摘要:

This paper is concerned with the solution of the coupled wave equations which arise in the application of the wave theory to the problem of ionospheric wave propagation. It concerns an extension of previous work [see 1 of “References” at end of paper], which will henceforth be referred to as [1]. The method of “variation of parameters” is used to obtain approximate solutions to the coupled equation from the uncoupled solutions obtained in [1].A diurnal and seasonal model representing theE‐region of the ionosphere above State College, Pennsylvania, is considered. This model, as in [1], consists of a Chapman‐likeE‐region whose maximum in electron density is at a constant height. Approximate 150 kc/sec wave solutions including coupling are obtained for this model. These wave solutions, of course, exhibit the well‐known reflection condition corresponding to an electron density of around 3,000 electrons/cm3.It is shown that the effect of the coupling is to cause a wave traversing a coupling region to excite a new wave propagated in the direction of propagation of the incident wave and also a back‐scattered wave propagated in the reverse direction. As indicated below, these coupling effects become important in our model below the “reflection” level. The back‐scattered wave due to the initial upgoing wave will thus appear as a reflected wave originating in the coupling region. The forward‐scattered wave due to the down‐going wave from the upper “reflection” level also must be considered, particularly in calculating the polarization of ionospherically reflected waves.It is shown that, in the case of 150 kc/sec waves, the coupling effects occur in the neighborhood ofN= 300 electrons/cm3, which corresponds to the “classical reflection” level for the “ordinary” wave. The coupling effects become greater as the collisional frequency, ν, associated with the couplingNvalue decreased toward the critical collisional frequency, νc[2], for the night‐time models due to the increase in heights of the “bottom” of the layer at these times. This results in stronger split echoes and greater departure from circularity in the polarization ellipses.The results of computations utilizing the theory, in comparison with experimental results, indicate that the stratification observed in the height records may be explained as outlined above. The absorption and polarization experimental results, however, cannot be accounted for by theE‐region model utilized alone. The consideration of an electronicD‐region, however, readily accounts for all three experimental facto

ISSN:0148-0227    

DOI:10.1029/JZ057i003p00323

年代:1952

数据来源: WILEY

摘要:

We have data of magnetic observations at Colaba, Bombay, from 1846 to 1905, and at Alibag, 18 miles to the south, from 1904 onward, with two years of comparative observations during 1904 and 1905. Moos had studied in 1910 the secular variations of the magnetic field with data up to 1905. In view of the changes in the magnetic field and the very large amount of data collected since, a further study was undertaken.The value ofHhas been increasing continuously since 1916, and it is likely that the increase will continue at least for some more years. The westward drift of declination commenced, from 1879 and is still continuing. The rate of drift, however, has decreased during the last five years, and within the next few years it may begin to return eastward or move westward at an increased rate. The vertical force had been continuously increasing from 1853 and it reached its maximum value in 1937, after which there was a fall for some years, but the falling tendency appears to have been arrested and the vertical force may again begin to increase. During the first six solar cycles, the average values ofH, ΔH, and Δ′Hare greater during sunspot minimum years than during sunspot maximum years, but this does not hold during the last three cycles. No periodicity of about 11 years was apparent in the curves representing the differences between the observed and calculated values ofH,D, andVor in the curves representing ΔH, Δ′H, ΔD, Δ′D, ΔV, and Δ′V, and no parallelism was noticeable between these curves and th

ISSN:0148-0227    

DOI:10.1029/JZ057i003p00339

年代:1952

数据来源: WILEY

摘要:

A procedure is given for the determination of the “true height of reflection” of a radio wave incident vertically on the ionosphere. Since—for a given operating frequency—the electron density required for reflection is easily found, the present procedure allows the electron density to be determined as a function of height. To find the “true height” at some particular frequency, ƒv, it is only necessary to take the average of the values of group height measured at a set of predetermined frequencies. These frequencies depend on ƒvand the accuracy desired in the results. In scaling‐ standard experimental curves for this work, it was sufficient to use five values, except near cusps or steps where double that number was found desirable.The present method is based on the use of the Gauss‐Christoffel quadrature formula, which is used for the numerical integration of the well‐known integral for “true height” as a function of group height. The restrictions on this integral apply to all of the work contained here and are: (1) The earth's magnetic field is neglected; (2) the effects of collisions are neglected; (3) it is assumed that ray theory may be used; (4) it is assumed that the curve of electron density as a function of height has no maxima or minima i

ISSN:0148-0227    

DOI:10.1029/JZ057i003p00357

年代:1952

数据来源: WILEY

摘要:

The monthly mean critical frequencies of theEandF1 layers at high latitudes are shown to vary diurnally with solar angle according to a modified Chapman law. The seasonal, latitude, and solar‐cycle dependence of theE‐layer sensitivity to solar angle and the sub‐solar frequency are measured.In the auroral zone, the sensitivity of theElayer to solar angle is shown to be very low, but to the north of the zone it is found to have the theoretical Chapman

ISSN:0148-0227    

DOI:10.1029/JZ057i003p00369

年代:1952

数据来源: WILEY

摘要:

The study of meteoric echoes is greatly facilitated by the use of a twin‐channel Doppler presentation, by means of which both the amplitude and phase of the returned signal may be determined independently. Such a “double‐Doppler” system has direct application to the verification of the mechanism of meteor‐whistle formation, to the determination of the motion of ionization trails drifting under the influence of upper air winds, and to spectrum analysis of those echoes which exhibit amplitude fading. Examples of the application of the double‐Doppler technique to these problems ar

ISSN:0148-0227    

DOI:10.1029/JZ057i003p00387

年代:1952

数据来源: WILEY

摘要:

A linear relation between the electrical current through a gaseous conductor in a magnetic field and the diffusion currents of the charge bearing particles is deduced from the kinetic theory of diffusion. For conduction by positive ions and electrons, a magnetic field does not alter the diffusion currents parallel to the electrical current, but does move the ions and electrons together transversely to the electrical current and to the magnetic field. The presence of additional negative ions can enhance transverse electronic diffusion and causes new components of the diffusion currents to appear along the magnetic lines of force. By this linear relation, the vertical lunar displacements of theE‐layer are derived from the lunar current system in the ionosphere. The derived amplitudes and phases can account for the observed motions on the hypotheses that the main lunar current flows in the lower part of theE‐layer and that approximately equal numbers of negative ions and electrons are present at the point of observat

ISSN:0148-0227    

DOI:10.1029/JZ057i003p00405

年代:1952

数据来源: WILEY

ISSN:0148-0227    

DOI:10.1029/JZ057i003p00413

年代:1952

数据来源: WILEY

ISSN:0148-0227    

DOI:10.1029/JZ057i003p00416

年代:1952

数据来源: WILEY

ISSN:0148-0227    

DOI:10.1029/JZ057i003p00419-02

年代:1952

数据来源: WILEY

ISSN:0148-0227    

DOI:10.1029/JZ057i003p00420

年代:1952

数据来源: WILEY