Rendezvous (NEAR), and CGRO spacecraft. For any given burst observed by CGRO and one other spacecraft, arrival time analysis (or "triangulation") results in an annulus of possible arrival directions whose half-width varies between 11 arcseconds and 21 degrees, depending on the intensity, time history, and arrival direction of the burst,as well as the distance between the spacecraft. This annulus generally intersects the BATSE error circle, resulting in an average reduction of the area of a factor of 20. When all three spacecraft observe a burst, the result is an error box whose area varies between 1 and 48000 square arcminutes, resulting in an average reduction of the BATSE error circle area of a factor of 87.

  5. The Interplanetary Network Supplement to the BATSE 5B Catalog of Cosmic Gamma-Ray Bursts

    E-print Network

    Hurley, K; Kippen, R M; Kouveliotou, C; Meegan, C; Fishman, G; Cline, T; Trombka, J; McClanahan, T; Boynton, W; Starr, R; McNutt, R; Boër, M

    2006-01-01

    We present Interplanetary Network (IPN) localization information for 343 gamma-ray bursts observed by the Burst and Transient Source Experiment (BATSE) between the end of the 4th BATSE catalog and the end of the Compton Gamma-Ray Observatory (CGRO) mission, obtained by analyzing the arrival times of these bursts at the Ulysses, Near Earth Asteroid Rendezvous (NEAR), and CGRO spacecraft. For any given burst observed by CGRO and one other spacecraft, arrival time analysis (or "triangulation") results in an annulus of possible arrival directions whose half-width varies between 11 arcseconds and 21 degrees, depending on the intensity, time history, and arrival direction of the burst,as well as the distance between the spacecraft. This annulus generally intersects the BATSE error circle, resulting in an average reduction of the area of a factor of 20. When all three spacecraft observe a burst, the result is an error box whose area varies between 1 and 48000 square arcminutes, resulting in an average reduction of t...

  6. Quiet-time Interplanetary ˜2-20keV Superhalo Electrons at Solar Minimum

    NASA Astrophysics Data System (ADS)

    Wang, L.; Lin, R. P.; Salem, C. S.; Pulupa, M.

    2011-12-01

    The average flux of the ~2-20 keV superhalo electrons in the solar wind during quiet-time periods, measured by the Suprathermal Electron instrument onboard the two STEREO spacecraft, slowly decreases with time from 2007 to 2009 and then increases in 2010, similar to the solar cycle variation around this solar minimum. We made a comprehensive study for a 2-year period from 2007 March through 2009 March, and found that the observed quiet-time ˜2-20 keV superhalo electrons have a nearly isotropic angular distribution and a power-law spectrum, f ˜ v-?, ranging from v-5 to v-8.7, with the average index of 6.69. The observed power-law spectrum varies significantly on spatial scales of >˜0.1 AU and/or temporal scale of >˜ days. There is no correlation (-0.1 < coefficient < 0.2) with the solar wind proton density, velocity and temperature, but the power-law index ? is weakly anti-correlated (coefficient -0.48) with the electron velocity distribution function at 14.8 keV. The origin of these quiet-time superhalo electrons remains unclear, but since they are present even in the absence of any solar activity, they may be due to resonant wave-particle interactions in the corona or the interplanetary space.

  7. Interplanetary Coronal Mass Ejections in the Near-Earth Solar Wind During 1996-2002

    NASA Technical Reports Server (NTRS)

    Cane, H. V.; Richardson, I. G.

    2003-01-01

    We summarize the occurrence of interplanetary coronal mass injections (ICMEs) in the near-Earth solar wind during 1996-2002, corresponding to the increasing and maximum phases of solar cycle 23. In particular, we give a detailed list of such events. This list, based on in-situ observations, is not confined to subsets of ICMEs, such as magnetic clouds or those preceded by halo CMEs observed by the SOHO/LASCO coronagraph, and provides an overview of 214 ICMEs in the near-Earth solar wind during this period. The ICME rate increases by about an order of magnitude from solar minimum to solar maximum (when the rate is approximately 3 ICMEs/solar rotation period). The rate also shows a temporary reduction during 1999, and another brief, deeper reduction in late 2000-early 2001, which only approximately track variations in the solar 10 cm flux. In addition, there are occasional periods of several rotations duration when the ICME rate is enhanced in association with high solar activity levels. We find an indication of a periodic variation in the ICME rate, with a prominent period of approximately 165 days similar to that previously reported in various solar phenomena. It is found that the fraction of ICMEs that are magnetic clouds has a solar cycle variation, the fraction being larger near solar minimum. For the subset of events that we could associate with a CME at the Sun, the transit speeds from the Sun to the Earth were highest after solar maximum.

