Volume 85, Number 4, February 2009
Article Number 49002
Number of page(s) 5
Section Geophysics, Astronomy and Astrophysics
Published online 03 March 2009
EPL, 85 (2009) 49002
DOI: 10.1209/0295-5075/85/49002

Transitional dynamics of the solar convection zone

A. Bershadskii1, 2

1  ICAR - P.O. Box 31155, Jerusalem 91000, Israel
2  ICTP - Strada Costiera 11, I-34100 Trieste, Italy, EU

received 17 July 2008; accepted in final form 30 January 2009; published February 2009
published online 3 March 2009

Solar activity is studied using a cluster analysis of the time-fluctuations of sunspot number. In the historic period (1850–1932) the cluster exponent $\alpha \simeq$ 0.37 (strong clustering) for the high-activity components of the solar cycles. In the modern period (last seven solar cycles: 1933–2007) the cluster exponent was $\alpha \simeq$ 0.50 (random, white-noise–like). Comparing these results with the corresponding data from laboratory experiments on convection it is shown that in the historic period the emergence of sunspots in the solar photosphere was dominated by turbulent photospheric convection. In the modern period, this domination was broken by a new more active dynamics of the inner layers of the convection zone. Cluster properties of the solar-wind magnetic field and the aa-geomagnetic-index also support this result. Long-range chaotic dynamics in the solar activity is briefly discussed.

96.60.qd - Sun spots, solar cycles.

© EPLA 2009