Solar-Planetary Relationships: Cosmic Rays
rotationally symmetric around the instantaneous sion profile on April 12 which peaked (>1100 km SC 22 -1 magnetic field direction, it is a function of s ) near the flare site (85° heliographic) with 1 a single variable, the pitch angle, and can be a half-width ~ 60° at velocities ~ 600 km s" . A SIMILARITY THEORY FOR ENERGETIC PAR written as a Fourier series. It is shown here The emission profile preserved its shape as it TICLE ENHANCEMENTS ASSOCIATED WITH INTER that there is a linear relation between its decayed on April 13 and 14. The initial injection PLANETARY SHOCKS coefficients and the set of sector counting of 7.5-45 MeV protons (measured by the UTD detec rates. It can therefore be expressed by a tors on Pioneers 6-9 and the APL/JHU detector on G. Skadron (Max-Planck Institut fur Aer matrix. The matrix elements depend on the number Explorer 34), may also have peaked over the flare onomie, 3411 Katlenburg-Lindau 3, West of sectors, the opening cone of the detector site on April 11 (00 h) but by April 12 (00 h) the Germany) telescope, the angle between spin axis and the peak of the proton injection profile had shifted W. I. Axford (Max-Planck Institut fiir magnetic field direction, and the angle between to 90° to the west of the flare site and remained Aeronomie, 3411 Katlenburg-Lindau 3, spin axis and detector axis. This algebraic ap there through April 16. The injection profiles West Germany) proach allows to determine the maximum obtain can be approximated by exponentials in longitude able number of Fourier coefficients and their with e-folding angles of cpg *** 28° and cpw **• 20° It is assumed that a spherically sym accuracy for any such experiment. for the east and west wings of the population metric forward-reverse shock pair sweeps In the interplanetary medium the Compton Getting April 12-13. By April 16, cpg =" 10° while cptf re radially through a quiet-day solar wind effect due to convection with the solar wind mained nearly constant. This solar event demon containing a spherically symmetric dis makes pitch angle distributions appear rotation- strates clearly that different coronal structures tribution of low energy cosmic rays. ally asymmetric. A reduction of this effect is control the emission of flare plasma and energetic The cosmic rays are allowed to pass, also possible using matrix notation. particles. without reflection, from the unshocked to the shocked solar wind. Using a solar wind velocity profile for strong shocks^ ' a similarity solution for the differential cosmic ray number density, valid for a general ambient cosmic ray PITCH ANGLE DISTRIBUTIONS OF CHARGED PAR spectrum, U (T), and an energy-dependent TICLES IN INTERPLANETARY SPACE MEASURED ON a radial diffusion coefficient, KT , is HELIOS DURING A SOLAR EVENT formulated. For the case in which Ua(T) is a power law and I = o, it is found G. Wibberenz that (1) similarity solutions exist only G. Green THE INTERPLANETARY SHOCK WAVE EVENT OF NOV. 1975 for a small range of U , (2) the cosmic R. Muller-Mellin OBSERVED BY HELIOS-A AND IMP-7,8 a ray amplification at the forward shock is M. Witte large for ambient spectra near the cri
H. Hempe P E.' T? Sarris| (Max-Planck-Institut, Lindau, FRG) tically steep Ua, (3) if the spectral H. Kunow (all Institut fur Reine und Angewandte index of U exceeds 2, the cosmic ray S. M. Krimigis (APL/JHU, Laurel, Maryland) a Kernphysik, Universitat Kiel, 2300 Kiel, density falls off vehind the forward W.-Germany shock, becoming small in the vicinity of In studying the interplanetary acceleration of G. Musmann the contact surface, and (4) the cosmic energetic particles, i.e. shock-spikes and in F.M. Neubauer (both Institut fiir Geophysik u. ray density in the vicinity of the re particular ESP events, it is important to distin Meteorologie der TU, 3300 Braunschweig, verse shock is qualitatively similar, guish the short term (few minutes) intensive W.