SH23B-01
Analysis of Solar Magnetic Activity with the Wavelet Coherence Method
The origin, behavior and evolution of the solar magnetic field is one of the main challenges of observational and theoretical solar physics. Up to now the Dynamo theory gives us the best approach to the problem. However, it is not yet able to predict many features of the solar activity, which seems not to be strictly a periodical phenomenon. Among the indicators of solar magnetic variability there is the 11-years cycle of sunspots, as well as the solar magnetic cycle of 22 years (the Hale cycle). In order to provide more elements to the Dynamo theory that could help it in the predicting task, we analyze here the plausible existence of other periodicities associated with the solar magnetic field. In this preliminary work we use historical data (sunspots and aurora borealis), proxies (Be10 and C14) and modern instrumental data (Coronal Holes, Cosmic Rays, sunspots, flare indexes and solar radio flux at 10.7 cm). To find relationships between different time-frequency series we have employed the t Wavelet Coherence technique: this technique indicates if two time-series of solar activity have the same periodicities in a given time interval. If so, it determines whether such relation is a linear one or not. Such a powerful tool indicates that, if some periodicity at a given frequency has a confidence level below 95%, it appears very lessened or does not appear in the Wavelet Spectral Analysis, such periodicity does not exist . Our results show that the so called Glaisberg cycle of 80-90 years and the periodicity of 205 years (the Suess cycle) do not exist . It can be speculated that such fictitious periodicities hav been the result of using the Fourier transform with series with are not of stationary nature, as it is the case of the Be10 and C14 series. In contrast we confirm the presence of periodicities of 1.3, 1.7, 3.5, 5.5, 7, 60, 120 and 240 years. The concept of a Glaisberg cycle falls between those of 60 and 120 years. We conclude that the periodicity of 120 years is one of the more important feature of Solar Activity which consequences are associated with the earth climatic change.
SH23B-02
The 120-yrs solar cycle of the magnetic solar activity
The solar periodicities of 55 yrs (Yoshimura cycle), 80-88 yrs (Gleissberg cycle) and 205 yrs (Suess cycle) using different time series of proxies of solar activity have been reported in a great number of papers. In this work we present a more objective and general cycle-length determination applying the wavelet transformation based on the Morlet wavelet to the cosmogenic isotopes. We use the INTERCAL98 for C14 time series and Be10 time series for both the South and North Poles as well as Auroral historical time series. The results obtained from the wavelet transformation show that there are no periodicities of 80-88 yrs or 205 yrs. This suggests that these periodicities may be the result of applying transformations to time series that do not fulfill the condition of stationary. The estimated periodicities obtained the from Morlet wavelet are of 60 yrs (Yoshimura-Gleissberg cycle), 120 yrs and 240 yrs (Suess Cycle). The 120-periodicity could possibly be one of the principal periodicities of magnetic solar activity.
SH23B-03
On the Physical Origin of the Cycles in Long-term Modulation of Solar Activity
By a Morlet wavelet analysis in sub harmonics of the 11 year fundamental frequency of sunspot number as a proxy for the toroidal component of solar dynamo magnetic field the evolution for the last 400 years of four well defined cycles- a decadal, a semi-secular, the Gleissberg and the Suess ones - in the modulation of this component of the solar dynamo field is found. The properties of these cycles as seen in geomagnetic index aa and Si as proxy data for polar dynamo field and CME's frequency and intensity, respectively, are described . From this procedure and by analyzing longer proxy time series in the light of the known non-linear properties of solar dynamo system, the meaning of the four cycles and its variability are discussed.
SH23B-04
Collective electric field effect on particle acceleration in a 3D reconnecting current sheet
Dynamics of proton and electron energy spectra at acceleration in 3D reconnecting current sheet (RCS) is investigated simultaneously with the collective electric field effects. In addition to the drift electric field, a polarisation electric field caused by the electron and proton separation and small scale electric field caused by Buneman and low-hybrid plasma turbulences are considered. The polarisation electric field parameters and turbulence growth rate are linked to the parameters and locations of the particles drifted and accelerated in an RCS. The small-scale electric fields increase mostly electron energies up to tens MeV while the polarisation field accelerates mostly protons up to GeV energies. Particle distributions in an RCS and their energy spectra are presented for different magnetic field topologies and combination of electric fields.