Vita-Finzi, C;
(2021)
The ~11 yr Solar Cycle.
UCL Department of Earth Sciences: London, UK.
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Abstract
Sunspot numbers and shifts in their distribution display a period of approximately 11 yr, a value sometimes uncritically applied to other measures of solar activity, direct and indirect, including the 10.7 cm radio flux, the inflow of galactic cosmic rays, solar flare frequency, terrestrial weather, and components of space climate, with a possible resulting loss of information. The ruling (Babcock) hypothesis and its derivatives link the sunspot cycle to dynamo processes mediated by differential solar rotation, but despite 60 years of observation and analysis the ~11 yr periodicity remains difficult to model; the possible contribution of planetary dynamics is also still controversial. The various solar sequences that genuinely display an ~11 yr cycle stand to benefit from an understanding of its periodicity that goes beyond statistical rigour. The outcome could ironically prompt the demotion of sunspots from their dominant historical role in favour of other possible indicators of solar cyclicity, such as the solar wind flux and its isotopic signatures, even if they are less accessible.
| Type: | Working / discussion paper |
|---|---|
| Title: | The ~11 yr Solar Cycle |
| Open access status: | An open access version is available from UCL Discovery |
| Publisher version: | https://www.ucl.ac.uk/earth-sciences/ |
| Language: | English |
| Keywords: | solar cycle, sunspot numbers, Babcock-Leighton model, solar wind, cosmogenic isotopes, planetary hypothesis |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10140133 |
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