Short-Term Correlation of Solar Activity and Sunspot: Evidence of Lifetime Increase |
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| Authors: | E M Blanter J-L Le Mouël F Perrier M G Shnirman |
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| Institution: | (1) International Institute of Earthquake Prediction Theory and Mathematical Geophysics, Warshavskoe sh. 79 korp 2, Moscow, Russia;(2) Equipe de Geomagnetisme, Institute de Physique du Globe de Paris, 5 pl. Jussieu, Paris Cedex 05, France |
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| Abstract: | We perform a nonlinear study of the short-term correlation properties of the solar activity (daily range) in order to reveal
their long-life variations. We estimate the lifetime of the high-frequency component of a Markov-type signal when the high-frequency
component is modulated by a slowly varying multiplicative factor. This treatment is applied to different series of solar activity:
Wolf Sunspot numbers (WSN), Sunspot Group numbers (SGN), and Royal Greenwich Observatory (RGO) sunspot group series. We obtain
that all the lifetime estimates exhibit similar temporal variations that agree with the variations of the sunspot lifetimes
directly measured from the RGO data and those of the sunspot areas. An increase of lifetimes by a factor 1.4 is observed from
1915 to 1940. At the same time, a stable ratio is observed between the sunspot group’s maximal area and the lifetime, confirming
the Gnevyshev–Waldmeier-type relationship. The analysis identifies also time intervals where the homogeneity of the different
time series may be questioned. |
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