Palaeomagnetic intensity data: an Achilles heel of solar activity reconstructions

Abstract

Reconstructions of solar activity prior to AD 1600 rely on estimates of the past production rates of cosmogenic radionuclides in the Earth's atmosphere. These rates are modulated by the strength of the solar magnetic field and the intensity of the Earth's geomagnetic dipole. One of the largest uncertainties associated with these reconstructions originates from palaeointensity data and to show how errors in palaeomagnetic data influence reconstructions of solar activity we present different radiocarbon based reconstructions of the solar magnetic modulation parameter (Φ) during the Holocene. We considered geomagnetic field changes according to (i) a global archaeomagnetic compilation, (ii) a geomagnetic field model covering the last 7000 years and (iii) a regional sediment relative palaeointensity record. Comparison between alternative solar modulation reconstructions shows that the uncertainties in palaeomagnetic data prevent us from making robust conclusions about solar variability at timescales longer than a few hundred years. Our analyses indicate that the geomagnetic dipole field dominates radiocarbon production at timescales longer than 500 years although a combination of solar and geomagnetic modulation could apply to all timescales. Long-term trends depend on which palaeomagnetic data set is used for correction and there are additional unexplained differences between ¹⁰Be and ¹⁴C records that question results about long-term changes in solar activity. The higher-resolution geomagnetic field records, which are usually very much smoothed in stacked records, also indicate that part of the shorter-term changes (~500 yr) in the radiocarbon production rate could be attributed to the geomagnetic dipole field. To test this hypothesis and improve our knowledge of past solar activity a higher resolution palaeomagnetic reconstruction of geomagnetic dipole moment is required.

Keywords

Palaeomagnetism cosmogenic radionuclides solar activity Holocene.

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References

Bard, E. and Frank, M. 2006: Climate change and solar variability: what's new under the Sun? Earth and Planetary Science Letters 248, 480—93 .

Bond, G. , Kromer, B. , Beer, J. , Muscheler, R. , Evans, M.N. , Showers, W. , Hoffman, S. , Lotti-Bond, R. , Hajdas, I. and Bonani, G. 2001: Persistent solar influence on North Atlantic climate during the Holocene . Science 294, 2130—36 .

Chambers, F.M. , Mauquoy, D. , Brain, S. , Blaauw, M. and Daniell, J.R.G. 2007: Globally synchronous climate change 2800 years ago: proxy data from peat in South America . Earth and Planetary Science Letters 253, 439—44 .

Denton, G.H. and Karlén, W. 1973: Holocene climatic variations — their pattern and possible cause . Quaternary Research 3, 155—205 .

Donadini, F. , Korhonen, K. , Riisager, P. and Pesonen, L.J. 2006: Database for Holocene geomagnetic intensity information . EOS 87, 137—43 .

Evans, M.E. 1976: Test of the dipolar nature of the geomagnetic field throughout Phanerozoic time . Nature 262, 676—77 .

Finkel, R.C. and Nishiizumi. K. 1997: Beryllium-10 concentrations in the Greenland ice sheet project 2 ice core from 3—40 ka . Journal of Geophysical Research 102, 26 699—706 .

Foukal, P. , North, G. and Wigley, T. 2004: A stellar view on solar variations and climate . Science 306, 68—69 .

Foukal, P. , Frölich, C. , Spuit, H. and Wigley, T.M.L. 2006: Variations in solar luminosity and their effect on the Earth's climate . Nature 44, 161—66 .

10.

Fröhlich, C. and Lean, K. 2004: Solar radiative output and its variability . Astronomy and Astrophysics Reviews 12, 273—320 .

11.

Genevey, A. , Gallet, Y. and Margueron, J. 2003: Eight thousand years of geomagnetic field intensity variations in the eastern Mediterranean . Journal of Geophysical Research 108 (B5) 2228 , doi:10.1029/2001JB001612.

12.

