Brightness of the Coronal Green Line and Prediction for Activity Cycles 23 and 24
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- Badalyan, O., Obridko, V. & Sýkora, J. Solar Physics (2001) 199: 421. doi:10.1023/A:1010343520424
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Cyclic variations of the mean semi-annual intensities Iλ of the coronal green line λ530.3 nm are compared with the mean semi-annual variations of the Wolf numbers W during the period of 1943–1999 (activity cycles 18–23). The values of Iλ in the equatorial zone proved to correlate much better with the Wolf numbers in a following cycle than in a given one (the correlation coefficient r is 0.86 and 0.755, respectively). Such increase of the correlation coefficient with a shift by one cycle differs in different phases of the cycle, being the largest at the ascending branch. The regularities revealed make it possible to predict the behaviour of W in the following cycle on the basis of intensities of the coronal green line in the preceding cycle. We predict the maximum semi-annual W in cycle 23 to be 110–122 and the epoch of minimum between cycles 23 and 24 to take place at 2006–2007. A slow increase of Iλ in the current cycle 23 permits us to forecast a low-Wolf-number cycle 24 with the maximum W∼50 at 2010–2011. A scheme is proposed on the permanent transformation of the coronal magnetic fields of different scales explaining the found phenomenon.