The study of time series of monthly averaged values of F10.7 from 1950 to 2010

TL;DR

This study analyzes the solar activity index F10.7 from 1950 to 2010 using wavelet analysis to identify cycles and their changes over time, comparing different wavelet functions for optimal results.

Contribution

It introduces a comparative wavelet analysis approach to study the F10.7 solar activity index, identifying the most effective wavelets for revealing solar cycle features.

Findings

All wavelets show similar maximum activity values.

Different wavelets reveal variations in cycle detection.

The average solar cycle length is about 10.2 years.

Abstract

Prior to 1947, the activity of the Sun was assessed by the relative numbers of sunspots (W). The 10.7 cm radio emission (frequency of 2.8 GHz) for observations of the variability of radiation of chromosphere and the lower corona (F10.7) became used from 1947. For the F10,7 are available more detailed observational archive data, so this activity index more often than the other indices is used in the prediction and monitoring of the solar activity. We have made the analysis of time series of F10.7 with the use of different mother wavelets: Daubechies 10, Symlet 8, Meyer, Gauss 8 and Morlet. Wavelet spectrum allows us not only to identify cycles, but analyze their change in time. Each wavelet has its own characteristic features, so sometimes with the help of different wavelets it can be better identify and highlight the different properties of the analyzed signal. We intended to choose the mother wavelet, which is more fully gives information about the analyzed index F10.7. We have received, that all these wavelets show similar values to the maximums of the cyclic activity. However, we can see the difference when using different wavelets. There are also a number of periods, which, perhaps, are the harmonics of main period. The mean value of 11-year cycle is about 10.2 years. All the above examples show that the best results we get when using wavelets Morley, Gauss (real-valued) and multiparameter family of wavelets Morley and Gauss (complex-valued).