Gleeson, L.J. and Axford, W.I. 1968: Solar modulation of galactic cosmic rays . Astrophysical Journal 154, 1011—18 .

13.

Gratton, M.N. , Shaw, J. and Herrero-Bervera, E. 2004: An absolute paleointensity record from SOH1 lava core, Hawaii using the microwave technique . Physics of the Earth and Planetary Interiors 248, 193—214 .

14.

Hoyt, D.V. and Schatten, K.H. 1998: Group sunspot numbers: a new solar activity reconstruction. Solar Physics 179, 189—219 .

15.

Korte, M. and Constable, C.G. 2005: The geomagnetic dipole moment over the last 7000 years — new results from a global model . Earth and Planetary Science Letters 236, 348—58 .

16.

——— 2006a: On the use of calibrated relative paleointensity records to improve millennial-scale geomagnetic field models . Geochemistry, Geophysics, Geosystems 7, Q09004 doi:10.1029/2006GC001368.

17.

——— 2006b: Centennial to millennial geomagnetic secular variation . Geophysical Journal International 167, 43—52

18.

Korte, M. , Genevey, A. , Constable, C.G. , Frank, U. and Schnepp, E. 2005: Continuous geomagnetic field models for the past 7 millennia: 1. A new global data compilation . Geochemistry Geophysics Geosystems 6, Q02H15, doi:10.1029/2004GC00800.

19.

Lean, J. 2005: Living with a variable Sun. Physics Today 58, 32—38 . Lockwood, M. , Stamper, R. and Wild, M.N. 1999: A doubling of the Sun's coronal magnetic field during the past 100 years . Nature 399, 437—39 .

20.

Masarik, J. and Beer, J. 1999: Simulation of particle fluxes and cosmogenic nuclide production in the Earth's atmosphere . Journal of Geophysical Research 104, 12 099—3012 .

21.

Merrill, R.T. , McElhinny, M.W. and McFadden, P.L. 1998: The magnetic field of the Earth: palaeomagnetism, the core and the deep mantle . International Geophysics Series 63, Academic Press , 531 pp.

22.

Michel, R. and Neumann, S. 1998: Interpretation of cosmogenic nuclides in meteorites on the basis of accelerator experiments and physical model calculations . Proceedings of the Indian Academy of Sciences 107, 441—57 .

23.

Muscheler, R. , Beer, J. , Wagner, G. , Laj, C. , Kissel, C. , Raisbeck, G.M. , Yiou, F. and Kubik, P.W. 2004: Changes in the carbon cycle during the last deglaciation as indicated by the comparison of 10Be and 14C records . Earth and Planetary Science Letters 219, 325—40 .

24.

Muscheler, R. , Joos, F. , Müller, S.A. and Snowball, I. 2005a: Not so unusual — today's solar activity . Nature E3-E4, doi:10.1038/ nature04045.

25.

Muscheler, R. , Beer, J. , Kubik, P.W. and Synal, H.-A. 2005b: Geomagnetic field intensity during the last 60,000 years based on 10Be & 36Cl from the Summit ice cores and 14C . Quaternary Science Reviews 10.1016/j.quascirev.2005.01.012.

26.

Raisbeck, G.M. and Yiou, F. 2004: Comment on millennium scale sunspot number reconstruction: evidence for an unusually active sun since the 1940s . Physical Review Letters 92, DOI: 10.1103/ PhysRevLett.92.199001.

27.

Reimer, P.J. , Baillie, M.G.L. , Bard, E. , Bayliss, A. , Beck, J.W. , Bertrand, C.J.H. , Blackwell, P.G. , Buck, C.E. , Burr, G.S. , Cutler, K.B. , Damon, P.E. , Edwards, R.L. , Fairbanks, R.G. , Friedrich, M. , Guilderson, T.P. , Hogg, A.G. , Hughen, K.A. , Kromer, B. , McCormac, G. , Manning, S. , Ramsey, C.B. , Reimer, R.W. , Remmele, S. , Southon, J.R. , Stuiver, M. , Talamo, S. , Taylor, F.W. , van der Plicht, J. and Weyhenmeyer, C.E. 2004. IntCal04 terrestrial radiocarbon age calibration, 0—26 cal kyr BP . Radiocarbon 46, 1029—58 .

