摘要:

In a previous paper (Krimigis et al., 1971), simultaneous observations in 1967 of solar particle events at low (<1 Mev) energies were presented. These observations were obtained with intercalibrated detectors on three spacecraft (Mariner 5, Explorer 35, and Mariner 4) separated by distances of ≳0.1 AU. In the present paper we combine the full complement of simultaneous plasma, magnetic field, and energetic particle data and give a complete analysis of all the events discussed in the original paper. The essential concept of ‘collimated convection’ is introduced, whereby the bulk velocity along the field lines of low‐energy solar particles is independent of solar local plasma velocity, and the particles are strongly collimated along the field line with no transverse velocity component other than that of the field line itself. Collimated convection effects are shown to exist in small‐scale convection (days 206–219) and large‐scale evolution (days 221–225) of particle fluxes; the particle fluxes are, in turn, used to delineate the small‐scale (days 227–229) and large‐scale (days 260–265) evolution of the interplanetary magnetic field. Use of collimated convection is made in demonstrating a technique whereby energetic particle intensity profiles in the interplanetary medium can be related to equatorial high coronal magnetic field structures, by using the instantaneous solar wind velocity. This technique is applied in mapping particle intensities from Mariner 5 onto Hα synoptic charts of chromospheric magnetic field structures (McIntosh, 1972) for Carrington rotations 1523 to 1525. The particle data are well ordered by means of this procedure, and the coronal injection profiles of energetic particles can be deduced. In particular, abrupt changes in the particle injection profile correspond to longitudes where magnetic neutral lines connected to active regions cross the solar equatorial plane. Typical of many low‐energy solar particle event histories is a ramplike increase lasting more than a day and terminating in a sharp drop associated with a coronal neutral line crossing. The mapping procedure is also able to explain the ‘open’ and ‘edge’ electron events reported by Lin (1970). The question of long‐term acceleration and/or storage is examined, and, in one event for which the two processes can be separated, evidence is found for acceleration with negligible storage. However six examples of acceleration lasting several days are given. Finally, the apparent differences between low‐energy solar particle events and higher‐energy solar cosmic ray events are noted; these differences imply that current interplanetary particle propagation theory is inadequate for the lower energies. In particular, the large field‐aligned anisotropies during the rise of flare‐associated events, the large anisotropies during quasi‐stationary corotating events, and the field‐aligned anisotropies during decays with small radial gradients imply the relative absence

ISSN:0148-0227    

DOI:10.1029/JA078i025p05375

年代:1973

数据来源: WILEY

摘要:

Two shocklike structures (i.e., abrupt steplike increases in number density, bulk speed, and proton temperature) were found in the data from Mariner 5 at 0.98 AU on June 26 and at 0.85 AU on August 29, 1967. The thickness of these ‘structures’ determined from the magnetic field data was more than 1,000 proton Larmor radii. They were also observed by Explorer 33, 34, and 35 at 1 AU, where the thicknesses were much smaller than in the Mariner 5 data. It is suggested that these two structures were nonlinear magnetoacoustic waves that were in the processes of steepening. It is further suggested that shocks would be formed just beyond 1 AU. These structures were not associated with corotating streams, but they could be associated with impressive solar events in which a flare was followed by type 2 and type 4 radio emission and a rare chromospheric w

ISSN:0148-0227    

DOI:10.1029/JA078i025p05411

年代:1973

数据来源: WILEY

摘要:

A theory and method previously used to calculate terrestrial eddy diffusion coefficients due to instabilities in internal gravity waves have been extended to obtain wave‐induced eddy diffusion coefficients in the upper atmosphere of Mars. If the Martian atmosphere is relatively dry (water vapor mixing ratio ≪10−3), the effects of radiative damping are minimal for all but the longest‐period waves. For greater concentrations of water vapor the effects of radiative damping are increased, but in any event it is reasonable to expect wave‐induced turbulence, with eddy diffusion coefficients of the order of 107cm² sec−1in the Martian uppe

