Abstract
Lost sunspot cycle in the beginning of Dalton minimum: New evidence and consequences
Lost sunspot cycle in the beginning of Dalton minimum: New evidence and consequences
I. G. Usoskin
Sodankylä Geophysical Observatory,
University of Oulu,
Finland
K. Mursula
Department of Physical Sciences,
University of Oulu,
Finland
G. A. Kovaltsov
Ioffe Physical-Technical Institute,
St.Petersburg,
Russia
We have recently suggested that one solar cycle was lost in the beginning of the Dalton minimum during 1790s [
Usoskin et al., 2001
]. Earlier, this cycle has been combined with the preceding activity to form the exceptionally long solar cycle 4 in 1784-1799
with an irregular phase evolution. Here we show that historical data of auroral occurrence provide independent evidence for
the existence of the new cycle. Using a heliospheric model we demonstrate that 10Be or any other cosmogenic isotope data do not exclude the possibility of a new cycle. We also discuss the other implications
of the new cycle for solar activity, in particular the cycle length distribution and the Waldmeier relation between the cycle
amplitude and the length of the ascending and descending phase. Including the new cycle also restores the Gnevyshev-Ohl rule
of cycle pairing and removes the phase catastrophe in the beginning of the Dalton minimum.
Published 24
December
2002.
Citation: Usoskin, I. G., K. Mursula, and G. A. Kovaltsov
(2002),
Lost sunspot cycle in the beginning of Dalton minimum: New evidence and consequences,
Geophys. Res. Lett.,
29(24),
2183,
doi:10.1029/2002GL015640.