Table Of ContentPOLAR AND MAGNETOSPHERIC SUBSTORMS
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J. E. BLAMONT, Laboratoire d'Aironomie, Verrieres, France
R. L. F. BOYD, University College, London, England
L. GOLDBERG, Harvard College Observatory, Cambridge, Mass., USA
C. DE J AG ER, University of Utrecht, Utrecht, Holland
G. H. LUDWIG, NASA, Goddard Space Flight Center, Greenbelt, Md., USA
R. LÜST, Institut für Extraterrestrische Physik, Garsching-München, Germany
B. M. MCCORMAC, Geophysics Division, /IT Research Institute, Chicago, Ill., USA
H. E. NEWELL, NASA, Washington, D.C., USA
L.1. SEDOV, Academy of Sciences ofthe USSR, Moscow, USSR
Secretary of the Editorial Board
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DE GRAAFF, Sterrewacht 'Sonnenborgh', University of Utrecht, Utrecht, Holland
VOLUME 11
SYUN-ICHI AKASOFU
Geophysical Institute, University 0/ Alaska, College, Alaska
POLAR
AND MAGNETOSPHERIC
SUBSTORMS
D. REIDEL PUBLISHING COMPANY
DORDRECHT-HOLLAND
ISBN-13: 978-94-010-3463-0 e-ISBN-13: 978-94-010-3461-6
DOI: 10.1007/978-94-010-3461-6
© 1968. D. Reidel Publishing Company, Dordrecht, Holland
Softcover reprint ofthe hardcover 1st edition 1968
No part of this book may be reproduced in any form, by print, photoprint,
microfilm, or any other means, without permission from the publisher
TO SYDNEY CHAPMAN
who, unbeknown to most scientists, has encouraged and
inspired the world's magnetic and auroral observatories
to maintain the essential records upon which our under-
standing of geomagnetism and the aurora rests.
PREFACE
It has become increasingly clear that the magnetosphere becomes intermittently
unstable and explosively releases a large amount of energy into the polar upper atmos
phere. This particular magnetospheric phenomenon is called the magnetospheric sub
storm. It is manifested as an activity or disturbance ofvarious polar upper atmospheric
phenomena, such as intense auroral displays and X-ray bursts. Highly active conditions
in the polar upper atmosphere result from a successive occurrence of such an element
ary activity, the polar substorm, which lasts typically of order one to three hours.
The concept of the magnetospheric substorm and its manifestation in the polar
upper atmosphere, the polar substorm, has rapidly crystallized during the last few
years. We can find a hint of such a concept in the term 'polar elementary storm'
introduced by Kristian Birkeland as early as 1908. However, we are greatly indebted
to Sydney Chapman, who established the basic foundation of magnetospheric physics
and has led researches in this field during the last half century. Indeed, the terms 'polar
magnetic substorm' and 'auroral substorm' were first suggested by Sydney Chapman.
The concept of the substorm was then soon extended by Neil M. Brice of Cornell
University, and Kinsey A. Anderson and his colleagues at the University ofCaliforrlia,
Berkeley, who introduced the term 'magnetospheric substorm'.
We owe many of these recent developments in magnetospheric physics to the
great international enterprise, the International Geophysical Year (IGY) and subse
quent international cooperative effort (IGC, IQSY).
However, as ten years have passed since the IGY, it is opportune to examine
critically what we have learned, what we should have learned and what should be
investigated in the near future. There have already been many excellent review articles
in the literature on various polar upper atmospheric phenomena and also many excel
lent edited books contributed by experts in various fields. What is lacking, in my
opinion, is a synthetic and unifying study, by a single author, of various polar upper
atmospheric phenomena and associated magnetospheric phenomena on the basis of
the concept of the polar substorm and the magnetospheric substorm.
It is quite obvious that for a single author to review studies in such diverse fields
is a formidable task. Nevertheless, I have volunteered to do so, since I feel, on the
basis of my studies of the polar substorm, that the concept of the polar substorm
and of the magnetospheric substorm can help greatly in our understanding of complex
polar upper atmospheric phenomena and magnetospheric phenomena.
In this mono graph, I have therefore concentrated my effort in organizing available
materials in terms of the polar substorm and the magnetospheric substorm. This has
vm POLAR AND MAGNETOSPHERIC SUBSTORMS
enabled me to construct the pattern of the development of substorms for various
polar upper atmospheric phenomena. I hope that no significant work has been over
looked in this respect. I am reasonably certain that most of the inaccuracies and
obscurities in the constructed patterns presented in this monograph are due to our
present lack of knowledge and understanding. Thus, it is my hope that this monograph
will prove useful in providing a basis for fruitful and constructive debate toward a
better understanding of polar upper atmospheric and magnetospheric phenomena.
It is for this very reason that I believe the monograph should also prove useful in
planning future international co operative studies. By its nature, it is not possible to
study the polar substorm without a well-organized network of observatories. A reason
able understanding of both the polar substorm and the magnetospheric substorm also
requires a well-planned effort, between 'satellite workers' and 'ground workers'.
I have written this monograph on the assumption that the reader is familiar with
at least one of the diverse polar upper atmospheric phenomena. Since it is written for
a very specific purpose, the quoted references are rather specialized; however, in
order for this book to be useful as an introductory one, I have also included a few
references for each chapter under the title 'general references'.
SYUN-ICHI AKASOFU
ACKNOWLEDGEMENTS
I would like to thank Dr Sydney Chapman whose encouragement has made this book
possible.
