Supergranular Fractal Dimension and Solar 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.