Table Of ContentPhysics and Chemistry in Space
Volume 6
Edited by
J. G. Roederer, Denver
Editorial Board:
H. Elsasser, Heidelberg· G. Elwert, Tiibingen
L. G. Jacchia, Cambridge, Mass.
J. A. Jacobs, Edmonton
N. F. Ness, Greenbelt, Md .. W. Riedler, Graz
Siegfried J . Bauer
Physics of Planetary
Ionospheres
With 89 Figures
Springer-Verlag
Berlin Heidelberg New York 1973
Siegfried J. Bauer
Associate Chief, Laboratory for Planetary Atmospheres, NASA Goddard
Space Flight Center, Greenbelt, MD 20771jUSA.
ISBN -13 :978-3-642-65557-9 e-ISBN -13 :978-3-642-65555-5
DOl: 10.1007/978-3-642-65555-5
This work is subject to copyright. All rights are reserved, whether the whole or part of
the material is concerned, specifically those of translation, reprinting, re-use of illus
trations, broadcasting, reproduction by photocopying machine or similar means, and
storage in data banks.
Under § 54 of the German Copyright Law, where copies are made for other than
private use, a ree is payable to the publisher, the amount of the fee to be determined
by agreement with the publisher.
© by Springer-Verlag Berlin' Heidelberg 1973. Library of Congress Catalog Card
Number 72-15455.
Softcover reprint of the hardcover 1s t edition 1973
The use of registered names, trademarks, etc. in this publication does not imply, even
in the absence of a specific statement, that such names are exempt from the relevant
protective laws and regulations and therefore free for general use.
Siegfried J. Bauer
Physics of Planetary
Ionospheres
With 89 Figures
Springer-Verlag
New York Heidelberg Berlin 1973
Siegfried J. Bauer
Associate Chief, Laboratory for Planetary Atmospheres, NASA Goddard
Space Flight Center, Greenbelt, MD 20771jUSA.
ISBN -13 :978-3-642-65557-9 e-ISBN -13 :978-3-642-65555-5
DOl: 10.1007/978-3-642-65555-5
This work is subject to copyright. All rights are reserved, whether the whole or part of
the material is concerned, specifically those of translation, reprinting, re-use of illus
trations, broadcasting, reproduction by photocopying machine or similar means, and
storage in data banks.
Under § 54 of the German Copyright Law, where copies are made for other than
private use, a fee is payable to the publisher, the amount of the fee to be determined
by agreement with the publisher.
© by Springer-Verlag Berlin· Heidelberg 1973. Library of Congress Catalog Card
Number 72-15455.
Softcover reprint of the hardcover I st edition 1973
The use of registered names, trademarks, etc. in this publication does not imply, even
in the absence of a specific statement, that such names are exempt from the relevant
protective laws and regulations and therefore free for general use.
Monophoto typesetting and offset printing: Zechnersche Buchdruckerei, Speyer. Book
binding: Konrad Triltsch, Wiirzburg.
Preface
Although there are, in addition to the classic but somewhat dated
books'l-, some excellent recent books on ionospheric physics and
aeronomy'l-..., their scope is quite different from that of the present
monograph.
This monograph concentrates on the fundamental physical and
chemical processes in an idealized planetary ionosphere as a general
abstraction, with actual planetary ionospheres representing special
cases. Such an approach appears most appropriate for a concise in
troduction to the field, at a time when increasing experimental in
formation on the ionospheres of other planets can be anticipated.
The main purpose of this monograph, in line with that of the whole
series, is to appraise where we stand, what we know and what we still
need to know. It is mainly addressed to graduate students and researchers
who are in the process of getting acquainted with the field.
Within the scope of this monograph it would be impossible to do
justice to all relevant publications. Hence, references are somewhat
selective and largely limited to the more recent original papers and to
authoritative reviews, the latter generally providing also detailed
references regarding the historical development of the particular topic.
Cgs (gaussian) units are generally used in this book, except where
practical units are more appropriate.
This book has evolved from a graduate course of the same title
which I gave at the Catholic University of America, Washington, D. C.
in 1964/65 at the invitation of Prof. C. C. Chang. Although many of the
details are new, the original organization of topics and the spirit of the
course has been retained.
During the past decade I have benefited from the fruitful interaction
with my colleagues at the Goddard Space Flight Center, first in the
Planetary Ionospheres Branch and more recently in the Laboratory for
* cf. S. K. Mitra, The Upper Atmosphere, The Asiatic Society, Calcutta,
2nd ed 1952; J. A. Ratcliffe (ed), Physics of the Upper Atmosphere Academic
Press, New York, 1960.
** cf. H. Rishbeth and O. K. Gariott. Introduction to Ionospheric Physics, Aca
demic Press, New York, 1969; R. C. Whitten and 1. G. Poppoff, Fundamentals of
Aeronomy, John Wiley & Sons, New York, 1971; J.A. Ratcliffe, An Introduction
to the Ionosphere and the Magnetosphere, Cambridge University Press, 1972.
VI Preface
Planetary Atmospheres. I am especially grateful to Dr. A. C. Aikin,
Dr. R. F. Benson, Dr. S. Chandra, Dr. R. E. Hartle, Dr. J. R. Herman,
Mr. J. E. Jackson and Dr. H. G. Mayr, who have read and commented
on drafts of the manuscript. In addition, I want to thank Prof. S. H.