28.

Rind, D. 2002: The Sun's role in climate variations . Science 296, 673—77 .

29.

Siegenthaler, U. , Heimann, M. and Oeschger, H. 1980: 14C variations caused by changes in the global carbon cycle . Radiocarbon 22, 177—91 .

30.

Snowball, I. and Sandgren, P. 2002: Geomagnetic field variations in northern Sweden during the Holocene quantified from varved lake sediments and their implications for cosmogenic nuclide production rates . The Holocene 12, 517—30 .

31.

——— 2004: Geomagnetic field intensity changes in Sweden between 9000 and 450 cal BP: extending the record of `archaeomagnetic jerks' by means of lake sediments and the pseudo-Thellier technique . Earth and Planetary Science Letters 227, 361—76 .

32.

Snowball, I. , Zillén, L. , Ojala, A. , Saarinin, T. and Sandgren, P. 2007: FENNOSTACK and FENNORPIS: varve dated Holocene palaeomagnetic secular variation and relative palaeointensity stacks for Fennoscandia . Earth and Planetary Science Letters 255, 106—15 .

33.

Solanki, S.K. , Usoskin, I.G. , Kromer, B. , Schüssler, M. and Beer, J. 2004: Unusual activity of the Sun during recent decades compared to the previous 11,000 years . Nature 431, 1084—87 .

34.

St.-Onge, G. , Stoner, J.C. and Hillaire-Marcel, C. 2003: Holocene paleomagnetic records from the St. Lawrence Estuary, eastern Canada: centennial- to millennial-scale geomagnetic modulation of cosmogenic isotopes . Earth and Planetary Science Letters 209, 113—30 .

35.

Usoskin, I.G. , Solanki, S.K. and Korte, M. 2006: Solar activity reconstructed over the last 7000 years: The influence of geomagnetic field changes . Geophysical Research Letters 33, L08103, doi:10.29/2006GL025921.

36.

Vogt, S. , Herzog, G.F. and Reedy, R.C. 1990: Cosmogenic nuclides in extraterrestrial materials. Reviews of Geophysics 28, 253—75 .

37.

Vonmoos, M. , Beer, J. and Muscheler, R. 2006: Large variations in Holocene solar activity — constraints from 10Be in the GRIP ice core . Journal of Geophysical Research 111, A10105 , doi:10.1029/ 2005JA011500.

38.

Wagner, G. , Masarik, J. , Beer, J. , Baumgartner, S. , Imboden, D. , Kubik, P.W. , Synal, H.-A. and Suter, M. 2000: Reconstruction of the geomagnetic field between 20 and 60 kyr BP from cosmogenic radionuclides in the GRIP ice core . Nuclear Instruments and Methods in Physics Research B172, 597—604 .

39.

Watkins, N.D. 1971: Geomagnetic polarity events and the reinforcement syndrome . Geophysics 2, 36—43 .

40.

Yang, S. , Odah, H. and Shaw, J. 2000: Variations in the geomagnetic dipole moment over the last 12 000 years . Geophysical Journal International 140, 158—62 .

41.

Yiou, F. , Raisbeck, G.M. , Baumgartner, S. , Beer, J. , Hammer, C. , Johnsen, S. , Jouzel, J. , Kubik, P.W. , Lestringuez, J. , Stiévenard, M. , Suter, M. and Yiou, P. 1997: Beryllium 10 in the Greenland Ice Core Project ice core at Summit, Greenland . Journal of Geophysical Research 102, 26 783—94 .

42.

Zhentao, X. 1990: Solar observations in ancient China and solar variability . Philosophical Transactions of the Royal Society of London A 330, 513—15 .