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The one hundredth year of Rudolf Wolf's death: Do we have the correct reconstruction of solar activity?In the one hundred years since Wolf died, little effort has gone into research to see if improved reconstructions of sunspot numbers can be made. We have gathered more than 349,000 observations of daily sunspot group counts from more than 350 observers active from 1610 to 1993. Based upon group counts alone, it is possible to make an objective and homogeneous reconstruction of sunspot numbers. From our study, it appears that the Sun has steadily increased in activity since 1700 with the exception of a brief decrease in the Dalton Minimum (1795-1823). The significant results here are the greater depth of the Dalton Minimum, the generally lower activity throughout the 1700's, and the gradual rise in activity from the Maunder Minimum to the present day. This solar activity reconstruction is quite similar to those Wolf published before 1868 rather than the revised Wolf reconstructions after 1873 which used geomagnetic fluctuations.
Document ID
Document Type
Reprint (Version printed in journal)
External Source(s)
Hoyt, Douglas V.
(Research and Data Systems Corporation Greenbelt, MD, United States)
Schatten, Kenneth H.
(NASA Goddard Space Flight Center Greenbelt, MD, United States)
Nesmes-Ribes, Elizabeth
(Observatoire de Paris Meudon, France)
Date Acquired
August 16, 2013
Publication Date
September 1, 1994
Publication Information
Publication: Geophysical Research Letters
Volume: 21
Issue: 18
ISSN: 0094-8276
Subject Category
Solar Physics
Funding Number(s)
Distribution Limits
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