摘要:

The motion of energetic, charged particles trapped in the geomagnetic field is reviewed, and the methods of calculating the effect of the ambient atmosphere on trapped electrons and protons are presented. The results of these theoretical considerations are compared with the available experimental data to determine the spatial regions where collisions of the trapped particles with atmospheric constituents govern the long‐term behavior of the particles. It is concluded that during periods of minimum solar activity atmospheric collisions are the most important loss mechanism for electrons in the regionL⪝ 1.25, whereLis McIlwain's magnetic shell parameter. Above this region the behavior of electrons is controlled by other, at present unknown, forces. For protons, it appears that the atmosphere controls the loss rate for the spatial regionL⪝ 1.4, although the evidence for this conclusion must be considered tentative at pr

ISSN:8755-1209    

DOI:10.1029/RG002i004p00543

年代:1964

数据来源: WILEY

摘要:

The great improvements in power and sensitivity of radar plus the development of more refined and elaborate data analyses have made it possible to obtain a variety of information about the planets. Measurements now include not only simple range by time delay; velocity by Doppler shift; and radar cross section by power returned; but also the roughness of the planetary surface and its variation from place to place through the shape of the reflected spectrum and the extent of double reflection of circularly polarized signals; the axis and rate of rotation of the planet by Doppler broadening, tracking of spectral features, and other techniques; and the mapping of the planet surface by range‐gated (i.e. location by coupling range and velocity) spectrums. The principal results obtained have been a greatly improved value of the astronomical unit; a period of rotation of Venus of about 250 ± 50 days retrograde; a surface variability and roughness of Venus comparable with that of the moon; a very smooth surface on Mars; a somewhat rougher surface on Mercury; the existence of one shiny spot 1000 or more miles wide on Jupiter; and negligible effects from planetary ionospheres and the interplanetary medi

ISSN:8755-1209    

DOI:10.1029/RG002i004p00579

年代:1964

数据来源: WILEY

摘要:

The governing equations for the steady two‐dimensional mountain wave problem are presented with both heightzand entropysas vertical coordinates. Some intrinsic advantages of usingsare discussed. A formal scaling of the equations for a wide mountain is shown. Some of the classical problems in isothermal atmospheres and multilayer models are reviewed. A discussion of the time‐dependent linear problem is presented as a problem of wave motion on an interface. The final part of the paper contains a brief review of the recent numerical work on the steady two‐dimensional problem. Some suggestions for further work in theoretical and numerical finite amplitude problems are

ISSN:8755-1209    

DOI:10.1029/RG002i004p00593

年代:1964

数据来源: WILEY

摘要:

Dissipation of tidal energy in the earth's mantle and the moon was calculated assuming a dissipation factor 1/Qconstant throughout both bodies. In the mantle the dissipation varies from about 2 × 10−6/Qerg cm−3sec−1near the pole at the bottom of the mantle to about 0.02 × 10−6/Qerg cm−3sec−1near the surface. The effects of compressibility and inhomogeneity are less than 3%. In a homogeneous moon the dissipation varies from a maximum of about 0.03 × 10−6/Qerg cm−3sec−1near the center to a minimum of about 0.4 × 10−9/Qerg cm−3sec−1at the surface. A theory of orbital evolution is developed in which the disturbing function is expressed in a Fourier series with respect to time, so that the effects of variation of dissipation factor 1/Q, or lag angle ϵ, with amplitude and frequency can be examined. Comparisons with resul

ISSN:8755-1209    

DOI:10.1029/RG002i004p00661

年代:1964

数据来源: WILEY