Quote:
Originally Posted by Tunga
All of this is happening at a time when the strength of the sun's magnetic field (as evidenced by the effects of the solar winds on perturbing the Earth's magnetic field - Ap index, AA index) are at unusual lows.
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I have looked through the Ae index given
here and I do not see anything unusual about it. So, magnetospherically there is nothing different. Also, IMHO, Ap and AA indices are not really very useful in describing the disturbance of the Earth's magnetosphere. In my 8 years or Earth magnetospheric work I have not used these indices in any of my papers.
Also, the solar wind magnetic field remains at its usual value, varying between 0.2 and 80 nT, with a normal value of about 6 nT.
Interestingly, I found the following comments on geomagnetic activity and solar cycle:
Quote:
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Originally Posted by Oulu Space Physics Dept
11-year variability
The 11-year variability of the geomagnetic activity (e.g., Ellis, 1900) has been recently studied by Vennestrom and Friis-Christensen (1996). They suggest that the activity can be divided into three peaks:
1. Shortly before sunspot maximum. Linked with transient solar activity, and seen with relatively larger amplitude in ring current (storm) activity than in substorm activity.
2. About 2 years after sunspot maximum. Largest peak compound of transient and recurrent magnetic activity (the former dominating?).
3. Descending phase of the solar cycle. Largely recurrent, and seen with larger amplitude in substorm activity than in ring current (storm) activity.
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So, as far as I can see, there is no "unusual low."
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Martin (
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