摘要:

This volume contains all of the fifteen invited review papers presented at the International Symposium on the Physics of the Magnetosphere, held in the U. S. Department of State, Washington, D. C., September 3–13, 1968. The contributed papers presented at the Symposium are not included; they are appearing in other appropriate journals. By arrangement with the Inter‐Union Commission on Solar‐Terrestrial Physics (IUCSTP), the Symposium was sponsored by the Committee on Space Research (COSPAR), the International Association of Geomagnetism and Aeronomy of the International Union of Geodesy and Geophysics (IUGG‐IAGA), the International Scientific Radio Union (URSI), the International Union of Pure and Applied Physics (IUPAP), and the International Astronomical Union (IAU). It was held by the U. S. National Academy of Sciences and the NASA Goddard Space Flight Center. The Symposium was attended by 325 scientists representing 18 different co

ISSN:8755-1209    

DOI:10.1029/RG007i001p00001

年代:1969

数据来源: WILEY

摘要:

The interaction of the solar wind with the geomagnetic field is a complicated physical phenomenon. This paper attempts to point out the various major effects involved directly in the interaction and to assess the degree to which the effects are, and are not, understood at the present time. It is a collection of my own thoughts, opinions, and prejudices on the solar wind interaction. I am looking forward to new results to be reported at this symposium, which, I hope, will render much of this review obsolete.

ISSN:8755-1209    

DOI:10.1029/RG007i001p00003

年代:1969

数据来源: WILEY

摘要:

A review is provided of the salient features of the flow of solar plasma past the magnetosphere, as they are revealed by observations in space and by theory. Discussed first are the properties of the solar wind, including the velocity, density, temperature and temperature anisotropies, and magnetic field, and their variations in space and time as observed beyond the disturbing influence of the earth and its magnetic field. Theoretical aspects of the steady‐state interaction of the solar wind and the geomagnetic field are taken up next, using the continuum description provided by the equations of magnetohydrodynamics of a perfect dissipationless gas as a basis. An outline is given of the series of approximations, and their observational and theoretical justifications, used to reduce the complex free‐boundary magnetohydrodynamic flow problem to a series of tractable problems; and a set of results is provided for representative conditions in the solar wind. The results are shown to be in good accord, even to numerous details, with observations made in space during quiet times. The results are also shown to be useful in interpreting many features of observations during disturbed times. Attention is drawn to other features of the flow of solar plasma past the magnetosphere for which quantitative theoretical descriptions must still be devised. These include the irregular or fluctuating character of the flow downstream of the bow wave, the nature of the magnetosphere tail and surrounding flow at great distances from the earth, numerous transient aspects of the flow, and the mechanisms underlying the many statistical correlations being discovered between variations of the surface geomagnetic field and various properties of the solar w

ISSN:8755-1209    

DOI:10.1029/RG007i001p00011

年代:1969

数据来源: WILEY

摘要:

The increasing number of laboratory experiments related to the solar wind and the magnetosphere calls for a critical review of the conditions under which a laboratory experiment can provide information about space phenomena. Naturally, the starting point is a discussion of the problem of physical similarity. For a unified presentation of the several sets of scaling laws that have been used, it is convenient to use the similarity laws of the Vlasov theory as a reference system. Clearly, the biggest obstacle for a strict reproduction of the solar‐wind‐magnetosphere interaction in the laboratory is collisional interaction. In the solar wind at the earth's orbit, strict simulation is possible only for phenomena with a dimension of the order of a few hundred kilometers or smaller, such as the bow shock structure. A discussion of the existing terrella experiments shows that most of them obtain similarity by scaling the interplanetary field and the geomagnetic field differently. This determines the processes for which quantitative agreement can be expected, e.g., the shape of the frontal part of the cavity boundary and the approximate shape and position of the bow shock. Strict similarity can be achieved in simulating the structure of the bow shock wave. The over‐all ranges of the shock parameters of seven collision‐free shock experiments discussed cover substantial parts of the bow shock parameter ranges. A comparative discussion of the magnetic‐field profiles of the estimated shock width and of the appearance of oscillatory structures shows strong resemblances between space and laboratory observations. Several other experiments related to the solar wind and the magnetosphere are al

ISSN:8755-1209    

DOI:10.1029/RG007i001p00051

年代:1969

数据来源: WILEY

摘要:

A clear understanding of the basic forms of motion of charged particles in the magnetic and electric fields of the outer magnetosphere is an essential ingredient to the study of the earth's radiation belts and plasma. To achieve this, one must work with a reliable quantitative model of the magnetospheric field. The main purpose of any such model is to provide a mathematical description of the field that is reasonably accurate within a given spatial and temporal domain and that can be used to analyze in a quantitative way any process influenced or governed by this field in the corresponding domain. In this review, magnetic field models of the magnetosphere are critically examined and their fit to in‐situ field measurements is discussed. Special attention is paid to the analysis of typical long‐term time variations of the field configuration and the matching changes in model parameters. Implications for adiabatic particle motion, such as shell geometry, regions of pseudo‐trapping, and adiabatic effects of slow time variations of the field, are ana

