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Sunspot Number Validation and Reconstruction: A Comprehensive Study

This study by L. Svalgaard presented at IUGG July 2007 focuses on the reconstruction and validation of the sunspot number record from 1841 to 2007. It delves into applications such as solar dynamo, space weather/climate, cosmic ray modulation, and climate change, using various sunspot number series and correlations with geomagnetic elements. The research aims to strengthen the existing series, extend observations before 1840, and investigate potential causes of anomalies in sunspot data, including the Earth's changing magnetic field.

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Sunspot Number Validation and Reconstruction: A Comprehensive Study

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  1. Validation/Reconstruction of the Sunspot Number Record, 1841-2007 [ ] L. Svalgaard Easy Tool Kit, Inc., Houston, TX IUGG July 2007

  2. Sunspot Number (SSN) Applications • Solar Dynamo • Space Weather/Climate • Cosmic Ray Modulation • Climate Change

  3. Two SSN Series RINT: 1700 - 2007 (SIDC/ROB) RG : 1610 - 1995 (Hoyt & Schatten, 1998)

  4. SSN Dec HF Ellis (1898) SSN correlated with daily range of geomagnetic elements

  5. SR Ionospheric Current System (Torta et al., 1997) SR at Hobarton (1848)

  6. Wolf (1875) used the SSN-daily range relationship to adjust the SSN for years before 1848 Rudolf Wolf

  7. Step 1 Show that over extended periods of time (decades, centuries) constant, stable relationships exist between rY at stations such as Niemegk and Honolulu that are widely separated in longitude and latitude.

  8. Step 2 Link together observations of the regular variation observed at long-term stations (normalizing to Niemegk and using Oslo to bridge the gaps for early years) to obtain the variation of SRsince 1840

  9. Step 3 Relate average rY to RINT ( & F10.7)

  10. Step 3 (continued) The daily range rY is highly correlated with RINT& F10.7 at all phases of the sunspot cycle

  11. Step 4 Use the RINTvs. rY relationship to obtain a new SSN series back to 1840

  12. Step 5 Obtain correction factors for each cycle for the International and Group SSN series

  13. Provisional SSN Series: Cycles 10 & 11 comparable to 22 & 23

  14. Work in Progress • Strengthen 1840-present series • Extend before 1840 • Determine causes of jumps in 1893 & 1945 • Determine effect of Earth’s decreasing • dipole (~10% since 1840)

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