摘要:

The spherical harmonic analysis is performed on a number of cosmic ray storms on the basis of the records collected from 26 stations whose asymptotic directions are reasonably uniformly distributed in the geographic coordinates. Here, we report in detail the results for 2 events, September 21–25, 1966, and March 20–26, 1966; the results for 8 other events are given in tabular form. It is shown that the worldwide component (C0) varies closely with the simultaneous cosmic ray variation observed by the Pioneer 7 space probe and for the September 23, 1966, event. The analysis also provides the maximum anisotropic component flux (P) and its asymptotic direction; both vary considerably even during single events. On September 23, 1966,Ptemporarily reached a value as large as 4

ISSN:0148-0227    

DOI:10.1029/JA076i001p00001

年代:1971

数据来源: WILEY

摘要:

Short‐duration increases in particle flux at 1‐Mev energy, detected by Explorer 34 just before the time of passage of interplanetary shocks are discussed. The effect is interpreted as particle acceleration associated with the shocks; most of the increase is found to be consistent in many ways with the idea of energy gain by successive reflection between the earth's bow shock and the interplanetary shock. Other mechanisms are not excluded, however. From the small sample observed, it appears that shocks occurring when the interplanetary magnetic field at the observer's position does not intersect the earth's bow shock did not show particle flux increases, and that the particles accelerated to 1 Mev by the observed shocks did not come from solar wind energies, but rather from solar particles in the hundred‐kev energy region which were available in the m

ISSN:0148-0227    

DOI:10.1029/JA076i001p00013

年代:1971

数据来源: WILEY

摘要:

Emission spectra between 288 and 458 nm from the photoionization of CO2by 58.4‐nm radiation have been obtained. The total cross sections for emission of theB2Σu+→X2ΠgandA2Πg→X2Πgsystems of CO2+are found to be 1.7 and 2.5×10−17cm2, respectively. Relative cross sections are given for the production of emission in individual vibrational features of theA→Xsystem. Previously unidentified bands in the CO2+A‐Xtransit

ISSN:0148-0227    

DOI:10.1029/JA076i001p00021

年代:1971

数据来源: WILEY

摘要:

During the Apollo 8 lunar flight, 3300 kg of liquid oxygen were released from the launch vehicle 45,000 km from the earth during a normal mission operation. The oxygen froze immediately, forming a 500‐km cloud of small particles. The cloud was photographed by the Smithsonian Astrophysical Observatory's satellite tracking station in Spain over a 90‐min period. We have reduced this photometric data, using a simple collisionless model for the expansion, and have deduced the following parameters. The particles that are responsible for the scattering have a bulk velocity of 1.4×104cm/sec and a random velocity of 0.3×104cm/sec. Though we have not yet been able to obtain the size of the scatterers directly, we did establish an estimate of 100–1000 μ for the initial radius of the particles. The particles are subliming, and the radius is given byr0e−t/τs, where τsis approxima

ISSN:0148-0227    

DOI:10.1029/JA076i001p00027

年代:1971

数据来源: WILEY

摘要:

Observations of solar electron fluxes, spectra, pitch‐angle distributions, and temporal and spatial behavior are used in investigating the quasi‐trapping region of the geomagnetosphere. Several features of this region are demonstrated using data from magnetic electron spectrometers on the polar‐elliptical orbiting satellite OV1‐19 (1969‐25C) during the period April 12 to April 17, 1969. The results indicate that, although solar electrons have ready access to closed field lines, they do not become stably trapped in significant quantities. Sharp persistent gradients between the quasi‐trapped zone and the polar plateau (a region of uniform isotropic fluxes) are regarded as indicating an abrupt transition between a region of the geomagnetic field that consists entirely of closed field lines (i.e., permit conjugate‐point mirroring) and a second region in which the field lines either connect directly to the interplanetary field or extend into a tail that is very turbulent on the scale of the gyroradius of 0.1‐ to

ISSN:0148-0227    

DOI:10.1029/JA076i001p00036

年代:1971

数据来源: WILEY

摘要:

During the moderate magnetic storm of September 29–30, 1969, an unusually large magnetic field decrease preceded by an impulsive increase of about 100 γ was observed by the geostationary satellite ATS 5 at about 1733 UT on September 29. The field remained low for about 1 min and returned to the pre‐event level as abruptly as it decreased. From the ATS 1 and ATS 5 observations and magnetograms from ground observatories, we inferred that the magnetosphere was greatly compressed before the event; the magnetopause distance was probably near 7REat the subsolar point. By comparing the changes observed by ATS 5 with the field measured by ATS 1, which was 3 hours behind ATS 5 in local time, we interpreted the event as a magnetopause crossing of ATS 5 caused by a localized rapid inward motion of the magnetopause and its subsequent recession, temporarily creating an indentation on the magnetopause surface and briefly exposing ATS 5 to the magnetosheath field. We suggest that the apparent ‘holes’ in the magnetic field observed by Ogo 3 and Ogo 5 in the magnetosphere near the magnetopause may have been caused, at least in some instances, by similar localized magnetopause

ISSN:0148-0227    

DOI:10.1029/JA076i001p00044

年代:1971

数据来源: WILEY

摘要:

