Long-term variations in the geomagnetic activity level Part II: Ascending phases of sunspot cycles
Monthly averages of the Helsinki Ak-values have been reduced to the equivalent aa-indices to extend the aa-data set back to 1844. A periodicity of about five cycles was found for the correlation coefficient (<i>r</i>) between geomagnetic indices and sunspot numbers for th...
| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
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| Series: | Annales Geophysicae |
| Online Access: | http://www.ann-geophys.net/12/1065/1994/angeo-12-1065-1994.html |