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Volume 32 (1980)
- Issue 12 Pages 721-
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Volume 29 (1977)
- Issue 6 Pages 507-
- Issue 5 Pages 441-
- Issue 4 Pages 229-
- Issue 3 Pages 143-
- Issue 2 Pages 65-
- Issue 1 Pages 1-
Volume 29, Issue 3
Displaying 1-6 of 6 articles from this issue
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M. K. GOEL, B. C. N. RAO, S. CHANDRA, E. J. MAIER1977 Volume 29 Issue 3 Pages 143-151
Published: 1977
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSMagnetic storm phenomena at low latitudes are discussed based on the ion composition (O+, H+, He+) and electron and ion temperature measurements from the OGO-4 and the ISIS-2 satellites.
For the moderately severe storms considered, the effects of changes in the neutral composition and in the neutral and plasma temperatures are discussed and it is shown that these changes would not produce the observed O+ increase during storms at low latitudes. It is suggested that the observed increase in O+ in the topside region is a manifestation of the vertical lifting of ionization of the F-layer. The argument in favour of the vertical lifting is further substantiated by the observed changes in the F-region critical frequency and the height parameters.View full abstractDownload PDF (689K) -
The 9.6 Micrometer Emission of Atmospheric OzoneHiromasa YAMAMOTO1977 Volume 29 Issue 3 Pages 153-179
Published: 1977
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThe band radiance of the 9.6μm emission of the atmospheric ozone was calculated in the presence of various excitation sources in the altitude range between 40 and 120km. The primary excitation processes considered are: (i) the thermal molecular collisions, (ii) the chemical reactions to form O3 in vibrationally excited levels, (iii) the resonance fluorescence of the solar radiation and (iv) the resonance fluorescence of the earth shine. By comparing the numerical result with some photometric results from sounding rocket experiments it was found that, although the thermal excitation manifests only in the region of the atmosphere below about 70km, the radiance above that level is still governed by the thermal radiation transferred from lower levels due to the multiple scattering. The excitation associated with the three-body reaction, O+O2+M=O3≠+M, is considerable above the 70km level; however, its contribution to the final radiance is relatively smalll compared with the thermal origin.View full abstractDownload PDF (2381K) -
V. RAMASWAMY, H. W. DOSSO1977 Volume 29 Issue 3 Pages 181-189
Published: 1977
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSThe effect of the dimension of the inducing source field on the behaviour of time-varying electromagnetic fields near a conductivity anomaly has been studied using a laboratory analogue model. The anomaly is a highly conducting horizontal cylinder embedded in a two-layer conductor. The sources studied are overhead magnetic dipoles, a line current, and a sheet current. For these sources the horizontal extent of the source field has been estimated, using PRICE's (1962) elementary solutions, to vary from about 200km for the dipole source to about 700km for the sheet current. The results indicate that the response of the cylinder is strongly influenced by the type of source field.View full abstractDownload PDF (811K) -
Hidehumi WATANABE1977 Volume 29 Issue 3 Pages 191-209
Published: 1977
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSA hydromagnetic αω-dynamo is investigated based on a simple, nearly homogeneous, isotropic and mirror-symmetric turbulence. An upper bound on the magnetic field in the core is derived by considering both the actions of the Coriolis and magnetic forces. It is unlikely that αω-dynamo produces a toroidal magnetic field larger than 30 gauss. Then the poloidal field in the core hardly exceeds 10 gauss.
From considerations of energy balance the possible ranges of the characteristic length scale and the intensity of turbulence in the core are also estimated. It follows that the scale of turbulence must be larger than 10km and the intensity must be smaller than 5×10-3cm/sec so that energy dissipation due to Joule heat may not exceed the possible energy available for the geodynamo.View full abstractDownload PDF (1462K) -
Naoto KAWAI, Takaharu SATO, Tsutomu SUEISHI, Kazuo KOBAYASHI1977 Volume 29 Issue 3 Pages 211-223
Published: 1977
Released on J-STAGE: March 12, 2010
JOURNAL FREE ACCESSDetailed behavior of the palaeomagnetic field during the upper Matuyama epoch including the Jaramillo event was studied using sliced thin sections of two deep-sea sediment cores taken from the Melanesia Basin.
It has been shown from the measurement of the declination and intensity of natural remanent magnetization in 785 specimens that the intensity of the geomagnetic field decreased to nearly the zero level at the beginning of the lower Jaramillo and Brunhes-Matuyama boundaries. Such a low field interval seems to have continued thereafter for an interval as long as 10, 000yrs. Detailed data for the transitional stages during the polarity reversals have further revealed that the intermediate directions hardly occurred at any time in the entire span of the time studied.View full abstractDownload PDF (841K) -
Seiya Uyeda1977 Volume 29 Issue 3 Pages 225-227
Published: 1977
Released on J-STAGE: August 11, 2011
JOURNAL FREE ACCESSDownload PDF (261K)
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