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.

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.

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.

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

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 Preliminary Results on Irradiance Measurements from Lyra and Swap

2012 ◽  
Vol 2012 ◽  
pp. 1-5 ◽  
Author(s):  
S. T. Kumara ◽  
R. Kariyappa ◽  
M. Dominique ◽  
D. Berghmans ◽  
L. Damé ◽  
...  
Keyword(s):  
High Temporal Resolution ◽  
Preliminary Results ◽  
Spatially Resolved ◽  
Large Yield ◽  
Active Pixel ◽  
Integrated Intensity ◽  
Actual Contribution ◽  
The Individual ◽  
Aluminum Filter ◽  
Full Disk

The first and preliminary results of the photometry of Large Yield Radiometer (LYRA) and Sun Watcher using Active Pixel system detector and Image Processing (SWAP) onboard PROBA2 are presented in this paper. To study the day-to-day variations of LYRA irradiance, we have compared the LYRA irradiance values (observed Sun as a star) measured in Aluminum filter channel (171 Å–500 Å) with spatially resolved full-disk integrated intensity values measured with SWAP (174 Å) and Ca II K 1 Å index values (ground-based observations from NSO/Sac Peak) for the period from 01 April 2010 to 15 Mar 2011. We found that there is a good correlation between these parameters. This indicates that the spatial resolution of SWAP complements the high temporal resolution of LYRA. Hence SWAP can be considered as an additional radiometric channel. Also the K emission index is the integrated intensity (or flux) over a 1 Å band centered on the K line and is proportional to the total emission from the chromosphere; this comparison clearly explains that the LYRA irradiance variations are due to the various magnetic features, which are contributing significantly. In addition to this we have made an attempt to segregate coronal features from full-disk SWAP images. This will help to understand and determine the actual contribution of the individual coronal feature to LYRA irradiance variations.

scholarly journals Observations on the increase in size at moulting in the lobster (Homarus vulgaris M.-Edw.)

1958 ◽  
Vol 37 (3) ◽  
pp. 603-606 ◽  
Author(s):  
H. J. Thomas
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Growth Increment ◽  
American Lobster ◽  
Limited Data ◽  
Preliminary Results ◽  
Home Department ◽  
The Individual ◽  
Marine Laboratory

A knowledge of growth rates is a pre-requisite in estimating the effect of fishing upon the available stocks. In Crustacea, where there is no known means of establishing accurately the age of the individual, the importance of measuring the growth rate is increased whilst its determination is made more difficult. In Homarus vulgaris some experiments were undertaken by Dannevig (1936), and Wilder (1953) gives considerable data for the American lobster. Results suggest that the growth increment is not uniform in all latitudes. Experiments to augment the limited data available for H. vulgaris and to establish the increase in size at moulting in local lobster stocks were therefore undertaken by the Marine Laboratory of the Scottish Home Department at Aberdeen. A statement of some preliminary results was given in Report on the Fisheries of Scotland (Lucas, 1957, p. 58).

scholarly journals Dissociation, recombination and attachment processes in the upper atmosphere—I

1937 ◽  
Vol 163 (915) ◽  
pp. 542-553 ◽  
Keyword(s):  
Reaction Rates ◽  
Upper Atmosphere ◽  
Radio Waves ◽  
Ionization Density ◽  
Pressure Discharge ◽  
Mechanical Methods ◽  
Order Of Magnitude ◽  
Quantitative Manner ◽  
The Individual ◽  
Atmospheric Ionization

The study of the properties of the earth’s upper atmosphere has now progressed so far as to provide what should be a sufficient basis for the development of a detailed theory. Since the state of the upper atmosphere approximates closely to that of the gas in a low-pressure discharge tube (except for the absence of solid boundaries), it is clear that such a theory must deal with the individual collision processes which can occur in such a system. Until the last few years no satisfactory theory of these phenomena was available, but it is now possible to apply quantum mechanical methods with reasonable expectation of results accurate at least as regards order of magnitude. We therefore propose to make use of these methods to obtain a deeper understanding of the physics of the ionosphere. In this paper we confine ourselves particularly to the qualitative study of certain problems associated with the two upper ionized layers (the E and F regions), making use of information already available concerning the probabilities of the various collision reactions which are important. The detailed evaluation of these reaction rates is being carried out, and in later papers it is hoped to deal with the various problems in a more nearly quantitative manner. The two main strata of atmospheric ionization are the E region extending roughly from 120 to 160 km. and the F region from 180 to 300 km., at night. During the day each splits into two distinct strata forming the E 1 and E 2 and the F 1 and F 2 regions. The ionization density in each region, as determined from experiments with radio waves, exhibits characteristic annual and diurnal variations besides irregular variations of considerable magnitude. The first problem which arises is the reason for the existence of the stratification. This being understood it is then necessary to account for the observed variations of density, the daytime splitting of the layers, and so on.

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