摘要:

The moment technique, which we used earlier to solve the problem of a dipole in a uniform pressure plasma, is extended to the problem of a dipole of moment Mev in a cold, field‐free plasma wind with densityN0Mtand velocity—U0ez. An assumed surface and current system containing 46 parameters is specified in such a way as to always have the local current density proportional to the cosine of the angle made by the wind arid the surface normal, as required by the boundary conditions. The parameters are varied until the magnetic multipole moments of the surface currents approximately cancel the corresponding moments of the magnetic sources within the surface making the field zero outside. The resulting approximate solution of the exact boundary condition is compared with the exact solution of Beard's approximate boundary condition. In a coordinate system (x, y, z) centered at the dipole, the neutral points, where the surface is parallel to the wind direction, occur at the points (0, ±RN, 0.27RN), and other points on the surface are (0, 0, 1.02RN), (0, ±2RN, ‐ ∞), and (±1.97RN) 0, ‐ ∞).RN= 1.0035[M/(MtN0U02)1/2]1/3is about nine earth radii for the solar wind. Plots of the surface and the current lines are given, and the perturbation of the magnetic field within the cavity

ISSN:0148-0227    

DOI:10.1029/JZ068i018p05111

年代:1963

数据来源: WILEY

摘要:

It is shown that far particles trapped in the geomagnetic field the first‐order effect of nonconservation of magnetic moment is to raise the mirror points by an amount depending on the position of the unperturbed mirror point. It is shown that the net change in the magnetic moment over a complete north‐south mirror oscillation is zero, and that the effect is therefore a static deformation of the orbit (i.e., there is not aprogressiveraising of the mirror points). An expression is derived for the angular derivative of the magnetic moment, and from this an expression is obtained for the increase in mirroring altitude. It is seen that the effect is most significant for high‐energy protons trapped on high magnetic shells and is essentially negligible for elec

ISSN:0148-0227    

DOI:10.1029/JZ068i018p05125

年代:1963

数据来源: WILEY

摘要:

Electron equilibrium energy in theDand lowerEregion of the ionosphere is calculated from a relationship between electron energy loss and attachment characteristic times. It is shown that solar photodetachment of electrons from O2−ions, which is the major short‐term ionization source between 50 and 90 km, is a source of energetic electrons of 2.9‐ev mean energy. Thus competition between energy loss by rotational excitation of molecules and dissociative attachment to oxygen will exist as the most probable processes for 3‐ev electrons. Approximate conditions are defined that allow calculation of maximum mean electron energy at equilibrium for the undisturbed or slightly disturbed daytime ionosphere. Comparison of these maximum values with a measured electron energy of 0.15 ev at 40 km shows agreement within a factor of 2, which may be accounted for by the disturbed condition of the ionosphere during the measurement. The range of maximum permissible electron energies lies between 12 times ambient at 30 km and 42 times ambient (0.74 ev) at 90 km. A method is outlined whereby one parameter among the set—equilibrium electron energy, energy loss characteristic time, or electron removal characteristic time—can be determined if the other two can be found experimentally and if the mean source energy of the electrons is known. Thus radio measurement techniques such as the Luxembourg effect or rocket probes can be used to relate temperature measurements and electron‐density measurements through a reaction model based on estimation of characteristic times of compet

ISSN:0148-0227    

DOI:10.1029/JZ068i018p05135

年代:1963

数据来源: WILEY

摘要:

Further details are given of a method of determining the vertical distribution of ozone by photometry of a balloon at twilight. The theory and apparatus are discussed, and some results are presented. The principle is analogous to the lunar eclipse method, and, apart from some differences in theoretical treatment of the data, it is similar to that applied elsewhere to observations of the Echo 1 satellite. The results, for the southern spring of 1962, show two maximums, one in the 10‐ to 15‐km layer and the other in the 20‐ to 25‐k

ISSN:0148-0227    

DOI:10.1029/JZ068i018p05143

年代:1963

数据来源: WILEY

摘要:

