Long-Term Solar Activity Reconstruction:
Grand Minima and Maxima Ilya Usoskin1, Sami K. Solanki2, Gennady Kovaltsov3 1 Sodankylä
Geophysical Observatory, University of Oulu, Finland 2 Max-Planck-Institut for Solar System Research, Katlenburg-Lindau, Germany 3 Ioffe Physical-Technical Institute, St.Petersburg, Russia
Solar activity variations: telescopic sunspot number record Group sunspot number
150
100
50
0 1600
1700
1800
1900
2000
• 11-year solar cycle (Christian Horrebow 1770s; Schwabe 1843)
• Variable amplitude/envelope (Gleissberg 1944); • Maunder minimum (Hivelius; Eddy 1976); • The contemporary level is high
Solar activity in the past Electronic Photographic data Geomagnetic measurements Sunspot counts and drawings Aurora sightings Naked eye sunspot observations Cosmogenic isotopes 1E+6
1E+5
1E+4
1E+3
1E+2
Years before present
1E+1
1E+0
Proxy of SA: Cosmogenic isotopes Geomagnetic field IMF, solar wind
Cosmic Rays
• Variable solar activity expands to the Heliosphere: solar wind, interplanetary
magnetic field, interplanetary transients (CME, corotation regions), etc. • Galactic cosmic rays are modulated by IMF, magnetic inhomogeneities, solar wind; • Geomagnetic field partly shields the Earth (mid- and low-latitude regions) from incoming cosmic rays; • This process is well understood and can be properly modelled (Beer, Space Sci. Rev., 2000; Usoskin et al., Phys. Rev. Lett., 2003; Solanki et al., Nature, 2004)
SN reconstruction from 14C or 10Be Sunspot numbers e.g. Model by Solanki et al. (2002) Sunspot number nonlinear
open magn. flux Heliospheric params
e.g. Model by Usoskin et al. (2002a) Modul. strength
nonlinear
CR intens. variations CR intensity
Deposition models, paleomagnetic models 10Be: Webber & Higbie, 14C: Usoskin & Kromer B⊕:Yang et al. (2000), Korte & Constable (2005) Cosmogenic isotopes Usoskin et al. (2002b) in natural archives Solanki et al. (2004) , Usoskin et al. (2004, 2007)
Sunspot number reconstructed from 14C Sunspot number
80
Smoothed Sunspot number over 11400 yr
60
40
20
0 -10000
-9000
-8000
-7000
-6000
-5000
-4000
Sunspot number
80
27 Grand minima 19 Grand maxima can be identified.
60
40
20
0 -4000
-3000
-2000
-1000
0
1000
2000
Minima cover 1880 yr ≈ 17% of time Maxima cover 1030 yr ≈ 9% of time
Years (-BC/AD)
Solanki,. Usoskin, Kromer, Schüssler, Beer, Nature, 2004 Usoskin, Solanki & Kovaltsov, A&A, 2007
Sunspot number statistics Max
Min
Number per bin
100
10
1
0
20
40
60
80
Red curve: best-fit normal distribution
100
Waiting time distribution Grand minima
Grand maxima waiting time distribution
Differential distribution
0.01
1E-3
1E-3
1E-4
100
1000
Interval length (Years)
1E-4 100
1000
Interval length (Years)
Closer to power law (red lines) than to exponential (dotted yellow lines) waiting time tends to show clustering of Min and Max
Durations of Minima & Maxima Grand minima
Grand maxima Differential distribution
Number per bin
6
4
2
0 50
100
150
Duration (Years)
Maunder
0.01
1E-3
0
50
100
150
Duration (Years)
Spoerer
Quasi-Bimodal
Exponential
200
Conclusions
The Sun spends 17% of the time in grand minima, 9% in grand maxima. Currently the Sun is in a grand maximum.
Grand minima/maxima are not due to long-term cyclic variations but rather to stochastic/chaotic processes.
Waiting time distribution of occurrence of grand minima and maxima deviates from an exponential distribution typical of non-Poisson processes with, e.g., self-organized criticality or processes related to accumulation and release of energy.
Grand minima can be classified into two different types: short minima of Maunder type and long minima of Spörer type.
Duration of grand maxima exponentially distributed leaving a grand maximum is a random process, unlike for grand minima
/kg) 44Ti activity (dpm/kg)
9
GSN
Ti-44 activity: measurements vs. model
S04
8
M05-A M05-M
7
Ti-44
6
5
4
3 1750
1800
1850
1900
1950
Model
χ2 (DoF)
Confid. level
GSN
7.55(17)
98%
S04
2.44 (8)
97%
M05-M
20.5 (11)
4%
M05-A
4.4 (11)
95%
2000
Preliminary results! New data are currently being finalized and analyzed