Gross of the Graduate Center, Brooklyn Polytechnic Institute, Far
mingdale, N. Y. and Dr. P. Stubbe of the Max-Planck-Institut fUr
Aeronornie, Lindau (Harz), Germany, for their reading of the manu
script and their helpful comments. The responsibility for the views
expressed in this book, however, remains my own.
Last, but not least, I wish to express my gratitude to Prof. O. Burkard
of the University of Graz, Austria, for introducing me-two decades
ago-to the field of ionospheric physics, and to my wife Inge and
daughter Sonya for their patience with my preoccupation.
It is my hope that this monograph will be useful as an introduction
to the physics of planetary ionospheres for a new generation of space
scientists and as a compendium for the old.
April 1973 S. J. Bauer
Contents
Introduction 1
Chapter I
Neutral Atmospheres
I.1 Nomenclature . . . . . . . . . 3
1.2 Barosphere: Distribution Laws . . 6
1.3 Thermosphere-Thermal Structure 17
1.4 Exosphere-Atmospheric Escape (Evaporation) . 26
1.5 Physical Properties of Planetary Atmospheres. . 40
Chapter II
Sources of Ionization
II.1 Solar EUV Radiation and X-Rays 45
II.2 Corpuscular Radiation 57
II.3 Meteor Ionization. . . . . . . . 62
Chapter III
Thermal Structure of Planetary Ionospheres
m.l Departures from Thermal Equilibrium. 67
III.2 Electron and Ion Temperatures. . . . 69
III.3 Heat Sources not Related to Photoionization 78
Chapter IV
Chemical Processes
IV.l General Comments 82
IV.2 Recombination. . . . . . 84
IV.3 Charge Exchange Reactions 86
IVA Negative Ion Reactions . . 90
IV.5 Chemical Reactions and Airglow 93
VIII Contents
Chapter V
Plasma Transport Processes
V.1 Plasma (Ambipolar) Diffusion . 96
V.2 Plasma Drift and Winds . 104
V.3 Plasma Escape ...... . 108
Chapter VI
Models of Planetary Ionospheres
VI.1 Equilibrium Models. . . . . . . . 113
VI.2 Observables and Derived Parameters 115
VI.3 Ionospheric Regions. . . . . . . . 120
VI.4 Realistic Models of Planetary Ionospheres 122
VI. 5 The Extent of Planetary Ionospheres. 123
Chapter VII
The Ionosphere as a Plasma
VII.1 General Plasma Properties . . . . . . 132
VII.2 The Ionosphere as a Dispersive Medium 134
VII.3 Ionospheric Plasma Instabilities. 149
Chapter VIII
Experimental Techniques
VIII. 1 Remote Sensing Radio Techniques 154
VIII.2 Direct Measurement Techniques 168
Chapter IX
Observed Properties of Planetary Ionospheres
IX.1 The Terrestrial Ionosphere. 178
IX.2 The Ionosphere of Mars . 194
IX.3 The Ionosphere of Venus. . 198
IX.4 The Ionosphere of Jupiter . 203
Appendix. Physical Data for the Planets and their Atmospheres 204
References . . 206
List of Symbols 219
Subject Index . 225
Introduction
The existence of the terrestrial ionosphere was verified experimentally
by Appleton and Barnett in England and by Breit and Tuve in the U. S.A.
less than half a century ago. An electrically conduciing layer in the
upper atmosphere had been postulated at the beginning of this century
independently by Kennelly in the U.SA, and by Heaviside in Great
Britain to explain Marconi's pioneering transatlantic radio transmissions.
Even earlier, during the 19th century, C. F. Gauss, W. Thomson (Lord
Kelvin) and Balfour Stewart had argued for the existence of such a
conducting layer to account for the daily variations of the Earth's
magnetic field. Originally known as the Kennelly-Heaviside layer, E. V.
Appleton, (who received the 1947 Nobel Prize in Physics for his pio
neering work in ionospheric research), called this layer the "E-Iayer"
for the electric vector of the reflected wave. When he found additional
reflecting layers, in 1925, he named them correspondingly D and F
layers, a terminology which is in present use. R. Watson-Watt, the
pioneer of Radar, is responsible for naming the complex of reflecting
layers the ionosphere.
Following the early theoretical work of E. O. Hulburt and Sydney
Chapman, the contributions by D. R. Bates, V. C. Ferraro, D. F. Martyn,
M. Nicolet, 1. A. Ratcliffe and many others during the past three decades
have led to our present understanding of the ionosphere as the result of
the interaction between ionizing radiations from the sun and the neutral
atmosphere, chemical processes and mass transport of plasma.
Over the past four decades the terrestrial ionosphere has been ex
plored, first by radio methods from the ground, and since the advent of
the space age also by means of spacecraft, thus making ionospheric
physics a "space science". In addition, a new and powerful groundbased
method, the incoherent backscatter radar technique was developed in
recent years. Especially during the last decade, our knowledge of the
terrestrial ionosphere has increased tremendously, in large part as the
result of simultaneous observations of pertinent parameters of the neutral
atmosphere, the ionizing radiations and the resulting charged particle
distributions, their composition and temperature. This has led to a
thorough examination of the physical and chemical processes governing
the behavior of the ionosphere.