-Germany producing an overall double-humped acceleration at shock fronts, which depends local profile across the shock pair. For a solar event of rather simple structure ly on the direction of the interplanetary magnetic observed by HELIOS sectorized particle data of field w.r.t. the short front, from a still unknown the University of Kiel Cosmic Ray Experiment but occasionally assumed to exist long-lasting 1. Simon, M. and Axford, W. I., Shock were analysed by the method described by Green (days) acceleration of particles in the downstream Waves in the Interplanetary Medium, in this meeting using flux gate magnetic field shocked medium. Favorable arrangements of widely Planet. Space Sci., 14, 901, 1966. data from the University of Braunschweig Mag separated spacecraft in the interplanetary medium netometer Experiment. are needed in order to study these events. Presum This event is an example for the advantages of ably, under different local conditions of the up this method: The pitch angle distributions are stream interplanetary magnetic field at the shock SC 23 determined up to the fourth harmonic, the in front the short term acceleration may be shut-off fluence of the magnetic field elevation out at one spacecraft whereas the long-lasting effects PERSISTENT SUNWARD FLOW OF M.6 MEV PROTONS of the ecliptic plane is revealed, field on the particle population may still persist. AT 1 AU aligned anisotropics can be detected down to low values by applying a Compton Getting Such a favorable geometry obtained during the F. E. Marshall correction and by accumulating the data on the Nov. 23, 1975 shock event between the HELIOS-A E. C. Stone (both at: Dept. of Physics, Calif. ground over sufficiently long time intervals and IMP-7 and 8 spacecraft where HELIOS-A was Inst, of Technology, Pasadena, CA 91125) to improve the statistics using a coordinate ~ 0.1 AU inside of the Earth orbit and only 6° off system which rotates together with the field the Sun-Earth line. Detailed directional and The anisotropy of 1.3 to 2.3 MeV protons has azimuth. spectral information on the energetic particle been measured with the Caltech Electron/Isotope event, which is associated with the shock wave Spectrometer aboard IMP-7 for periods between passage by both HELIOS-A and the Earth, were prompt solar particle events from 72/273 to obtained by the E 8 experiment on HELIOS-A 74/2. The diffusive anisotropy, which has been (80 keV £E 6200 keV, 16 keV SEp £2000 keV) and p computed by subtracting the independently de by the APL/JHU experiments on IMP-7 and 8 termined convective anisotropy from the ob SOLAR PARTICLE OBSERVATIONS AT SOLAR MINIMUM (Ep > 290 keV, E >220 keV, % > 640 keV/nuc, e served anisotropy, is predominantly directed E (Z *3)* 770 keV/nuc). The measurements and their u toward the sun with a typical radial component J. Maslev implications on the acceleration mechanism(s) are of 14%. This sunward diffusion is typical of _• M. B. Baker (both at: Aerojet ElectroSysterns discussed. intensities from 0.012 to 1.2 (cm2-sec-sr-MeV)~ Co., Azusa, CA 91702) and indicates that a positive radial gradient of 1.3 to 2.3 MeV protons is associated with Characteristics of 8 solar cosmic ray events these modestly enhanced fluxes. The direction observed during the minimum of the current solar of this flow is opposite to that produced by cycle will be discussed. The events were ob the continuous solar sources used to explain served during the period 1974-1976 by orthogonal increases previously observed near 1 AU. The solid state detector telescopes on ATS-6 in direction of the diffusive anisotropy strongly synchronous orbit. The telescopes determine a depends on the direction of the concurrently differential energy spectrum for protons from measured magnetic field, indicating that 300 KeV to 200 MeV and for alpha particles from ACCELERATION OF ENERGETIC PARTICLES BY SHOCK diffusion is preferentially along rather than 2 MeV to 220 MeV with North and East view direct WAVES .,Kj_< K ). ions. The observed proton intensity will be dis across the magnetic field lines (i.e |( cussed as a function of energy, arrival direction, E. Leer magnetic activity, local time and the inter G. Skadron planetary intensity. W.I. Axford (all at: Max-Planck-Institut fiir SC 24 Aeronomie, 3411 Katlenburg-Lindau 3, FRG)
A STEADY-STATE MODEL OF SUNWARD FLOW OF LOW The problem of acceleration of energetic par ENERGY PROTONS ticles by shock waves propagating in a scatter CORONAL CONTROL OF PLASMA AND ENERGETIC PARTICLE ing medium has been considered by Fisk in his E. C. Stone EMISSION FROM THE APRIL 10, 1969 SOLAR FLARE discussion of energetic storm particle events F. E. Marshall (both at: Dept. of Physics, and shock spikes. We will review this work and Calif. Inst, of Technology, Pasadena, CA R. Reinhard (ESTEC, ESA, Noordwijk, Holland) add some additional comments concerning steady 91125) R. E. Gold state solutions and energy spectra of general E. P. Keath form. In addition, we will discuss the situation The persistent sunward flow of M.6 MeV in which the energetic particle pressure is suf E. C. Roelof (all at: JHU/APL, Laurel, Maryland) protons observed on