Dynamo and Dynamics, a Mathematical Challenge pp 331-338 | Cite as
Symmetries of the Solar Dynamo: Comparing Theory With Observation
Abstract
Since the discovery by Schwabe in 1843 of the cyclic nature of sunspot activity, there has been a great deal of attention paid to the nature of these cycles. In 1849 Wolf established a measure of sunspot activity, the Wolf number, defined as W = k(10g + f where g is the number of sunspot groups, f is the total number of spots and k is a factor allowing comparison between different observation series. Based on this measure we have the Zurich series of Wolf numbers which extends back to 1749. Since the counts for W are taken over the whole visible surface of the sun, all information about the spatial distribution of the sunspot activity is lost. Realising the importance of such spatial information, Carrington in 1853 began the recording of the latitudes and longitudes of spots and this eventually resulted in the Greenwich series of photographic recordings of the solar surface which lasted from 1874 to 1976. Maunder introduced the famous Maunder or butterfly diagram (so called because the pattern of the cycles resembles the wings of a butterfly) which shows spot activity as a travelling wave beginning in the higher latitudes and proceeding to the equator.
Keywords
Solar Cycle Sunspot Group Maunder Minimum Magnetic Equator Wolf NumberPreview
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