Table Of ContentMAGNETOSPHERIC PARTICLES AND FIELDS
ASTROPHYSICS AND
SPACE SCIENCE LIBRARY
A SERIES OF BOOKS ON THE RECENT DEVELOPMENTS
OF SPACE SCIENCE AND OF GENERAL GEOPHYSICS AND ASTROPHYSICS
PUBLISHED IN CONNECTION WITH THE JOURNAL
SPACE SCIENCE REVIEWS
Editorial Board
J. E. BLAMONT, Laboratoire d 'Aeronomie, Verrieres, France
R. L. F. BOYD, UniJ1ersity College, London, England
L. GOLDBERG, Kitt Peak National Observatory, Tucson, Ariz., U.S.A.
C. DE JAGER, University of Utrecht, Holland
Z. KOPAL, University of Manchester, Manchester, England
G. H. LUDWIG, NOAA, National Em'ironmental Satellite Service, Suitland, Md., U.S.A.
R. LOST, President Max-Planck-Gesellschaft zur F6rderung der Wissenschaften, Milnchen, F.R. G.
B. M. MCCORMAC, Lockheed Palo Alto Research Laboratory, Palo Alto, Calif., U.S.A.
H. E. NEWELL,NASA, Washington, D.C., U.S.A.
L. I. SEDOV, Academy of Sciences of the U.S.S.R., Moscow, U.S.S.R.
Z. SVESTKA, American Science and Engineering, Cambridge, Mass., U.S.A.
VOLUME58
PROCEEDINGS
MAGNETOSPHERIC
PARTICLES AND FIELDS
PROCEEDINGSOFTHESUMMERADVANCEDSTUDYSCHOO~
HELD IN GRAZ, AUSTRIA, AUGUST 4-15,1975
Edited by
B. M. Me CORMAC
Lockheed Palo Alto Research Laboratory,
Palo Alto, Calif, U.S.A.
D. REIDEL PUBLISHING COMPANY
DO RDRECHT -HOLLAND /BOSTON -U.S.A.
Library of Congress Cataloging in Publication Data
Main entry under title:
Magnetospheric particles and fields.
(Astrophysics and space science library; v. 58)
Includes bibliographies and index.
1. Magnetosphere-Congresses. 2. particles (Nuclear
physics)-Congresses. 3. Field theory (Physics)-Congresses.
I. McCormac, Billy Murray. II. Series.
QC809.M35M327 538'.766 76-25177
ISBN-13: 978-94-010-1505-9 e-ISBN-I3: 978-94-010-1503-5
DOl: 10.1007/978-94-010-1503-5
Published by D. Reidel Publishing Company,
P.O. Box 17, Dordrecht, Holland
Sold and distributed in the U.S.A., Canada, and Mexico
by D. Reidel Publishing Company, Inc.
Lincoln Building, 160 Old Derby Street, Hingham,
Mass. 02043, U.S.A.
All Rights Reserved
Copyright © 1976 by D. Reidel Publishing Companv. Dordrecht, Holland
Softcover reprint of the hardcover I st edition 1976
No part of the material protected by this copyright notice may be reproduced or
utiliied in any form or by any means, electronic or mechanical,
including photocopying, recording or by any informational storage and
retrieval system, without written permission from the copyright owner
TABLE OF CONTENTS
PREFACE vii
VYTENIS M. VASYLIUNAs/Magnetospheric Particles and Fields 1975: Summary
EUGENE W. GREENSTADT/ Phenomenology of the Earth's Bow Shock System.
