摘要:

Mariner 6 and 7 observations of the Mars upper atmosphere show the ultraviolet emission spectrum to consist of the CO2+A‐XandB‐Xbands, the COa‐XandA‐Xbands, the CO+B‐Xbands, the C I 1561‐ and 1657‐A lines, the O I 1304‐, 1356‐, and 2972‐A lines, and the H I 1216‐A line. Laboratory measurements and theoretical calculations show that the CO2+band systems are produced by the combination of photoionization excitation of CO2and fluorescent scattering of CO2+. An analysis of the vibrational populations of the CO Cameron bands shows that they may be produced from photon or electron dissociative excitation of CO2. The vibrational distribution of the CO fourth positive bands is the same in the Mars spectrum as in a laboratory CO2dissociative excitation spectrum, except for the bands that are self‐absorbed by CO in the Mars atmosphere. Since the C I 1561‐ and 1657‐A lines and the O I 1356‐ and 2972‐A lines may be produced in the laboratory by CO2dissociative excitation processes, these are the most likely sources in the Mars atmosphere. The altitude distribution of all the emissions is the same, except for the H I 1216‐A and O I 1304‐A lines and part of the CO2+A‐Xbands. The scale heights indicate a cold, predominantly CO2atmosphere. The O I 1304‐A line emission extends to much higher altitudes than the CO2emissions showing that atomic oxygen is present. Its profile suggests that it is excited by more than one mechanism. Fluorescent scattering of the CO2+A‐XandB‐Xbands indicates the presence of CO2+, but CO2+is not necessarily an abundant ion. Lyman α radiation with a single scale height extending several radii from the planet establishes the prese

ISSN:0148-0227    

DOI:10.1029/JA076i010p02213

年代:1971

数据来源: WILEY

摘要:

Observations of protons with kinetic energy>0.31 Mev in interplanetary space during quiet times made from the spacecraft Explorer 33 show that there is an anisotropy of ∼15%, the maximum flux being directed approximately radially outward from the sun. This observation, and the corresponding radial gradient results reported by S. M. Krimigis, are shown to be in very good agreement with those expected from a model in which the observed protons are convected outward at the solar wind speed. It is concluded that these particles have come from an interior region and that the most probable source is the sun, but the possibility that they are of galactic origin, although remote, cannot be positively exclude

ISSN:0148-0227    

DOI:10.1029/JA076i010p02228

年代:1971

数据来源: WILEY

摘要:

The role of heat conduction in the solar wind is assessed by a dimensional analysis of the electron energy equation. The relaxation time for transient perturbations of electron temperature is shown to be ∼4×104sec for reasonable solar wind parameters. For phenomena requiring longer times to propagate or develop (e.g., disturbances propagating near the solar wind speed) the electron energy equation can be approximated as time independent. Two such specific classes of solar wind variations, namely overtaking streams and shock waves, are considered as sources of electron temperature perturbations. In both cases heat conduction is found to be so efficient as to ‘smooth out’ the electron temperature, thus causing any increase to be much smaller than would be observed for protons. The few available pertinent observations of electron temperature are consistent with this analysis. A few effects of electron heat conduction on small‐scale phenomena (e.g., the modification of the Rankine‐Hugoniot relations applicable to interplanetary shocks) are briefly

ISSN:0148-0227    

DOI:10.1029/JA076i010p02236

年代:1971

数据来源: WILEY

摘要:

The propagation of flare‐associated disturbances through the interplanetary medium is examined by using numerical solutions of time‐dependent two‐dimensional hydrodynamic flow in spherical coordinates. The study is limited to blast wave phenomena, and the dependence on initial disturbance energy and angular extent is examined. For constant energy disturbances initially occupying cones of half angle up to ∼15° at 0.1 AU, the angular dependence of the transmit time to 1 AU and of the shock shape at 1 AU is very small. For disturbance energies at 0.1 AU of a few times 1030ergs, transit times to 1 AU are ∼65 hours. The calculated disturbance shapes at 1 AU and the transit times are found to be in good agreement with the observat

ISSN:0148-0227    

DOI:10.1029/JA076i010p02245

年代:1971

数据来源: WILEY

摘要:

By using Explorer 33 and 35 interplanetary plasma and magnetic field data, it is confirmed that there are at least two basic modes in the interaction mechanism between the solar wind and the magnetosphere. The first is the change in the magnetospheric dimension that results from changes in the solar wind dynamic pressure exerted at the magnetopause, and the second is the fluctuation in the magnetosphericDP2 electric field that is related to fluctuations in the north‐south component of the interplanetary magnetic field. Whereas the first can be interpreted essentially by the classical Chapman‐Ferraro theory, the second suggests that the interplanetary electric field penetrates deep into the magnetosph

ISSN:0148-0227    

DOI:10.1029/JA076i010p02254

年代:1971

数据来源: WILEY

摘要:

The complex structure of the near‐earth termination of the plasma sheet in the pre‐ and post‐midnight sectors of the magnetosphere near the magnetic equator was observed with a sensitive electrostatic analyzer array flown on the earth satellite Ogo 3 during June and July 1966. The ‘trapping boundary’ for energetic electronsE≳40 kev was found to be within the extraterrestrial proton ring current and near its outer edge. The region characterized by an exponential decrease of electron energy densities (or average electron energy) with decreasing radial distance, i.e., the earthward edge of the plasma sheet, is located in the post‐midnight sector such that its inner boundary is coincident with the plasmapause position. This inner boundary of the earthward edge of the plasma sheet is at 1 to 3REbeyond the plasmapause position in the pre‐midnight sector. An electron ‘trough’ characterized by relatively low, constant electron energy densities lies between the plasmapause and the inner boundary of the earthward edge of the plasma sheet in the pre‐midnight sector. The plasmapause is within the region of the proton ring current. The near‐earth termination of proton ring current is usually at ∼0.5 to 1REinside the plasmapause position. The ‘trapping boundary’ for energetic electrons is usually coincident with or beyond the outer boundary of the earthward edge of the plasma sheet. The earthward edge of the plasma sheet and the electron trough are within the proton ring current. During the main phases of two moderate geomagnetic storms on June 25 and July 9, the interrelationships of these various boundaries and regions remained similar to those observed during periods of relative magnetic quiescence as the entire distribution moved earthward. For two measurements available during a polar magnetic substorm and a main‐phase magnetic storm July 9 in the pre‐midnight sector, the electron trough disappears and the structure appears to be similar to

ISSN:0148-0227    

DOI:10.1029/JA076i010p02265

年代:1971

数据来源: WILEY

摘要:

A numerical model for the magnetosphere is used to investigate possible mechanisms for the injection of low‐energy protons into the magnetosphere. The proton distribution function is assumed to consist of two monoenergetic components. The effects of day‐night asymmetries in the geomagnetic field, the earth's rotation, and a finitely conducting ionosphere are included in the model. The model was used to determine if one group of particles could result in the injection of another group of particles. The calculations indicated that coupling between particles of different energies would be ineffective in injecting particles. Another numerical experiment sought to determine the effect of the internal polarization fields of the injected particles on particle injection by an externally imposed convection electric field. It was found that the external field tended to be canceled out by the internally generated field. The calculations indicate that an external convection field is unlikely to result in the injection of significant particles deep within the magetosphere unless the effective ionospheric conductivity is very high, as might exist in an ionosphere bombarded by auroral ionization. Another experiment was used to investigate the effect of the earth's rotation and the asymmetric geomagnetic field in causing injection. It was found that significant injection of 80‐ev/γ particles occurred on a time scale of a day without any assist from external electric fields. It is pointed out that much faster and deeper injection may occur if a self‐consistent model of the geomagnetic field were used in the calculations. A mechanism of this type would also require the existence of a highly conductive ionosphere. A final numerical experiment suggests that certain features of the auroral substorm could result from rapid changes in the effective ionospheric cond

ISSN:0148-0227    

DOI:10.1029/JA076i010p02276

年代:1971

数据来源: WILEY

摘要:

We examined the intensities and differential energy spectra of electrons between 1 and 3.6 Mev obtained with an instrument flown on polar‐orbiting AF Satellite OV1 9 during May and June 1967, which almost coincided with the time of maximum solar activity. We observed a severe depletion of the outer‐belt electrons withEe>0.94 Mev coincident with the onset of the magnetic storm of May 25, and the subsequent growth of the peak flux atL≃3.0 (pre‐stormL≃3.8). Over the region 2.5≲L≲5, and on May 23, 24, and June 16, thee‐folding energies (E0) versusLdistributions were found to be characteristic of the bimodal diffusion process. After the May 25 storm, theE0distributions were independent ofL, and we observed a spectral hardening from 〈E0〉 = 482 ± 67 kev (May 27) to the pre‐storm value of 〈E0〉 = 567 ± 57 kev (June 14). On June 5, a secondary electron maximum appeared atL=3.40, which then diffused outward across field lines,

ISSN:0148-0227    

DOI:10.1029/JA076i010p02298

年代:1971

数据来源: WILEY

摘要:

The proton energy spectrum in the radiation belt has been measured with the Injun 5 satellite for the period August 29 through November 15, 1968, in the energy range 0.3 to 74 Mev. The most salient features of the differential energy spectrum are: (a) in the inner belt there is a minimum at about 2 Mev, and (b) in the outer belt theE0parameter at constant invariant radial distance is proportional toL−1.74±0.

ISSN:0148-0227    

DOI:10.1029/JA076i010p02306

年代:1971

数据来源: WILEY

摘要:

The purpose of this paper is to predict in an exhaustive way the solar cycle time variations to be expected in the trapped radiation belt proton flux on the assumption of a neutron decay source. By ‘exhaustive’ we mean that, once the interested reader decides on suitable models for the earth's atmosphere and magnetic field (we will recommend some), he should, by reading this paper, be able to predict the time variations expected for protons of any energy and pitch angle at any point in space. We have also devoted considerable attention to a derivation from the Boltzmann equation of the simplified proton transport equation commonly used in discussing energetic protons at lowLvalues. Emphasis is given to the various approximations invol

ISSN:0148-0227    

DOI:10.1029/JA076i010p02313

年代:1971

数据来源: WILEY