ISSN:8755-1209    

DOI:10.1029/RG007i001p00077

年代:1969

数据来源: WILEY

摘要:

The solar wind flows past the earth and stretches the geomagnetic field behind it, forming a tail to the magnetosphere. Magnetic‐field lines are directed toward the sun in the upper half of the tail and oppositely directed in the lower half. The separation region where the field reversal takes place is occupied by an enhanced plasma flux, which keeps the oppositely directed fields from annihilating themselves. Satellite observations have also found intense transient electron fluxes within the plasma sheet region. Although the role of the tail in the magnetic substorm phenomena is not yet clear, during the main phase of a magnetic storm the tail appears to contribute significantly to the dynamical distortion of the magnetosphere, the decrease of the horizontal geomagnetic field on the earth's surface, and the lowering of the latitude of the trapping boundary. Although the tail shows a well‐defined theta geometry at 80RE, lunar orbit = 60RE, it has not been clearly observed at 500 and 1000RE. A radial gradient of the magnetic field magnitude is consistent with merging occurring at the neutral sheet and with the tail length being of the order of 100–200RE. The basic mechanism for terminating the tail, as well as the means for momentum transfer on its boundary forming the tail, are not yet established. This paper reviews past experimental and theoretical models of the geomagnetic tail, outlines our present knowledge, and identifies the current major problems associated with its dyn

ISSN:8755-1209    

DOI:10.1029/RG007i001p00097

年代:1969

数据来源: WILEY

摘要:

The results of observations of auroras and polar magnetic substorms are compared with magnetospheric models. In general, present qualitative or semi‐quantitative magnetospheric models describe fairly well the basic features of auroras and magnetic substorms, or they can probably be adapted to the observations by minor modifications. However, some observations cannot currently be easily interpreted in terms of the models. Of these, the existence of two daytime precipitation zones and some detailed features of the observed particle energy spectrum are among the most important. The stationary models cannot account for the high‐energy part of the auroral particle spectrum seen also in quiescent auroras. Some peaks in the observed spectrum also seem to pose problems. On the whole, the quantitative problems of entry and energization of the auroral particles are still unsol

ISSN:8755-1209    

DOI:10.1029/RG007i001p00129

年代:1969

数据来源: WILEY

摘要:

Comparison is made between the position of the auroral oval during both night and day and that of the boundaries of trapped radiation according to observations from the satellite Alouette 2. We show that visual auroras are located on the poleward side of the boundary of smoothly closed field lines. From the data on auroral dynamics, information is obtained on some parameters of the geomagnetic field, i.e., field intensity in the magnetospheric tail, cross‐sectional dimensions of the tail at various geocentric distances, and the length of the tail. The density of low‐energy plasma at geocentric distances of 5 to 9REis estimated for various periods of the solar activity cycle. The influence of the magnetospheric ring current on the position of the auroral oval is considered. On the basis of polar auroral observations, estimates are made of variations in ring current parameters at times of ring current enhancement.DPandDPCmagnetic field variations at high latitudes, linked with the structure of the geomagnetic field in the magnetosphere, are also discussed.DPvariations are characterized by current electrojets, a western one within the auroral oval and an eastern one in the evening hours at Φ ∼ 65°, where Φ is the invariant latitude. TheDPCvariations of greatest intensity are noted on the daytime side of the earth. The field variations are due to a counterclockwise current. We show that the current system of Chapman'sSDvariations is a superposition of two different types of variations,

ISSN:8755-1209    

DOI:10.1029/RG007i001p00179

年代:1969

数据来源: WILEY

摘要:

In this paper we review present theories relating to the formation of the earth’s radiation belts and consider prospects for future development of these theories. The first part is devoted to the discussion of the possibility of particle injection into the zone of trapped radiation when the drift orbits of particles are perturbed during geomagnetic storms. In the second part we show that the experimental data on particle diffusion in the belts are generally in agreement with the concept of sudden impulses. The third is an analysis of the problem of proton and electron leakage due to ionization deceleration and cyclotron instabilit

ISSN:8755-1209    

DOI:10.1029/RG007i001p00219

年代:1969

数据来源: WILEY

摘要:

The object of this paper is to review observational work by the University of Iowa having to do with the dynamics of the population of charged particles in the outer radiation zone of the earth's magnetosphere.Specific topics are as follows:a. Intensity fluctuations and apparent lifetimes of outer zone electrons having kinetic energies E6 ranging from 40 kev to several Mev.b. Ring current particles, protons and electrons EPJ E6 ^>200 ev.c. Geomagnetically trapped a particles, 2.09

ISSN:8755-1209    

DOI:10.1029/RG007i001p00233

年代:1969

数据来源: WILEY