Research Article

Statistical properties of solar Hα flare activity

¹ Yunnan Observatories, Chinese Academy of Sciences, Kunming 650216, PR China
² Key Laboratory of Geospace Environment, Chinese Academy of Sciences, University of Science & Technology of China, Hefei 230026, PR China
³ CAS Key Laboratory of Solar Activity, National Astronomical Observatories, Beijing 100012, PR China
⁴ School of Software Engineering, Chongqing University of Arts and Sciences, Chongqing 402160, PR China
⁵ University of Chinese Academy of Sciences, Beijing 100049, PR China

^* Corresponding author: lhdeng@ynao.ac.cn

Received: 30 March 2017
Accepted: 23 November 2017

Abstract

Magnetic field structures on the solar atmosphere are not symmetric distribution in the northern and southern hemispheres, which is an important aspect of quasi-cyclical evolution of magnetic activity indicators that are related to solar dynamo theories. Three standard analysis techniques are applied to analyze the hemispheric coupling (north-south asymmetry and phase asynchrony) of monthly averaged values of solar Hα flare activity over the past 49 years (from 1966 January to 2014 December). The prominent results are as follows: (1) from a global point of view, solar Hα flare activity on both hemispheres are strongly correlated with each other, but the northern hemisphere precedes the southern one with a phase shift of 7 months; (2) the long-range persistence indeed exists in solar Hα flare activity, but the dynamical complexities in the two hemispheres are not identical; (3) the prominent periodicities of Hα flare activity are 17 years full-disk activity cycle and 11 years Schwabe solar cycle, but the short- and mid-term periodicities cannot determined by monthly time series; (4) by comparing the non-parametric rescaling behavior on a point-by-point basis, the hemispheric asynchrony of solar Hα flare activity are estimated to be ranging from several months to tens of months with an average value of 8.7 months. The analysis results could promote our knowledge on the long-range persistence, the quasi-periodic variation, and the hemispheric asynchrony of solar Hα flare activity on both hemispheres, and possibly provide valuable information for the hemispheric interrelation of solar magnetic activity.