Scaling Properties and Persistence of Long-Term Solar Activity

Fabio Lepreti,Vincenzo Carbone,Antonio Vecchio

doi:10.3390/atmos12060733

Abstract

The long-range correlations associated with the presence of persistence are investigated by applying the detrended fluctuation analysis (DFA) on three different proxies of long-term solar activity. The considered datasets are a sunspot number reconstruction (SNR04) obtained from the atmospheric activity of the cosmogenic isotope 14C derived from tree rings, a total solar irradiance reconstruction (TSIR12) obtained from several 10Be ice core records from Greenland and Antarctica in combination with the global record of 14C in tree rings and a new multi-proxy sunspot number reconstruction (SNR18), also derived from 10Be datasets and the global 14C production series. The DFA scaling exponents found for the three time series are similar (lying in the range between 0.70 and 0.77) and the scaling ranges are comparable. These results indicate the presence of long-range correlations with persistence, in substantial agreement with the findings of previous studies carried out on other solar activity indices and proxies.

Highlights

Solar activity phenomena are the manifestation of the magnetic dynamo process occurring inside the Sun
detrended fluctuation analysis (DFA)(1) method applied to the sunspot number reconstruction (SNR18), reprinted from Wu et al [32]
Since the scaling exponent estimated from the fit of log F1 (n) of the original time series lies out of this interval, we can conclude that the presence of long-range correlations with persistence is a significant result

Summary

Introduction

Solar activity phenomena are the manifestation of the magnetic dynamo process occurring inside the Sun. It is known that this modulation, called the “Gleissberg cycle”, strictly speaking it is not a cycle, occurs with a timescale varying in the range of 60–130 y This has been found from analyses of both sunspot number indices (see, e.g., [12]) and solar activity proxies obtained from cosmogenic isotope records [11,13,14,15]. The first method used to this aim has been the rescaled range (R/S) analysis, which allows to quantify persistence (memory) effects in time series through the determination of the Hurst exponent H This has been done for monthly averaged sunspot numbers [23], 14 C data covering a ~8000 year interval [24], Doppler solar rotation data [25] and daily averaged intensity of optical flares [26]. Sun’s magnetic activity at long timescales (&100 y) are investigated by using the DFA technique to analyse three different solar activity proxy datasets for which the persistence analysis has not yet been performed, to the aim of further investigating this topic

Data and Methods

Results

Discussion