List of Figures

View Image Figure 1:
Sunspot numbers since 1610. a) Monthly (since 1749) and yearly (1700 – 1749) Wolf sunspot number series. b) Monthly group sunspot number series. The grey line presents the 11-year running mean after the Maunder minimum. Standard (Zürich) cycle numbering as well as the Maunder minimum (MM) and Dalton minimum (DM) are shown in the lower panel.
View Image Figure 2:
Cyclic variations. Panel a: Time profiles of sunspot numbers; Panel b: Cosmic-ray flux as the count rate of Climax neutron monitor (NM) (100% NM count rate corresponds to May 1965).
View Image Figure 3:
Geomagnetic field intensity over millennia: VADM compilation by Yang et al. (2000, – Y00 curve with 1σ statistical errors of the sample distribution); dipole moment according to Hongre et al. (1998, – HBI red dots) since 800 AD, dipole moment according to CALS7K.2 model (Korte and Constable, 2005, – K05 magenta curve with 1 σ error band) as well as a recent ArcheoInt compilations of VADM/VDM (Genevey et al., 2008, – A08 azure diamonds) and (Knudsen et al., 2008, – K08 blue stars).
View Image Figure 4:
Schematic representation of 14C (left) and 10Be (right) production chains. The flux of cosmic rays impinging on the Earth is affected by both heliospheric modulation and geomagnetic field changes. The climate may affect the redistribution of the isotopes between different reservoirs. Dashed line denotes a possible influence of solar activity on climate.
View Image Figure 5:
Radiocarbon series for the Holocene. Upper panel: Measured content of Δ14C in tree rings by INTCAL-98/04 collaboration (Stuiver et al., 1998Reimer et al., 2004). The long-term trend is caused by the geomagnetic field variations and the slow response of the oceans. Lower panel: Production rate of 14C in the atmosphere, reconstructed from the measured Δ14C (Usoskin and Kromer, 2005).
View Image Figure 6:
Differential production rate for cosmogenic isotopes and ground-based neutron monitors as a function of cosmic-ray energy. Panel A): Yield functions of the globally averaged and polar 10Be production (Webber and Higbie, 2003), global 14C production (Castagnoli and Lal, 1980), polar neutron monitor (Clem and Dorman, 2000) as well as the energy spectrum of galactic cosmic protons for medium modulation (ϕ = 550 MV). Panel B): The differential production rate for global and polar 10Be production, global 14C production, and polar neutron monitor.
View Image Figure 7:
Globally-averaged production rate of 14C as a function of the modulation potential ϕ and geomagnetic dipole moment M, computed using the yield function by Castagnoli and Lal (1980), LIS by Burger et al. (2000) and cosmic-ray–modulation model by Usoskin et al. (2005a). Another often used model (Masarik and Beer, 1999) yields a similar result.
View Image Figure 8:
A 12-box model of the carbon cycle (Broeker and Peng, 1986Siegenthaler et al., 1980).The number on each individual box is the steady-state Δ14C of this particular reservoir expressed in per mil. (After Bard et al., 1997)
View Image Figure 9:
Wet (panel a) and dry (panel b) deposition of 10Be, computed using the NASA GISS model (Field et al., 2006) for a fixed sea-surface temperature.
View Image Figure 10:
Scatter plot of smoothed group sunspot numbers vs. (2-year delayed) 10Be concentration. a) Annual (connected small dots) and 11-year averaged (big open dots) values. b) Best-fit linear regressions between the annual (dashed line) and 11-year averaged values (solid line). The dots are the same as in panel (a). (After Usoskin and Kovaltsov, 2004).
View Image Figure 11:
An unsuccessful attempt at the reconstruction of cosmic-ray intensity in the past using a regression with sunspot numbers (After Belov et al., 2006). Dots represent the observed cosmic-ray intensity since 1951. Note the absence of a long-term trend.
