摘要:

The interplanetary monitoring platform Imp 1, or Explorer 18, launched on November 27, 1963, has provided the first accurate measurements of interplanetary magnetic fields. The initial apogee of the satellite was 197,616 km on the sunlit side of the earth, with an apogee‐earth‐sun angle of 26°. This paper presents the initial results of the detailed measurements of the interplanetary magnetic field and the interaction of the solar wind with the geomagnetic field. The strength of the interplanetary magnetic field is found to vary between 4 and 7 γ, with extreme values as low as 1 and as high as 10 γ. The magnitude, however, is extremely stable over times of hours, although changes of direction are significant. The average direction of the interplanetary magnetic field is slightly below the plane of the ecliptic and approximately along the streaming angle predicted for a steady‐state solar wind. A significant feature of the magnetic field measurements is the discovery of fields pointed diametrically opposite the streaming angle, indicating filamentary structure of the interplanetary field. Associated with the fields of opposite direction are null surfaces between the filaments and in the over‐all field structure. The complex interaction of the solar wind and the geomagnetic field shows a variety of magnetic field fluctuations and transition characteristics. The detection of the collisionless magnetohydrodynamic shock wave at 13.4Reat the stagnation point associated with the super Alfvénic flow of solar plasma is one of the major results of this experiment. Details of the fluctuations are discussed, as well as the gross structure and shape of the magnetospheric surface (10.2Reat the subsolar point) and the shock wave from the subsolar point to the nighttime geomagnetic tail. The transition region between the shock wave and the magnetopause is one of high turbulence in the magnetic field. A unique aspect of the magnetic field data is the detection of the magnetohydrodynamic wake of the moon during the fifth orbit, when the satellite was eclipsed by the moon's magnetosphere while in interplanetary space. The implications of this experimental discovery ar

ISSN:0148-0227    

DOI:10.1029/JZ069i017p03531

年代:1964

数据来源: WILEY

摘要:

The magnetodynamic instability of a system consisting of a tenuous proton‐electron plasma penetrating along an external magnetic field in a cool partly (or fully) ionized gas is investigated by means of the perturbation method. The criterion of instability is found. It is pointed out that this instability might play the role of a primary source of several pulsation

ISSN:0148-0227    

DOI:10.1029/JZ069i017p03571

年代:1964

数据来源: WILEY

摘要:

Two solid‐state detector telescopes, vertically and horizontally oriented, were launched into a polar orbit during a time of low geomagnetic activity. A small flux of 1.5‐Mev protons, interacting with the geomagnetic field as individual particles, was observed at all latitudes above a characteristic cutoff latitude. The observed vertical cutoff was 65° (equivalent dipole latitude) on the night side and 67° on the day side, as compared with a theoretical Störmer cutoff of 76°. The local time dependence was also apparent in the cutoff transition width characterized by the difference in the latitude at which the flux is first detectable and the latitude at which the maximum (plateau) flux is first observed. On the night side, the transition width was about 1°; on the day side it was about 3° and variable. The horizontal cutoff latitudes were similar. Essentially identical results were obtained over north and south poles. These results are not adequately predicted by currently postulated cutoff theories and should be considered in the calculation of proton fluxes associated with polar‐cap

ISSN:0148-0227    

DOI:10.1029/JZ069i017p03577

年代:1964

数据来源: WILEY

摘要:

Some results of an investigation of whistling atmospherics at Durban over a two‐year period are presented. Very few long whistlers were recorded. The occurrence of short whistlers at Durban is found to be correlated with the occurrence of spreadFnear the conjugate point. The diurnal variation of whistler occurrence is explained in terms of the diurnal variation in spreadFnear the conjugate point. No correlation is found between the number of whistlers recorded and the value of the magneticKindex at the time of recording. Times of peaks in whistler activity are found to follow times of peaks in magnetic activity by a mean interval of 2.2 day

ISSN:0148-0227    

DOI:10.1029/JZ069i017p03583

年代:1964

数据来源: WILEY

摘要:

Diffusion of plasma across a homogeneous magnetic field (B) orthogonally bounded by two conducting planes is examined. Random curl‐free electric fields (E), such thatE·B= 0, consisting of fluctuations with periods greater than the time it takes to establish the magnetic field lines as equipotentials, are considered to cause the diffusion. The diffusion coefficient is 2E2¯τB−2, where τ is the correlation time of the random electric field andE2¯its variance. Within the geomagnetic field there is a region of noisy geomagnetic fluctuations of periods in excess of 100–200 seconds. In this noise region diffusion changes the equatorial radial density profile from the quietn∝R−3inton∝R−4(approximately). It is suggested that the diffusion explains the first‐order decrease in density in the outer magnetosphere observed with whistler techniques during magnetic disturbances. In the process of diffusion caused by disturbance there is a net energization of ambient plasma sufficient to make a major contribution to the main phase

ISSN:0148-0227    

DOI:10.1029/JZ069i017p03595

年代:1964

数据来源: WILEY

摘要:

The rate of occurrence of small fluctuations of the earth's magnetic field (micropulsations) on a sensitive very narrow bandwidth recorder at 1.5 cps is found to be strongly influenced during the daylight hours by magnetic effects associated with the electrical network of a city some 15 miles distant. Practically all micropulsation activity under the observing conditions ceased on a Sunday, providing a simple test for man‐made influences. An isolated dc electric train system, also about 15 miles distant, is found to produce pulsations of large amplitude on a wide‐band micropulsation recor

ISSN:0148-0227    

DOI:10.1029/JZ069i017p03603

年代:1964

数据来源: WILEY

摘要:

Observations, at Hobart, Tasmania, of magnetic ionospheric and radiation effects of the Starfish shot are presented. The interpretation of the results is briefly discussed. Consideration of the magnitude of the ionospheric absorption that accompanied a radiation enhancement recorded by a balloon‐borne Geiger counter appears to exclude atmospheric precipitation of electrons as the cause of the enhancemen

ISSN:0148-0227    

DOI:10.1029/JZ069i017p03607

年代:1964

数据来源: WILEY

摘要:

About 500 ionograms obtained with the Alouette satellite have been used to construct the mean diurnal variation of the mid‐latitude topside ionosphere. Since this diurnal variation is based on observations from October to December 1962, quasi‐seasonal effects had to be removed. The data are presented in the form of electron‐density contours at fixed altitudes for two latitude ranges, 35°N−40°N and 40°N−45°N. These ranges, which are approximately separated at the 75°W meridian by the 70° magnetic dip line, show remarkable differences in the detailed behavior of electron density as a function of time and altitude. From the scale heights of these mean distributions it is apparent that there is absence of thermal equilibrium, at least during the day, and that light ionic constituents become important in the altitude region from 500 to 1000 km, especially during the night. There is also the suggestion of latitude gradients in the electron temperature and

ISSN:0148-0227    

DOI:10.1029/JZ069i017p03613

年代:1964

数据来源: WILEY

摘要:

The results of orbital prediction over periods of 2 to 6 months are presented. The orbits used in the predictions were based on Doppler data obtained within not more than 24 hours. After removal of the drag contribution, the remaining prediction error is found to grow linearly with time, contrary to the theory of Moe. An alternative expression for the growth of error is given. It is shown that the contribution from measurement error is an order of magnitude below the contribution from geodetic errors.

ISSN:0148-0227    

DOI:10.1029/JZ069i017p03619

年代:1964

数据来源: WILEY

摘要:

Vertical phase path measurements of pulsed radio waves reflected from the ionosphere at 5953 and 6110 kc/s, and an oblique Loran A 1850‐kc/s path were examined during known solar flares. A synthesis of a solar‐induced ionization component leads to the conclusion that deposition is predominantly in theFreg

ISSN:0148-0227    

DOI:10.1029/JZ069i017p03625

年代:1964

数据来源: WILEY