A Summary Description of Experimental Results 13
L. A. FRANK and K. L. ACKERSON/ Examples of Plasma Flows within the
Earth's Magnetosphere 29
G. PASCHMANN, N. SCKOPKE and H. GRUNWALDT/Plasma in the Polar Cusp
and Plasma Mantle 37
R. B. TORBERT and c. W. CARLsoN/Impulsive Ion Injection into the Polar Cusp 47
WERNER PILIPP and GREGOR MORFILL/The Plasma Mantle as the Origin of
the Plasma Sheet 55
D. H. FAIRFIELD/Waves in the Vicinity of the Magnetopause 67
K. SCHINDLER/Magnetotail Model 79
DAVID A. HARDY, JOHN W. FREEMAN, and H. KENT HILLs/Plasma Obser
vations in the Magnetotail 89
VYTENIS M. VA SY LIUNAs/An Overview of Magnetospheric Dynamics 99
1. R. BURROWS, MARGARET D. WILSON, and I. B. MCDIARMID/Simultaneous
Field Aligned Current and Charged Particle Measurements in the Oeft 111
F. s. M0 ZE R/ Anomalous Resistivity and Parallel Electric Fields 125
L. R. LYONS/Explorer 45 Observations of the Proton Ring Current 137
J. F. FENNELL and J. B. BLAKE/Geomagnetically Trapped Alpha Particles 149
RICHARD MANSERGH THORNE/The Structure and Stability of Radiation Belt
Electrons as Controlled by Wave-Particle Interactions 157
THEODORE A. FRITZ and BEREND WILKEN/Substorm Generated Fluxes of
Heavy Ions at the Geostationary Orbit 171
M. ASHOUR-ABDALLA and c. F. KENNEL/Convective Cold Upper Hybrid In-
stabilities 181
DONALD A. GURNETT/The Earth as a Radio Source 197
A. ROUX and R. PELLAT/A Study of Triggered Emissions 209
c. D. ANGER and J. S. MURPHREE/ISIS-2 Satellite Imagery and Auroral Mor
phology 223
FOKKE CREUTZBERG/Morphology and Dynamics of the Instantaneous Auroral
Oval 235
D. D. WA LLIs/Comparison of Auroral Electrojets and the Visible Aurora
247
G. KREMSER/Auroral X-ray Morphology
257
K. D. COLE/Magnetosphere-Ionosphere Interactions Via Electric Currents and
Fields
267
VI TABLE OF CONTENTS
D. R. LEPINE, D. S. HALL, and D. A. BRYANT/The Role of Fluctuating Accel-
eration in Multiple Auroral Arcs 279
T. EDWARDS, D. A. BRYANT, M. J. SMITH, U. FAHLESON, C.·G. FALT·
HAMMAR, and A. PEDERsEN/Electric Fields and Energetic Particle Precipi-
tation in an Auroral Arc 285
JAMES WARWICK/Magnetic Fields in the Solar System 291
LEVERETT DAVIS, JR. and E. J. SMITH/The Jovian Magnetosphere and Magneto-
pause 301
M. H. ACUNA and N. F. NEss/The Magnetic Field of Jupiter 311
GLOSSARY 325
INDEX OF SUBJECTS 329
PREFACE
This book contains the lectures presented at the Summer Advanced Study School,
'Magnetospheric Particles and Fields' which was held at Graz, Austria during the period
August 4-15, 1975. One hundred and one persons from fifteen different countries
attended the Schoo!.
The authors and publisher have made a special effort for rapid publication of an up-to
date status of particles, fields, and processes in planetary magnetospheres. Special thanks
are due to the lecturers for their diligent preparation and excellent presentations. The in
dividuallectures and the published papers were deliberately limited; the authors' cooper
ation in conforming to these specifications is greatly appreciated. Many thanks are due to
Drs C. D. Anger, Gerhard Haerendel, George P. Haskell, Carl McIlwain, Vytenis Vasy
liunas, Martin Walt, and James Warwick who served as session chairmen during the
School and contributed greatly to its success by skillfully directing the discussion period
in a stimulating manner after each lecture.
Many persons contributed to the success of the School. Drs C. D. Anger, Carl-Gunne
Falthammar, Gerhard Haerendel, George P. Haskell, Carl McIlwain, David Nunn, Willi
Riedler, Finn S¢raas, Vytenis M. Vasyliunas, Martin Walt, and James Warwick were
especially helpful in preparing the technical program. Dr Willi Riedler assisted in ar
ranging for the facilities in Graz. Drs Gerhard Kremser and Martin Friedrich were most
helpful with many aspects of the local arrangements in Graz.
The assistant editor, Mrs Diana R. McCormac, checked the manuscripts and proofs,
and worked hard to achieve a uniform style in this book.