View Image Figure 12:
Several reconstructions of the decade-averaged modulation potential ϕ for the last few centuries: from sunspot numbers (SN(U02) – Usoskin et al., 2002b), from 14C data (14C(S04), 14C(M05), 14C(M07) – Solanki et al., 2004Muscheler et al., 20052007, respectively), from Antarctic 10Be data (10Be(U03), 10Be(MC04) – Usoskin et al., 2003cMcCracken et al., 2004, respectively). The thick black NM curve is based on direct cosmic-ray measurements by neutron monitors since 1951 (Usoskin et al., 2005a) and ionization chambers since 1936 (McCracken and Beer, 2007).
View Image Figure 13:
An example of reconstruction of the heliospheric magnetic field at Earth orbit for the last 600 years from 10Be data (McCracken, 2007).
View Image Figure 14:
Long-term sunspot-number reconstruction from 14C data (after Usoskin et al., 2007). All data are decade averages. Solid (denoted as ‘Y00’) and grey (‘K05’) curves are based on the paleo-geomagnetic reconstructions of Yang et al. (2000) and Korte and Constable (2005), respectively. Observed group sunspot numbers (Hoyt and Schatten, 1998) are shown after 1610.
View Image Figure 15:
10-year averaged sunspot numbers: Actual group sunspot numbers (thick grey line) and the reconstructions based on 10Be (thin curve, Usoskin et al., 2003c) and on 14C (thick curve with error bars, Solanki et al., 2004). The horizontal dotted line depicts the high activity threshold.
View Image Figure 16:
Immediate 44Ti activity in stony meteorites as a function of time of fall. Dots with error bars correspond to measured values (Taricco et al., 2006). Curves correspond to the theoretically expected 44Ti activity, computed using the method of Usoskin et al. (2006c) and different reconstructions of ϕ shown in Figure 12.
View Image Figure 17:
Sunspot activity (over decades, smoothed with a 12221 filter) throughout the Holocene, reconstructed from 14C by Usoskin et al. (2007) using geomagnetic data by Yang et al. (2000). Blue and red areas denote grand minima and maxima, respectively.
View Image Figure 18:
Histogram of sunspot-number distribution for the series shown in Figure 17. Hatched areas correspond to directly-observed sunspots after 1610. The curve represents the best fit normal distribution.
View Image Figure 19:
Wavelet (Morlet basis) spectrum of the sunspot-number reconstruction shown in Figure 17. Left and right-hand panels depict 2D and global wavelet spectra, respectively. Upper and lower panels correspond to period ranges of 500 – 5000 years and 80 – 500 years, respectively. Dark/light shading denotes high/low power.
View Image Figure 20:
Histogram of the duration of grand minima from Table 1.
View Image Figure 21:
Daily fluence of solar energetic particles (dashed curve) and galactic cosmic rays for the day of January 20, 2005. Open circles represent space-borne measurements (Mewaldt, 2006).
View Image Figure 22:
Measured (dots) and calculated (curves) 14C activity in a lunar sample 68815 (Jull et al., 1998). The big diamond implies contamination of a thin surface layer by 14C implanted from solar wind. The dotted curve represents the expected production due to GCR, while the solid curve is the best fit SEP+GCR model production.
View Image Figure 23:
Altitude profile of the cosmic-ray–induced ionization (CRII) rate in the polar atmosphere, computed using the model by Usoskin and Kovaltsov (2006). Dashed and dotted curves depict the average CRII for solar maxima and minima, respectively. The solid curve denotes the average CRII due to solar energetic particles for the day of January 20, 2005.
View Image Figure 24:
Cumulative probability of a large solar energetic particle event to occur (after McCracken et al., 2001b). The black histogram, extrapolated from the blue line corresponds to the directly observed SEP events (Reedy, 1996). Arrows (extrapolated from the brown line) depict an upper limit obtained from the analysis of lunar rock (see Table 3) assuming that the entire fluence has been produced within a few extreme events. Diamonds represent the result derived from the nitrate data for 1561 – 1950 (McCracken et al., 2001b).