An expression for the contribution made by tropospheric refraction to the Doppler shift of a satellite signal is derived. It is assumed that the troposphere is horizontally stratified and does not vary during the time of a pass; a two‐parameter quadratic expression is used as an approximation to the refractivity profile. The qualitative effect of the troposphere during any satellite pass is to steepen the slope of the Doppler shift versus time curve, making the tracking station appear slightly closer to the orbit than it actually is. When Doppler data from several passes are used for orbit computation, the resultant effect of the troposphere in general is not zero; thus it may bias the orbit slightly, the amount depending on the geometry of the selected passes. Conversely, if the orbit is assumed to be known, the station position as determined by a single satellite pass may be shifted toward the orbit by 50 meters or more. Such errors are not negligible if precise geodetic work is to be done with satellites. The residual tropospheric error in the Doppler shift can probably be reduced by an order of magnitude by using a computed tropospheric correction of the type described here. Some Doppler data from observed satellite passes are presented in corroboration of the theor

ISSN:0148-0227    

DOI:10.1029/JZ068i018p05157

年代:1963

数据来源: WILEY

摘要:

Radio emission from clouds, not associated with lightning, has been observed and recorded as such on several occasions. Since the source of this radiation cannot be the lightning discharge, a study has been started to explain its nature and origin. Preliminary studies have revealed radio emission from colliding charged water drops at frequencies of the order of tens of megacycles, possibly higher. Microwave radiation is known to result from the contact of charged mercury drops with a grounded probe. We find microwave radiation from the contact of mercury drops with glass, plexiglass, or a pool of mercury. Plans are discussed for using the mercury drop radiation phenomenon as a control in studying the radiation from cloud drops.

ISSN:0148-0227    

DOI:10.1029/JZ068i018p05169

年代:1963

数据来源: WILEY

摘要:

Equipment for measuring atmospheric potentials has been developed, using antennas without radioactive collectors, water droppers, or other special means for coupling to the atmosphere. The antennas thus far used are well‐insulated horizontal wires about 20 m long, but the method is not limited to this type of antenna. After any initial net charge on the antenna has leaked off, the antenna is at atmospheric potential and subsequently closely follows variations in the atmospheric potential. Antenna potential is sensed with an electrometer tube, coupled to an amplifier providing feedback for neutralizing input capacitance and for guarding. Examples are given of potential recordings made with antennas at heights ranging from 25 cm to 3

ISSN:0148-0227    

DOI:10.1029/JZ068i018p05173

年代:1963

数据来源: WILEY

摘要:

In the preceding paper W. D. Crozier proposed the application of a passive antenna to measure the atmospheric electric potential. He must be congratulated for realizing this principle and developing a practicable measuring technique, thus introducing a third measuring principle for the atmospheric electric field, in addition to the radioactive collector and the different types of field mills. It should be stated, however,that the choice of measuring methods depends on the measuring task to be solved.

ISSN:0148-0227    

DOI:10.1029/JZ068i018p05181

年代:1963

数据来源: WILEY

摘要:

Analysis of Baker Nunn camera observations of satellites 1959α1over 1032 days; 1959η over 792 days; 1960t2over 480 days; 1961δ1over 150 clays; and 1961αδ1over 54 days yielded results greatly improved over those previously reported. This improvement is primarily due to the use of much more data and secondarily to various modifications in the method of analysis. As indicated by the discrepancies between results from appreciably different orbits, the datum shifts obtained have standard deviations of ±4 to ±23 meters. The tesseral harmonic of the gravity field most firmly determined appears to beJ11, followed byJ22,J31,J42,J13, andJ32. The principal sources of error suggested are the influence of preassigned variances on separation of gravitational coefficients having the same periodic effects on an orbit (e.g.,J22andJ42) and the holding fixed with respect to each other stations on the same geodetic datum, but they do not seem adequate to explain all systematic discrepancies in the results. A comparison of gravitational and geometric geoid heights at station positions gave a mean equatorial radius of 6,378,196±11

ISSN:0148-0227    

DOI:10.1029/JZ068i018p05183

年代:1963

数据来源: WILEY

摘要:

Heat flow was determined at sixteen stations regularly spaced over a region of the North American basin between Bermuda and the Bahama Banks. The results show a remarkable uniformity of heat flow in this area, which measures about 800 by 900 km. The mean heat flow at the sixteen stations is 1.14 μcal/cm2sec, with a standard deviation of 0.06. When allowance is made for experimental errors the actual standard deviation of heat flow in the region is estimated to be only 4½ per cent. Another measurement made at the southern edge of this area, near the Puerto Rico trench, showed a heat flow of 1.76 μcal/cm2sec, while three measurements made a few hundred km to the northwest, close to the continental slope, gave values of 117, 0.94, and 0.81 μcal/cm2

ISSN:0148-0227    

DOI:10.1029/JZ068i018p05191

年代:1963

数据来源: WILEY