摘要:

Auroral spectra have been obtained in the wavelength region 1050–1550 A over the altitude range 90–160 km in an Aerobee rocket at Fort Churchill, Manitoba. Spectral lines of atomic hydrogen, nitrogen and oxygen, and eighteen bands of the Lyman‐Birge‐Hopfield system of molecular nitrogen were identified. The primary electron flux and the 3914‐A emission of N2+were also measured throughout the flight. Altitude profiles for several spectral features and the electron flux are given, and correlations among the various observations are discussed. The hydrogen‐Lyman‐α radiation at 1216 A is found to be independent of the aurora. Other origins for this radiation

ISSN:0148-0227    

DOI:10.1029/JA073i011p03353

年代:1968

数据来源: WILEY

摘要:

The recent important observation of Rao et al. (1967) of the quiet‐time anisotropy of cosmic‐ray particles in the 10‐Mev range indicates a surprisingly small value, approximately 0.2%. This low value has a number of general implications. It shows either (a) that the ordinary diurnal variation is suppressed at these low energies by gradient drifts, which is in agreement with the low diffusion coefficient across the lines of force deduced from the observed power spectrum of the interplanetary magnetic field fluctuations, or (b) that κ⊥≅ κ∥is a consequence of large power at zero wavenumber in the Fourier spectrum of the interplanetary magnetic field. Further, adiabatic deceleration of cosmic rays in the expanding fields of the wind leads to a radial anisotropy of 1.2 ± 0.3% if it is assumed that the radial gradient of the cosmic‐ray density is as large between the sun and earth as reported in the vicinity of earth. The low value of 0.2% observed by Rao et al. indicates that in fact the gradient must be very much less between the sun and earth, which in turn implies that the diffusion coefficient for 10‐Mev protons between the sun and earth must be rather greater (less scattering by magnetic inhomogeneities) than at the orbit of earth. These two predictions are subject to

ISSN:0148-0227    

DOI:10.1029/JA073i011p03367

年代:1968

数据来源: WILEY

摘要:

During geomagnetic storms, there occurs anincreaseof cosmic‐ray flux, superposed on the well‐known Forbush decrease, although the increase, in general, is rather hard to detect by a casual inspection of cosmic‐ray records. By carefully eliminating the Forbush decrease, it is shown that the time variation of this increase closely follows the storm‐time variation ofDst(H), which is an approximate measure of the intensity of the ring current field. For storms with a weakDstdecrease, the increase is small or absent, regardless of the magnitude of the Forbush decrease. By using a model ring current that takes into account the three adiabatic motions of ring current particles, it is shown that the observed increase can be reasonably explained. Further, it is suggested that a large asymmetry of the storm‐time cosmic‐ray increase is caused by the asymmetry of the r

ISSN:0148-0227    

DOI:10.1029/JA073i011p03377

年代:1968

数据来源: WILEY

摘要:

The calculation of the energy of confinement of a shielded magnetic dipole field is reformulated in terms of the concept of flux linkages. By means of this approach an important theorem relating to magnetic storms can be generalized. In addition, the interaction of the interplanetary magnetic field with the magnetopause is considered in the limits of negligible and complete merging. An upper limit on the amount of energy available for particle energization in the magnetopshere is thereby determined analytically and is computed, using characteristically observed magnetic field amplitudes. A method is developed for determining directly from the data the amount of merging that occurs at the magnetopause.

ISSN:0148-0227    

DOI:10.1029/JA073i011p03395

年代:1968

数据来源: WILEY

摘要:

Magnetic field observations made by IMP 1 satellite are used to study sudden impulses (si) in the magnetospheric tail. A total of seven si's that are correlated with the satellite data in the tail were observed terrestrially. Large and well‐defined si's in the surface magnetograms show definite correlation with the tail field. However, not all sudden changes observed in the tail field have associated si's. The characteristics of these observed si's are discussed, and velocities of the propagation in the tail from 870 to 1300 km per sec are obtained. There is an indication that some of the sudden impulses were originated in the tail and propagated to the surface of the earth. Also, in some events the sudden impulses originated on the sunward side of the magnetosphere and propagated into the tail. Possible mechanisms for the generation of the si's are discussed. Two events of micropulsations associated with the sudden impulses are also found. In one case, the propagation of these micropulsations from the tail to the earth's surface appears to have been confined to 10° longitudinal ran

ISSN:0148-0227    

DOI:10.1029/JA073i011p03407

年代:1968

数据来源: WILEY

摘要:

Detailed measurements of the interplanetary magnetic field in the vicinity of the moon have been performed on the Explorer 35 selenocentric spacecraft launched July 1967. The observational evidence fails to reveal the existence of a lunar bow shock wave. A pseudo‐magnetosphere as suggested by Gold and interpreted from Luna 10 measurements is not observed. The interplanetary magnetic field appears to be convected through the lunar body without a large‐scale distortion of its direction or magnitude. Perturbations as much as 30% of the average magnitude are noted in the solar plasma umbra and penumbra. As the satellite passes through the leeward flow, an alternating pattern of magnitude increases and decreases is observed in the penumbra, while generally only an increase is observed in the umbra. Using a theoretical model of plasma flow due to Whang, a first‐order solution of the perturbed interplanetary magnetic field is compared with observations. It is concluded that the perturbations can be partially explained on the basis of the magnetization, gradient, and curvature currents induced in the disturbed solar plasma flow. The umbral increase and the innermost penumbral decrease are consistent with the first‐order theory, and it is suggested that a higher‐order approximation is required to explain the newly detected penumbral increases and additional penumbral flu

ISSN:0148-0227    

DOI:10.1029/JA073i011p03421

年代:1968

数据来源: WILEY

摘要:

We have intercompared geomagnetic field models inB‐Lspace for 0.20 ≤B≤ 0.24 gauss and 1.2 ≤L≤ 1.8RE(earth radii). Three field models were selected because of their general usage in the analysis of trapped radiation data: Jensen and Whitaker (569 coefficient); Jensen and Cain (48 coefficient); GSFC (9/65) (99 coefficient). These models were compared with the GSFC (12/66) field model (120 coefficient). The geographic coordinates of constantB‐Ltraces were computed, using the GSFC (12/66) field in both the southern and northern hemispheres. At each geographical point along the traces thus defined,BandLvalues were recalculated, using different geomagnetic field models. We find that variations inB‐Lspace of the 48‐ and 569‐coefficient models with respect to the 120‐coefficient model are great enough to cause significant ambiguities in flux contours of the trapped radiation. We also have examined the effects of temporal variations of the geomagnetic field onB‐Lspace. The uncertainties in the proton flux contours inB‐Lspace caused by errors in the field models and time variations of the geomagnetic field demonstrate the need for careful re‐evaluation of existing data that pertain to possible time variations of inner‐belt protons. The GSFC (12/66) appears to be sufficiently accurate to u

ISSN:0148-0227    

DOI:10.1029/JA073i011p03441

年代:1968

数据来源: WILEY

摘要:

Three rapid increases in the low‐energy, electron (20–100 kev) and proton (>100 kev) flux were observed on October 27, October 28, and December 1, 1961. The increases were marked by a drastic change in the intensity and/or spectrum of the measured radiation during a 2‐ to 3‐minute interval. The time histories of the intensities and spectra are presented. The close association between the events and the occurrence of polar substorms is shown. The similarity of the events and those of December 20, 1962, and April 15, 1965, is discussed. It is also shown that the October 28, 1961, event is consistent with adiabatic acceleration of particles during a storm sudden comme

ISSN:0148-0227    

DOI:10.1029/JA073i011p03449

年代:1968

数据来源: WILEY

摘要:

Particle observations by the Rice University/ONR satellite Aurora 1 have revealed a large universal‐time variation in the low‐energy electron fluxes in the northern polar region during summertime. The electron fluxes are highest near 1800–2000 UT, both on the night‐ and the day‐side of the earth above ∼75° invariant latitudes, whereas a minimum in the fluxes is reached between 0600 and 1200 UT. It is suggested that these variations are associated with the diurnal changes in the tilt of the geomagnetic axis relative to the solar wi

ISSN:0148-0227    

DOI:10.1029/JA073i011p03459

年代:1968

数据来源: WILEY

摘要:

Electron and proton detectors covering the energy range 1–300 kev were flown on rockets to an altitude of 240 km at Fort Churchill, Canada, during particle precipitation events. Flights were made during the day and at night. The main results were: (1) the electrons at 0° pitch angle having energy 1‐5 kev were present with nearly constant intensity during a rocket flight. The 5‐ to 20‐kev electron flux increased by a factor of 10 in 50 seconds and the 80‐ to 160‐kev electrons increased by a factor of 100 in 50 seconds. (2) On one occasion microbursts (rapid increases in electron flux of about 0.6‐second duration) were detected in the 80‐ to 160‐kev and 160‐ to 320‐kev electrons, while no rapid variations occurred in the 1‐ to 20‐kev range. (3) In the day flights, a peak was found in the electron energy spectra between 2 and 5 kev. The average flux over this interval was 6 × 107(cm² ster sec kev)−1. (4) During the night, the spectral peak was between 5 and 20 kev, and the average flux was 1.6 × 108(cm² ster sec kev)−1. (5) The slope of the electron energy spectrum above 20 kev was much steeper at night than during the day. (6) The largest proton flux appeared in the 0.75‐ to 1.5‐kev interval a

ISSN:0148-0227    

DOI:10.1029/JA073i011p03469

年代:1968

数据来源: WILEY