摘要:

Magnetic field measurements made by means of Explorer 10 over geocentric distances of 1.8 to 42.6Reon March 25–27, 1961, are presented. Results from the MIT plasma experiment on the same satellite are referenced in interpretations. The close‐in data are consistent with the existence of a very weak ring current below 3Realong the trajectory, but alternative explanations for the field deviations are possible. Between 8 and 22Rethe existence of a large‐scale field directed away from the sun and earth within the geomagnetic cavity on the evening side of the earth is demonstrated. At distances greater than 22Reand before a storm sudden commencement late in the flight the geomagnetic cavity boundary apparently crossed the satellite trajectory on six principal occasions. Interpretations bearing on the form and boundary conditions of the cavity and solar‐interplanetary fields external to the cavity are treated. Correlations with magnetic variations at the earth's surface are noted under quiet magnetic conditions as well as at the time of the sc. These indicate that changes in the solar wind have a direct influence on surface magnetic activity associated with changes in the structure of the

ISSN:0148-0227    

DOI:10.1029/JZ068i001p00001

年代:1963

数据来源: WILEY

摘要:

The birth spectrums of high‐energy electrons from the decay of energetic neutrons from cosmic ray albedo have been calculated. Assuming that energy loss is the principle loss mechanism for these energetic electrons, an equilibrium flux of electrons has been derive

ISSN:0148-0227    

DOI:10.1029/JZ068i001p00047

年代:1963

数据来源: WILEY

摘要:

The trapped protons in the outer zone of the Van Allen radiation belt were measured on October 4, 1960, by means of a Scout rocket payload containing a two‐crystal scintillation spectrometer. Protons with energies above 1 Mev were detected, the intensity rising above background at an altitude of 1200 km. Representative intensities for 1≤Ep≤0 Mev at 2, 3, 4, and 5 times; 03km, through a range of 42°N to 30°N geomagnetic latitudes, were 0.27, 0.90, 2.02, and 4.56 times; 05protons/cm2sec ster. These intensities are averages for protons having pitch angles between 90° and ∼60°. The proton energy spectrum at 5000 km isJ(E)= 2.0 × 106E−5.2protons/cm2sec ster Mev for 1.02≤Ep≤2.24 Mev, andJ(E)= 0.71 × 106E−3.9for 2.24≤Ep≤7.3 Mev. The pitch angle distributions for altitudes of 4600 km and 5150 km were also obtained for angles between 90° and 58°. There was no evidence for a proton intensity maximum c

ISSN:0148-0227    

DOI:10.1029/JZ068i001p00055

年代:1963

数据来源: WILEY

摘要:

Continuum electromagnetic radiation from solar flares is discussed in terms of the energy loss processes of electrons in the solar atmosphere. It is shown that it is possible to attribute the continuum radiation both at radio frequencies and at visible frequencies to synchrotron radiation by exponential rigidity distributions of electrons.

ISSN:0148-0227    

DOI:10.1029/JZ068i001p00065

年代:1963

数据来源: WILEY

摘要:

Data from several Alaskan stations observing the natural VLF electromagnetic radiation known as chorus permit a number of statistical investigations, especially of latitudinal variations of the phenomenon. Maximum occurrence lies at 60° to 70° geomagnetic latitude. Seasonal variations at individual stations depend intricately on latitude. Below, but not above, the auroral zone the diurnal maximum depends on an ‘eccentric geomagnetic latitude.’ Chorus correlates with other phenomena, such as geomagnetic activity, the correlation varying seasonally and diurnally. Correlations between stations show a diurnal behavior consistent with the possibility of the existence of isochronic lines for chorus. Temporal variations in the highest frequency (kilocycles per second) of chorus for each sample show a diurnal minimum near noon and seasonal peaks near equinoxes; temporal variations in the rate of change of frequency of chorus show similar pat

ISSN:0148-0227    

DOI:10.1029/JZ068i001p00083

年代:1963

数据来源: WILEY

摘要:

At extremely low frequencies (1 to 3000 cps), relatively slight amounts of ionization can produce notable effects on electromagnetic phenomena in the terrestrial system. Representative atmospheric conditions are examined to find minimum conditions that can produce such strong ELF effects at geophysically quiet periods. On the basis of analyses of ion production parameters, it is found that even for quiet nights, when only cosmic radiation is important for producing ionization in the mesosphere, large refractivities can be produced in this portion of the atmosphere below the ionosphere. For even a minimum electron detachment condition the refractive index of the mesosphere has the large magnitude of 4 at an altitude 75 km. For a more inclusive ion production condition with a maximum detachment factor that collates with VLF observations, strong refractivity effects occur at quite low altitudes: 35 km at 1 cps, 50 km at 10 cps, 55 km at 100 cps, and 65 km at 1000 cps. At very low frequencies (10 kc/s and above) effective altitudes for the nighttime lower ionosphere take on values normally assumed. During daytime and active solar periods it is indicated that strong refractivity effects will occur at altitudes below 30 km.

