A THEORETICAL RATE–AMPLITUDE RELATION IN METEORIC FORWARD-SCATTERING

1958 ◽  
Vol 36 (5) ◽  
pp. 539-554 ◽  
Author(s):  
C. O. Hines
Keyword(s):  
Observational Data ◽  
Forward Scattering ◽  
Occurrence Rate ◽  
Radio Waves ◽  
Scaling Factors ◽  
Meteor Trails ◽  
Amplitude Level ◽  
Good Agreement

The theory of the forward-scattering of radio waves by ionized meteor trails is applied to the development of a rate-amplitude relation. This relation expresses the anticipated occurrence rate of scattered signals which exceed a chosen amplitude level, as a function of that level. It is compared with preliminary observational data, and found to be in good agreement both qualitatively and quantitatively. Closest agreement is obtained only with an appropriate choice of two scaling factors. These provide an abstract of the observations in a form which is convenient for further study and interpretation.

DIURNAL VARIATIONS IN THE NUMBER OF SHOWER METEORS DETECTED BY THE FORWARD-SCATTERING OF RADIO WAVES: PART I. THEORY

1955 ◽  
Vol 33 (9) ◽  
pp. 493-503 ◽  
Author(s):  
C. O. Hines
Keyword(s):  
Diurnal Variation ◽  
Incidence Rate ◽  
Forward Scattering ◽  
Diurnal Variations ◽  
Time Interval ◽  
Weight Factor ◽  
Radio Waves ◽  
Meteor Trails

Various observational factors affect the number of shower meteors which can be detected, in a given time interval, by the scattering of radio waves from the ionized meteor trails. The pertinent factors in the case of forward-scattering, where the transmitter and receiver are widely separated, are expressed approximately as functions of the position of the shower radiant. In combination, they provide an observational weight factor which may change appreciably as the radiant moves in the course of a day. The consequent diurnal variation in the occurrence of scattered signals may then be determined, and distinguished from variations due to random changes in the incidence rate of the meteors.

THE FORWARD-SCATTERING OF RADIO WAVES FROM OVERDENSE METEOR TRAILS

1957 ◽  
Vol 35 (9) ◽  
pp. 1033-1041 ◽  
Author(s):  
C. O. Hines ◽  
P. A. Forsyth
Keyword(s):  
Charge Density ◽  
Forward Scattering ◽  
Point Of View ◽  
Radio Waves ◽  
Geometric Factors ◽  
Meteor Trails

The forward-scattering of radio waves from overdense meteor trails is treated from an elementary point of view. The results indicate that the same geometric factors enter this problem as enter the problem of forward-scattering from underdense trails, and that the transition between underdense and overdense trails occurs at the same value of charge density as in the backscatter case. These conclusions are not expected to be generally valid when applied to individual trails, but at least they should provide a valid basis for the interpretation and prediction of the effects produced statistically by a large number of trails.

THE NUMBER DENSITY OF METEOR TRAILS OBSERVABLE BY THE FORWARD-SCATTERING OF RADIO WAVES

1956 ◽  
Vol 34 (10) ◽  
pp. 997-1004 ◽  
Author(s):  
Robert E. Pugh
Keyword(s):  
Forward Scattering ◽  
Radio Waves ◽  
Number Density ◽  
Meteor Trails

The number of meteor trails which can be detected by the forward-scattering of radio waves varies with the region of the sky under observation. The number density is determined theoretically, as a function of position relative to the transmitter and receiver.

FORWARD-SCATTERING OF RADIO WAVES BY METEOR TRAILS

1955 ◽  
Vol 33 (5) ◽  
pp. 176-188 ◽  
Author(s):  
P. A. Forsyth ◽  
E. L. Vogan
Keyword(s):  
Forward Scattering ◽  
Radio Waves ◽  
Preliminary Results ◽  
Meteor Trails ◽  
The Individual

Radio waves which are too high in frequency to be reflected by the ionospheric layers are often reflected back to the earth's surface by the ionization in meteor trails, and may be detected at distances of the order of 1000 kilometers from the transmitting station. These forward-scattered signals have been studied by the use of several transmission paths in Canada. The paper summarizes the characteristics of the individual signals and presents some preliminary results of the investigation. It seems likely that the technique will prove to be useful in meteoric studies.

HEIGHT-GAIN IN THE FORWARD-SCATTERING OF RADIO WAVES BY METEOR TRAILS

1957 ◽  
Vol 35 (1) ◽  
pp. 125-127 ◽  
Author(s):  
C. O. Hines ◽  
M. O'Grady
Keyword(s):  
Forward Scattering ◽  
Radio Waves ◽  
Height Gain ◽  
Meteor Trails

DIURNAL VARIATIONS IN THE NUMBER OF SHOWER METEORS DETECTED BY THE FORWARD-SCATTERING OF RADIO WAVES: PART II. EXPERIMENT

1955 ◽  
Vol 33 (10) ◽  
pp. 600-606 ◽  
Author(s):  
P. A. Forsyth ◽  
C. O. Hines ◽  
E. L. Vogan
Keyword(s):  
Specular Reflection ◽  
Forward Scattering ◽  
Diurnal Variations ◽  
Radio Waves ◽  
Forward Scatter ◽  
Transmission Path ◽  
Signal Rate ◽  
Cedar Rapids ◽  
Good Agreement

The theory developed in Part I is applied to derive the expected diurnal variations of the meteor signal rate for four showers as observed by means of a particular forward-scatter transmission path (Cedar Rapids – Ottawa). These results are then compared with the experimental signal rates. The good agreement obtained indicates that the approximations inherent in the theory are sufficiently accurate for practical purposes. The results also indicate that very few meteors, if any, are observed under conditions which do not satisfy the requirements for specular reflection.