ISSN:0148-0227    

DOI:10.1029/JA078i025p05425

年代:1973

数据来源: WILEY

摘要:

The fourth positive system of CO [A¹Π →X¹Σ] has been excited in a static afterglow experiment by the dissociative recombination of CO2+ions. From combined absolute optical and microwave measurements the specific recombination coefficient for exciting the CO (A→X) system was found to be (2−0.5+1) × 10−8cm³/sec. This value represents approximately 5% of the total recombination coefficient (4.0 ± 0.5) × 10−7cm³/sec measured in this experiment, implying that CO2+dissociative recombination will contribute significantly to the excitation of the CO fourth positive system in the martian airglow. Corroborative electron heating experiments showed that the magnitude of the specific recombination coefficient decreased as the electron temperature was increased. Evidence was also found for the presence of vibrationally excited ions in the CO2+plasma, a result which indicates that analogous laboratory studies on the dissociative recombination of O2+, N2+, and NO+ions may have also involved vibrati

ISSN:0148-0227    

DOI:10.1029/JA078i025p05429

年代:1973

数据来源: WILEY

摘要:

The asymmetric lunar electromagnetic induction theory of Schubert et al. (1973a) is tested by using data from the Apollo 12 Lunar Surface Magnetometer and from the Ames magnetometer on Explorer 35. The comparison of data and theory shows that the moon displays an induction asymmetry due to the flow of the solar wind and the formation of the diamagnetic cavity on the darkside, i.e., the component transfer functions are found to depend on local time. Vacuum theory is a poor description of the darkside induction; symmetric plasma confinement theory applied to the frontside also is incorrect, but the errors introduced are smaller than for the darkside. It is inferred that the induced field forms a magnetospheric‐like configuration, with the field confined mostly to the crust of the moon. Although the magnetospheric spectrum is time dependent, for all frequencies examined, the distance traveled by the solar wind is so large that a quasi‐static magnetospheric configuration can be assumed. The differential power spectrum of the interplanetary magnetic field that excites the moon is compared with the resulting induction spectrum, which has a linear differential power frequency dependence over the frequency range 2 × 10−4to 2 × 10−2Hz, falling off on either side of these limits. The integrated power in this band is about 5 γ² for the interplanetary field local north‐south component and about 12 γ² for the induced spectrum of this component on the lunar surface. Calculated magnetic field line configurations are shown for the moon immersed in a magnetic disturbance field along, perpendicular, and at 45° to the solar wind direction. Current systems on the lunar sunlit hemisphere and cavity boundary are also shown. Previous estimates of the deep conductivity, based on inversion of dayside data, are not grossly affected by the presence of the asymmetry. We expect the lunar magnetospheric configuration first described in this paper to be typical of the fields induced by the solar wind in all planetary bodies, e.g., Mercury, that lack atmospheres and

ISSN:0148-0227    

DOI:10.1029/JA078i025p05437

年代:1973

数据来源: WILEY

摘要:

Recent solar proton measurements over the polar caps have shown up some startling features during times of interplanetary particle anisotropies. Explanations of the observations have been based on diffusive entry into the magnetotail, direct entry by motion along trajectories without scattering, and models incorporating both entry mechanisms. The direct entry mode is based on the computation of particle orbits, of points of access, and asymptotic directions at the magnetopause and in the tail. Although different research groups have used trajectory calculations in order to explain observed polar cap structure, there is considerable disagreement on the computed trajectories and especially on the proposed access mechanisms of solar particles to these trajectories at the magnetopause. In this paper the different models are evaluated, and it is found that the nonadiabatic reconnection model is in good accord with the observations, whereas other models show serious inconsistencies.

