摘要:

Interactions between radio waves and charged particles change their character when the particles have high average velocities. We investigate the nature of such interactions assuming no collisions, no external magnetic field, and low particle densities. A stream of such particles makes the medium anisotropic. As a result the medium propagates two waves of unchanging (characteristic) polarization, one linearly polarized perpendicular to the particle stream and a second at right angles to the first. Such a medium can change the polarization ellipse of a propagating wave. The sun produces such streams radiating outward either in the form of a steady ‘solar wind’ or in bursts associated with sun spots. Three experiments are suggested to detect the streams by measuring polarization of waves propagated through them. The least sensitive of the three, moon radar, would have measurable effects only during increased solar activity; the other two, transmission to a deep space probe and observation of polarized cosmic noise sources, show effects even during quiet solar conditions. These sensitivities are based on observations of the proton component of the solar w

ISSN:0148-0227    

DOI:10.1029/JZ068i020p05617

年代:1963

数据来源: WILEY

摘要:

The intensity and spectrum of neutrons leaking out of the earth's atmosphere are calculated by a multigroup diffusion code as a function of latitude and solar cycle. The absolute intensity is obtained from normalization of the calculated flux to measured values in the atmosphere. The calculated neutron leakage intensity and spectrum are then compared with rocket and satellite measurements above the atmosphere.

ISSN:0148-0227    

DOI:10.1029/JZ068i020p05633

年代:1963

数据来源: WILEY

摘要:

During part of the ‘Plumbbob’ series of nuclear explosions at the Nevada testing grounds in September 1957, whistler recording equipment was installed and operated by NRL personnel near Fallon, Nevada, about 260 miles north of the explosion area. Whistlers were obtained that proved to be two‐hop whistlers originating in electromagnetic pulses associated with the explosions. It is shown that the probability of a naturally‐excited whistler (from lightning) occurring at the exactly correct times in each case is extremely small. The electromagnetic pulse from the explosion was recorded simultaneously on the whistler recorder in Nevada and on the AWS sferic direction‐finding equipment at Andrews AFB near Washing

ISSN:0148-0227    

DOI:10.1029/JZ068i020p05641

年代:1963

数据来源: WILEY

摘要:

The simultaneous occurrence of whistler‐mode and northscatter echoes monitored at Stanford University has been analyzed. The whistler‐mode studies were made using NPG transmissions (18.6 kc/s) from Jim Creek, Washington, 1200 km north of Stanford. The north‐scatter observations were made using a 12‐Mc/s IGY sounder and a high‐power 23.1‐Mc/s radar. The geometry ofF‐region northscatter is such that the scattering irregularities are in the general latitude region in which the whistler‐mode signals are believed to be propagating. A Pearson correlation coefficient of 93 per cent was found for theF‐region and whistler‐mode echoes. The percentage correlation was calculated on the basis of active or inactive nights, the quality and quantity of data being insufficient to draw significant conclusions about correlations on an hour‐to‐hour basis. The few times for which hourly correlations could be made further substantiate the remarkable coefficient. The important result of this analysis is the direct evidence of meter‐scale field‐aligned irregularities in that part of theFregion through which whistler‐mode signals are believed to have passed. These irregularities may be related to the field‐aligned ducts that have been postulated to ex

ISSN:0148-0227    

DOI:10.1029/JZ068i020p05649

年代:1963

数据来源: WILEY

摘要:

This report describes a test of the reality and practical importance of long distance HF propagation in which multiple successive reflections from theFlayer take place. Such modes are launched and recovered by appropriate tilts. In this test westbound transmissions at various high frequencies from Okinawa were received both in the Mediterranean area and at the island of Guam, 2250 km southeast of Okinawa and very nearly on the same great circle. It is shown that at times when the Okinawa signals were inaudible in Europe they were readily audible at Guam via the long path over a comparatively wide band of frequencies. This result was predicted on the basis of the magnitude and location ofF‐layer tilts present at the time. Since there is strong evidence that the Okinawa‐Guam long‐path signals followed the great circle, it is concluded that they must have passed over the European receiving sites while propagating along the under side of theFlayer in a tilt‐supported mode. The finding supports the hypothesis that around‐the‐world propagation is primarily by successive earth‐ionosphere reflections in the daylight hemisphere, and by ionosphere‐ionosphere reflections in the

ISSN:0148-0227    

DOI:10.1029/JZ068i020p05659

年代:1963

数据来源: WILEY

摘要:

Under conditions thought to be realized during auroral disturbances, the magnetosphere plasma is shown to be unstable to low‐frequency transverse waves that propagate perpendicular to the external field, B0, and have an electric vector parallel to B0. This instability, recently discovered by Krall and Rosenbluth, is generated by positive ions that drift with the phase velocity of the wave. In a dipole field the predominant wave frequency will be the mean bounce frequency for electrons; the wavelength will be of the order of the mean radius of gyration of the positive ions. The mechanism, providing a means of dumping trapped particles out the ends of the flux tubes, suggests an unforced explanation of several heretofore puzzling features of auroras. Observational tests and desirable extensions to the theory are propose

ISSN:0148-0227    

DOI:10.1029/JZ068i020p05667

年代:1963

数据来源: WILEY

摘要:

The spectrum of electron density fluctuations is computed using a collisionless two‐fluid plasma model with isotropic pressure. The major disagreements with kinetic theory are (a) the fluid theory gives sharp lines only, with no Landau broadening, and (b) the gyroresonant structure of the kinetic theory is missing in the fluid theor

ISSN:0148-0227    

DOI:10.1029/JZ068i020p05675

年代:1963

数据来源: WILEY

摘要:

The exact theory of radiative transfer in a Rayleigh atmosphere is used for computing the molecular optical thickness of the Martian atmosphere, as a function of altitude above the planetary surface, for sixteen different wavelengths in five atmospheric models. Surface values vary by a factor of about 3 among the different models, and by a factor of approximately 300 between wavelengths of 2500 A and 10,000 A for a given model. Although the optical thickness of the total Martian atmosphere is up to nearly an order of magnitude less than that of the earth's atmosphere, the less rapid decrease of optical thickness with height for Mars results in a generally greater optical thickness above 10–20 km for Mars than for the earth. By establishing reasonable criteria for the applicability of light‐scattering techniques for atmospheric measurements, we show that such techniques would be useful from the surface to altitudes of 50 to 130 km in the various models at a wavelength of 2500 A, and up to 10 to 20 km at 10,000 A. The corresponding altitudes for the earth's atmosphere are 57 and 15 km, respectiv

ISSN:0148-0227    

DOI:10.1029/JZ068i020p05681

年代:1963

数据来源: WILEY

摘要:

Thirty‐minute simultaneous records of bottom pressure and bottom fluid velocity have been made in 12‐m water depths off Block Island, R. I. Small glass‐enclosed bead thermistors were used in the velocity measurements. Four runs were made with the thermistor at various heights above the sand bottom, ranging from zero to 38cm. These data have been digitized at 1‐sec intervals and analyzed to extract power spectrums and cross spectrums. Both the pressure and the velocity measurements made at a height of 38 cm above the bottom show a typical double‐peak spectrum having maximums at wave periods of 8 and 13 sec. In the peak regions of the spectrum the coherency of the two variables is of the order of 70 to 80 per cent. Quantitatively, the pressure and the velocity power spectrums agree in magnitude to within 30 per cent over the major part of the frequency range. The pressure and the velocity are in phase to within 10° over the major part of the frequency range. Theoretical calculations suggest that at the bottom there is a viscous boundary layer about 0.5 cm thick. Since the thermistor bead is approximately 0.12 cm in diameter, it is capable of resolving a boundary layer of this thickness. Measurements made with the thermistor on the bottom do in fact reveal the presence of such a boundary layer. The operation of the velocity sensor has been checked independently by means of convolution calculations based on the measured botto

ISSN:0148-0227    

DOI:10.1029/JZ068i020p05689

年代:1963

数据来源: WILEY

摘要:

Forty‐eight‐year records of sea level, and other variables, were analyzed for Balboa and Cristobál. It was found that from 1909 to 1962 the sea level has increased by 8.5±1.5 cm at Balboa and 7.1±2.0 cm at Cristobál. No significant trends were found in the climatological records. The increase in sea level at Panama, therefore, is probably due to subsidence of the land. The sea level oscillations at Balboa are similar to those occurring elsewhere along the northwest coast of South America. The rms amplitude of the annual sea level oscillation is 10.5 cm at Balboa and 3.8 cm at Cristobál. The corresponding values of the nonannual sea oscillations are 4.5 cm and 3.3 cm, respectively. The sea level difference, Balboa minus Cristobál, varies from about 8 cm in March to about 33 cm in June, In exceptional spring months the sea level may be higher by a few centimeters on the Caribbean side of the isthmus than on the Pacific side. A spectral analysis of the records in the frequency range between zero and 6 cycles per year showed significant peaks corresponding to the annual and semiannual cycles. An interesting peak suggesting a 4‐year oscillation was found in the atmospheric pressure spectrums, but not elsewhere. At Balboa, there is a strong and direct relation between oscillations of sea level and sea surface

ISSN:0148-0227    

DOI:10.1029/JZ068i020p05701

年代:1963

数据来源: WILEY