Spectral characteristic of mid-term quasi-periodicities in sunspots dataстатья
Статья опубликована в высокорейтинговом журнале
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Дата последнего поиска статьи во внешних источниках: 16 декабря 2020 г.
Аннотация:Numerous analyses suggest the existence of various quasi-periodicities in solar activity. The
power spectrum of solar activity recorded in sunspot data is dominated by the ∼11-yr quasiperiodicity,
known as the Schwabe cycle. In the mid-term range (1 month–11 yr) a pronounced
variability known as a quasi-biennial oscillation is widely discussed. In the shorter time-scale
a pronounced peak, corresponding to the synodic solar rotation period (∼27 d), is observed.
Here we revisit the mid-term solar variability in terms of statistical dynamics of fully turbulent
systems, where solid arguments are required to accept an isolated dominant frequency in a
continuous (smooth) spectrum. For this, we first undertook an unbiased analysis of the standard
solar data, sunspot numbers and the F10.7 solar radio flux index, by applying a wavelet tool,
which allows one to perform a frequency–time analysis of the signal. Considering the spectral
dynamics of solar activity cycle by cycle, we showed that no single periodicity can be separated,
in a statistically significant manner, in the specified range of periods. We examine whether a
model of the solar dynamo can reproduce the mid-term oscillation pattern observed in solar
data.We found that a realistically observed spectrum can be explained if small spatial (but not
temporal) scales are effectively smoothed. This result is important because solar activity is a
global feature, although monitored via small-scale tracers like sunspots.