Abstract: Wave-number frequency spectra of seismic background recordings from the large aperture seismic array (LASA) in eastern Montana have been used to study the source locations of different wave types in the frequency band from 40 to 500 mHz. Microseisms in this band consist of surface waves of the Rayleigh and Love type and compressional body, waves. The peak power band near 140 mHz (7-sec microseisms) and the lower frequency band near 70 mHz consist of fundamental Rayleigh waves, which often come from the same direction. This is especially true for directions from coasts in the vicinity of large storms. The average directional properties of the two bands are similar, indicating coastal sources for both. Love waves and higher mode Rayleigh waves in some instances come from the same coastal directions as the fundamental mode. Compressional body wave sources, pinpointed by using horizontal phase velocity to measure range, occur near storms both in coastal and pelagic regions. Pelagic storm sources were found only at frequencies that were high compared with double the frequency of ocean waves having a group velocity equal to the storm velocity. Located in the wake of a moving storm, such sources appear to be due to the oppositely traveling waves set up when a storm moves faster than its waves.

Abstract: Pitch angle diffusion of trapped electrons in terrestrial radiation zones, discussing diffusion theory based on Fokker-Planck equation, atmospheric Coulomb scattering mechanism, etc

Abstract: Satellite observations of geomagnetic tail in magnetosphere near midnight meridian plane, discussing formation, shape, plasma sheet and models

Abstract: Quantitative magnetic field models of magnetosphere for analyzing field configuration variations and adiabatic particle motion

Abstract: Dynamics of magnetosphere, discussing auroral oval position, ring currents, plasma density and magnetic field variations in near polar region

Abstract: Low energy plasma fluxes in magnetosphere, discussing plasmapause position dependence on geomagnetic activity

Abstract: Particle fluxes in outer radiation belt and unstable radiation zone of outer geomagnetic field, discussing electron diffusion into magnetosphere and magnetic disturbances

Abstract: Auroras and polar magnetic substorm observations limited comparison due to magnetospheric models inability to interpret daytime precipitation zones and particle energy spectra

Abstract: 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 < Ea < 15 Mev. d. The electric field in the magnetospheric tail. The spirit of the discussion is to invite attention to a number of phenomena that appear sufficiently well established and significant to merit substantial interpretative effort.

Abstract: Measurements of the distribution of auroral particles with energy and pitch angle have not given much of a clue to the precipitating mechanism, except to indicate that it occurs locally, in the magnetosphere. The available data, including observations of periodicities in auroral bombardment, hint that at least two different mechanisms are operative. With the aid of a simplified model for an accelerating electric field, the kind of dependences on angle and energy to be expected are illustrated. Quantitative discussion is restricted to cases where the electric potential is small compared with the energy dispersion of trapped particles, and the results are thus probably more applicable to instability mechanisms than to the electrostatic precipitation treated by Taylor and Hones. Simultaneous measures of the spectrum at different pitch angles above the atmosphere could be combined to test any given model of electric acceleration. In spite of the wealth of measurements, adequate data do not yet seem to be available.

Abstract: Solar wind interaction with geomagnetic field, considering bow shock, field confinement in magnetosphere and stretching out of lines of force

Abstract: Interplanetary dust measurements near earth compared to theories predicting dust characteristics, discussing concentration, flux, impact rate and solar radiation pressure

Abstract: Strategy for exploration of inner solar system leading to origin and history, detailing lunar exploration program

Abstract: 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 countries.

Abstract: A thermodynamic study of homogeneous nucleation is presented. A thermodynamic equilibrium condition sufficiently general to be applied to any closed system is presented and then used to describe the thermodynamic equilibrium state of a liquid drop-vapor system. The Einstein development of the theory of fluctuations is applied to homogeneous nucleation, a fluctuation phenomenon, and the thermodynamic meaning of homogeneous nucleation obtained. The activation energy for homogeneous nucleation is discussed and explicitly calculated. A peculiarity of the equilibrium state of the liquid drop-vapor system indicating possible stability of this state is discussed. A thorough discussion of previous thermodynamic studies of homogeneous nucleation is presented in order to distinguish the correct and incorrect approaches to the problem.

Abstract: Earth radiation belts formation as function of particle injection into trapped radiation zones or proton and electron leakage

Abstract: The Neel theory of magnetization relaxation has been systematically and quantitatively tested for six samples containing synthetic and natural single domain grains. The results of a wide range of experiments involving time, temperature, and direct and alternating magnetic fields were compared with theoretical results predicted by using the Neel theory and the experimental grain size-coercivity distribution of each sample. Good agreement was found for many experiments involving small field remanences, where grain interaction effects are negligible. Most of the discordant results could be explained by using either the Preisach theory or an extended form of the Neel theory, which takes account of interactions. The two methods are shown to be equivalent, but the Neel theory is more useful in analyzing thermal processes that are intractable by the Preisach method. The similarity of the behavior of synthetic and natural samples suggests that monodomain material is important in many rocks, but experiments on a wide variety of rock types are needed for verification.

