Sunspot number recalibration: The ~1840–1920 anomaly in the observer normalization factors of the group sunspot number
We analyze the normalization factors (k′-factors) used to scale secondary observers to the Royal Greenwich Observatory (RGO) reference series of the Hoyt & Schatten (1998a, 1998b) group sunspot number (GSN). A time series of these k′-factors exhibits an anomaly from 1841 to 1920, viz., the avera...
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| Format: | Article |
| Language: | English |
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EDP Sciences
2017-01-01
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| Series: | Journal of Space Weather and Space Climate |
| Online Access: | https://doi.org/10.1051/swsc/2017010 |