摘要:

By using power spectrum analysis on the µ meson intensity records of a high counting rate instrument (106counts/min) operated at Chacaltaya, Bolivia, it has been possible to identify the presence of cosmic ray fluctuations of 15 to 19 and 25 to 28 cycles per hour (cph). These frequencies were found at a 99% level of significance in the average of 1034 three‐hour samples extending from November 1965 to June 1966. Comparison with Pioneer 6 measurements (Ness et al., 1966) indicates that the magnetosheath field, at a distance of about 10 earth radii (RE), and the interplanetary magnetic field show peaks in spectral density that correspond closely (though not identically) with peaks in muon intensity. It is most plausible that these cosmic ray fluctuations are caused by the fluctuations of geomagnetic field corresponding to an amplitude of about 20 γ in the dipole magnetic field. Magnetic field measurements conducted in the magnetosphere by Explorer 6 (Judge and Coleman, 1962) and Explorer 12 (Patel and Cahill, 1964) show similar oscillations. Recent observations by ATS 1 confirm the presence of magnetic oscillations of similar frequencies at about 6RE. These frequencies are also found in the geomagnetic micropulsations observed at the surface of the earth. The integrated power of cosmic ray oscillations in the frequency range of 6 to 30 cph has been studied at various periods, and its solar‐terrestrial relationship is examined. The association of observed frequencies in cosmic rays with frequencies in the solar photosphere and the interplanetary magnetic field, as well as the resonance frequencies of the magnetosphere, are disc

ISSN:0148-0227    

DOI:10.1029/JA075i010p01795

年代:1970

数据来源: WILEY

摘要:

The amplitudes of the first harmonic of the diurnal variation in the pressure‐corrected cosmic‐ray neutron monitor rate have been examined for several stations at different altitudes but at the same cutoff rigidity (∼1.3 Gv). An increase in the amplitude of the mean diurnal variation from sea level to 800 g/cm² is observed, which is 19.4±4.2% for 1964 to 1965, and 7.8±3.3% for 1967 to 1968. Several effects are required to explain this variation with altitude and its observed time dependence, the most significant of which is the diurnal change in geomagnetic cutoff

ISSN:0148-0227    

DOI:10.1029/JA075i010p01802

年代:1970

数据来源: WILEY

摘要:

A balloon‐borne directional spectrometer for gamma rays from 30 kev to 6.3 Mev is described, based on a high‐resolution Ge(Li) detector. The sun was observed from 4.7 g cm−2on May 5, 1968. Seven lines present in the background are attributed to neutron capture reactions in the detector. No evidence of monochromatic solar gamma‐ray emission was detected. An upper limit of 6.9×10−3cm−2sec−1was found for 511 kev radiation from the quiet sun. Upper limits 4.5×10−3cm−2sec−1and 3.2×10−2cm−2sec−1were found for the flux of 2.223‐Mev gamma rays at the earth for the quiet sun and for a period of s

ISSN:0148-0227    

DOI:10.1029/JA075i010p01811

年代:1970

数据来源: WILEY

摘要:

We extend the previous work on non‐spherically symmetric solar wind models, which involved only two independent variables, by deriving the perturabtion equations for the three independent variables, γ, θ, and η, of a spherical polar coordinate system corotating with the sun. The results can be applied to an arbitrary distribution of coronal inhomogeneities with lifetimes long as compared with a flow time of several days and, hence, are restricted to large scale solar wind variations. Two special distributions are given as examples, one north‐south symmetric and one north‐south antisymmetric; both have four perturbation cycles in one solar rotation. Boundary conditions appropriate to a ‘pure fast‐slow stream interaction’ are applied. Comparison with solar wind data suggest that this simple boundary condition can explain occasionally seen structures, but more generally a boundary condition that includes entropy variati

ISSN:0148-0227    

DOI:10.1029/JA075i010p01817

年代:1970

数据来源: WILEY

摘要:

We find that the magnetopause is permanently covered by a layer of energetic electrons extending from the dayside of the magnetosphere to at least about 60REdownstream along the tail. The layer has a thickness of about 1 to 2RE. The flux of energetic electrons in this layer shows a clear dependence on the geomagnetic activity indicated by the 3‐hourKpindex. These findings are based on the observations of energetic electron fluxes of IMP 1, IMP 3, and lunar‐orbiting Explorer 35 satelli

ISSN:0148-0227    

DOI:10.1029/JA075i010p01827

年代:1970

数据来源: WILEY

摘要:

The intensity of Lyman α was measured from the OGO 3 spacecraft at altitudes from 5 to 19RE(earth radii). The variation of intensity with distance reveals a mean hydrogen density at 50,000 km of about 20 atoms cm−3for the summer 1966 epoch and negligible contribution to the signal from geocoronal hydrogen beyond 12 radii. An extraterrestrial background of some 750 rayleighs was observed at apogee. Asymmetry of intensity variations on either side of apogee suggest an enhancement of the background from regions near the galactic plane, and correlation of the background with solar activity over a 40‐day period suggests that a portion of the background is solar‐r

ISSN:0148-0227    

DOI:10.1029/JA075i010p01837

年代:1970

数据来源: WILEY

摘要:

The high‐resolution profile of the solar H Ly α line has been measured for five altitudes from spectrograms taken during an Aerobee flight. The absorption due to the earth's hydrogen atmosphere was analyzed. As an illustration of the geophysical application of the absorption data, these data are compared with the absorption predicted by two current models of the earth’s hydrogen atmosphere. The density of deuterium in the earth's atmosphere as a function of altitude is calculated on the basis of one experimental point and simple th

ISSN:0148-0227    

DOI:10.1029/JA075i010p01849

年代:1970

数据来源: WILEY

摘要:

Two new types of low‐frequency noise, designated ‘broadband’ and ‘highpass’ have been detected in the distant magnetosphere by the VLF/LF experiment on the OGO 1 satellite. Broadband noise extends over the entire range of observations from 0.2 to 100 kHz and the intensity decreases with increasing frequency. It occurs in bursts having durations of a few minutes or less. It shows no connection with any of the expected plasma cutoff or resonance frequencies and is believed to be a nonpropagating disturbance generated in the vicinity of the satellite. Highpass noise extends from a characteristic low‐frequency cutoff to above 100 kHz and occurs in bursts lasting tens of minutes. This cutoff has only been observed above 20 kHz. Above the cutoff the intensity shows little variation with frequency. Both types of noise are observed predominantly atLgreater than 5 in or near the night hemisphere. The occurrence of both types of noise is highly correlated with the auroral electrojet index. Several times noise bursts began within 2 min of the onset of micropulsations in the polar region even though the satellite was near apogee (24 earth radii). The peak rms magnetic intensity in a highpass noise burst has a maximum of 8×10−5γ Hz1/2and averages 10−5γ Hz−1/2. In free space these magnetic intensities correspond, respectively, to 10−12and 3×10−14watt m−2Hz−1. The peak levels of both types of noise are 3 or more orders of magnitude stronger than emissions from extraterrestrial sources observ

ISSN:0148-0227    

DOI:10.1029/JA075i010p01854

年代:1970

数据来源: WILEY

摘要:

In this paper we describe a drift instability of Alfvén waves driven by the sharp electron thermal gradient at the inner edge of the electron plasma sheet. The analysis predicts a localized instability with wavelengths, perpendicular to the magnetic field, comparable with an ion cyclotron radius and parallel wavelengths comparable with the length of field lines. The fastest growing wave should have a period of ≃10 seconds, consistent with observations of 5‐ to 15‐second micropulsations observed during sub

ISSN:0148-0227    

DOI:10.1029/JA075i010p01863

年代:1970

数据来源: WILEY

摘要:

We describe a large enhancement of the O2(¹Δg‐ ³Σg), infrared oxygen band at 1.27 µ in

ISSN:0148-0227    

DOI:10.1029/JA075i010p01879

年代:1970

数据来源: WILEY