Solar activity over the last 1150 years: does it correlate with climate? S.K. Solanki 1, I. Usoskin 2, M. Schüssler 1, K. Mursula 2 1: Max-Planck-Institut.

Solar activity over the last 1150 years: does it correlate

with climate?

S.K. SolankiS.K. Solanki11, , I. UsoskinI. Usoskin22, ,

M. SchM. Schüsslerüssler11, K. Mursula, K. Mursula22

1: Max-Planck-Institut für Sonnensystemforschung 1: Max-Planck-Institut für Sonnensystemforschung (previously Max-Planck-Institut für Aeronomie)(previously Max-Planck-Institut für Aeronomie)

2: University of Oulu2: University of Oulu

Direct solar activity recordSunspot numbers provide the longest running record of directly measured solar activity

H. Avercamp

Open and closed magnetic fluxOpen and closed magnetic flux

Open flux: fast solar wind

Closed flux: slow solar wind

A small part of the total flux through the solar surface connects as open flux to interplanetary space

Reconstruction of Open Flux back to 1700, based on Sunspot Number

10Be Open solar flux

Interplanetary fieldInterplanetary field

Solanki et al. 2000 Nature

Proxy: 10Be concentration in ice cores

-500

0

500

1000

1500

800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 2000

Years

10 B

e (p

erm

ille)

-0.7

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1.8

10 B

e (1

0 4 a

tom

/g)

Antarctica

Greenland

Method Sunspot numbersSunspot numbers

Model by Solanki et al. (2000)Model by Solanki et al. (2000)

Sunspot number Sunspot number open magn.open magn. fluxflux

Heliospheric paramsHeliospheric params

Model by Usoskin et al. (2002a)Model by Usoskin et al. (2002a)

Modul. strength Modul. strength CR intens. variationsCR intens. variations

CR intensityCR intensity

Models of Masarik & Beer (1999) Models of Masarik & Beer (1999) Webber & Higbie (2003)Webber & Higbie (2003)

Cosmogenic Cosmogenic isotopes isotopes Usoskin et al. (2002b)Usoskin et al. (2002b) in natural archives in natural archives

Usoskin et al. (2004) Usoskin et al. (2004)

nonlinearnonlinear

nonlinearnonlinear

Sunspot number 850-2000 AD Since 1610 telescopic measurement of sunspot numberSince 1610 telescopic measurement of sunspot number Prior to that, reconstructed sunspot number from Be-10 Prior to that, reconstructed sunspot number from Be-10

concentrations (using simple physical model for each step)concentrations (using simple physical model for each step)

Usoskin et al. 2003 Phys. Rev. Lett.

Sun is more active since ~1940 than in previous 1100 yearsSun is more active since ~1940 than in previous 1100 years

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1000 1200 1400 1600 1800 2000

T a

nom

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)

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Sun

spot

num

berSunspot

T_n, MBH99

Comparison: Sunspot number & ClimateMann & Jones 2003Mann & Jones 2003

Mann, Bradley & Hughes 1999Mann, Bradley & Hughes 1999

CorrelationsNorthern hemisphere:

Correlation between SN and northern hemisphere temperatures approx. 0.5-0.55 (significance 98-99%)

Trend correlates at 0.7-0.8 level (signific. 94-98%)

On short term, marginal correlation, 85-95% signific.

Southern hemisphere:

No significant correlation for raw data and trend

On short term, marginal correlation (as for N-hemisp.)

Open magnetic flux and cosmic ray flux:

Same correlations

Calculation of significance

Standard formulae give very high significance Standard formulae give very high significance for correlations involving raw data (10for correlations involving raw data (10-8-8 false false alarm probability).alarm probability).

We have chosen to use the non-parametric We have chosen to use the non-parametric “random phase” Monte Carlo method “random phase” Monte Carlo method (following Ebisuzaki 1997) to determine the (following Ebisuzaki 1997) to determine the true significance. This takes into account the true significance. This takes into account the possibility that nearby data points are not possibility that nearby data points are not totally independent (which appears to be the totally independent (which appears to be the case).case).

Influence of Sun on climate or influence of climate on 10Be?

Could the good correlation be due to climate influence on 10Be concentration?

Cross-correlation shows: SN runs ahead of climate by 10 years (~1 sampling interval),which argues against climate effect on 10Be as dominant influence.

Conclusions Sunspot numbers, open flux and cosmic ray Sunspot numbers, open flux and cosmic ray

flux reconstructed over the past 1150 years flux reconstructed over the past 1150 years show correlations with climate in the northern show correlations with climate in the northern hemisphere significant at 98% level.hemisphere significant at 98% level.

Main effect is due to the “hockey stick” shape, Main effect is due to the “hockey stick” shape, which is also shown by solar data! which is also shown by solar data!

We live not just in climatically special times, We live not just in climatically special times, but also in times of exceptional solar activity!but also in times of exceptional solar activity!

Analysis excludes last 25 years, when Sun Analysis excludes last 25 years, when Sun did not behave like climate (e.g. Solanki & did not behave like climate (e.g. Solanki & Krivova 2003)Krivova 2003)

Outlook

Compare SN with other temperature series Compare SN with other temperature series (in (in progress)progress) and carry out multivariate regression and carry out multivariate regression including greenhouse gases and volcanoes etc. including greenhouse gases and volcanoes etc.

Use the sunspot number record to reconstruct Use the sunspot number record to reconstruct irradiance record via magnetic flux irradiance record via magnetic flux (in progress)(in progress)

Test SN reconstruction using other cosmogenic Test SN reconstruction using other cosmogenic isotopes isotopes (in progress)(in progress)

Reconstruct SN further back in time: is the current Reconstruct SN further back in time: is the current period of high solar activity unique or were there period of high solar activity unique or were there also earlier such episodes? How rare are they? also earlier such episodes? How rare are they? (in (in progress)progress)