Journal of geomagnetism and geoelectricity
Online ISSN : 2185-5765
Print ISSN : 0022-1392
ISSN-L : 0022-1392
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Volume 26, Issue 6
Displaying 1-5 of 5 articles from this issue
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  • A Study of the Effect of Geomagnetic Storms on Low Latitude Whistlers
    Manoranjan RAO, V. V. SOMAYAJULU, S. K. DIKSHIT
    1974 Volume 26 Issue 6 Pages 515-528
    Published: 1974
    Released on J-STAGE: March 12, 2010
    DOIhttps://doi.org/10.5636/jgg.26.515
    JOURNAL FREE ACCESS
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    This paper presents the results of a detailed study of the influence of geomagnetic storms on low latitude whistlers recorded on ground. Studied in detail is the effect of the geomagnetic storm of March 6-10, 1970 on whistlers recorded at Gulmarg (Geomagnetic coordinates: 24°10′N; 147°24′E); results of analysis for the earlier storm of January 13-15, 1967 are included for comparison. Some of the important results of the present study are: (i) Both the whistler occurrence rate and dispersion increase simultaneously with Kp, (ii) During the decaying phase of the storm, changes in occurrence rate and in dispersion lag behind those in Kp, (iii) There is an indication of the existence of a cross-over latitude where tube contents may not change appreciably during storm periods, (iv) Multipath whistlers are observed only during disturbed conditions, (v) Duct life ranges between several hours to few days and (vi) Maximum number of ducts is observed during the main and recovery phases of the storm.
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  • On the Occurrence of SSC (-+) at Geomagnetic Observatories in India
    R. G. RASTOGI, N. S. SASTRI
    1974 Volume 26 Issue 6 Pages 529-537
    Published: 1974
    Released on J-STAGE: March 12, 2010
    DOIhttps://doi.org/10.5636/jgg.26.529
    JOURNAL FREE ACCESS
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    It is shown that about half of the sudden commencements in geomagnetic field at any equatorial station during the midday hours are preceded by a preliminary negative excursion. The negative excursions are seen in all the three components of the geomagnetic field. The amplitude of negative excursion decreases with increasing latitude much faster than the amplitude of main positive excursion. It is suggested that the mechanism of the generation and enhancement of the negative excursion over the magnetic equator is to be sought in the ionospheric region itself, and the height of the equivalent current system is slightly lower than that of the Sq current system.
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  • A Quasilinear Dynamics of Pc-1 Geomagnetic Pulsations (Pearls)
    F. Z. FEYGIN, Yu. P. KURCHASHOV
    1974 Volume 26 Issue 6 Pages 539-548
    Published: 1974
    Released on J-STAGE: March 12, 2010
    DOIhttps://doi.org/10.5636/jgg.26.539
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    A development of ion-cyclotron instability is simulated by numerical procedure on a basis of quasilinear theory. Particle and wave losses are taken into account. The diagrams included in this paper show variations of wave spectrum with time. Maximal wave amplitudes for different magnetospheric conditions in the region of Pc-1 generation are found to vary from -10 to -100mγ and duration of the event (an interval with square amplitude being greater than a half of maximum) from -7min to -70min. This data were used to verify an approximate expression which connects amplitude and duration of emission with initial parameters of plasma.
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  • Paleomagnetism of Late Cretaceous Alkaline Rocks in the Nemuro Peninsula, Hokkaido, N. E. Japan
    Yoshiki FUJIWARA, Toshinori OHTAKE
    1974 Volume 26 Issue 6 Pages 549-558
    Published: 1974
    Released on J-STAGE: March 12, 2010
    DOIhttps://doi.org/10.5636/jgg.26.549
    JOURNAL FREE ACCESS
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    A paleomagnetic study was made on 747 specimens from 57 sites from Late Cretaceous alkaline rocks in the Nemuro Peninsula, Hokkaido, N. E. Japan (43.3°N, 145.8°E). Direction of magnetization of samples from the marginal parts of some monzonite or piclitic dolerite complex are quite different from those from the central parts. This suggests that the transitional change of geomagnetic field polarity might have occurred during cooling of the rock body. The paleomagnetic results suggest the presence of two short reversed zones in the Upper Cretaceous in which normal polarity was predominant. Recent K-A age determinations suggest that these reversals took place at 88m. y. and 84m. y. ago. They should become important time markers in Cretaceous paleomagnetic stratigraphy.
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  • Uniqueness on Ionospheric Wind Deduced from Geomagnetic Sq Variation
    Susumu KATO
    1974 Volume 26 Issue 6 Pages 559-561
    Published: 1974
    Released on J-STAGE: March 12, 2010
    DOIhttps://doi.org/10.5636/jgg.26.559
    JOURNAL FREE ACCESS
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