yes / We derive two principal components (PCs) of temporal magnetic field variations over the solar
cycles 21–24 from full disk magnetograms covering about 39% of data variance, with σ = 0.67.
These PCs are attributed to two main magnetic waves travelling from the opposite hemispheres
with close frequencies and increasing phase shift. Using symbolic regeression analysis we also derive
mathematical formulae for these waves and calculate their summary curve which we show is linked
to solar activity index. Extrapolation of the PCs backward for 800 years reveals the two 350-year
grand cycles superimposed on 22 year-cycles with the features showing a remarkable resemblance
to sunspot activity reported in the past including the Maunder and Dalton minimum. The summary
curve calculated for the next millennium predicts further three grand cycles with the closest grand
minimum occurring in the forthcoming cycles 26–27 with the two magnetic field waves separating
into the opposite hemispheres leading to strongly reduced solar activity. These grand cycle variations
are probed by α − Ω dynamo model with meridional circulation. Dynamo waves are found generated
with close frequencies whose interaction leads to beating effects responsible for the grand cycles
(350–400 years) superimposed on a standard 22 year cycle. This approach opens a new era in
investigation and confident prediction of solar activity on a millenium timescale.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/11803 |
| Date | 25 September 2015 |
| Creators | Zharkova, Valentina V., Shepherd, Simon J., Popova, E., Zharkov, Sergei I. |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Article, Published version |
| Rights | © 2015 The Authors. Published open access by Nature Publishing under the CC BY licence (Creative Commons Attribution v4.0 International License). |
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