  8. Solar source of energetic particles in interplanetary space during the 2006 December 13 event

    E-print Network

    Li, C; Vial, J -C; Owen, C J; Matthews, S A; Tang, Y H; Fang, C; Fazakerley, A N

    2013-01-01

    An X3.4 solar flare and a fast halo coronal mass ejection (CME) occurred on 2006 December 13, accompanied by a high flux of energetic particles recorded both in near-Earth space and at ground level. Our purpose is to provide evidence of flare acceleration in a major solar energetic particle (SEP) event. We first present observations from ACE/EPAM, GOES, and the Apatity neutron monitor. It is found that the initial particle release time coincides with the flare emission and that the spectrum becomes softer and the anisotropy becomes weaker during particle injection, indicating that the acceleration source changes from a confined coronal site to a widespread interplanetary CME-driven shock. We then describe a comprehensive study of the associated flare active region. By use of imaging data from HINODE/SOT and SOHO/MDI magnetogram, we infer the flare magnetic reconnection rate in the form of the magnetic flux change rate. This correlates in time with the microwave emission, indicating a physical link between the...

  9. Properties of waves in the range of several Hz associated with interplanetary shocks

    NASA Astrophysics Data System (ADS)

    Goncharov, Oleksandr; Nemecek, Zdenek; Safrankova, Jana; Prech, Lubomir; Zastenker, Georgy N.

    2015-04-01

    The interplanetary (IP) shocks are often associated with high-frequency (several Hz) wave packets in both upstream and downstream regions. These waves could be resolved only in fast magnetic field data because the time resolution of plasma instruments is often insufficient for their detection. The BMSW instrument onboard the Spektr-R spacecraft measures solar wind parameters with a resolution of 32 ms and allows a detailed analysis of these waves. Since the magnetometer onboard Spektr R is not in operation, we compare its plasma observations with Wind fast magnetic field measurements. Our analysis of low-Mach-number fast forward shocks have shown that (1) the wavelengths of both upstream and downstream waves conserve over the spacecraft separation, (2) in the frequency range of 0.5-5 Hz, their wavelengths are directly proportional to the shock ramp thickness that is controlled by the ion thermal gyroradius, and (3) the phase shift between density and temperature variations within downstream wave packets is about 90°. These results emphasize a role of kinetic processes in the formation of low-Mach number shocks. We discuss a nature of these waves and their properties.

  10. THE SOLAR WIND AND INTERPLANETARY FIELD DURING VERY LOW AMPLITUDE SUNSPOT CYCLES

    SciTech Connect

    Wang, Y.-M.; Sheeley, N. R. Jr., E-mail: yi.wang@nrl.navy.mil, E-mail: neil.sheeley@nrl.navy.mil [Space Science Division, Naval Research Laboratory, Washington, DC 20375-5352 (United States)

    2013-02-10

    Cosmogenic isotope records indicate that a solar-cycle modulation persists through extended periods of very low sunspot activity. One immediate implication is that the photospheric field during such grand minima did not consist entirely of ephemeral regions, which produce a negligible amount of open magnetic flux, but continued to have a large-scale component originating from active regions. Present-day solar and heliospheric observations show that the solar wind mass flux and proton density at the coronal base scale almost linearly with the footpoint field strength, whereas the wind speed at Earth is uncorrelated with the latter. Thus a factor of {approx}4-7 reduction in the total open flux, as deduced from reconstructions of the interplanetary magnetic field (IMF) during the Maunder Minimum, would lead to a similar decrease in the solar wind densities, while leaving the wind speeds largely unchanged. We also demonstrate that a decrease in the strengths of the largest active regions during grand minima will reduce the amplitude of the Sun's equatorial dipole relative to the axial component, causing the IMF strength to peak near sunspot minimum rather than near sunspot maximum, a result that is consistent with the phase shift observed in the {sup 10}Be record during the Maunder Minimum. Finally, we discuss the origin of the 5 yr periodicity sometimes present in the cosmogenic isotope data during low and medium amplitude cycles.