IMP-7 has been modeled as ficient to affect the background flow. The re steady-state injection of protons beyond 1 AU. We have re-examined interplanetary solar wind sults are of interest with regard to the termi The propagation of these particles is computed and energetic particle data for the March-April nation of the solar wind and to the acceleration using a series solution to the Fokker-Planck 1969 period of solar activity from Pioneers 6-9 of low energy cosmic rays in corotating inter equation, which includes diffusion, convection, in deep space and Explorer 34 near Earth. The action regions. In the latter case, the forward and adiabatic energy loss. The equation has solar wind velocities are used to estimate the and reverse shock pairs which arise must be se been simplified by assuming 1) azimuthal symme high coronal emission longitudes of the plasma, parated by a contact surface in the vicinity of try, 2) < independent of energy and radius, and these are also assumed to be the injection which the medium undergoes a gross expansion. rr longitude onto interplanetary field lines for the The observed signatures of the energetic parti 3) no injection of particles inside r = L>1 AU, energetic particles. The observations from the cles associated with such interaction regions 4) a finite density at r = 0, and 5) the solar 5 spacecraft (nearly equi-spaced over 210°), re provides clear evidence for the adiabatic de wind velocity V independent of radius. The veals that the large solar wind disturbance from celeration of particles which must result from calculated diffusive anisotropy is found to be the April 10 east limb flare had a velocity emis- such an expansion. strongly dependent on V but only weakly
980 Solar-Planetary Relationships: Magnetospheric Physics dependent on < . Using the mean observed rr Solar-Planetary spectral index y of -3.15 and the mean solar PLASMAPAUSE SIGNATURES IN THE IONOSPHERE AND wind speed of 440 km-sec"', the model produces MAGNETOSPHERE a range of radial diffusive anisotropy from Relationships: 20 21 ? -1 u E. J. Maier 10% to 17% for KRR from 10^ to KT' cm-sec Magnetospheric L. H. Brace (both at: Goddard Space Flight Cen (the observed anisotropy is 14%). This range ter, Greenbelt, Md. 20771) of < is comparable to that previously rr Physics J. C. Foster (Aeronomy Center, Utah State Uni reported using a similar, but time-dependent, versity, Logan, Ut. 84321) model to best fit the temporal development of C. G. Park (Stanford Univ., Stanford, Ca. 94305) J. H. Hoffman (U. Tex. Dallas, Richardson, Tx. prompt solar particle events. A K of CM 1 21 2 -1 75080) 10 cm -sec produces a modulation factor of THE LARGE SCALE IONOSPHERIC J. H. Whitteker (Communications Research Centre, Ottawa, Ontario, Canada K2H852) 11 between 1 AU and 3 AU. Evidence for compa ELECTRIC FIELD: ITS VARIATION WITH rable modulation in corotating streams has been MAGNETIC ACTIVITY AND RELATION TO found by Pioneer XI. The approximately linear Latitude profiles of ionospheric composition, TERRESTRIAL KILOMETRIC RADIATION + dependence of the diffusive anisotropy on the density, temperature, and H vertical velocity, solar wind speed predicted by the model is measured by the polar orbiting ISIS2 satellite at found to be consistent with the observed R. H. Holzworth (Physics Dept. & Space Sci. 1400 km, are compared with simultaneous equatori dependence. Lab, Univ. of Cal., Berkeley, Ca. 94720) al electron density profiles determined by whist J.-J. Berthelier (CNRS etUniversite Paris ler analysis during a six day period of moderate to quiet magnetic activity. The low latitude VI, St. Maur 94100, France) boundary of the light ion trough does not exhibit U.V. Fahleson a diurnal variation in latitude and lies - 2°- 5° C. -G. Falthammar (both at: Royal Institute of equatorward of the whistler plasmapause at both SC 25 Technology, Stockholm Sweden) dawn and dusk. Maxima in the electron tempera ture and H+ upward velocity also lie equatorward EFFECTS OF PARTICLE DRIFT ON SOLAR P. J. Kellogg (University of Minnesota, of the plasmapause latitude. The data suggest MODULATION OF GALACTIC COSMIC RAYS Minneapolis, Minnesota 55455) P. Tanskanen (Univ. of Oulu, Oulu, Finland) that the low altitude troughs are associated with flux tubes on which the equatorial density is be J. R. Joki pi i (Department of Planetary Sciences D.K. Cullers (Physics Dept. &Space Sci. Lab, low its equilibrium value, and which are thus re University of Arizona, Tucson, Arizona 85721) Univ. of Calif., Berkeley, Ca. 94720) filling from below. Trapped