摘要:

Using a shielded Geiger tube in the Explorer 7 satellite a comprehensive geographic survey of the intensity of charged particles in the latitude range ±50.5°, in the altitude range 550 to 1100 km, and over the 16‐month period October 13, 1959, to February 17, 1961, has been conducted. It has been found possible to identify and eliminate contributions by geomagnetically trapped particles and thus to obtain the sum of the absolute intensities of primary galactic cosmic rays and of their charged‐particle secondaries (albedo) produced in the atmosphere. Specific results are as follows: (1) The counting‐rate data from both northern and southern hemispheres and over a considerable range of longitudes are represented in a simple and coherent manner as a function of a single parameter, the Mcllwain magnetic shell parameterL. (2) The counting rate increases monotonically with increasingLand has an accurately constant value forL>2.9. (3) The high‐latitude knee of the counting rate versusLcurve occurs atL= 2.6 (corresponding to the invariant latitude 52°) and is indiscernibly different in the northern and southern hemispheres. (4) The absolute omnidirectional intensity is 0.56 (cm2sec)−1at the equator and 2.0 (cm2sec)−1at high latitudes, the ratio being 3.6. (5) At high latitudes the intensity increases by the factor 1.046±0.045 during the 16‐rnonth period. (6) In terms of the Quenby‐Wenk vertical cutoff rigidityR, in billion volts, the total omnidirectional intensityJ0(>R) = 4.3R−0.83±0.02(cm2sec)−1for 3

ISSN:0148-0227    

DOI:10.1029/JZ068i017p04885

年代:1963

数据来源: WILEY

摘要:

Various measurements of the intensity of radiation within the inner Van Allen belt have indicated little possibility that the equatorial magnetic field of the belt should exceed 0.5 γ. The 12‐year means of geomagnetic disturbance data show an equatorial latitude variation, which could arise from a transient equatorial ring current at a height within the outer reaches of the inner belt. This small transient equatorial ring current may be introduced to‐ suitable equatorial heights by downward expansion of a higher ring current present during magnetic storms. This possibility would be susceptible of experimental check. Another possibility is increased westward current flow within the equatorial ionosphere or enhanced compression of the equatorial magnetosphere during storm

ISSN:0148-0227    

DOI:10.1029/JZ068i017p04897

年代:1963

数据来源: WILEY

摘要:

Quasi‐periodic variations of the energy speetrum of auroral zone X rays have been observed during a balloon flight from Andenes in northern Norway. Several bursts of electron bremsstrahlung were recorded during that flight. By comparing the counting rates of two Geiger counters with different energy responses, we found that the X‐ray spectrum frequently varied in a nearly periodic manner with periods from 4 to 7 minutes. No corresponding variations of the X‐ray intensity itself were observed. It is suggested that the observed spectral variations may have been caused by hydromagnetic waves in the magnetosphere, through a violation of the third adiabatic inva

ISSN:0148-0227    

DOI:10.1029/JZ068i017p04909

年代:1963

数据来源: WILEY

摘要:

Measurements of the effects of the ionosphere on the polarization and the Doppler shift of radio transmissions from earth satellites permit the electron content of the ionosphere to be calculated. Thirty‐five passages of Transit 2A have been analyzed in a variety of ways to estimate the accuracy of the several methods. The most accurate method is a hybrid analysis using both Faraday and Doppler data simultaneously. Methods based on the rate of polarization rotation, on the number of rotations between two times, and on best‐fitting polynomials to either the Faraday or the Doppler data are compared and their errors estima

ISSN:0148-0227    

DOI:10.1029/JZ068i017p04917

年代:1963

数据来源: WILEY

摘要:

Estimates of the meteoroid penetration of vehicles in space are improved from the author's 1957 values. The meteoritic data are improved by the measurement of luminous efficiency in the artificial meteor experiment of Trailblazer 1 analyzed by McCrosky and Soberman, and by independent determinations from three asteroidal meteors by Cook, Jaechia, and McCrosky. A review of the photographic meteor data leads to an adopted meteoroid density of 0.44 g cm−3and a mass of 1.0 gram for a zero‐magnitude visual meteor of velocity 30 km sec−1. Hawkins and Upton's influx rate of visual meteors is utilized after correction for the zero‐magnitude mass. A mean velocity of 22 km sec−1is adopted. The formula by Herrmann and Jones from their summary of hypervelocity impact experiments provides the penetration of a low‐density body against a semi‐infinite target. The ratio of perforation thicloiess for a thin target to the penetration in a semi‐infinite target is adopted as 1.5. The calculated perforation rate on a 0.1‐cm‐thick plate of aluminum in the earth's neighborhood is reduced by a factor of more than 3000 from the 1957 estimate. The change logarithmically is divided about equally between the changes in meteoroid data and in the impact formula. The present calculations are still subject to considerable uncertainty and can be greatly improved by further research in both the areas of radar‐meteors and hypervelocity experiments at velocities exceeding 20 km sec−1. Possibly an unobserved, large flux rate in the mass range

