Hemispheric Asymmetry in the Sunspot Cycle as a Nonextensive Phenomenon

The appearance of dark sunspots over the solar photosphere is not considered to be symmetric between the northern and southern hemispheres. Among the different conclusions obtained by several authors, we can point out that the north-south asymmetry is a real and systematic phenomenon and is not due to random variability. In the present work, we select the sunspot area data of a sample of 13 solar cycles divided by hemisphere extracted from the Royal Greenwich Observatory and USAF/NOAA Sunspot databases to investigate the behavior of probability distributions using an out-of-equilibrium statistical model, also known as nonextensive statistical mechanics. Based on this statistical framework, we obtain that the nonextensive entropic parameter q has a semisinusoidal variation with a period of approximate to 22 years (Hale cycle). Among the most significant results, we can highlight that the asymmetry index q(A) supports the dominance of the northern hemisphere over the southern one, a result already confirmed by other authors who used the same data but with different statistical methods. Thus, we conclude that the parameter q(A) can be considered an effective measure for diagnosing daily variations of the solar dynamo. Finally, our study opens a new approach to investigating solar variability from the nonextensive perspective.