ISSN:0148-0227    

DOI:10.1029/JA078i025p05449

年代:1973

数据来源: WILEY

摘要:

Measurements of magnetotail plasma flow made with an electrostatic analyzer on Vela 4B were reported in an earlier paper. Those observations were made with the spin axis of Vela 4B oriented along a radius vector from the earth. They were therefore particularly insensitive, when made in the midnight sector of the plasma sheet, to sunward or antisunward flows, directions of plasma convection to be anticipated under present theories of magnetospheric dynamics. In the present paper we describe similar observations made with Vela 4A at times when the rotational vector of that satellite was oriented approximately perpendicular to the ecliptic plane. This orientation favors, in general, observation of plasma flow directed in the plane of the plasma sheet and, in particular, observations of sunward or antisunward flow. These measurements with Vela 4A confirm two major results reported from Vela 4B: (a) a very rapid flow, approximately sunward, is typically encountered for a few minutes as plasma sheet recovery is first detected late in a substorm; and (b) less rapid flow, approximately antisunward, is encountered for a few minutes early in some substorms as the plasma sheet thins down. Two hours of continuous observations by Vela 4A very near the neutral sheet and very near local midnight during a period of only weak magnetic activity and no substorms revealed no evident plasma flow at speeds greater than the ∼40‐km/sec threshold of the observations. The Vela 4A measurements also provide further strong evidence that the recovery of the plasma sheet late in isolated substorms is causally related to a rapid poleward shift of the auroral electrojet from typical auroral latitudes to low polar cap latitudes late in these substo

ISSN:0148-0227    

DOI:10.1029/JA078i025p05463

年代:1973

数据来源: WILEY

摘要:

A geomagnetic storm beginning with a sc occurred on April 9, 1971. During the storm the charged particle lunar environment experiment at the Apollo 14 site, the solar wind spectrometer experiment at the Apollo 12 site, and the Ames magnetometers on Explorer 35 took data in the magnetosheath, at the magnetopause, in the plasma sheet, and in the high‐latitude geomagnetic tail. The MIT Faraday cup and Ames magnetometers on‐board Explorer 33 monitored the solar wind. The data show that the storm was caused by a corotating tangential discontinuity in the solar wind, the magnetopause position is strongly dependent on the attack angle of the solar wind, and the tail field strength was indirectly measured to increase from 10 to 14 γ after the sc. During the main phase the field strength in the tail was observed to increase to between 28 and 34 γ. This increase is consistent with a thermal and magnetic compression of the tail radius from ∼26 to ∼16RE. The data also show that plasma sheet electrons were observed to drift into the magnetosheath, the thickness of the magnetopause was measured by spatially separated instruments to be>3000 km, and the plasma and magnetic field data are consistent with a model for currents flowing along magnetic field lines in the

ISSN:0148-0227    

DOI:10.1029/JA078i025p05477

年代:1973

数据来源: WILEY

摘要:

During the large May 25, 1967, magnetic storm a solid state detector spectrometer aboard the polar‐orbiting satellite OV1‐9 measured 0.24‐ to 0.96‐Mev protons. A nonadiabatic semi‐permanent enhancement of protons was observed following the storm in the region 2.25

ISSN:0148-0227    

DOI:10.1029/JA078i025p05490

年代:1973

数据来源: WILEY

摘要:

The inner zone population of trapped α particles in the energy range 2.14–9.0 Mev was measured during 1969. The measurements show that inner zone α particles are strongly peaked in pitch angle and that the intensity decreases rapidly with decreasingLvalue. The α particle spectra are flat and closely resemble inner zone proton spectra at comparable energies. The α/pratio is roughly independent ofL(1.6 ≲L≲ 2.0) and energy (0.293–1.14 Mev/nucleon) and is ∼1–4 × 10−3. The computed α particle distribution function strongly suggests that the inner zone is populated by α particles that diffuse inward, conservingMandJ. A value of the diffusion coefficient is derived,DLL= 1.2 × 10−8L10day−1, that is in good agreement wi

ISSN:0148-0227    

DOI:10.1029/JA078i025p05498

年代:1973

数据来源: WILEY