Dv. Hoyt et al., THE 100TH YEAR OF WOLF,RUDOLF DEATH - DO WE HAVE THE CORRECT RECONSTRUCTION OF SOLAR-ACTIVITY, Geophysical research letters, 21(18), 1994, pp. 2067-2070
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. B
ased upon group counts alone, it is possible to make an objective and
homogeneous reconstruction of sunspot numbers. From our study, it appe
ars that the Sun has steadily increased in activity since 1700 with th
e 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 r
ise in activity from the Maunder Minimum to the present day. This sola
r activity reconstruction is quite similar to those Wolf published bef
ore 1868 rather than the revised Wolf reconstructions after 1873 which
used geomagnetic fluctuations.