Two dynamo waves derived with Principal Component Analysis of solar magnetic field and prediction of solar activity on millenium scales
Tuesday, 15 December 2015
Poster Hall (Moscone South)
We present principal components analysis (PCA) of temporal magnetic field variations over the solar cycles 21-24. These PCs reveal two main magnetic waves with close frequencies (covering 40$\%$ of data variance) travelling from the opposite hemispheres with an increasing phase shift. Extrapolation of these PCs through their summary curve backward for 2000 years reveals a number of $~$350-year grand cycles superimposed on 22 year-cycles with the features showing a remarkable resemblance to sunspot activity reported in the past. The summary curve calculated forward for the next millennium predicts further three grand cycles with the closest grand minimum occurring in the forthcoming cycles 25-27 when the two magnetic field waves have a phase shift of 11 years. These grand cycle variations are probed by Parker's two layer dynamo model with meridional circulation revealing two dynamo waves generated with close frequencies. Their interaction leads to beating effects responsible for the grand cycles (300-350 years) superimposed on standard 22 year cycles and for the super-grand cycle of 900-1000 years. This approach opens a new era in investigation and prediction of solar activity on long-term timescales.