Bifractal behavior of Solar supergranulation and magnetic activity

TL;DR

This study investigates the fractal properties of solar supergranulation across an entire solar cycle, revealing bifractal behavior and differences in scale measurement methods, which enhances understanding of solar magnetic activity.

Contribution

It introduces a refined analysis of supergranular fractal dimensions across the solar cycle, highlighting bifractal behavior and clarifying scale measurement discrepancies.

Findings

Supergranular cells exhibit bifractal behavior across the solar cycle.

Larger cells tend to have a slightly higher fractal dimension than smaller ones.

Discrepancies in scale measurements are due to selection biases in detection methods.

Abstract

We study the complexity and scale of the supergranular network across the 23rd solar cycle, using the Ca II K digitized intensitygrams from the Kodaikanal Solar Observatory (KSO). Enhancing our previous data and refining our data analysis, we study supergranular fractal dimension as a function of cell size. We find that across the cycle phases, the cells show a bifractal behavior, with approximately half the larger cells in the studied scale range showing a slightly greater fractal dimension than the smaller cells. We also study the discrepancy between supergranular scale as determined by direct inspection methods (around 17 Mm) and autocorrelation (around 30 Mm), and attribute this to a preferential selection of well defined cells in the former case.