Mariner 2 observations of the solar wind. II.
Solar wind plasma properties, noting relation between positive ion component and interplanetary magnetic field as measured by Mariner II
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Solar wind plasma properties, noting relation between positive ion component and interplanetary magnetic field as measured by Mariner II
%T The Latitudinal Distribution of Magnetic Holes in the Solar Wind%A D. Winterhalter%A M. Neugebauer%A E. J. Smith%A A. Balogh%J American Geophysical Union, 1995 Spring Meeting%C Baltimore, Maryland%D May 29-June 2, 1995%K Interplanetary Magnetic Fields%K Solar Wind%U http://techreports.jpl.nasa.gov/1995/95-0554.pdf!
We have examined interplanetary magnetic field power spectral density during four previously identified 3He-rich flare periods when the about 1 MeV nucleon-1 particles exhibited nearly scatter-free transport from the sun to 1 AU. Since the scattering mean free path A was large, it might be expected that interplanetary turbulence was low, yet the spectral density value was low only for one of the four periods. For the other three, however, the spectral index q of the power density spectrum was near 2.0, a value at which quasi-linear theories predict an increase in the scattering mean free path. Comparing the lambda values from the energetic particles with that computed from a recent quasi-linear theory which includes helicity and the propagation direction of waves, we find lambda(QLT)/lambda(SEP) = 0.08 +/- 0.03 for the four events. Thus, the theory fits the q-dependence of lambda; however, as found for previous quasi-linear theories, the absolute value is low.
Correction of magnetic measurements made by Mariner II, noting use of second-order approximation for interplanetary magnetic field
Charged particle behavior in idealized interplanetary magnetic field, discussing Parker spiral field model
Charged particle dynamics in spiral interplanetary magnetic field model, discussing electric drift velocity, point of origin and distribution
On January 21, 1972, the Mars 3 spacecraft observed a variation in the magnetic field during its periapsis passage over the dayside of Mars that was suggestive of entry into a Martian magnetosphere. Original data and trajectory of the spacecraft have been obtained (Dolginov, 1983) and an attempt is made to simulate the observed variation of the magnetic field by using a gas dynamic simulation. In the gas dynamic model a flow field is generated and this flow field is used to carry the interplanetary magnetic field through the Martian magnetosheath. The independence of the flow field and magnetic field calculation makes it possible to converge rapidly on an IMF orientation that would result in a magnetic variation similar to that observed by Mars 3. There appears to be no need to invoke an entry into a Martian magnetosphere to explain these observations.
Direct measurements of the solar wind and the interplanetary magnetic field acquired over more than three solar cycles both near Earth and in interplanetary space are used to search for signatures of a persistent dependence of solar wind properties on solar longitude.
Results of analyses of data received from a scientific instrument designed to study solar wind and plasma wave phenomena on the ISEE-3 mission are discussed in two papers prepared for publication. A study of plasma wave levels in and interplanetary magnetic field orientation preceding observations of interplanetary shocks by the satellite infers that quasi-parallel, interplanetary shocks are preceded by foreshocks whose presence is not obviously attributable to scattering of ion beams generated at quasi-perpendicular zones of these interplanetary shocks. Investigations of whistler mode turbulence in the disturbed solar wind resulted in various indirect lines of evidence indicating that these whistler waves are generated propagating at large angles to the local interplanetary field, a fact which helps identify possible free energy sources for their growth.
The magnetic field measurements from Voyager and the magnetohydrodynamic (MHD) processes in the outer heliosphere are reviewed. A bibliography of the experimental and theoretical work concerning magnetic fields and plasmas observed in the outer heliosphere is given. Emphasis in this review is on basic concepts and dynamical processes involving the magnetic field. The theory that serves to explain and unify the interplanetary magnetic field and plasma observations is magnetohydrodynamics. Basic physical processes and observations that relate directly to solutions of the MHD equations are emphasized, but obtaining solutions of this complex system of equations involves various assumptions and approximations. The spatial and temporal complexity of the outer heliosphere and some approaches for dealing with this complexity are discussed.
The possible origin of the anomalous cosmic rays (ACR) are studied in terms of stellar wind injection from O type stars and their acceleration in shock fronts of SNR's. It is assumed that a fraction of heavy ions will encounter interstellar shock fronts of SNR's and these are accelerated to about 5 to 100 MeV/N and give rise to ACR's. Typically these ions would travel a distance of the order of a few 1000 pc. Therefore it is estimated that O type stars in a volume of radius of a few Kpc around the solar system are contributing to the intensity of ACR in the local ISM. From observational data, the intensity of ACR in the local ISM is estimated. It is suggested that these ACR ions enter the solar system along the solar dipole field lines connected to the interplanetary magnetic field lines.