Abstract: LF wave propagation and emission in magnetosphere, discussing steady noise and discrete emissions

Abstract: The excitation of various atmospheric wave motions by switch-on sources is investigated. An asymptotic description of the propagation of the transient forerunners and the stationary forced motion contained within a Brillouin front is given. Three-dimensional Rossby waves generated in an unbounded atmosphere by a traveling point source and several kinds of oscillating point sources are discussed. Also given is the solution for the switch-on of a horizontally traveling gravity wave or vertically traveling atmospheric acoustic wave. Various one-dimensional switch-on Rossby wave problems in a periodic domain are solved in terms of image sources.

Abstract: Linear equations for the motions of inviscid ideal gas atmospheres are considered, a brief description of the climatology of the relevant propagation parameters being given An operational formalism is developed for obtaining elementary solutions for point impulse sources The propagation of a pulse according to the Boussinesq gravity wave model is analyzed in terms of convergent series solutions for small time and in terms of asymptotic series solutions for large time Elementary propagators for the gravity wave mode and buoyancy oscillation mode are defined by contour integrals about the singularities of the propagator operator The theory is extended to the propagation of a pulse in a stratified compressible atmosphere All motion is then confined within an acoustic front expanding radially with the speed of sound Series solution in powers of the distance behind the front is described Sufficiently far behind the front, the motion is given by an acoustic oscillation, buoyancy oscillation, and gravity wave mode Consideration of the analogous problem, except for a hydrostatic atmosphere on a rotating plane, indicates when and where the assumptions of hydrostatic balance and absence of rotation are tenable With rotation, a potential vorticity mode describing time-independent motion also occurs, or, if the variation of the earth's vorticity is included in the model, Rossby waves occur Addition of a lower boundary is discussed with emphasis on the horizontal propagation of the Lamb wave mode Impulsive addition of heat excites a Lamb pressure wave pulse strongly modulated by buoyancy oscillations

Abstract: 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 also listed.

Abstract: Solar plasma flow around magnetosphere, discussing plasma velocity, density and temperature and magnetic field space and time variations

Abstract: Shock-wave data are now available for a variety of rocks, minerals, and oxides of geophysical interest in the pressure range appropriate for the lower mantle. These data are analyzed to obtain equation-of-state parameters with emphasis on the shock-induced high-pressure phases. Of twenty-four materials for which Hugoniot data are analyzed, all but MgO, Al_2O_3, and MnO_2 undergo at least one shock-induced phase change below 800 kb. Birch-Murnaghan parameters for the raw Hugoniots, metastable Hugoniots, adiabats, and 25°C isotherms are obtained for the high-pressure phases. On correcting the raw Hugoniot data for MgO and Al_2O_3 for strength effects, we find that the calculated adiabatic equations of state are in good agreement with recent ultrasonic data. The zero-pressure densities of high-pressure phases are obtained by constraining the adiabats calculated from the Hugoniot data such that the zero-pressure densities and the zero-pressure slopes of the adiabats satisfy Anderson's seismic equation of state. Probable crystallographic structures of the high-pressure phases are inferred from the classical laws of crystal chemistry and, in some cases, from static high-pressure recovery experiments on analog compounds. Shock data for SiO_2 (stishovite) indicate that transformation to the fluorite-type structure (observed in TiO_2) does not take place under shock, at least to ∼2000 kb. Fe_2O_3 probably transforms to either the perovskite or B rare earth structure with a zero-pressure density of 5.96 g/cm^³. MgAl_2O_4 (spinel) may transform to the CaFe_2O_4 structure with a zero-pressure density of 4.19 g/cm_³. Feldspars transform to the hollandite structure (density, of ∼3.85 g/cm^³). Olivine-rich rocks containing greater than 10% FeO either disproportionate to the ilmenite and rock salt structure or transform to a new post-spinel polymorph having the Sr_2PbO_4 structure. Pyroxenes containing greater than 10% FeO probably transform to the ilmenite structure. High-pressure forms of sillimanite and andalusite have calculated densities of 4.00 and 3.95 g/cm^³, respectively. This probably represents disproportionation reaction products, Al_2O_3 + SiO_2 (stishovite), which would give a density of 4.09 g/cm^³. The Birch-Murnaghan second-order parameter ξ is nearly zero for MgO and Al_2O_3. 0.73 for stishovite, and ∼1 for the high-pressure phases of the olivines and pyroxenes. The values of K′ = dK/dP are calculated along the Hugoniots and adiabats and are found to decrease at a rate of −0.5 to −1.6 cm³/g when the density is increased either by compression or by iron substitution.