ISSN:0148-0227    

DOI:10.1029/JZ068i001p00101

年代:1963

数据来源: WILEY

摘要:

On occasion, the amplitude of the pattern produced by a radio star on the record of a phase‐switching interferometer is observed to decrease. The interpretation of these fade‐outs is discussed, and they are shown to be caused mainly by phase scintillations. Simultaneous observations of fadeouts on two 53‐Mc/s phase‐switching interferometers having antenna separations of 25 and 50 wavelengths show that many of the fadeouts are caused by phase fluctuations having scales of a few hundred meters, and rms amplitudes of one or two radians. These irregularities appear to accompany rather than supplant the large‐scale irregularities normally associated with radio star scint

ISSN:0148-0227    

DOI:10.1029/JZ068i001p00111

年代:1963

数据来源: WILEY

摘要:

Scintillations of the radio star Cassiopeia A were observed at Saskatoon on 53 Mc/s with two phase‐switching interferometers having antenna separations of 25 and 50 wavelengths. The scintillations on the 50‐wavelength interferometer record were found to correlate well with auroral and magnetic activity, whereas those obtained from the 25‐wavelength interferometer showed relatively little relation to these phenomena. The conclusion is that these scintillations are characterized more by fluctuations in the phase of the wave from the radio star than by fluctuations in its amplitude. This appears to explain why studies of the correlation between radio star scintillations and auroral and magnetic activity have often been inconclusive when made with equipment sensitive primarily to amplitude scintillations. Observations were made on periods of decreased interferometer pattern amplitude, called ‘fadeouts’ which supported this conclusion. These fadeouts were found to correlate well with magnetic activity and line‐of‐sight aurora, and to be accompanied by large fluctuations in the phase of the wave from t

ISSN:0148-0227    

DOI:10.1029/JZ068i001p00117

年代:1963

数据来源: WILEY

摘要:

The development of the main phase and of auroral activities during magnetic storms is examined for a number of storms. It varies much more than a mere difference of pressure of the solar streams would seem to produce. Some intrinsic differences between solar streams are suggested.

ISSN:0148-0227    

DOI:10.1029/JZ068i001p00125

年代:1963

数据来源: WILEY

摘要:

Gold has pointed out that the gas in the magnetosphere of the earth can take part in large‐scale motions in which tubes of force of equal flux and the gas within them are interchanged. Such motions leave the magnetic field and its energy almost unchanged, and may therefore be driven by variation in the state of the gas. In this paper the stability of the magnetosphere against such motion occurring spontaneously is studied by investigation of the change in potential energy of the system during a hypothetical interchange of two tubes of force. For isothermal interchanges the energy criterion may be cast into a useful form without further physical assumptions. Our analysis shows that, except possibly at low latitudes, such motions are not of importance. The more realistic case of adiabatic interchanges is discussed in the two limits where the gravitational energy is much smaller or much larger, in absolute value, than the internal energy of the gas. Smaller gravitational energy applies to the outer tubes of force for which the energy content is dominated by the internal energy of the fully ionized hot gas residing far out in the geomagnetic field; spontaneous interchanges occur only if the energy content of the tubes of force decreases sufficiently rapidly in the outward direction.Larger gravitational energy applies to the inner tubes of force since the energy content of these tubes is dominated by the gravitational energy of the cold gas at the feet of the tubes of force, i.e. the ionospheric material. It is shown that spontaneous adiabatic interchanges may occur if the temperature in the upper ionosphere increases sufficiently rapidly with increasing latitude. It is also demonstrated that the temperature gradients in subauroral latitudes, caused by the heating of the ionosphere in the auroral zones by fast particles, may be sufficient to trigger this instability. Thus an inner convective zone may exist in the magnetosphere. The size and location of this zone are discusse

ISSN:0148-0227    

DOI:10.1029/JZ068i001p00131

年代:1963

数据来源: WILEY