The magnetic field measurements from Voyager and the magnetohydrodynamic (MHD) processes in the outer heliosphere are reviewed. A bibliography of the experimental and theoretical work concerning magnetic fields and plasmas observed in the outer heliosphere is given. Emphasis in this review is on basic concepts and dynamical processes involving the magnetic field. The theory that serves to explain and unify the interplanetary magnetic field and plasma observations is magnetohydrodynamics. Basic physical processes and observations that relate directly to solutions of the MHD equations are emphasized, but obtaining solutions of this complex system of equations involves various assumptions and approximations. The spatial and temporal complexity of the outer heliosphere and some approaches for dealing with this complexity are discussed.
Plasma data from the ISEE-1 and -2 spacecraft during 1977-1980 have been used to determine the distribution of data points in the magnetotail in the range of distances -20 < XGSM < --15, i.e. which of the records that were located in the current sheet, in the tail lobe, in the magnetosheath and in the boundary layers respectively. The ISEE-1 and -2 magnetic field data for the records in the tail lobe were then used to model the tail lobe magnetic field dependence on the solar wind dynamic pressure, on the Interplanetary Magnetic Field (IMF) and on the Dst index. The tail lobe magnetic field was assumed to be dependent on the square root of the dynamic pressure based on the balance between the total magnetic pressure in the tail lobes and the dynamic pressure of the solar wind. The IMF dependent terms, added to the pressure term, were sought in many different forms while the Dst dependence of the tail lobe magnetic field was assumed to be linear. The field shows a strong dependence on the square root of the dynamic pressure and the different IMF dependent terms all constitute a significant contribution to the total field. However, the dependence on the Dst index turned out to be very weak at those down-tail distances. The results of this study are intended to be used for parameterizing future versions of the data-based models of the global magnetospheric magnetic field.
This study focuses on Time History of Events and Macroscale Interactions During Substorms (THEMIS) observations of a long \duration transient event in the vicinity of the dayside magnetopause at approx.15:34 UT on 18 July 2008 that was characterized by features typical of a magnetospheric flux transfer event (FTE): a bipolar negative-positive 5-7 nT signature in the Bn component, a positive monopolar variation in the Bl and Bm components, a approx.5-7 nT enhancement in the total magnetic field strength, and a transient density and flow enhancement. The interplanetary magnetic field (IMF) was mostly radial and disturbed during the intervals studied; that is, it was favorable for the repeated formation, disappearance and reformation of the foreshock just upstream from the subsolar bow shock. We show that varying IMF directions and solar wind pressures created significant effects that caused the compressions of the magnetosphere and the bow shock and magnetopause motions and triggered the transient event. Global signatures of magnetic impulse events (MIEs) in ground magnetograms during the period suggest a widespread pressure pulse instead of a localized FTE as the cause of the event in the magnetosphere. The directions of propagation and the flow patterns associated with the event also suggest an interpretation in terms of pressure pulses.
The paper examines sources of magnetic fields in recurrent streams observed by the Imp 8 and Heos spacecraft at 1 AU and by Mariner 10 en route to Mercury between October 31, 1973 and February 9, 1974, during Carrington rotations 1607-1610. Although most fields and plasmas at 1 AU were related to coronal holes and the magnetic field lines were open in those holes, some of the magnetic fields and plasmas at 1 AU were related to open field line regions on the sun which were not associated with known coronal holes, indicating that open field lines may be more basic than coronal holes as sources of the solar wind. Magnetic field intensities in five equatorial coronal holes, certain photospheric magnetic fields, and the coronal footprints of the sector boundaries on the source surface are characterized.
Interplanetary magnetic field and plasma velocity variations observed during Mariner II flight
Regions where a draped model magnetosheath magnetic field is nearly antiparallel to a model geomagnetic field are shown to be asymmetric for an interplanetary magnetic field (IMF) at the garden hose angle, as suggested by Heelis. When the IMF has a southward component, the asymmetry favors the dawn region for both IMF polarities. The dusk region is favored when the IMF has a northward component. If the regions of antiparallel fields are assumed to be sites of maximum magnetic merging, then the asymmetry is consistent with observed seasonal variations of geomagnetic activity and with dawn-displaced magnetospheric phenomena. In the alternate merging geometry of a line passing through the subsolar region, the asymmetry is predominantly north-south rather than dawn-dusk. Merging line geometry is consistent with the seasonal variations but not with the dawn-displaced phenomena.
Regions where a draped model magnetosheath magnetic field is nearly antiparallel to a model geomagnetic field are shown to be asymmetric for an interplanetary magnetic field (IMF) at the garden hose angle, as suggested by Heelis. When the IMF has a southward component, the asymmetry favors the dawn region for both IMF polarities. The dusk region is favored when the IMF has a northward component. If the regions of antiparallel fields are assumed to be sites of maximum magnetic merging, then the asymmetry is consistent with observed seasonal variations of geomagnetic activity and with dawn-displaced magnetospheric phenomena. In the alternate merging geometry of a line passing through the subsolar region, the asymmetry is predominantly north-south rather than dawn-dusk. Merging line geometry is consistent with the seasonal variations but not with the dawn-displaced phenomena.