摘要:

A pulse‐propagation experiment was performed between Sterling, Virginia, and Maui, Territory of Hawaii, with the object of studying the mechanism determining the classical MUF at long distances, and also of obtaining a general idea of the mode structure. Simultaneous oblique‐incidence records of the transmitter pulses were made at Boulder, Colorado, which lies along the path. Some backscatter records were obtained at the transmitter site; and vertical‐incidence records were made at the midpoint of the Sterling to Boulder portion of the path.Results showed greatly differing mode structures between one day and the next, indicating that the long path is very sensitive to ionospheric conditions, and also thatMandNreflection and layer tilts play an important part. Experimental evidence was strong that sporadic‐Eionization enables the propagation of a wave over the path whereF2 ionization at one end of the path is not sufficient for ref

ISSN:0148-0227    

DOI:10.1029/JZ063i003p00445

年代:1958

数据来源: WILEY

摘要:

A magnetometer was operated in conjunction with the Super‐Schmidt cameras of the Harvard Meteor Project. No magnetic pulses were detected from meteors with visual magnitudes between +5 and −3. The minimum signal detectable with the equipment was 5×10−2gamma in the first series of measurements, and was subsequently reduced to 3×10−3gamma. This result is in direct contradiction with the work of A. G. Kalashnikov, and reasons for the discrepancy are

ISSN:0148-0227    

DOI:10.1029/JZ063i003p00467

年代:1958

数据来源: WILEY

摘要:

Various studies on the interaction between charged particles and the geomagnetic field indicate the existence of a source of magnetism located above the earth's surface. It is likely that for the near future, magnetic studies connected with the external source and with upper‐air magnetic properties in general, will be conducted primarily with magnetometers measuring only the magnitude of the intensity, not its direction. With this type of data, the customary methods of analysis are not applicable.An appropriate analytic method is treated which utilizes a series for the square of the scalar magnetic intensity. The terms of this series are obtained through the use of the series of spherical harmonics generally applied to each component of the intensity. Through an analysis of scalar intensity alone, the method yields the magnetic characteristics that are normally obtainable through a spherical harmonic analysis of the vector magnetic intensity. Also, the variation with altitude of the magnetic equator is treated in conjunction with the location of the equator for cosmic ray

ISSN:0148-0227    

DOI:10.1029/JZ063i003p00477

年代:1958

数据来源: WILEY

摘要:

Jackson's method of computing electron density distributions fromh′frecords has been modified slightly and adapted for use on an electronic computer. Reduction of a singleh′frecord takes about 20 seconds of computer time.The method makes allowance for the geomagnetic field and is exact save for the uncertainty about the electron density between ionospheric layers which is inherent in the method of pulse sounding from the ground. Rocket measurements (Seddon,et al., 1954) enable a reasonable resolution of this uncertainty.Some examples of electron density distribution at Brisbane are given. It is shown that the night‐time distributions are much closer to the Chapman than the parabolic form. This is to be expected (Martyn, 1956) in a region in which the electron distribution is determined by the opposing processes of downward diffusion under gravity, and a height gradient of electron decay. The effect of geomagnetic disturbance on the day and night electron density profile is illustrated and disc

ISSN:0148-0227    

DOI:10.1029/JZ063i003p00491

年代:1958

数据来源: WILEY

摘要:

New evidence is presented which shows that VHF radio echoes from auroral ionization are reflections from aspect‐sensitive columns aligned with the earth's magnetic field. Previous experimental data, interpreted in terms of a distribution of ionization along a line of magnetic latitude, are shown to be consistent with this hypothesi

ISSN:0148-0227    

DOI:10.1029/JZ063i003p00501

年代:1958

数据来源: WILEY

摘要:

Arguments are made for the existence above the ionosphere of very large amplitude hydromagnetic waves. Crude estimates show that it is not unreasonable to expect hydromagnetic waves above the ionosphere to have an amplitude of the order of 102times the amplitude of geomagnetic fluctuations observed at the surface of the earth. It is suggested that these hydromagnetic waves produce the irregularities in electron density which are responsible for radio‐star scintillation. It is also suggested that the large amplitude hydromagnetic waves are responsible for producing the high intensity particle radiation observed above about 1,000 km by Van Allen,et a

ISSN:0148-0227    

DOI:10.1029/JZ063i003p00507

年代:1958

数据来源: WILEY

摘要:

An instrument which uses “optical pumping” techniques to measure the earth's magnetic field has been constructed at the Fredericksburg Magnetic Observatory (USG&GS). Absolute values of the field were measured and compared with values obtained from the magnetograph records of the observat

ISSN:0148-0227    

DOI:10.1029/JZ063i003p00513

年代:1958

数据来源: WILEY

摘要:

Investigation of the aurora australis at a radio frequency of 69 Mc/s is reported. A value for the range exponent in the radar equation has been determined and values of the reflection coeficient deduced. Mechanisms of auroral reflection of radio waves are discussed, and only those involving column models are found to be substantiated. Noise emission from auroral ionisation has been observed and measured at 69 Mc/s.

ISSN:0148-0227    

DOI:10.1029/JZ063i003p00517

年代:1958

数据来源: WILEY

摘要:

In determining the direction of arrival of atmospherics by using a “crossed”‐loop cathode‐ray tube direction‐finder, it was found that, on occasions, in addition to the usual straight‐line responses on the oscillographic screen, there were elliptic patterns of gradually decreasing eccentricity, size, and tilt‐angle. The observed elliptic patterns are considered as due to the abnormal polarization of the atmospheric pulses reflected successively from the ionosphere, while the linear responses are due to the direct atmospheric pulses. It has been shown in the paper how from the observed polarization ellipses and the orientation of the linear response, the polarization characteristics of the atmospheric pulses reflected successively from the ionosphere can be determined. On analysing the observed patterns, it is found that, in general, the phase‐difference between the normal and abnormal components increases gradually with the increasing order of reflection. It is suggested that the observed straight lines in theD/Fpattern, bunched within a small angle, are due to the radiation pulses orginating at the branching points of a long horizontal or slightly inclined lightning channel from one cloud to another. The approximate calculation from the observed angular width of the bunch of straight lines has shown that the horizontal length of the channel is consistent with Shipley's observations of horizontal lightning channels along the lower

ISSN:0148-0227    

DOI:10.1029/JZ063i003p00527

年代:1958

数据来源: WILEY

摘要:

The electron‐ion recombination coefficient αeiin ionized nitrogen gas is investigated as to its variation with pressure (0.2 to 2 mm Hg) and electron temperature (92°K to 300°K) corresponding to various low electron energies. At 1.3 mm Hg, αeivaries from about 8.5×10−7cm3/sec at 300°K to 6.7×10−6cm3/sec at 92°K, almost an order of magnitude difference. Discussion of the possible modes of recombination in a nitrogen gas plasma is given and dissociative recombination is found to be the most probable means of electron loss. Microwave transmission methods were used

ISSN:0148-0227    

DOI:10.1029/JZ063i003p00539

年代:1958

数据来源: WILEY