Direct financial support was provided to the School by the Defence Nuclear Agency,
Lockheed Palo Alto Research Laboratory, and the Office of Naval Research.
Palo Alto BILLY M. McCORMAC
December 1975
MAGNETOSPHERIC PARTICLES AND FIELDS 1975: SUMMARY
VYTENIS M. VASYLIUNAS
Max-Planck-Institut fUr Aeronomie, D-3411 Katlenburg-Lindau 3, Germany
1. Introduction
The purpose of these introductory remarks is to set the stage for the detailed summaries
that follow and to identify some of the main topics ofinterest at this conference, occasion
ally comparing or contrasting them with those of previous conferences_
One of the strong points of the Magnetospheric Particles and Fields series of con
ferences has been the wide coverage of essentially all the topics of primary interest to
magnetospheric physics at the time of each conference. Looking at the subject matter of
the successive conferences thus gives one a good idea of how magnetospheric physics
has evolved over the past ten years. From the initial concern with the limited inner part
of the magnetosphere and the small fraction of the particle population represented by
the trapped radiation, emphasis has shifted to the outer regions of the magnetosphere,
to the system as a whole and to physical and plasma processes within it. The fundamental
topic of the solar wind has grown into a large subject in its own right, almost too large to
fit together with the magnetosphere into a single conference; the aspects of solar wind
and magnetosheath studies discussed at this conference were largely limited to those of
direct concern to magnetospheric physics. (It may be remarked that the interaction
between the solar wind and the magnetosphere appears to be somewhat stronger than the
interaction between the investigators of the respective fields.)
The theme of the 1975 Magnetospheric Particles and Fields conference (if anyone
topic can be so designated) was the interface between the geomagnetic field and the solar
wind plasma - the outermost regions of the magnetosphere and the various boundary
layers and phenomena found therein. This subject was already widely discussed at the
1973 conference but primarily from a theoretical point of view, with only preliminary
and sketchy data. By contrast, the 1975 conference was predominantly concerned with
observations, in this as well as in other areas. The vast quantities of measurements in the
outermost magnetosphere obtained in recent years are now being analyzed and reported;
we now have an almost complete survey of the particles and fields in the magnetosphere
at all distances, local times, and latitudes, and are able to examine the interface regions in
some detail. Theoretical progress has been slow by comparison; it is to be hoped that the
large amount of observational material will serve as both an incentive and a guide to the
theorist.
Another topic that received a lot of emphasis at this conference was the phenom
enology of what might be called the inner regions of the outer magnetosphere: the
vicinity of the synchronous orbit, which lies at the interface between the undistorted
dipolar field of the inner magnetosphere and the extended geomagnetic tail. Here again
the primary impression is that of vast quantities of observational data now being looked
at and revealing an impressive richness of detail. The two aspects of outer magnetosphere
B.M.McCormac (ed.), Magnetospheric Particles and Fields, 1-11. A II Rights Reserved.
Copyright © 1976 by D. Reidel Publishing Company, Dordrecht-Holland.
2 VYTENIS M. VASYLIUNAS
studies that have dominated previous conferences, namely, the theoretical description
of magnetospheric convection and the phenomenology of magnetospheric substorms,
tended to recede somewhat into the background at this conference. The theory of con
vection has been regarded for some time now as essentially complete in its formal aspects
and awaiting further observational inputs - which have been forthcoming as a nearly
overwhelming amount of new data on electric fields, plasma flows, and related obser
vations. For the case of sub storm phenomenology it appears that the grand controversies
of previous years have been fought to a standstill; new observations and/or new insights
are needed to break the stalemate.
The topic of particle-wave interactions, a staple item at these conferences for a number
of years, received additional emphasis and seems also to be acquiring a closer touch with
the rest of magnetospheric physics. (As in the case of the solar wind and the magnet
osphere, the phenomena interact perhaps more strongly than the investigators.) We
are learning that particle-wave interactions can have quite significant (and measurable)
effects on such major aspects of magnetospheric dynamics as the ring current and the
precipitation of particles. Thus the subject is becoming less of an isolated theoretical
entity and is beginning to bear more directly on observational and other aspects of
magnetospheric physics.
