Latitudinal effect in semiannual variation of geomagnetic activity
نویسندگان
چکیده
منابع مشابه
Semiannual Variation of Geomagnetic Activity
The semiannual variation in geomagnetic activity is well established in geomagnetic data Its explanation has remained elusive, however. We propose, simply, that it is caused by a semiannual variation in the effective southward component of the interplanetary field. The southward field arises because the interplanetary field is ordered in the solar equatorial coordinate system, whereas the inter...
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We investigate the cause of the unusually strong semiannual variation of geomagnetic activity observed in the solar minimum years of 1954 and 1996. For 1996 we separate the contributions of the three classical modulation mechanisms (axial, equinoctial, and Russell-McPherron) to the six-month wave in the aam index and find that all three contribute about equally. This is in contrast to the longe...
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By making use of the techniques of power spectrum analysis and simple linear filtering procedures, it is shown that the amplitude of the 27-day variation of the geomagnetic disturbance index Ci is subject to a significant semiannual modulation. It is also shown that there is no amplitude modulation of this component with other periods such as the annual or 11-year period. The semiannual amplitu...
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[1] Mursula et al. [2011] (MTL11) suggest that there is a 22-year variation in solar wind activity that coupled with the variation in heliographic latitude of the Earth during the year, gives rise to an apparent semiannual variation of geomagnetic activity in averages obtained over several solar cycles. They suggest that the observed semiannual variation is seriously overestimated and is largel...
متن کاملThe Boller-stolov Mechanism and the Semiannual and Daily Mcintosh Effects in Geomagnetic Activity
According to Boller and Stolov (1974), the probability of instabilities (and the magnetic activity) should be proportional to A o + A 1 sin 2 •M, where A o and A 1 are constant and •4 is the angle between the solar wind and the dipole axis of the earth. Such an expression permits one to fit very well, in phase and in amplitude, both the semiannual and the daily variation of the magnetic activit...
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ژورنال
عنوان ژورنال: Journal of Geophysical Research: Space Physics
سال: 2003
ISSN: 0148-0227
DOI: 10.1029/2002ja009467