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Solar Wind Variability and Reconstruction Techniques during Solar Grand Minima

This presentation at the 2nd Space Climate Symposium in 2006 focuses on the historical analysis and reconstruction of solar wind parameters, such as speed and magnetic field strength, during grand solar minima. Using cosmogenic nuclei data and consistency checks, the study provides insights into the solar wind behavior dating back to the 17th century. The findings support the existence of a stable "floor" in solar wind magnetic field strength during grand minima periods.

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Solar Wind Variability and Reconstruction Techniques during Solar Grand Minima

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  1. The Solar Wind During Grand Minima [ ] L. Svalgaard Easy Tool Kit, Inc. 2nd Space Climate Symposium 13-16 September 2006

  2. Outline • - History • ~ 130 Years of Solar Wind • - Solar Wind Speed (IDV) • - Interplanetary Magnetic Field (IDV & IHV) • Extrapolation to the Maunder Minimum via SSN • Consistency Checks via 10Be & 14C • Conclusion

  3. SSN & 14C aa Jack Eddy Feynman & Crooker (1978)

  4. Interdiurnal Variability (IDV) Index • Based on Bartel’s u-index • Average of absolute values of differences between • H-component measured at midnight on consecutive • days for mid-latitude stations • Time resolution = 1-year • Available since 1872 Svalgaard & Cliver (2005)

  5. IDV - Independent of V - Strongly-Correlated with B Svalgaard & Cliver (2005)

  6. B since 1872 Svalgaard & Cliver (2005)

  7. A strong correlation also exists between yearly SSN & B Svalgaard & Cliver (2005)

  8. Interhourly Variability (IHV) Index • Recalibrated aa index • Based on local midnight observations • for worldwide mid-latitude stations • - Highly-correlated with BV2

  9. Two Equations, Two Unknowns - Solve for V(IHV) - Compute V for years before 1965

  10. Combining - direct solar wind measurements (1965 - present) - geomagnetic measurements (1872 - present) - sunspot observations (1610 - present) We obtain: Is it true?

  11. To answer this question, we make consistency checks based on cosmogenic nuclei (10Be & 14C)

  12. Tutorial on Cosmogenic Nuclei The solar wind magnetic field modulates the incoming galactic cosmic ray intensity & the production of cosmogenic nuclei such as 10Be which are deposited in ice cores.

  13. We compared our inferred ~400-yr time-profile of solar wind B with recent determinations of this parameter by - Caballero-Lopez et al. (2004) (10Be) - Muscheler et al. (2005) (14C) In each case our reconstruction agreed with one of a range of estimates obtained by the above authors. This, in itself, does not guarantee that our inferred time history of B is correct. That said, and model uncertainties aside, we are able to state that our reconstruction is consistent with available evidence to date.

  14. Caballero-Lopez et al. (2005)

  15. Mueschler et al. (2005)

  16. Reconstructions of Solar Wind B “Floor” in Solar Wind B of ~4.5 nT

  17. Conclusions • Reconstruction of Solar Wind B to ~1600 • Reconstruction of Solar Wind V to ~1870 • Inferred Solar Wind During Grand Minima • - B = ~4.5 nT • - V = ~300 km/s (inferred from 1901)

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