Solar Eclipses and the Ionosphere: A NATO Advanced Studies Institute held in Lagonissi, Greece, May 26–June 4, 1969 PDF
Preview Solar Eclipses and the Ionosphere: A NATO Advanced Studies Institute held in Lagonissi, Greece, May 26–June 4, 1969
SOLAR ECLIPSES and the IONOSPHERE SOLAR ECLIPSES and the IONOSPHERE A NATO Advanced Studies Institute held in Lagonissi, Greece, May 26-June 4, 1969 Edited by Michael Anastassiades Professor of Physical E/ectronics Athens University and Director, lonospheric Institute National Observatory of Athens Athens, Greece ~ PLENUM PRESS· NEW YORK-LONDON • 1970 Library of Congress Calalog Card Number 71-119056 ISBN-13: 978-1-4684-1841-5 e-ISBN-13: 978-1-4684-1839-2 DOI: 10.1007/978-1-4684-1839-2 © 1970 Plenum Press, New York Softcover reprint ofthe hardcover 1st edition 1970 A Division 01 Plenum Publishing Corporation 227 West 17th Street, New York, N.Y. 10011 United Kingdom edition published by Plenum Press, london A Division 01 Plenum Publishing Compony, ltd. Donington House, 30 Norlolk Street, london W.C.2, England All rights reserved No port 01 this publication moy be reproduced in any lorm without written permission Irom the publisher PREFACE It is a 10ng-standing tradition in this country for any event re1ated to solar activity to enjoy special importance. Because we enjoy the advantage of pro10nged sunny periods, we consider the incidence of some thirty c10udy days each year as a personal af front. I cannot say that we have the facu1ty to produce solar ec1ipses in order to justify an Institute on this subject to be held in Athens, but I can say that the occurrence of a solar ec1ipse over Greece wou1d present, for optica1 and solar astronomers, the highest possibi1ity of exce11ent conditions for observation. We had this opportunity during the May 20, 1966 annu1ar solar ec1ipse over North Africa and southern Europe. At that time we had the p1easure to co11aborate with a 1arge number of research groups of various nationa1ities, who insta11ed optica1 and radio instru ments near or in Lagonissi, which 1ay a10ng the centra1 path, in order to fo110w the ec1ipse. A first meeting was then organized in order to discuss methods of data handling and avai1abi1ity of resu1ts. After a pre1iminary discussion it was suggested that a 1ater meeting shou1d be organized when final resu1ts were avai1ab1e. Owing to the fact that a 1arge number of discip1ines were in vo1ved, it was imperative to se1ect one topic and promote our know1edge in this special fie1d. The choice went to the study of the ionosphere during solar ec1ipses. This was justified because the last international conference on this subject had taken p1ace 15 years aga in Cambridge, and since then other manifestations, whi1e very important, were not so specific. The second reason was that if this meeting, fo110wing the suggestion of the participants of the pre1iminary meeting of 1966, cou1d again be held in Athens, the host 'country wou1d choose a subject of special interest to its research workers. v Preface I cannot claim that our research team at the University of Athens has a very long tradition in ionospheric investigations. It is only nine years since we installed, at Scaramanga ne ar Athens, an ionosonde, and this is not enough time to create scientific tradition. However the advantages due to our location here offer an opportunity for specializing in the field of solar-terrestrial relations. The principal advantage, already mentioned, is our clear sky. Using this advantage, we have created a very good service of opti cal observations of the sun, which is supplemented by collaboration with the American Air Weather Service, which provides excellent instrumentation. This activity in the optical solar field of observations can be combined with other geophysical measurements. Our obvious experience based on the direct correlation between optical extra solar events and variations observed on ionospheric parameters created the evidence that the ionosphere is a photocell sensitive to any change of solar flux. It would be then of importance to investigate the behavior of ionospheric layers during the May 20, 1966 solar eclipse when its path crossed the Greek area from south west to northeast by using our network of three ionosondes and all other devices and new techniques at our disposal: radio-astro nomical, riometer, satellite, and partial-reflection-technique measurements were performed by our group, and results from all the above measurements were compared with data obtained directly by rockets launched by NASA. For all. the above reasons our group selected the topic "Solar Eclipses and the Ionosphere" for an Advanced Studies Institute to be held in Athens. The meeting was a very successful one, and as Director of this Institute