  11. Faraday Rotation (FR) and Interplanetary Scintillation (IPS) Case Studies Using the LOw Frequency ARray (LOFAR)

    NASA Astrophysics Data System (ADS)

    Bisi, M. M.; Fallows, R. A.; Sobey, C.; Eftekhari, T.; Jensen, E. A.; Jackson, B. V.; Yu, H. S.; Gershman, D. J.; Raines, J. M.; Odstrcil, D.

    2014-12-01

    We present an update on the progress made using the LOw Frequency ARray (LOFAR) next-generation radio telescope for space-weather related activities - namely observations of interplanetary scintillation (IPS) and the first tests of observing heliospheric Faraday rotation (FR). The former has been used for half a century for heliospheric science and much progress has been made in recent years for using IPS in space weather science and forecasting. The latter, typically an astrophysical technique that uses pulsars and extragalactic radio sources to study the Galactic magnetic field, is now being investigated for heliospheric studies. The determination of heliospheric FR, combined with observations of IPS, can provide essential information on the Sun's extended magnetic-field structure out into the inner heliosphere, especially when also combined with other forms of remote-sensing/heliospheric imaging data, and in-situ measurements. Here, we will present recent observations of IPS using LOFAR, including preliminary highlights from the first LOFAR joint IPS and heliospheric FR science campaign and investigate pathways for determining Bzfrom, and an overview of the potential of, such observations. LOFAR is an interferometric phased-array radio telescope that can be used to observe between 10 MHz (depending on ionospheric conditions) and 240 MHz, and consists of many relatively-low-cost antennas. These antennas are organised into 'stations' located in an area of ~100km diameter in the Netherlands, with additional international stations spread across central and western Europe with several more in the planning stages.

  12. Average Rate of Change

    NSDL National Science Digital Library

    Roberts, Lila F.

    2005-04-21

    This demo provides students with a concrete understanding of the average rate of change for physical situations and for functions described in tabular or graphic form. Animations in gif and Quicktime format are available, as well as Excel programs for classroom or student use.

  13. A decametric wavelength radio telescope for interplanetary scintillation observations

    NASA Technical Reports Server (NTRS)

    Cronyn, W. M.; Shawhan, S. D.

    1975-01-01

    A phased array, electrically steerable radio telescope (with a total collecting area of 18 acres), constructed for the purpose of remotely sensing electron density irregularity structure in the solar wind, is presented. The radio telescope is able to locate, map, and track large scale features of the solar wind, such as streams and blast waves, by monitoring a large grid of natural radio sources subject to rapid intensity fluctuation (interplanetary scintillation) caused by the irregularity structure. Observations verify the performance of the array, the receiver, and the scintillation signal processing circuitry of the telescope.

  14. Numerically-simulated formation and propagation of interplanetary shocks

    NASA Technical Reports Server (NTRS)

    Wu, S. T.

    1985-01-01

    The present numerical method for simulating the formation and propagation of interplanetary shocks is based on the shock-capturing finite difference scheme of Lax (1950) and Lax and Wendroff (1960), as well as the recent method of NEAR characteristics of Nakagawa (1980, 1981). Attention is given to examples which strongly suggest that all the shocked solar wind plasma parameters due to given physical perturbations, such as flare-generated shocks, can be predicted through the use of this method; the method is, however, limited to the supersonic and super-Alfvenic flow.

  15. MEXART. Interplanetary Scintillation Array in Mexico in the IHY2007

    NASA Astrophysics Data System (ADS)

    Gonzalez-Esparza, A.; Carrillo, A.; Andrade, E.; Jeyakumar, S.; Perez-Enriquez, R.; Kurtz, S.

