Supergranular Fractal Dimension and Solar Rotation

TL;DR

This study investigates how the fractal dimension of solar supergranulation varies with latitude and solar rotation, revealing that rotation influences boundary irregularity and cell size, with implications for understanding solar dynamics.

Contribution

It demonstrates the relationship between solar rotation, supergranular boundary irregularity, and cell size using spectroheliographic data from solar cycle 23.

Findings

Fractal dimension decreases from 1.37 at the equator to 1 at 20° latitude.

Solar rotation affects supergranular boundary irregularity.

Cell size correlates with fractal dimension and is influenced by rotation.

Abstract

We present findings from an analysis of the fractal dimension of solar supergranulation as a function of latitude, supergranular cell size and solar rotation, employing spectroheliographic data in the Ca II K line of solar cycle no. 23. We find that the fractal dimension tends to decrease from about 1.37 at the equator to about 1 at 20 degree latitude in either hemisphere, suggesting that solar rotation rate has the effect of augmenting the irregularity of supergranular boundaries. Considering that supergranular cell size is directly correlated with fractal dimension, we conclude that the mechanism behind our observation is that solar rotation influences the cell outflow strength, and thereby cell size, with the latitude dependence of the supergranular fractal dimension being a consequence thereof.