Many colleagues at the Geophysical Institute, University of Alaska (past and
present) have contributed direct1y and indirect1y to this book. It would have been
impossible to produce a book of this scope without their help. It is a pleasure to be
able to record here my gratitude to the former director Dr C. T. Elvey, the present
director Dr K. B. Mather, and Dr T. N. Davis for their encouragement. I should like
particularly to thank Dr c.-1. Meng for his collaboration in studying the polar sub
storm. I had many stimulating discussions with Messrs. A. E. Belon, F. T. Berkey,
R. R. Heacock, J. L. Hook, R. Parthasarathy, G. J. Romick, D. W. Swift, and C. R.
Wilson during the preparation of the manuscript.
It is also a great pleasure to thank Drs W. I. Axford, Y. I. Feldstein, E. W. Hones,
Jr., G. K. Parks, J. H. Piddington, J. A. Van Allen and J. R. Winckler for their illu
minating discussions. My frequent visits to the High Altitude Observatory, NCAR,
Boulder, Colorado, have been most useful. I would like to thank the colleagues who
have provided me with many of the illustrations used, and also the Editors and
Publishers for their kind permission to reproduce these illustrations.
I acknowledge with pleasure the support given to my study by the Atmospheric
Sciences Section of the National Science Foundation and the National Aeronautics
and Space Administration.
Mr. K. Kawasaki and Mrs. C. Abney read the manuscript with care and found
many obscurities. The staff members of the steno, drafting and photo departments
of the Geophysical Institute worked hard during the hot (88°1) summer days during
the preparation of the manuscript. Special thanks are due to Mrs. J. Lipscomb for
her help in the editorial work, and to D. Reidel Publishing Company for its special
care in the publication of this monograph. Finally, I would also like to thank my
wife who shared with me the 'Arctic' life.
TABLE OF CONTENTS
PREFACE VII
ACKNOWLEDGEMENTS IX
LIST OF FREQUENTLY USED SYMBOLS XVII
CHAPTER 1/ INTRODUCTION
1.1. Polar Upper Atmosphere and the Outer Magnetosphere
1.2. Polar Substorms and Magnetospheric Substorms 2
1.3. Magnetospheric Substorm and Magnetospheric Storm 5
1.4. Auroral Oval as a Natural Coordinate 7
1.5. Four Circumpolar Structures and the Corresponding Magnetospheric
Structures 16
1.6. Changing Auroral Oval 18
1.7. Scope of the Monograph 20
CHAPTER 2/ AURORAL SUBSTORM AND ASSOCIATED MAGNETIC
DISTURBANCES 22
2.1. Introduction: Typical Daily Variation 22
A. Auroral Substorm 22
B. Polar Magnetic Substorm 31
sn
1. Analysis 31
2. Spiral Analysis 34
2.2. Auroral Substorm and Associated Magnetic Disturbances in the Mid-
night Sector 36
2.3. Auroral Substorm and Associated Magnetic Disturbances in the Evening
Sector 37
2.4. Auroral Substorm and Associated Magnetic Disturbances in the Morning
Sector 44
2.5. Auroral Substorms in the Geomagnetically Conjugate Areas 45
CHAPTER 3/ POLAR MAGNETIC SUBSTORM 49
3.1. Introduction 49
3.2. Polar Magnetic Substorms on December 13, 1957 53
XII POLAR AND MAGNETOSPHERIC SUBSTORMS
3.3. Polar Magnetic Substorm on December 16, 1964 56
3.4. Three-Dimensional Model Current System 62
3.5. Polar Magnetic Substorms in Geomagnetically Conjugate Areas 68
CHAPTER 4/ IONOSPHERIC SUBSTORM 73
4.1. Introduction 73
4.2. Typical Daily Variation of the Cosmic Radio Wave Absorption 75
4.3. Statistical Daily Variation Pattern 77
4.4. N Type Absorption 80
4.5. E Type Absorption 83
4.6. M Type Absorption 91
4.7. Cosmic Radio Noise Absorption at Geomagnetically Conjugate Areas 95
4.8. Development of the Ionospheric Substorm (Absorption) 96
4.9. Deformation of the Ionosphere 97
4.10. Radio Auroras 100
4.11. Atmospheric Wave Substorm 103
A. Traveling Disturbances 103
B. Infrasonic Pressure Waves from Active Auroras 103
4.12. Atmospheric Heating in the Auroral Zone 106
CHAPTER 5/X-RAY SUBSTORM 110
5.1. Introduction 110
5.2. Typical Daily Variation 111
5.3. Statistical Daily Variation Pattern 114
5.4. Midnight Bursts 114
5.5. X-Ray Bursts Associated with Westward Traveling Surges 117
5.6. X-Ray Bursts in the Morning and Midday Hours 120
5.7. Fine Structures of the X-Ray Bursts 122
5.8. X-Ray Bursts at the Geomagnetically Conjugate Areas 122
5.9. Development of the X-Ray Substorm 122
CHAPTER 6/PROTON AURORA SUBSTORM 126
6.1. Introduction 126
6.2. Typical Daily Variation 128
6.3. Statistical Daily Variation Pattern 129
6.4. Protons in the Auroral Bulge and Patches 132
6.5. Protons and Westward Traveling Surges 133
6.6. Development of the Proton Aurora Substorm 136
CHAPTER 7/ VLF EMISSION SUBSTORM 140
7.1. Introduction 140