Analysis of meteor trails providing combined forward and backward scattering of radio waves

2021 ◽  
Vol 195 ◽  
pp. 105135
Author(s):  
I. Lapshina ◽  
S. Kalabanov ◽  
A. Karpov ◽  
A. Sulimov
Keyword(s):  
Radio Waves ◽  
Meteor Trails

scholarly journals <i>Letter to the Editor</i> Why do ultra-low-frequency MHD oscillations with a discrete spectrum exist in the magnetosphere?

2005 ◽  
Vol 23 (3) ◽  
pp. 1075-1079 ◽  
Author(s):  
A. S. Leonovich ◽  
V. A. Mazur
Keyword(s):  
Discrete Spectrum ◽  
Observational Data ◽  
High Latitude ◽  
Plasma Sheet ◽  
Low Frequency ◽  
Magnetosonic Wave ◽  
Letter To The Editor ◽  
Morning Sector ◽  
Good Agreement

Abstract. A new concept of the global magnetospheric resonator is suggested for fast magnetosonic waves in which the role of the resonator is played by the near-Earth part of the plasma sheet. It is shown that the magnetosonic wave is confined in this region of the magnetosphere within its boundaries. The representative value of the resonator's eigenfrequency estimated at f~1MHz is in good agreement with observational data of ultra-low-frequency MHD oscillations of the magnetosphere with a discrete spectrum (f~0.8, 1.3, 1.9, 2.6...MHz). The theory explains the ground-based localization of the oscillations observed in the midnight-morning sector of the high-latitude magnetosphere.

scholarly journals On the Deterioration of a Grounded Iceberg

1986 ◽  
Vol 32 (111) ◽  
pp. 161-167
Author(s):  
S. Venkatesh
Keyword(s):  
Observational Data ◽  
Water Volume ◽  
Ocean Bottom ◽  
Model Simulations ◽  
Seaward Side ◽  
Mass Losses ◽  
Wave Erosion ◽  
S Model ◽  
Simulated Time ◽  
Good Agreement

AbstractThis paper examines the deterioration of an iceberg grounded outside St. John’s Harbour, Newfoundland, Canada, in terms of its initial velocity prior to grounding. Theoretical expressions for the lifting of the iceberg and hence its buoyancy loss during grounding are derived as a function of initial iceberg velocity and ocean-bottom slope. Wave erosion and calving are two of the most significant mechanisms for iceberg deterioration. With wave erosion occurring on the seaward side of the grounded iceberg, model simulations are compared with observational data from a field study conducted on the grounded iceberg between 10 and 17 June 1983. Model–simulated time of re-flotation of the iceberg agrees with observations, for initial iceberg velocity of 0.3–0.5 m/s. Model simulations of the deterioration of the iceberg beyond the point of re-flotation are also compared with observations. Allowing for a 10% error in the observed above-water volume of the iceberg on 10 June, the model-simulated mass losses are in good agreement with observations. Best results are obtained for the model initialized with data observed on 14 June 1983, the first day for which detailed observational data are available following re-flotation of the iceberg.

Hydrogen Atmospheres in the Absence of Thermodynamic Equilibrium. IV. The Solar Chromosphere

1948 ◽  
Vol 1 (4) ◽  
pp. 360
Author(s):  
RG Giovanelli
Keyword(s):  
Observational Data ◽  
Density Gradient ◽  
Electron Concentration ◽  
Hydrostatic Equilibrium ◽  
Profile Measurement ◽  
Solar Chromosphere ◽  
Hydrogen Atoms ◽  
Lower Accuracy ◽  
Good Agreement ◽  
Lower Chromosphere

A discussion of the observational data shows that in the range 0<z<2.5 x 108 cm. the electron concentration in the lower chromosphere may be expressed as Ne=5x 1011 exp(-6 x 10-9z) per cc., where z cm. is the height measured from a level 500 km. above the base of the chromosphere. It is shown that above the 500-km. level hydrogen atoms are almost completely ionized, and that with hydrostatic equilibrium the observed density gradient corresponds to a temperature of 2.7 X 104 �K . This is in good agreement with the temperature derived by Redman from line profile measurement, so that the lower chromosphere appears to be effectively in thermal and hydrostatic equilibrium. Estimates of lower accuracy are given for the electron concentrations at some higher levels in the chromosphere. A discussion is given of the mechanism of absorption of Hα radiation by a chromosphere whose temperature is well above that of the photosphere.

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