摘要:

A simple ray analysis is used to derive expressions for the angular spread and spectral broadening of coherent radio signals on traversing the turbulent interplanetary medium, when the anisotropy and radial gradient of the turbulence and the large‐scale motions of the medium (solar wind) are important. The resulting expressions are used to interpret observations, reported in the literature, of the angular broadening of natural radio sources and of the spectral broadening of Mariner 4 during superior conjunction. In the region 10–100 solar radii our results are consistent with a coronal electron concentration behaving asr−2and a statistical correlation length which during solar minimum does not vary withrbut which tends to increase linearly withrnear solar maximum, indicating that the interplanetary plasma tends to develop a radial filamentary structure during solar maximum; we find no necessity to invoke nonradial outflow to explain the observations. In the region 3–6 solar radii the data implya²/b∼r³, whereais the correlation length in the radial direction andbis the correlation length in the transverse direction. We point out that this behavior can result if both the transverse correlation length and the anisotropy ratio,a/b, increase linearly withrin

ISSN:0148-0227    

DOI:10.1029/JA073i023p07221

年代:1968

数据来源: WILEY

摘要:

Radial diffusion by nonconservation of the third adiabatic invariant of particle motion is assumed in analyzing experiments in which electrons appeared to move across field lines. Time‐dependent solutions of the Fokker‐Planck diffusion equation are obtained numerically and fitted to the experimental results by adjusting the diffusion coefficient. Values deduced for the diffusion coefficient vary from 1.3 × 10−5RE²/day atL= 1.76 to 0.10RE²/day atL= 5. In the interval 2.6

ISSN:0148-0227    

DOI:10.1029/JA073i023p07231

年代:1968

数据来源: WILEY

摘要:

Results of a preliminary study are given in which a dependence is observed between Λb, the average high latitude boundary of 35‐kev electrons, and ø, the angle between the earth‐sun line and the geomagnetic axis. The variation of Λbwith ø has a minimum near ø ∼ 90° and is approximately symmetrical about this angle. The maximum variation of the average Λbwith ø is between 2° and 3°. There is some indication that the dependence of Λbon ø is greatest in the morning hours, although this conclusion has to be regarded as tentative at present. The results are interpreted as indicating a stronger coupling between the solar wind and the magnetosphere when ø ∼ 90°, which results in more geomagnetic flux being swept back into th

ISSN:0148-0227    

DOI:10.1029/JA073i023p07237

年代:1968

数据来源: WILEY

摘要:

The relationship of locally mirroring and precipitating ≥40‐kev electrons was studied on magnetically quiet days in the region of the high‐latitude outer‐zone boundary with satellite Injun 3. There was usually an enhancement of precipitating ≥40‐kev electrons observed in the region of the high‐latitude boundary for all local times. On the night side the flux of ≥40‐kev electrons was always observed to approach isotropy over the upper hemisphere at the position of the satellite in this boundary region. The condition of isotropy in the boundary region was found to be strongly dependent on local time, being always present on the night side and being less frequently observed with increasing local time around to local dusk (1800 hours) where isotropy was seldom observed in the boundary region. During magnetically quiet periods large intensities of ≥40‐kev electrons were observed precipitating into the atmosphere for Λ ≥ 65°, and the position of the high‐latitude boundary (intensity cutoff) was observed to vary by ΔΛ ≃ 7° while little magnetic activity was occurring. On the night side, the latitude where the ratio of the trapped to the precipitated ≥40‐kev electron fluxes breaks toward one (φ boundary) is introduced as a more meaningful concept of the high‐latitude limit to durably trapped ≥40‐kev electrons than the usual intensity cutoff. The concept that the high‐latitude outer‐zone boundary region at all local times is controlled or driven by a mechanism (s) a

ISSN:0148-0227    

DOI:10.1029/JA073i023p07245

年代:1968

数据来源: WILEY

摘要:

Reversal of the ambient tail field by 180° when the moon and Explorer 35 in lunar orbit traverse the neutral sheet permits a separation of permanent and induced field contributions to the total field observed near the moon. When compared with calculated permanent and induced field effects, the results of this analysis lead to new upper limits of 1020gauss cm³ on the lunar magnetic moment and 4 γ on the lunar surface field. Limiting the moment induced in the moon by the magnetotail field permits an upper limit of 1.8 to be set on the bulk relative magnetic permeability of the mo

ISSN:0148-0227    

DOI:10.1029/JA073i023p07257

年代:1968

数据来源: WILEY

摘要:

The interaction of the solar wind with a two‐layered moon is considered from the point of view of the induction generator model of Sonett and Colburn (1967). We show that a highly conducting lunar core, shielded by a thin insulating outer layer, cannot reasonably be consistent with the observed absence of a lunar bow shock, since a 10‐meter thick surface dust layer would require a conductivity less than 10−10mho/m, while a 10‐kilometer thick layer would require a conductivity less than 10−7mho/m to shield the core; conductivities in this low range do not seem reasonable. We thus establish an upper limit of 10−5mho/m for the core conductivity, but point out that this figure can be consistent with the existence of a highly conducting surface layer. Two mechanisms are suggested for the formation of a lunar limb shock wave. It is shown that in the steady‐state unipolar generator model a limb shock will be expected to form in the vicinity of the plane defined by the solar wind velocity and magnetic field directions, while a limb shock may be expected to form also in the nonsteady state if the moon possesses a conducting outer layer (10−4<σ<10−3mho/m) of thickness between one‐tenth an

ISSN:0148-0227    

DOI:10.1029/JA073i023p07269

年代:1968

数据来源: WILEY

摘要:

The expected properties of the lunar wake at large distances are examined in light of the Explorer 35 data on the solar wind interaction with the moon. It is concluded that any geomagnetic activity expected by means of the interaction of this wake with the magnetosphere would be below the limit of detectability by present methods. It is also concluded on the basis of energy conservation that the December 14–15, 1983, disturbance observed on Explorer 18 and interpreted by Ness to the wake of the moon was actually a disturbance already in the solar wind itself and not generated by the moon, although the very mild disturbance of February 11, 1964, might be attributed to the lunar wake, as was suggested by Ness. The December disturbance involved at least two orders of magnitude more disturbance energy than could be generated by a lunar source. The February disturbance is quantitatively consistent with turbulence being present in the lunar wak

ISSN:0148-0227    

DOI:10.1029/JA073i023p07277

年代:1968

数据来源: WILEY

摘要:

Electron concentrations and temperatures measured in a nocturnal rocket flight (NASA 18.02) at Fort Churchill, Manitoba, were considerably higher than nocturnal values measured at lower latitudes, particularly in theF1region. We attribute this to a high‐latitude energy source provided by bombardment of the atmosphere by energetic auroral electrons. By calculating the ionospheric electron concentrations and temperatures that result from auroral bombardment we can deduce the flux and energy spectrum of the incident particles. The ionospheric data correspond to a bombarding flux of 1.25 × 108electrons cm−2sec−1with a mean energy of 1.2 kev. Other data indicate that weak auroral bombardment and enhanced electron concentrations in theEandF1regions are permanent features of the nocturnal aurora

ISSN:0148-0227    

DOI:10.1029/JA073i023p07285

年代:1968

数据来源: WILEY

摘要:

The atmospheric composition in the altitude range between 120 and 210 km over White Sands, New Mexico (32°24′N, 106°20.6′W) has been measured by mass spectrometers in three rocket flights at 1249 MST on June 21, 1967, and at 0200 MST and 1224 MST on July 20, 1967. The day‐to‐night variations of the ambient number densities found are larger than the model predictions and extend down to 120 km. Diffusive equilibrium profiles for the atmospheric constituents are compared with the measured number densities. The level where the Ar/N2ratio reaches the ground level value was computed to be at 99, 99, and 101 km for the three flights, respectively. The He number densities, when compared with results obtained in earlier flights, indicate a seasonal decrease of the He content from the winter to the summer by a factor of

ISSN:0148-0227    

DOI:10.1029/JA073i023p07291

年代:1968

数据来源: WILEY

摘要:

Horizontal temperature variations contribute to horizontal transport of constituents in an exosphere. If gas concentrations are not uniform, their gradients will also give rise to horizontal transport through the exosphere. The sum of these two transport effects plus the transport due to rotation of the planetary body involved, must balance the integrated sources and sinks of gas in the exosphere, mainly by flow up or down through the base of the exosphere. The relative magnitudes of these effects are evaluated for helium in the earth's exosphere and for neon and heavier constituents in the lunar atmosphere. In the absence of significant sources and sinks the temperature and concentration effects tend to set up distributions such thatnT5/2= constant on the base of the exosphere, but rotation of the planetary body tends to establish distributions such thatnT= constant.

ISSN:0148-0227    

DOI:10.1029/JA073i023p07307

年代:1968

数据来源: WILEY