Size of the coming solar cycle 24 based on Ohl's Precursor Method, final estimate
In Ohl's Precursor Method (Ohl, 1966, 1976), the geomagnetic activity during the declining phase of a sunspot cycle is shown to be well correlated with the size (maximum sunspot number <I>Rz</I>(max)) of the next cycle. For solar cycle 24, Kane (2007a) used <I>aa</I>(...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2010-07-01
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| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/28/1463/2010/angeo-28-1463-2010.pdf |
| Summary: | In Ohl's Precursor Method (Ohl, 1966, 1976), the
geomagnetic activity during the declining phase of a sunspot cycle is shown
to be well correlated with the size (maximum sunspot number <I>Rz</I>(max)) of the next
cycle. For solar cycle 24, Kane (2007a) used <I>aa</I>(min)=15.5 (12-month running
mean), which occurred during March–May of 2006 and made a preliminary estimate
<I>Rz</I>(max)=124±26 (12-month running mean). However, in the next few months,
the <I>aa</I> index first increased and then decreased to a new low value of 14.8 in
July 2007. With this new low value, the prediction was <I>Rz</I>(max)=117±26
(12-month running mean). However, even this proved a false signal. Since
then, the aa values have decreased considerably and the last 12-monthly
value is 8.7, centered at May 2009. For solar cycle 24, using <I>aa</I>(min)=8.7,
the latest prediction is, <I>Rz</I>(max)=58.0±25.0. |
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| ISSN: | 0992-7689 1432-0576 |