摘要:

The development of our knowledge of the outer Van Allen radiation zone is surveyed. In general, the approach within each topic is historical. The early discoveries of the gross features of the radiation belt, the difficulties encountered in determining the electron energy spectrum, and the misinterpretation of geomagnetic storm intensity changes due to inadequate knowledge of the electron spectrum are discussed. Also considered are the equatorial pitch angle distributions of electrons, the presence of protons in the outer zone, and the question of a ‘slot’ between the inner and outer zones. The calculations of the neutron albedo contribution of electrons to the outer zone are reviewed; the contribution appears to be inadequate, because the resulting energy spectrum is incorrect, the intensity inadequate, and the required lifetime too long. Observations of electron precipitation into the atmosphere are briefly reviewed, and several possibilities for the connection of such observations to the intensity and lifetimes of trapped electrons are lis

ISSN:8755-1209    

DOI:10.1029/RG001i001p00003

年代:1963

数据来源: WILEY

摘要:

The rate of production of carbon 14 by cosmic‐ray neutrons is calculated by multigroup diffusion theory as a function of altitude, latitude, and time, and it is normalized to absolute cosmic‐ray neutron flux measurements. The global average production rate over the last ten solar cycles is found to be 2.50 ± 0.50 carbon 14 atoms per square centimeter per second. This value is compared with recent estimates of the decay rate of 1.8 ± 0.2 and 1.9 ± 0.2, and some of the possible implications are dis

ISSN:8755-1209    

DOI:10.1029/RG001i001p00035

年代:1963

数据来源: WILEY

摘要:

A 1962 revision of the United States standard atmosphere was recently announced. The high‐altitude part of the previous standard was based upon a small number of relatively inaccurate pressure and density data available in 1955. High‐altitude atmospheric data obtained with IGY rockets and satellites demonstrated the inadequacies of the standard and provided the basis for a major revision above 20‐km altitude. The large amount of satellite‐drag density data and rocket‐derived pressure data required the use of model‐generation processes involving both pressure‐temperature altitude relationships and density‐temperature altitude relationships. A high‐altitude model (90–700 km) was developed by using the process of linearly segmented temperature functions, starting from reference values and working upward, matching observed pressure‐altitude and density‐altitude profiles. This technique of model generation permitted continuity with an independently developed low‐altitude model (20–90 km). The imposed requirement that the high‐altitude part of the new standard be defined in terms of molecular‐scale temperature functions that are linear with respect to geometric, rather than geopotential, altitude, introduced considerable complexity to the defining equations. With molecular‐scale temperature as the principal defining property, it was necessary to establish a molecular‐weight function as a secondary defining property in order to compute kinetic temperatures and other atmospheric properties not directly related to molecular‐scale temperature. The assumption that diffusive equilibrium dominates the atmosphere above 120‐km altitude, coupled with numerous assumptions concerning photodissociation and recombination rates of known atmospheric molecules, served as the basis for the computation of number density of the various species and, hence, mean molecular weight as a function of altitude. The definitions of this revised atmospheric model were adopted by the Committee on Extension to the United States standard atmosphere on March 15, 1962, and thereby this model became the basis for the 90‐ to 700‐km region of th

ISSN:8755-1209    

DOI:10.1029/RG001i001p00057

年代:1963

数据来源: WILEY

摘要:

The long‐range (secular) effects caused by the moon and the sun are of primary importance for establishing the stability of highly eccentric orbits of satellites. At present no complete analytical theory exists that can treat such orbits. In this paper Halphen's method of treating secular planetary effects is suggested also for the determination of long‐range lunar effects in the motion of artificial satellites, using step‐by‐step integration. Halphen's method permits the numerical integration of long‐range lunar effects over an interval of many years. The long‐range solar effects can be treated by averaging the disturbing function over the orbit of the satellite. Halphen's method is applicable to the determination of long‐range effects in the motion of minor planets over the interval of hundreds of thousands of years. We assume that no sharp commensurability between mean motions of the disturbed and disturbing bodies exists. A complete theory of Halphen's method is presented, using modern symbolics. Goursat transformations and a summability process are applied to speed up the convergence of series appearing

ISSN:8755-1209    

DOI:10.1029/RG001i001p00085

年代:1963

数据来源: WILEY