ISSN:0148-0227    

DOI:10.1029/JZ068i017p04929

年代:1963

数据来源: WILEY

摘要:

By considering the boundary conditions at the surface of a thunderstorm cloud, it can be shown that most descriptions of the charge configuration found in these storms are compatible with relatively high electrical conductivity within the cell. The problem is formulated by having a vertical column of current carry positive charge upward and deposit this charge in a spherical region of space. The only electrodynamic quantity not included in the analysis is the time variation of the magnetic field. The solutions are then studied in terms of spatial variations in the electrical conductivity. It is concluded that observations made on active thunderstorms agree best with a situation in which a relatively high electrical conductivity is developed within the cloud.

ISSN:0148-0227    

DOI:10.1029/JZ068i017p04941

年代:1963

数据来源: WILEY

摘要:

Using a spherical finite‐difference grid system covering the hemisphere, numerical solutions of the nondivergent barotropic vorticity equation have been obtained for periods of up to 10 days by relaxation methods. If initial conditions are analytic, the solutions are sensitive to abrupt changes of the longitudinal mesh size in the regions of appreciable amplitude of the stream‐function tendency. A doubling of the longitudinal mesh size from 5° to 10° at 45°N produces a progressive tearing or shearing in the stream function which is quite noticeable at 10 days. When this grid variation is moved to 70°N, however, the solutions at 10 days are free of this defect, although they exhibit the expected phase lag relative to the analytic solution. When applied to hemispherical barotropic prediction with actual 500‐mb data, this spherical grid scheme appears to perform as satisfactorily as conventional (rectangular) grid for

ISSN:0148-0227    

DOI:10.1029/JZ068i017p04949

年代:1963

数据来源: WILEY

摘要:

The results of a theory which accounts for observed errors in orbital predictions are presented. The errors in predictions are assumed to arise from three causes: a sinusoidal variation in atmospheric density with a 27‐day period, a random fluctuation in atmospheric density, and errors of observation. The theoretical errors are evaluated for Vanguard 1 and for the Tiros weather satellites as a function of the length of the predictions. Errors in predictions for the Anna 1‐B geodetic satellite are expected to be approximately the same as for the Tiros satellites because the altitudes and ballistic parameters are similar. The theoretical errors are compared with errors in actual predictions issued by the Vanguard and National Aeronautics and Space Administration computing centers. The errors for Vanguard 1 are also given as a function of the year in which the prediction was made, illustrating the influence of perigee insolation. The problem of determining the location of clouds which appear on the Tiros weather photographs is discus

ISSN:0148-0227    

DOI:10.1029/JZ068i017p04953

年代:1963

数据来源: WILEY

摘要:

Dissipation of tidal energy in the moon was calculated under the assumption that it can be represented as due to imperfect elasticity. If the factor 1/Qfor dissipation per cycle is assumed to be 1/100 for distortional strain energy and 1/1000 for dilatational strain energy, the heat now being generated in the moon by tides is less than 0.010 erg/g/yr.; i.e., negligible compared to radioactive heating by a chondritic composition. Tidal heating would be comparable to radioactive heating, however, if the semimajor axis of the moon's orbit was one‐third as great, so the mechanism does limit the possible history of the moon's orbit. Also, appreciable tidal dissipation would cause thermal stresses and be conducive to convection, since it is much greater in the center than near the surface of the moon, and has a non‐uniform distribution in latitude (and longitude as well, if rotation is synchronous with revoluti

ISSN:0148-0227    

DOI:10.1029/JZ068i017p04959

年代:1963

数据来源: WILEY

摘要:

Static earth‐tide theory was modified to include interior loads expressible as spherical harmonics, and elastic moduli were assumed to be functions of radius only. Variations of density from this model and the corresponding stress distributions in the crust and mantle were calculated to correspond to observed variations in the gravitational field plus the surface topography up to 4th‐degree spherical harmonics. These solutions were made determinate by imposing the condition of minimization of strain energy. For the elastic parameters derived from seismology, the maximum stress difference obtained from the discrepancy between the observed and equilibrium flattenings of the earth was 163 bars. The maximum stress difference found for the sum of all other terms was 97 bars in the lower mantle and 300 bars in the crust. Displacements were always less than 70 meters. Modifications of the solution which take into account finite strain, creep, and viscous deformation are discussed. A model consisting of a fluid layer 35 to 400 km deep and a rigidity ½ seismic in the rest of the mantle results in a reduction, of the maximum stress difference in the mantle to 54 bars and an increase of the maximum displacement to 1500 me

ISSN:0148-0227    

DOI:10.1029/JZ068i017p04967

年代:1963

数据来源: WILEY