I am deeply indebted to all our out standing lecturers and participants for their very valuable con tributions. The emphasis which the discussions during the Athens eclipse meeting placed on the contribution of the solar corona to the ionospheric eclipse phenomena, on the chemistry of iono spheric layers, on aeronomical problems which still remain open, on the dynamics of the F layers, etc., will be of particular im portance for all investigators during the solar eclipse over Mexico and the USA on March 7, 1970. We are indebted to the Advisory Panel of the NATO Science Committee on Summer Schools, who sponsored this Institute for a s~cond time. Following the NATO policy, the Institute gives an opportunity to young scientists from countries un4er development and from other developed countries to stimulate their research with lectures given by outstanding scientists and by participating Preface ~i in a free and frank discussion. A successful Advanced Studies Institute must give certain time for relaxation. We hope that Lagonissi proved weIl suited for this purpose. The Director of the Institute hopes to have done his best to keep lectures to a suitable length and to offer a social program to relax all par ticipants after their studies and discussions. Michael Anastassiades Professor, Athens University Director of the Ionospheric Institute, National Observatory of Athens Director, NATO Advanced Studies Institute on Solar Eclipses and the Ionosphere, 1966 and 1969 CONTENTS Contributors . . • • • . • • • • • • • • • • • • • • • • •• xiii THEORETICAL ASPECTS Ionospheric Effects in Solar Eclipses 3 S. A. Bowh i 11 Theoretical Aspects of Solar Eclipses 19 H. Rishbeth The Earth's Exospheric Plasma with Some Comments on Eclipses as a Means of Studying the Ionosphere 29 J. O. Thomas D-REGION CHEMISTRY The Chemistry of the D-Region 45 A. P. Mitra Mesures d'ozone pendant les eclipses solaires 65 A. Vassy Direct Rocket Measurements of the Ionosphere during the Solar Eclipse of November 12, 1966 •••••• 81 L. C. HaIe SOLAR RADIATION AND LAYER THEORY Observations of Solar Ionizing Radiations and Their Significance for the Eclipse-Ionosphere • • 93 H. Friedman ix x Contents X-Ray Emissions from the Sun • • • • • • • • • • • • • • •. 115 S. M. Krimigis RADIO-ASTRONOMICAL OBSERVATIONS Microwave Spectra1 Observations of Corona1 Condensations • • • • • • • • • • 151 R. M. Straka A Survey of Solar Ec1ipse Measurements in the 1-30 mm Range 177 D. L. Croom Distribution of X-Ray Emission from the Sun Deduced from Measurements of Ionospheric Absorption 187 O. Boviatsos ECLIPSE STUDIES BY ROCKET, SATELLITE, AND PARTIAL REFLECTION TECHNIQUES D-Region E1ectron Density Measurements during the Solar Ec1ipse of May 20, 1966 •••••• 199 J. A. Kane Partial Ref1ection Measurements on the D-Region during the May 20, 1966 Solar Ec1ipse • 211 E. Tsagakis E1ectron Content Measurements by Beacon S-66 Sate11ite during the May 20, 1966 Solar Eclipse •••• 225 D. Matsoukas IONOSPHERIC ECLIPSE EFFECTS Recent Ionospheric E and F Region Measurements during Solar Ec1ipses, and Their Interpretation 237 J. O.,Thomas and M. J. Rycroft The Annu1ar Solar Ec1ipse on May 20, 1966 and the Ionosphere •. . • •• ... • • • . 253 M. Anastassiades L'Eclipse de Soleil du 20 Mai 1966 . • • • • • • • • • • •• 273 I. Ozdogan and T. Bu1at Quelques Resultats Preliminaires d'Observations Ionospheriques lors de l'Eclipse du Mai 20 1966 " 281 A. Haubert Contents xi Changes in the Topside Ionosphere during Solar Eclipses . . • • . 285 P. A. Smith and J. W. King CONCLUDING REMARKS Concluding Remarks 299 E. Vassy Concluding Statement 301 S. A. Bowhill Index 305 CONTRIBUTORS Anastassiades, Michael, Electronics Laboratory, University of Athens, Athens, Greece Boviatsos, Demetrius, Electronics Laboratory, University of Athens, Athens, Greece Bowhill, S. A., Aeronomy Laboratory, Department of Electrical Engineering, University of Illinois, Urbana, Illinois Bulat, T., Jeofosik KUrsUsU, Istanbul Universitesi, Istanbul, Turkey Croom, D. L., Radio and Space Research Station, Dittor Park, Slough, Bucks., England Friedman, H., United States Naval Research Laboratory, Washington, D. C. Hale, L. C., Ionosphere Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania Haubert, A., Groupe de Recherehes Ionosph~riques, France Kane, J. A., Laboratory for Space Sciences, NASA Goddard Space Flight Center, Greenbelt, Maryland Krimigis, S. M., The Johns Hopkins University Applied Physics Laboratory, Silver Spring, Maryland King, J. W., Radio and Space Research Station, Dittor Park, Slough, Bucks., England Matsoukas, Demetrius, Electronics Laboratory, University of Athens, Athens, Greece Mitra, A. P.,National Physical Laboratory, New Delhi-l2, India xiii
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