Reconstruction of the Sunspot Group Number: The Backbone Method

By L. Svalgaard, K. Schatten. 2015

230 citations recorded by the source corpus.

We have reconstructed the sunspot-group count, not by comparisons with other reconstructions and correcting those where they were deemed to be deficient, but by a re-assessment of original sources. The resulting series is a pure solar index and does not rely on input from other proxies, e.g. radionuclides, auroral sightings, or geomagnetic records. “Backboning” the data sets, our chosen method, provides substance and rigidity by using long-time observers as a stiffness character. Solar activity, as defined by the Group Number, appears to reach and sustain for extended intervals of time the same level in each of the last three centuries since 1700 and the past several decades do not seem to have been exceptionally active, contrary to what is often claimed.

Subfields: Astronomy and Astrophysics

View Paper: https://www.semanticscholar.org/paper/95efe38e55b4e1f8a72606dffbef2766f1041bff

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In Astronomy and Astrophysics

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4. M. Lockwood
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7. N. Krivova
8. Paul Charbonneau

Citations in the corpus

• A New Calibrated Sunspot Group Series Since 1749: Statistics of Active Day Fractions (2015, methodology): “…for the difference between the sunspot-activity levels resulting from this work and previous recent reconstructions ( e.g. Clette et al. , 2014; Svalgaard and Schatten, 2016) is that the latter were based on linear regressions between annually averaged data of individual observers, which can…”