The beautiful and complex phenomena of the aurora and related processes received
due attention. Here again, the hallmark of the conference was the preponderance of
observations, as a result of the recent availability of global data on the aurora as well as
continued pursuit of more conventional ground-based, balloon, and rocket investigations.
The problem of auroral small-scale structures, in particular, is still one of the frontier
areas of magnetospheric physics. In my opinion, we still lack a clear focus for theoretical
efforts - we are still groping to see what is going on, although significant progress can be
hoped for given the considerable amount of available data.
The 1975 conference was the first in the series to have a complete session on the
magnetospheres of other planets. This reflected the availability of direct in situ obser
vations, particularly of the magnetospheres of Jupiter and Mercury. Instead of simply
speculating what might be there, we now have observations of what is there, which we
can try to understand and compare with what we know about the Earth's magnetosphere.
One might say that this changes magnetospheric physics from a branch of geophysics,
where we deal with one unique object (albeit one of great concern to us since we live on
it!) to a branch of astrophysics, where we now study the magnetosphere not as one
isolated system but as one example out of many interesting such systems in the universe.
2. Solar Wind and Magnetosheath *
We heard about correlations between the solar wind parameters and the magnetosheath
and magnetosphere; the interplanetary magnetic field direction, in particular, is very
important in determining what the magnetosphere does. We heard about upstreaming
* Presented by Donald Fairfield.
MAGNETOSPHERIC PARTICLES AND FIELDS 1975: SUMMARY 3
particles, solar wind particles reflected from the bow shock and going back upstream,
ranging all the way from low energy electrons (detected as a heat flux coming from the
bow shock) to protons with hundreds of keV in energy; associated with the particles in
the upstream region there are waves, generally thought to be generated by these upstream
ing particles. We heard about the structure of the bow shock, studied in recent years by
Greenstadt, Formisano, and others; the structure depends primarily on three different
parameters, the i3 of the plasma, the (magnetosonic or Alfven) Mach number, and the
angle between the magnetic field and the shock normal (this parameter is the most im
portant one for the typically high Mach number bow shock of the Earth). The magni
tude of this angle provides the basis for the classification of the various bow shock
observations into a whole matrix of different categories, primarily developed by Green
stadt.
Biskamp discussed the theory of shock structure, in a remarkable attempt to explain
a large body of theoretical plasma physics to a group of geophysicists. The agreement
between theory and experiment appears to be fairly good for low Mach number shocks
but not so good elsewhere, where a great deal of work remains to be done.
Very little was said about the magnetosheath at this meeting. The familiar hydro
dynamic picture of post-shock flow deflected around the magnetosphere is quite a good
first approximation and few, if any, significant additions or modifications have been
made in recent years.
Let us now consider some of the outstanding problems in these areas. As far as the
solar wind is concerned, its outstanding problems are of great interest in themselves and
of considerable relevance to solar physics but, for the most part, have little direct bearing
on the magnetosphere. The magnetosphere responds to the basic solar wind parameters -
density, bulk velocity, and magnetic field - which have all been measured; it appears
unlikely that there is some as yet hidden quantity in the solar wind that significantly
influences what happens in the magnetosphere.
The measurements of upstreaming particles need to be improved, particularly measure
ments of some important numbers such as the fraction of the incoming solar wind energy
reflected at the bow shock (a number as high as 40% has been mentioned but the basis
for it is not certain and a complete rechecking is desirable). The thickness of the bow
shock, a crucial input to the plasma theory, is not very well measured; this will be one of
the primary areas of interest in the upcoming International Sun-Earth Explorer (ISEE)
mission. Another aspect of the bow shock structure that needs considerable expansion
is a detailed comparison of magnetic field and plasma observations.
Other than the confirmation of the basic hydrodynamic pattern, the magnetosheath
is really a rather unknown quantity; I think it is the forgotten topic in solar wind -
magnetosphere interactions. We have little idea of what wave modes are present in the
magnetosheath or where do the various waves come from - convected from the solar
wind, produced at the bow shock or at the magnetopause, or generated by instabilities
within the magnetosheath itself; this is really an open area in which little work has been
done. There have been reports of magnetospheric particles observed within the magnet
osheath; I think this is an interesting topic of which we should hear more in the future.
