摘要:

On July 29, 1956, quite suddenly as a result of a heart attack, the remarkably active and fruitful career of Dr. John Adam Fleming, the retired director of the Department of Terrestrial Magnetism of the Carnegie Institution of Washington, came to an end at San Mateo, California.The Journal of Geophysical Research, the continuation of “Terrestrial Magnetism and Atmospheric Electricity,” esteems it a privilege to honor the memory of Dr. Fleming, its former able editor from 1928–1948 and subsequently its honorary e

ISSN:0148-0227    

DOI:10.1029/JZ061i004p00589

年代:1956

数据来源: WILEY

摘要:

During the DanishGalatheaexpedition, 1950–52, investigations were made of the vertical gradient of the geomagnetic field, in an attempt to test the probability of the new “fundamental” theory for the main geomagnetic field proposed by P. M. S. Blackett in 1947.Three relative, self‐recording magnetometers—one needle instrument measuring theZ‐component, one needle and one rotating‐coil instrument measuring theH‐component—are described. All instruments may be lowered to extreme depths in the sea in non‐magnetic containers.In the Pacific Ocean, a series of trial measurements were carried out, and at least one of theHmagnetometers proved to be of the desired accuracy of 10γ during a single relative measurement. All trial stations were situated in places with locally disturbed geomagnetic field, which makes the gradient results unreliable, and a breakdown of the technical equipment of the surveying vessel prevented measurements at stations better suited to magnetic work. However, summed up, the trial results indicate a case against the fundamental theory—in accordance with gradient measurements ashore i

ISSN:0148-0227    

DOI:10.1029/JZ061i004p00593

年代:1956

数据来源: WILEY

摘要:

The high electrical conductivity of the region surrounding Earth, inferred from the observations of atmospheric whistlers and the zodiacal light, requires abandoning the customary models for producing a geomagnetic storm field with impressed current system. It becomes necessary to adopt a purely hydromagnetic approach wherein one focuses his attention only on the magnetic lines of force of the geomagnetic field and their displacement with the conducting gas surrounding Earth. From the hydromagnetic point of view, a decrease of the horizontal component is brought about by lifting the lines of force in the region above the observer. It is suggested that heating in the upper atmosphere may produce the necessary lifting; this model, along with another, is developed quantitatively to show that lifting the lines of force a distance of only 5 km will produce a decrease in the horizontal component of 0.2 per cent at the equator.

ISSN:0148-0227    

DOI:10.1029/JZ061i004p00625

年代:1956

数据来源: WILEY

摘要:

The time variations of cosmic‐ray intensity associated with a large solar flare and a period of strong solar activity are reported. A possible interpretation of these semi‐regular time variations in terms of matter emanating from the sun is conside

ISSN:0148-0227    

DOI:10.1029/JZ061i004p00639

年代:1956

数据来源: WILEY

摘要:

During the period of July 10 to September 15, 1955, detection of electromagnetic signals in the frequency range 10 to 900 cycles per second was undertaken. Loops and a vertical antenna were used in a site remote from man‐made interference. The spectrum was analyzed with a narrow bandwidth (2 to 6 cycles per second) amplifier. Indicated diurnal patterns show a maximum around local midnight. The peak in the band lies in the region 40 to 200 cycles per second. During one period of several hours, a large increase in narrow band energy was seen near 33 cycles per second. The possibilities of this being radiation at the gyrofrequency of the sodium ion is discusse

ISSN:0148-0227    

DOI:10.1029/JZ061i004p00647

年代:1956

数据来源: WILEY

摘要:

A calculation of the resonance scattering from a sodium layer between 70 and 100 km for all daylight angles of solar depression is presented. Observations at zenith distance zero and in a plane perpendicular to the sun are considered. The calculation is based on a previous computation of the density of sodium excited by the sun. The effect of absorption in the sodium layer is taken into account. The intensity rises by a factor of about 5 from sunset to noon for a layer 2×1011cm−2thick and by about 27 for a layer only 2×109cm−2

ISSN:0148-0227    

DOI:10.1029/JZ061i004p00663

年代:1956

数据来源: WILEY

摘要:

Because of the discreteness of the data obtained in magnetic surveys, it is necessary to interpolate between measured points before charts can be drawn. Rigorous relations connecting surface variations of different elements are herein introduced into the interpolation formulas, so that the resulting charts are mutually consistent. Related elements are continued by a power series in which the unknown coefficients are computed under the conditions for consistency.

