摘要:

Data on atmospheric conductivity obtained experimentally in the altitude region between 35 and 80 km by use of rocket‐borne Gerdien condensers are presented. Analytic expressions based on ion equilibrium and ionization by cosmic rays only are derived for comparison. The experimental technique is described, and several factors that might influence the measurements are evaluated.There is good agreement between the measured and predicted values of negative conductivity at altitudes up to 50 km. Low conductivity values observed between 50 and 80 km are attributed to ionic diffusion to particulate matter, the reduction agreeing quantitatively with that calculated from present estimates of the radius and concentration of noctilucent cloud particles. It is suggested that meteoritic dust may be an important agent for electron destruction in the ionospher

ISSN:0148-0227    

DOI:10.1029/JZ064i010p01363

年代:1959

数据来源: WILEY

摘要:

Measurements of the Faraday rotation of lunar radio echoes on a frequency of 151 Mc/s are used to determine the time variation in the total ionospheric electron content. Absolute values of ionospheric electron content are determined from these measurements in conjunction with information on the electron content below theF2peak computed from vertical‐incidence sounding data. Diurnal, day‐to‐day, and seasonal variations in the total electron content are presented. The rationa∶nbof the number of electrons above theF2peak to that below is found to be in the order of 4 to 5 during three summer nights (June) before sunrise and about equal to 3 after sunrise. For two days in November the rationa:nbis found to be equal to about three both before and after sunrise. Possibilities of inferring other characteristics of the upper ionosphere from observed variations in the total electron content are briefly di

ISSN:0148-0227    

DOI:10.1029/JZ064i010p01371

年代:1959

数据来源: WILEY

摘要:

During a magnetic storm on 6 August 1957, a rocket‐borne magnetometer was launched near the coast of Greenland. The time and location of the flight and the magnetic measurements obtained provide evidence that the rocket entered the postulated sheet current flowing across the polar cap. An estimate is made of the magnitude of the detected curren

ISSN:0148-0227    

DOI:10.1029/JZ064i010p01377

年代:1959

数据来源: WILEY

摘要:

Visual auroral observations from the Halley Bay, Shackleton, and Southice, antarctic bases, are tabulated to show how the frequency of occurrence of aurora varied with the geomagnetic latitude, from 63° to 79°, in the sector 20°E during the IGY. The distribution of quiet arcs, and its diurnal variation, are given particular attention. The center of the quiet arc zone is found to be at geomagnetic latitude 71.7°; the interquartile range is

ISSN:0148-0227    

DOI:10.1029/JZ064i010p01381

年代:1959

数据来源: WILEY

摘要:

Auroral observations made during the Antarctic winter of 1957 are summarized. The data discussed include daily variation, east‐west drift, and hydrogen emission. From a comparison of observations made at Ellsworth and the South Pole evidence is obtained of a spiraling zone of maximum auroral activit

ISSN:0148-0227    

DOI:10.1029/JZ064i010p01389

年代:1959

数据来源: WILEY

摘要:

Oscillations are defined as comprising only the more regular of the short‐period geomagnetic fluctuations (periods from 1 to 200 seconds) and may be recognized as representing electromagnetic energy in narrow frequency bandwidths and identified by objective criteria. The characteristics of these oscillations, as indicated by the available observational data, are examined with a view toward the eventual identification of their resonant sources. Three distinct frequency ‘bands’ are observed. Two of them, a 20‐sec band (that is, oscillations having similar characteristics and having periods centered at about 20 sec) and a 70‐sec band, are predominantly daytime phenomena, whereas the third, an 8‐sec band, occurs at night. The 8‐sec oscillations show a strong positive correlation, both in amplitude and duration, with theKindex; this correlation is less pronounced for the 20‐sec band and is absent (or perhaps negative) for the 70‐sec band. An additional nighttime band containing periods longer than about 95 sec is not yet defin

ISSN:0148-0227    

DOI:10.1029/JZ064i010p01395

年代:1959

数据来源: WILEY

摘要:

The observed characteristics of the oscillations, quasi‐sinusoidal geomagnetic fluctuations having periods from 1 to 200 seconds, are compared with theories of their origins and with observations of other ionospheric phenomena. The results favor the hypothesis of intra‐layer hydromagnetic resonance in the ionosphere as the source mechanism and suggest that the ‘daytime’ oscillations comprising the 20‐ and 70‐sec bands arise in theEregion, whereas the ‘nighttime’ 8‐sec band originates in theFregion. Simultaneous studies of the different phenomena are needed to confirm these results and to furnish data for comparisons with further developme

ISSN:0148-0227    

DOI:10.1029/JZ064i010p01405

年代:1959

数据来源: WILEY

摘要:

A method for computing field lines in space is used to derive conjugate points of some auroral and magnetic stations of the IGY. The study uses a total of 48 coefficients with computations done on an electronic computer.

ISSN:0148-0227    

DOI:10.1029/JZ064i010p01411

年代:1959

数据来源: WILEY

摘要:

A theory is presented which relates those properties of meteoric echoes that depend on distortion of the trail by winds. It is shown that existing results on the delay in the start of echo fading, the delay in echo appearance with aspect, the spectral composition of the received signal, and the regularity of the fading pattern are quantitatively explicable. In addition, the theory predicts that the ensemble‐average rate of echo fading should rise characteristically with time and should then drop precipitously at the end of the ensemble echo; moreover, it predicts that the correlation of fading patterns at two ground receivers should be a gaussian function of the product of receiver spacing and echo fading cycle‐number. Experimental results are given which confirm these predictions and make possible the determination of the principal properties of the wind profile. It is concluded that at the times of observation the small‐scale cutoff wavelength of the turbulence spectrum was about a kilometer, that lack of correlation of wind velocities existed in a vertical range of about a scale height, that the rms variable component of N‐S wind velocity was about 50 m/s, and that the rms value of the relative maxima of the vertical gradient of a component of the wind velocity was about 100 m/s. These figures agree with Whipple's photographic studies of meteor

ISSN:0148-0227    

DOI:10.1029/JZ064i010p01415

年代:1959

数据来源: WILEY

摘要:

A series of balloon‐borne soundings in the atmosphere with single Geiger tubes has been made during the period January to September 1958. The counting rate determined at the Pfotzer maximum is compared with that recorded by the nucleonic detector at Mt. Washington (1909 m; λ = 55°N). Large changes in the counting rate of each detector were observed, and the ratio of these changes is ∼2 ‐ 1. Several large deviations from this normal ratio were also observed; they occur for flights on which the shape of the intensity‐altitude curve near the Pfotzer maximum is quite different from the normal. The changes are explained either in terms of depressions of the low‐energy portion of the cosmic‐ray spectrum following marked decreases in the nucleonic component or by the presence of excess low‐energy radiation. An anomalous increase of ∼100 per cent observed at high altitudes during one flight is attributed to high‐energy X‐radiation. It is found that the hemispherical average unidirectional intensity above the atmosphere derived from the counting rate at the Pfotzer maximum has decreased ∼200 per cent from 1954 to 1958 at λ = 53°N, and this change is compared with r

ISSN:0148-0227    

DOI:10.1029/JZ064i010p01427

年代:1959

数据来源: WILEY