%0 Journal Article
%T Identification of Gleissberg Cycles and a Rising Trend in a 315-Year-Long Series of Sunspot Numbers
%+ Institut de Physique du Globe de Paris (IPGP)
%A Le Mouël, Jean-Louis
%A Lopes, Fernand
%A Courtillot, Vincent
%< avec comité de lecture
%J SOLAR PHYSICS
%V 292
%8 2017
%D 2017
%Z 2017SoPh..292...43L
%R 10.1007/s11207-017-1067-6
%K Solar cycle
%K observations
%K models
%K Gleissberg cycle
%K Sunspot number
%K Singular spectrum analysis
%K Schwabe cycle
%K Secular trend
%Z Sciences of the Universe [physics]Journal articles
%X We show in this short note that the method of singular spectrum analysis (SSA) is able to clearly extract a strong, clean, and clear component from the longest available sunspot (International Sunspot Number, ISN) time series (1700 - 2015) that cannot be an artifact of the method and that can be safely identified as the Gleissberg cycle. This is not a small component, as it accounts for 13% of the total variance of the total original signal. Almost three and a half clear Gleissberg cycles are identified in the sunspot number series. Four extended solar minima (XSM) are determined by SSA, the latest around 2000 (Cycle 23/24 minimum). Several authors have argued in favor of a double-peaked structure for the Gleissberg cycle, with one peak between 55 and 59 years and another between 88 and 97 years. We find no evidence of the former: solar activity contains an important component that has undergone clear oscillations of ≈90 years over the past three centuries, with some small but systematic longer-term evolution of "instantaneous" period and amplitude. Half of the variance of solar activity on these time scales can be satisfactorily reproduced as the sum of a monotonous multi-secular increase, a ≈90-year Gleissberg cycle, and a double-peaked (≈10.0 and 11.0 years) Schwabe cycle (the sum amounts to 46% of the total variance of the signal). The Gleissberg-cycle component definitely needs to be addressed when attempting to build dynamo models of solar activity. The first SSA component offers evidence of an increasing long-term trend in sunspot numbers, which is compatible with the existence of the modern grand maximum.
%G English
%L insu-03748865
%U https://insu.hal.science/insu-03748865
%~ INSU
%~ UNIV-PARIS7
%~ AFRIQ
%~ CNRS
%~ IPGP
%~ USPC
%~ SORBONNE-UNIVERSITE
%~ UNIV-PARIS
%~ ALLIANCE-SU
%~ TEST3-HALCNRS