摘要:

For charged particles trapped in the geomagnetic field, the frequencies of the mirror oscillations ωmand the azimuthal drift ωdare defined as appropriate averages over the helical motion around the field lines and the mirror motion between reflection points in the two magnetic hemispheres. These integrals for ωmand ωdare evaluated numerically. Results are tabulated, illustrated, and represented by approximate analytical expressi

ISSN:0148-0227    

DOI:10.1029/JZ066i001p00001

年代:1961

数据来源: WILEY

摘要:

The first results of investigations of earth current pulsations in the range of periods of 1 to 15 seconds are presented. Data of earth current stations located in the Arctic (5 stations), in the Antarctic (2 stations), and in middle latitudes of the USSR (10 stations), as well as data of high‐sensitivity installations for magnetic‐field (Z) registration at 3 stations, were used. Several characteristic types of pulsations were defined in this range of periods, and their correlation with phenomena in the high atmosphere was studied, among them: (a) short irregular pulsations (T∼1–15 sec) composing the microstructure of several forms of macroscopic disturbances of the magnetic field and showing a close correlation with aurora; and (b) pulsations of the ‘pearl’ type (T∼1–4 sec), distinguished by their regular form and showing a correlation with cosmic‐ray intensity bursts in the stratosphere.The main features of magnetic‐storm microstructure, as well as the microstructure of SSC, are given. The importance of the occurrence during magnetic storms of ‘pulsations with diminishing periods’ and correlation studies with high‐atmosphere phenomena is stressed. The dependence on local time of the fine structure of SSC is described. Contrary to some theoretical expectations the time difference between the first movements due to SSC was found to be very small; the movements may even have been simultaneous. For the Argus III explosion the onset time of oscillation was fo

ISSN:0148-0227    

DOI:10.1029/JZ066i001p00005

年代:1961

数据来源: WILEY

摘要:

Observations of 5 kc/s radio noise with a network of four stations extending across southern Australia are described. It is shown that there is often good correlation of the amplitude variations over a distance of 3000 km and that the observed amplitude differences may be explained by assuming that the radiation propagates in the earth‐ionosphere wave guide from geographically large sources. Some discrete sources were observe

ISSN:0148-0227    

DOI:10.1029/JZ066i001p00019

年代:1961

数据来源: WILEY

摘要:

A study in March and April, 1960, showed variations in the auroral zone ionospheric absorption of cosmic noise to be closely related to magnetic field micropulsations and short period coruscations of λ 3914. At times of polar‐cap type absorption, magnetic micropulsation amplitudes were diminished. Auroral ionization in theEregion, estimated from a particular luminosity‐height profile, accounted for 50 per cent, at least, of the cosmic noise absorp

ISSN:0148-0227    

DOI:10.1029/JZ066i001p00025

年代:1961

数据来源: WILEY

摘要:

Sudden changes of VLF propagation characteristics, caused by the very high altitude Hardtack nuclear detonations in the summer of 1958, occurred on propagation paths thousands of kilometers from the burst point. The anomalies were caused by bomb‐induced ionization in the ionosphericDlayer, and their onset was much more sudden than those occasioned by natural phenomena such as solar flares. The model discussed provides an explanation of how ionization is suddenly produced in ionospheric regions shadowed from a high‐altitude detonation or its conjugate po

ISSN:0148-0227    

DOI:10.1029/JZ066i001p00035

年代:1961

数据来源: WILEY

摘要:

Short period variations in the N2+(0, 0) auroral emission band represent 5 per cent of the total light in the 3914 A region. These quasi‐periodic coruscations have a dominant period of 6 to 10 seconds. They attain a maximum amplitude in the predawn hours and are closely related to magnetic field micropulsations and ionospheric absorption of cosmic noise. Spectroscopic triangulation showed that the variations originate in theEregion of the ionosphere. The profile of the electron density associated with the aurora was found to have a maximum value of 1.1×104electrons per cubic centimeter at 98 kilomete

ISSN:0148-0227    

DOI:10.1029/JZ066i001p00041

年代:1961

数据来源: WILEY

摘要:

Cosmic‐radio‐noise measurements at 18 Mc/s made in Hawaii during the period of November 1958 to December 1959 are reported. Diurnal attenuation curves are presented for the summer, winter, and equinoctial months that show a very pronounced resemblance to theF‐region critical frequency curves. It is shown that an important part of the total attenuation can be accounted for by an ionospheric window effect. The remaining attenuation is attributed to deviative absorption in theFregion and nondeviative absorption in theDregion. A nighttime component of attenuation is observed and it is suggested that this phenomenon is related to the cooling of the ionosphere. Finally, it is observed that on numerous occasions when theF‐region critical frequency exceeds the operating frequency, considerable flux continues to arrive at the antenna. It is suggested that this can be accounted for in terms of cosmic radio radiation trapped and propagated underneath the ionosphere. It is also possible that thermal radiation from the ionosphere plays a secondary role in this phe

ISSN:0148-0227    

DOI:10.1029/JZ066i001p00057

年代:1961

数据来源: WILEY

摘要:

The nose whistler dispersion equation was numerically integrated using the following assumed functions for the electron density distribution:(1)N=K(2)N=KR−3.(3)N=KR−3exp(3.03/R).Nis the electron number density,Ris the distance from the earth's center, andKa constant of proportionality.Several whistlers that were received at College on March 19, 1959, were analyzed to obtain electron densities. Each of these whistlers consists of a number of branches having successively lower nose frequencies. Measurements of the nose frequencies and the time of propagation of the nose frequency yield values of the constantKfrom which the electron density can be determined at any point.It was found that the results for the first two functions disagree systematically with the curve of the assumed function. The third function, suggested by F. S. Johnson on the basis of theoretical considerations, fits the data well within the experimental errors. The resulting distributions cover the range between 4 and 6 earth's radii, giving densities varying from 20 to 5 electrons per cubic centime

ISSN:0148-0227    

DOI:10.1029/JZ066i001p00067

年代:1961

数据来源: WILEY

摘要:

Outgoing radiation from the atmosphere is calculated at several frequencies in the 15‐μ carbon dioxide band according to the random Elsasser band model and the Curtis‐Godson approximation to the mean line width. From the resulting values, an inversion of the problem is performed, with simplifying assumptions, to recover the temperature structure of the upper part of the atmosphere. This abbreviation of the experiment proposed by Kaplan would yield the temperatures and the lapse rates in two layers of the atmosphere from three measurements of the outgoing radiation. Results from three model atmospheres indicate that calculated mean lapse rates and mean temperatures in the two layers, as they might be deduced from measurements made from a satellite, are in good agreement with actual temperature struct

ISSN:0148-0227    

DOI:10.1029/JZ066i001p00077

年代:1961

数据来源: WILEY

摘要:

The possibility that a significant part of the energy of the planetary‐wave disturbances of the troposphere may propagate into the upper atmosphere is investigated. The propagation is analogous to the transmission of electromagnetic radiation in heterogeneous media. It is found that the effective index of refraction for the planetary waves depends primarily on the distribution of the mean zonal wind with height. Energy is trapped (reflected) in regions where the zonal winds are easterly or are large and westerly. As a consequence, the summer circumpolar anticyclone and the winter circumpolar cyclone in the upper stratosphere and mesosphere are little influenced by lower atmosphere motions. Energy may escape into the mesosphere near the equinoxes, when the upper‐atmosphere zonal flow reverses. At these times tunneling of the energy through a reflecting barrier is also possible. Most of the time, however, there appears to be little mechanical coupling on a planetary scale between the upper and lower atmospheres.Tropospheric sources of wave disturbances in the zonal flow are baroclinic instability and the forcing action of zonally asymmetric heating and topography. The transmissivity of the upper atmosphere increases with wavelength and is greater for the forced perturbations than for the unstable tropospheric waves, whose lengths must be smaller than the critical length for instability. The analysis indicates that baroclinically unstable wave disturbances originating in the troposphere probably do not propagate energy vertically at all.When energy is propagated to great heights, nonlinear vertical eddy transports of heat and momentum associated with the vertically propagating waves should modify the basic zonal flow. However, when the wave disturbance is a small stationary perturbation on a zonal flow that varies vertically but not horizontally, the second‐order effect of the eddies on the zonal flow is

ISSN:0148-0227    

DOI:10.1029/JZ066i001p00083

年代:1961

数据来源: WILEY