Magnetopause Currents

Knowledge of the magnetopause currents and their spatial distribution is required for studies of possible relationships between current density and electric magnetic fluctuation levels within the layer, and for investigating the fine-structure of the currents, both in magnitude and direction. Individual spacecraft crossing the magnetopause can sample changes in the magnetic field across the current layer, which, in a 1-D geometry, can in principle give an estimate of the current density in the...

Info

Bow shock normals (short lines) deduced from four spacecraft timings, plotted extending from their measured locations (circles). The three panels show the projection of the positions and normals onto the X-Y, X-Z and Y-Z GSE planes. Note that shocks near the nose are not sampled due to the polar Cluster orbit. From Horbury et al. (2002). Figure 5.1. Bow shock normals (short lines) deduced from four spacecraft timings, plotted extending from their measured locations (circles). The...

Observations of High Frequency Waves

3.5.1 Electromagnetic waves Lion roars Lion roars are intense, short-duration, narrow-band packets of whistler mode waves observed in Earth's magnetosheath, first reported by Smith et al. (1967) using data from OGO 1. The average mean frequency of these waves in the magnetosheath is 100 Hz (0.25-0.5 fee) with typical amplitudes of 0.1 nT and burst durations of 1 -2 s (Smith and Tsurutani, 1976). When Lion roars are excited inside mirror modes, their frequency is much lower because of the...

Cm Pi

Left Structure of the diffusion region from a numerical Hall fluid simulation by Rogers et al. (2003). The magnetic field lines are shown in white, the out-of-plane magnetic field is colour coded (white duskward, black dawnward). Also shown projection of Cluster configuration with colour coded spacecraft, and approximate location relative to the diffusion region. Right Cluster observations, simulation results are in grey lines. a Reconnecting magnetic field component. b...

Upstream Waves and Particles

It has been mentioned earlier that the main field signature of the ion foreshock is the presence of low frequency fluctuations. Identification of the properties of these waves, their nature, dispersion, diffusion and free energy source as well as their effect on the solar wind are therefore of prime interest. In this section we review Cluster observations and the Cluster-based analysis of these waves. Figure 2.9. Magnetic field observed by Cluster 1 between 00 00 and 12 00UT, January 16, 2001....

Mirror Mode Theory and Modelling

Mirror modes, as described in Section 3.2.1, frequently occur in the magnetosheath under conditions of enhanced ion temperature anisotropy (T > T ) and high 2. They are non-propagating magnetic bottle structures, characterised by large amplitude variations in the magnetic field magnitude, AB B 1, anti-correlated with variations in the plasma number density introducing inhomogeneity into the plasma. Anticorrelation between magnetic field and density perturbations is not unique to mirror modes....

Introduction

Quasi Parallel Shock Depends Imf

Although collisionless shocks primarily exist to mediate the flow of supermagnetosonic plasma, they also act as sites for particle acceleration. It is now well known that for certain magnetic field geometries, a portion of the inflowing plasma returns to the upstream region rather than being processed by the shock and passing irreversibly downstream. The combination of the inflowing plasma and this coun-terstreaming component upstream of the shock is subject to a number of plasma instabilities,...

Foreshock Boundaries

The electron foreshock, as sketched in Figure 2.1 occupies the region from the bow-shock to just downstream of the tangent magnetic field line. Like the ion foreshock, the electron foreshock is a very dynamic region in which bow shock reflected electrons are convected downstream toward the bow shock by the v x B electric field in the solar wind. Similar to the ions in the ion foreshock, the highest energy electrons are observed close to the foreshock boundary, while the lower energy electrons...

References

B. Strong 1968, 'Outward flow of protons from the Earth's bow shock'. J. Geophys. Res. 73(12), 5777. Bagenal, F., J. W. Belcher, E. C. Sittler, Jr., and R. P. Lepping 1987, 'The Uranian Bow Shock Voyager 2 Inbound Observations of a High Mach Number Shock'. J. Geophys. Res. 92, 8603. Bale, S. D., F. S. Mozer, and T. S. Horbury 2003, 'Density-transition scale at quasiperpendicular collisionless shocks'. Physical Review Letters 91(26), 265004. Balikhin, M., M....

S Haaland

Reprinted from Space Science Reviews, Volume 118, Nos. 1-4, 2005 A.C.I.P. Catalogue record for this book is available from the Library of Congress Published by Springer P.O. Box 990, 3300 AZ Dordrecht, The Netherlands Sold and distributed in North, Central and South America by Springer, 101 Philip Drive, Norwell, MA 02061, U.S.A. In all other countries, sold and distributed by Springer, P.O. Box 322, 3300 AH Dordrecht, The Netherlands All Rights Reserved 2005 Springer No part of the material...

Flux Transfer Events

Russell and Elphic (1978) reported a regularly occurring characteristic magnetic field signature observed at low latitude by Isee-1 and -2, which they termed a flux transfer event (FTE). This signature consists of a bipolar fluctuation in the field component normal to the magnetopause over a timescale of a few minutes, corresponding to spatial scales of 1 RE. Statistical studies of FTEs (e.g., Rijnbeek et al., 1984 Berchem and Russell, 1984 Southwood et al., 1986 Lockwood, 1991 Lockwood and...

The Solar Wind at 1 AU

Observational evidence for a continuous stream of plasma filling interplanetary space was deduced from the properties of cometary tails by Biermann 1951 . Parker 1958 demonstrated that solutions of the fluid equations describing the solar atmosphere necessitated the existence of a continuous supersonic wind. The first in situ measurements of this wind were made by Gringauz et al. 1960 , and Snyder and Neugebauer 1966 . At 1 Astronomical Unit AU the solar wind is a tenuous ionised gas that...