Magnetic field measurements made at the synchronous equatorial satellite ATS 1 during nine geomagnetic storms are compared with simultaneous field measurements made at low‐latitude observatories. The nine storms occurred during the first 6 months of 1967. The results indicate that the sudden‐commencement (sc) compression of the cavity persists through the initial phase and well into the main phase decrease, perhaps until the time of the main phase minimum. The sc is often accompanied by an increase in the tail current, which then also persists through the initial phase. The tail current increases further during the main phase decrease. However, both the compression and particularly the tail current are sometimes intermittently variable during this part of the storm. There is some evidence that the neutral‐sheet current in the tail and the ring current are contiguous while the ring current is developing. As the recovery phase begins, or shortly thereafter, the compression and the tail current return to their respective quiet‐day states. As the tail current decreases the ring current and neutral‐sheet current apparently separate. During the rest of the recovery phase, the compression and the tail current remain at typical quiettime levels, and the decreasing ring current mov

ISSN:0148-0227    

DOI:10.1029/JA076i001p00051

年代:1971

数据来源: WILEY

摘要:

This paper presents examples of electron and proton differential energy spectra between ∼100 ev and 18 kev measured with hemispherical plate electrostatic analyzers on the Vela satellites at a geocentric distance of ∼18REin the magnetotail plasma sheet. The spectra were obtained under several conditions of geomagnetic activity: (a) during very quiet conditions, (b) during the expansive phase of substorms, and (c) following a sudden impulse (si) at the earth. Most of the published auroral particle differential energy spectra measured by rockets are sketched in a single figure for easy comparison with the plasma sheet spectra. The plasma sheet particle fluxes generally, but not always, appear nearly isotropic (to within a factor of 2) to a relatively wide‐angle detector such as the analyzer used here. Comments (a) through (e) below cite features of these sample spectra, referring to averages of measurements made in the antisolar direction and perpendicular to this, i.e., directionally ‘averaged’ results. This is not a statistical study and we do not claim that the features cited are strictly ‘typical’ for the corresponding geomagnetic conditions. But we know, from observation of hundreds of spectra, that these are fairly representative samples and that the conclusions of this study would remain essentially unchanged upon selection of another group of spectra obtained under the same range of geomagnetic conditions. (a) Plasma sheet electron spectra are usually smooth single‐peaked distributions often resembling Maxwellian distributions from several hundred ev to a few kev and frequently (especially during magnetically active periods) becoming power‐law spectra above several kev. (b) In quiet times peak electron intensities were ∼108el/cm2sec ster kev and occurred from one hundred to several hundred ev. Following polar magnetic substorms the peak electron intensities were ∼107el/cm2sec ster kev and occurred at ∼1 to a few kev. The electron number density varied between these two conditions about inversely as the electrons' average energy so that the electron energy density changed relatively little, remaining at ∼30 ev/cm3ster. (c) Proton peak fluxes during quiettimes were ∼ 106p/cm2sec ster kev and appeared near or below 1 kev. Following substorms the peak flux was ∼105p/cm2sec ster kev and occurred near 10 kev. (d) After a sudden impulse the electron and proton energy densities rose to unusually high values (3 to 4 times the values seen during quiettimes and following substorms). This was achieved by the fluxes reaching their quiettime values (∼108and 106particles/cm2sec ster kev, respectively) but with peak energies several times higher than the quiettime values, (e) The electron and proton fluxes measured at rocket altitudes typically exceed fluxes in the plasma sheet by factors of 10 to 100 over most of the energy range (∼100 ev to 18 kev) of the Vela measurements. At rocket altitudes the electron spectra often have secondary intensity peaks in the range of a few kev in sharp contrast to the usual smooth single‐peaked distributions in the plasma sheet. (f) A careful analysis of the data shows that the angular distribution of the plasma sheet electrons can be sharply peaked along the presumed direction of the magnetic field lines; certain unique characteristics of the measurements with the Vela electrostatic analyzers permitted the detection of this feature and a rough measure of the degree of the anisotropy. In one example studied, the peak in the angular distribution was ∼15° wide (full width, half maximum), and the intensity parallel to the magnetic field was ≳27 times the intensity perpendicular to it. We infer that at these times the protons and also perhaps higher energy electrons (Ee>45 kev) have similarly peaked angular distributions. The much higher fluxes of all of these particles measured by rockets simply reflect the fact that the rockets measure only the flux in the very narrow (∼1°) loss cone of the plasma sheet angular distribution, while the detectors (generally wide‐angle) in the plasma sheet average over a lar

ISSN:0148-0227    

DOI:10.1029/JA076i001p00063

年代:1971

数据来源: WILEY

摘要:

The directional differential spectrums of proton intensities mirroring near the magnetic equator in the outer radiation zone are obtained for the energy range 200 ev ≲E≲ 1 Mev with measurements from the spacecrafts Ogo 3, Explorer 12 and 14, and Mariner 4. The average proton spectrum is characterized by a single maximum of differential intensities at 5 to 10 kev and monotone decreasing intensities with lower and higher proton energy. It is suggested that the appropriate boundary region for models of radial diffusion of protons into the outer radiation zone is located in the vicinity of the earthward edge of the quiettime extraterrestrial ring current atL≃

ISSN:0148-0227    

DOI:10.1029/JA076i001p00088

年代:1971

数据来源: WILEY

摘要:

The damping of proton whistlers is found to be much more gradual than predicted by the cyclotron damping theory of Gurnett and Brice (1966) for an assumed homogeneous plasma with an isotropic Maxwellian proton velocity distribution. Several possible causes of the discrepancy are: nonlinear effects, anisotropy, a non‐Maxwellian velocity distribution, and irregularities in proton density. It is concluded that plasma density irregularities are responsible for the observed gradual damping. When these effects are included, the deduced proton temperature increases significantly (about a factor of 2) and the magnitudes of the variations in proton plasma frequency estimated are about 15–

ISSN:0148-0227    

DOI:10.1029/JA076i001p00092

年代:1971

数据来源: WILEY