Was one sunspot cycle lost in late XVIII century?

Citation
Ig. Usoskin et al., Was one sunspot cycle lost in late XVIII century?, ASTRON ASTR, 370(2), 2001, pp. L31-L34
Citations number
13
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Space Sciences
Journal title
ASTRONOMY AND ASTROPHYSICS
ISSN journal
0004-6361 → ACNP
Volume
370
Issue
2
Year of publication
2001
Pages
L31 - L34
Database
ISI
SICI code
0004-6361(200105)370:2<L31:WOSCLI>2.0.ZU;2-N
Abstract
We suggest that one solar cycle was lost in the beginning of the Dalton min imum because of sparse and partly unreliable sunspot observations. So far t his cycle was combined with the preceding activity to form the exceptionall y long solar cycle #4 in 1784-1799, leading to an irregular phase evolution of sunspot activity (known as a phase catastrophe) and other problems. We reanalyze the available group sunspot numbers and suggest that solar cycle #4 was in fact a superposition of two cycles: a normal cycle in 1784-1793 e nding at the start of the Dalton minimum and a new weak cycle in 1793-1800 which was the first full cycle within the Dalton minimum. Including the new cycle resolves the problems mentioned above and leads to a consistent view of sunspot activity around the Dalton minimum. Moreover. it will restore t he Gnevyshev-Ohl rule of cycle pairing throughout the 400-year interval of sunspot observations.