ISSN:0148-0227    

DOI:10.1029/JZ061i004p00667

年代:1956

数据来源: WILEY

摘要:

The irregularities in electron‐density responsible for incoherent scattering of radio waves in the ionosphere are discussed on the assumption of isotropic turbulence in the neutral molecules, with allowance made for the effect of the earth's magnetic field on the associated irregularities in the density of the charges particles. The atmospheric model used is based on rocket observations, extrapolated upwards in height where necessary. Tentative formulas are deduced for the large eddies based on a non‐standard application of the Richardson number. For the small eddies, the standard formulas of turbulence‐theory are used.These formulas all depend on a quantityw, which is the rate of supply of turbulence‐energy to the large eddies and also the rate of removal of turbulence‐energy from the small eddies, measured per unit mass of atmosphere. The value of w at the meteoric level (90 km) is found to be around 25 watts/kg by comparison between the theory and meteoric observations (both visual and radio). By the same technique, a more tentative value of 1,000 watts/kg is deduced for the level responsible for scintillation of radio stars, although a lower value is probably appropriate when scintillation is weak. These values ofwin the ionosphere are high compared with Brunt's value of 5×10−4watt/kg for the troposphere. It is shown, however, that these high values ofwin the ionosphere are quite possible and even reasonable.It is deduced that the time of onset of irregular fading of meteoric echoes in the VHF band is more likely to be due to roughness of the trail caused by the small eddies than to gross distortion of the trail caused by the large eddies. It follows that, after about a second, VHF radar echoes from a meteor‐trail must be calculated using a theory based on incoherent scattering, thereby questioning the theory of Kaiser and Closs [37] as an explanation of long‐duration meteor‐echoes. It is also shown that radio‐star scintillation cannot be explained in terms of turbulence at a level of 400 km, but that reasonable results can be obtained if the level is reduced to 200–300 km.Among other applications considered is the possibility of radio communicationviaincoherent scattering in theFregion of the atmosphere. The conditions under which such communication should be sought are d

ISSN:0148-0227    

DOI:10.1029/JZ061i004p00673

年代:1956

数据来源: WILEY

摘要:

A theory of long‐duration meteor‐echoes is developed, based on the assumption that a meteor‐trail is rendered rough by the action of the small eddies in the atmosphere. This theory leads to the conclusion that, if loss of electrons from the trail by recombination and/or attachment is neglected, the field‐strength of a long‐duration meteor‐echo in its decay‐phase should be inversely proportional to the cube of time subsequent to formation of the trail. It is shown that this law is verified experimentally in the early part of the decay but that at later times the decay becomes more rapid. This can be explained in terms of the loss of electrons from the trail, provided that the loss is due to attachment to atmospheric molecules and the attachment time has an average value of the order of seven seconds.It is shown that the spectrum of incoherent scattering associated with turbulent mixing in a gradient of electron‐density may be derived experimentally by measuring the frequency‐dependence of long‐duration meteor‐echoes during their decay‐phase. This measurement is carried out, and the results are related to the CRPL experiments concerning the frequency‐dependence of long‐distance VHF scatter‐transmission (see Fig. 12).It is deduced that the contribution of meteoric ionization to the background‐signal of scatter‐transmission arises mainly from the incoherent scattering associated with mixing of this ionization by atmospheric turbulence. According to our analysis, McKinley's data concerning the contribution of meteor‐trails to scatter‐tra

ISSN:0148-0227    

DOI:10.1029/JZ061i004p00707

年代:1956

数据来源: WILEY

摘要:

The role of magnetostriction in the problem of rock magnetism has heretofore been neglected. Based on some experimental observations and on reconsiderations of well‐known factors affecting rocks, the conclusion is reached that magnetostriction may figure prominently in establishing the directions of magnetization observed in many cases. Therefore, the practice of interpreting meager magnetic data in terms of polar wandering and continental drift can be in erro

ISSN:0148-0227    

DOI:10.1029/JZ061i004p00735

年代:1956

数据来源: WILEY