Mountains versus valleys: 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...
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The morphology of glacial valley can be described in terms of power law or quadratic equations fitted to valley cross-profiles. These two models are used to study the cross-profiles of 86 valley cross-profiles in the Zardkuh Mountain in order to understand the evolutional patterns of valleys. Assessment of using the power law function indicates that b values for both valley sides range from 1.0...
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ژورنال
عنوان ژورنال: Journal of Geophysical Research: Space Physics
سال: 2000
ISSN: 0148-0227
DOI: 10.1029/1999ja900439