    The Mexican Array Radio Telescope MEXART consists of a 64x64 4096 full wavelength dipole antenna array operating at 140 MHz occupying 9 500 square meters 70 m x 140 m to carry out interplanetary scintillation IPS observations This is a dedicated radio array for IPS observations located in the state of Michoacan 350 km north-west from Mexico City lat 19° 48 N long 101° 41 W and 1964 m above sea level We report the system testings radio source measurements and the collaboration plans for the International Heliophysical Year 2007

  16. MEXART. Interplanetary Scintillation Array in Mexico in the IHY2007

    NASA Astrophysics Data System (ADS)

    Gonzalez-Esparza, A.; Andrade, E.; Carrillo, A.; Kurtz, S.; Jeyakumar, S.; Perez-Enriquez, R.; Sierra, P.; Vazquez, S.; Manoharan, P.

    2006-12-01

    The Mexican Array Radio Telescope (MEXART) consists of a 64x64 (4096) full wavelength dipole antenna array, operating at 140 MHz, occupying 9,500 square meters (70 m x 140 m) to carry out interplanetary scintillation (IPS) observations. This is a dedicated radio array for IPS observations located in the state of Michoacan (350 km north-west from Mexico City, lat. 19^ 48' N, long. 101^ 41' W and 1964 m above sea level). We report the system testings, radio source measurements and the collaboration plans for the International Heliophysical Year 2007.

  17. A statistical study of interplanetary shock associated proton intensity increases

    NASA Technical Reports Server (NTRS)

    Reinhard, R.; Van Nes, P.; Sanderson, T. R.; Wenzel, K.-P.; Smith, E. J.; Tsurutani, B. T.

    1983-01-01

    Large intensity increases of low-energy protons are frequently observed in connection with interplanetary forward shocks. Essentially two different particle acceleration mechanisms to explain these 'ESP events' are presently under discussion. To find out which is the dominant process for particle acceleration a large number of these events observed on ISEE-3 was analyzed. The events with the highest fluxes of 35-56 keV protons are associated with shocks which are quasi-parallel and originate close to the central meridian of the sun, and it is concluded that they are produced by a first order Fermi acceleration process.

  18. Relationship between interplanetary/magnetosheath parameters and magnetopause reconnection events

    NASA Astrophysics Data System (ADS)

    Koga, D.; Gonzalez, W. D.; Mozer, F.

    2011-12-01

    Physical quantities observed by recent satellites in the magnetosheath, magnetosphere and in the solar wind during selected magnetopause reconnection events are used in order to study some related features. In particular, we use magnetosheath and magnetosphere parameters to evaluate the position of the reconnection line and do a statistical study to test the Gonzalez-Mozer 1974 hypothesis for the location of that line. We also do a statistical study of magnetopause reconnection parameters as a function of basic properties of interplanetary structures arriving to the magnetosphere during the reconnection events of interest.

  19. Interplanetary electrons - What is the strength of the Jupiter source

    NASA Technical Reports Server (NTRS)

    Fillius, W.; Ip, W.-H.; Knickerbocker, P.

    1978-01-01

    On the basis of conservative assumptions, a phenomenological approach is used to address the source strength of Jupiter for interplanetary electrons. It is estimated that Jupiter emits approximately 10 to the 24th - 10 to the 26th electrons per sec with energies in excess of 6 MeV, which sources may be compared with the population of approximately 3 x 10 to the 28th electrons of the same energy in the Jovian outer magnetosphere. It is concluded that Jupiter accelerates particles at a rate exceeding that of ordinary trapped particle dynamic processes.

  20. Analysis of Interplanetary Dust Experiment Detectors and Other Witness Plates

    NASA Technical Reports Server (NTRS)

    Griffis, D. P.; Wortman, J. J.

    1992-01-01

    The development of analytical procedures for identifying the chemical composition of residue from impacts that occurred on the Interplanetary Dust Experiment (IDE) detectors during the flight of Long Duration Exposure Facility (LDEF) and the carrying out of actual analysis on IDE detectors and other witness plates are discussed. Two papers on the following topics are presented: (1) experimental analysis of hypervelocity microparticle impact sites on IDE sensor surfaces; and (2) contaminant interfaces with secondary Ion Mass Spectrometer (SIMS) analysis of microparticle impactor residues on LDEF surfaces.