Long-term Solar Variability and the Solar Cycle in the 21 st Century Zasshikai short talk Boncho P. Bonev, Kaloyan M. Penev, and Stefano Sello ApJ 605, L81, 2004

1. Introduction Variation of the soar activity –11 year cycle –Maunder minimum From 1600AD to 1700AD –Long-term variation Gleissberug period (from optical solar record) –T = years  100 years (from recent analysis) Suess cycle (from aurora record) –T = quasi 200 years Solar activity forecast ?

2. The Time Series Analyzed 1. The 14 C radiocarbon data –4500 years span, 10 years step –Dendrochronology 2. The Schove series (aurora data) –1700 years span from 296AD –Quasi 200 year cycle (Activity in odd century) < (even century) during the past millennium 3. The Group Sunspot Number (GSP) –400 years span from 1610AD –R G = 12.08/N ∑k i G i G i : number of sunspot group, k i : correction factor N : number of observer, i : observer index

Fig.1 14 C data Large Δ 14 C value  low solar activity M : Maunder Minimum

Schove series (aurora) (Komitov & Bonev, ApJ 554, L119, 2001)

Group Sunspot Number (GSN) GSN Wolf (Hoyt & Schatten, SolPyhs, 181, 491, 1998)

3. Approach 1.Fast-Moving Window Periodogram Algoritm (MWPA) -800 years subset 2.Multiresolution Wavelet Analysis (WA)

Fig. 2-2 MWPA result for 14 C data

Fig. 2-1 WA result for 14 C data Regime 1 Regime 2

Regime 1 Large Δ 14 C value  low solar activity M : Maunder Minimum

4.2 Two Regimes of the Long- Term Solar Variability Regime 1 –Strong quasi 200 years cycle –Strognly suppressed 100 years cycle –( year cycle) Regime 2 –low 200 year cycle –Unstable and weak 100 year cycle Schove series (aurora) is very similar to 14 C data

4.3 Synthesis Regime 1 –210 years cycle –Low activity (Maunder type) Regime 2 –Overall active

4.3 Synthesis (continue 1) On the longer time scale –After Maunder Minimum Weak 200 year cycle Activity was highest in the middle of 20th century Changing from regime 1 to 2 ? On the shorter time scale –Now in the minimum phase of 100 year cycle –In the declining phase of 200 year cycle Untypical behavior of solar cycle 23 against the Gnevyshev-Ohl rule (the cycle 23 was magnetically weaker than the cycle 22)

4.3 Synthesis (continue 2) Long-term minimum in the next several decades Less deep than the Maunder Minimum ?

Thank you

Fig. 2 WA and MWPA