摘要:

A balloon flight was made on March 16, 1959, near the peak of the last solar cycle, to search for solar γ rays. Although two active regions were visible on the sun, the γ radiation above 20 Mev was<2.8×10−2photons cm−2sec−1. Upper limitsE) ∝E−0.50±0.06for 20

ISSN:0148-0227    

DOI:10.1029/JZ071i013p03119

年代:1966

数据来源: WILEY

摘要:

The disturbance field caused by charged particles trapped in the earth's magnetosphere is fairly uniform near the earth. Its value at the earth's center, ΔHz(0), which can be calculated easily, is therefore a good approximation for the field at the surface. Several years ago, Dessler and Parker derived for two special pitch‐angle distributions of particles the simple relationΔHz(0) = ‐2E/3Embetween ΔHz(0) and the total energy of the particles,E. (H0andEmare constants denoting the horizontal component of the main field at the earth's equator and the total energy of the main field external to the earth, respectively.) It is shown in this paper that this relation is applicable for any steady configuration of trapped particles, regardless of their pitch‐angle dist

ISSN:0148-0227    

DOI:10.1029/JZ071i013p03125

年代:1966

数据来源: WILEY

摘要:

Using plasma scale height profiles obtained from the Alouette topside sounder and planetary geomagnetic data published in the Journal of Geophysical Research, correlation is observed betweenKpand plasma scale height in the topside ionosphere. From the observed correlation it is deduced that nighttime particle temperatures increase by about 4 per cent for each unit increase inKpand that nighttime midlatitude transition from O+ions to lighter (He+, H+) ions, normally occurring at around 550 km, rises about 30 km per unit increase inKp.

ISSN:0148-0227    

DOI:10.1029/JZ071i013p03131

年代:1966

数据来源: WILEY

摘要:

The effects of 4‐kev protons on the earth's upper atmosphere at midlatitudes have been investigated. A Monte Carlo calculation of the flux distribution in the atmosphere, assuming that the initially monoenergetic protons are uniformly mirroring at altitudes where neutralization is important, shows that two thirds of the incident protons are lost to space and none penetrate to altitudes lower than 135 km. The largest energy deposition occurs near 200 km. An initial flux of 5×107protons cm−2sec−1gives up 10−1erg cm−2(column) sec−1to neutral heating and about 10−3erg cm−2(column) sec−1to electron heating. The calculated intensity of 3914 A radiation is 1.0 R at a magnetic field inclination of 45°; protons and neutrals produce 5.3 R of 6300 A light and 2.0 R of 5577 A light, but the secondary electrons may increase these latter numbers. Equilibrium solutions to the five coupled diffusion equations involving the major atmospheric ions have been found both with and without the proton neutral flux. To maintain the nighttime ionosphere above 250 km, 1.2×108ions cm−2sec−1must diffuse down from the exosphere; the additional 4‐kev proton flux has little effect. Below 250 km diffusion alone can account for only about 2% of the observed ion concentration; the proton neutral flux can support the ionosphere down to about 150 km, depending somewha

ISSN:0148-0227    

DOI:10.1029/JZ071i013p03141

年代:1966

数据来源: WILEY

摘要:

Observations on pulsating auroras occurring near the equatorward boundary of auroral displays during their postbreakup phase have been made with an image orthicon television system and with photometers. It is found that the pulsating phase of the display is composed of numerous relatively short sequences of pulsations that are restricted to small field‐aligned volumes. The luminosity varies synchronously within a given auroral form, but adjacent forms may pulsate asynchronousl

ISSN:0148-0227    

DOI:10.1029/JZ071i013p03155

年代:1966

数据来源: WILEY

摘要:

Measurements of quasi‐trapped electrons with energies greater than 300 kev in August 1964 have extended the temporal observations of these precipitating particles. These electrons are lost in the atmosphere as they drift into the South Atlantic magnetic anomaly. ForL= 3.5 andB= 0.40 gauss, typical fluxes of precipitating electrons with energies greater than 300 kev were 102–103/cm2‐sec in August 1964. For energies greater than 700 kev the flux was less than 10/cm2‐sec in the August 1964‐to‐April 1965 period. The flux forEe>700 kev is much lower than that measured in September 1962 and indicates that the spectrum of precipitating electrons has softened considerably between September 1962 and August 1964. Simultaneous measurements of the electric components of longitudinal waves in the 1.7–14.5‐kc/s region were made by a separate experiment; these waves could be effective in precipit

ISSN:0148-0227    

DOI:10.1029/JZ071i013p03165

年代:1966

数据来源: WILEY

摘要:

This paper concerns the change in energy spectrum of a group of electrons being convected downwind in the magnetosheath. Recent observations that the spectrums of the energetic electron pulses in the magnetosheath soften with increasing LSEP and with decreasing distance from the magnetopause are discussed in terms of a model in which each pulse is due to a group of electrons being blown past the satellite. It is demonstrated that the change in spectrum may be naturally interpreted as a consequence of more rapid diffusion of faster electrons through the turbulent magnetic field of the magnetosheath. In particular, the magnitude of the change is readily explained if the mean free path is of the order of the electron cyclotron radius. Other consequences of the diffusion hypothesis are briefly discussed.

ISSN:0148-0227    

DOI:10.1029/JZ071i013p03173

年代:1966

数据来源: WILEY

摘要:

A least‐squares method is presented to determine simultaneously the temporal variations in temperature and drift velocity in the ionosphere from the observed temporal variations in electron density profiles. These are determined so that the continuity equation for electron density may be satisfied very well at all heights and at all hours. The application of the method to the nighttime variations ofF‐region electron density profiles at Puerto Rico, March 1959, indicates that the implied nocturnal variations in temperature and drift velocity are quite reasonable and that the relative significance of these two effects strongly depends upon time; the effect of a rapid temperature decrease predominates over the effect of small drift velocity before midnight, while the effect of a large downward drift velocity overcomes the effect of small temperature variations for several hours after midnight. After around 0400 hours in the morning the temperature rises rapidly and both effects of temperature variation and drift velocity are equally dominant. It remains difficult to reconcile the theoretical value of ambipolar diffusion cross section with rocket observations of neutral atmosphere density and composition on the one hand, and with ionospheric observations on the other h

ISSN:0148-0227    

DOI:10.1029/JZ071i013p03177

年代:1966

数据来源: WILEY

摘要:

The first‐order corrections toD‐region probe theory are discussed. It is shown that the largest corrections are due to heat transfer and compressibility. These corrections tend to cancel each other for small angles of attack. The largest correction is due to heat transfer and is at most ten per cent. The first‐order theory, unconnected, is valid to within ten per

ISSN:0148-0227    

DOI:10.1029/JZ071i013p03191

年代:1966

数据来源: WILEY

摘要:

The diurnal oscillation in the earth's atmosphere is investigated, and allowed modes of that oscillation are determined. Some of these modes are analogous to the oscillation of an ocean withnegativedepths. However, these oscillations should be allowed not in the ocean but in the atmosphere, because we find no specific reason to discard them. We find a good resemblance of the pressure variation of the first negative mode to that deduced from the geomagneticSqvariations. In Part 2 we shall discuss the vertical structure of this negative mode under thermal excitation in the upper atmosphere and find conspicuous differences from positive mode.

ISSN:0148-0227    

DOI:10.1029/JZ071i013p03201

年代:1966

数据来源: WILEY