plasma sheet elec E. H. Levy M.K. Hudson (Space Sci. Lab, Univ. of Calif., trons are observed to extend inward to the plas W. B. Hubbard (both at: Department of Berkeley, Ca. 94720) mapause at both dawn and dusk and could be used Planetary Sciences, University of Arizona, to identify the equatorial plasmapause latitude Tucson, Arizona 85721) M.C. Kelley (Cornell Univ., Ithaca, New York, 14854) in the absense of whistler measurements. Although gradient and curvature drifts are M. Temerin explicitly contained in the general equations F.S. Mozer (both at: Physics Dept. & Space of cosmic-ray transport, they have been almost Sci. Lab, Univ. of Calif., Berkeley, Ca. universally neglected in applications of these 94720) equations. We evaluate the drifts explicitly for the Parker spiral magnetic field and show that, for particles with rigidities greater Four days of simultaneous auroral zone than -0.3 GV in the solar wind, they are larger electric field measurements on balloons flown SM 4 than the solar-wind velocity over much of the from six sites spaced 180° in magnetic longi heliosphere. Hence most current models of tude have been analyzed. The average electric EVIDENCE FOR DRIFT WAVES AT THE PLASMAPAUSE solar modulation and solar-flare particle field behavior during this magnetically very events neglect terms which in many cases are as P. M. Kintner quiet epoch are consistent with earlier single important as those retained. Calculations are D. A. Gurnett (Dept. of Physics and Astronomy, point measurements. When these data are presented which demonstrate the importance of Univ. of Iowa, Iowa City, IA 522^2) mapped to the equator, a steady dawn-to-dusk the effects for simple modulation models. We conclude that comparisons of presently avail component is apparent only on the average, As the Hawkeye-1 spacecraft crosses the plas able model calculations with observations do while instantaneously the field is quite variable. mapause at high altitudes (R > 3 Re) a band of not provide a fair test of transport theory The ionospheric electric field during isolated electric field noise is often detected in the frequency channels from 1.7 Hz to 178 Hz. No since they neglect drifts. Results of Monte substorms is shown to have differing signatures corresponding magnetic field noise is detected, Carlo simulations show that the heliocentric east and west of 2200 LT. A world wide posi cosmic-ray gradient and mean energy change can indicating that the noise is electrostatic (or tive correlation is shown to exist between the be significantly reduced by the inclusion of at least quasi-electrostatic), and the electric auroral zone electric field strength and the in drifts. field is polarized perpendicular to the plasma tensity of terrestrial kilometric radiation. density gradient. The noise is only detected when the scale length of the plasmapause is
0.1 Rg or less, indicating that a large density gradient is required to produce the noise. These characteristics are all consistent with the interpretation that this noise consists of electrostatic waves excited by the drift mode METEORITE GRADIENTS AND THE MAUNDER MINIMUM instability. Using reasonable assumptions con cerning the wavelengths of these waves the M. A. Forman observed frequency spectrum can be explained 0. A. Schaeffer as being due to doppler shifts caused by the G. A. Schaeffer (all at: Dept. of Earth and Space spacecraft motion through the plasma. Sciences, State Univ. of New York at Stony Brook, N. Y. 11794)
A recent compilation of 48 measurements of the Argon-39 (269 year half-life) activity in the SM ? metallic phase of meteorites showed values of 22.5 ± 2.5 dpm/kg. This spread could be due to RELATION BETWEEN BOUNCE-AVERAGED experimental errors alone, and the true variation COLLISIONAL TRANSPORT COEFFICIENTS SM 5 is probably smaller. Since such a sample of met FOR GEOMAGNETIC ALLY TRAPPED ELEC RADIATION BELT PROTONS DURING GEOMAGNETICALLY eorites can reasonably be expected from meteor TRONS QUIESCENT CONDITIONS data to have a spread of mean distances from the sun of 2.5 ± 1 AU, an upper limit of 10%/AU on Michael Schulz (Space Sciences Laboratory, W. N. Spjeldvik, (NOAA/ERL/Space Environment the magnitude of the integral cosmic ray gradient The Aerospace Corporation, El Segundo, Laboratory, Boulder, Colorado 80302) between about 1.5 and 3.5 AU averaged over about California 90245) the last 500 years was deduced. The mean Argon- The average steady state structure of energetic 39 activity of 22.5 dpm/kg is a little high com The unweighted bounce average