Statistical properties of solar Hα flare activity

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 Ha 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 Ha 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 Ha flare activity, but the dynamical complexities in the two hemispheres are not identical; (3) the prominent periodicities of Ha 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 Ha 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 Ha flare activity on both hemispheres, and possibly provide valuable information for the hemispheric interrelation of solar magnetic activity.

Phase and amplitude asymmetry in the quasi-biennial oscillation of solar Hα flare activity

“…Their phase difference is found to be 9 months where the correlation coefficient has a largest value (0.64), which is above the 95% confidence levels shown by the red dash-dotted lines. It is worthy of note that the phase difference obtained by us is slightly larger than the results given by previous authors, such as 5-7 months by studying the sunspot areas (Ravindra & Javaraiah 2015) and flare index (Deng et al 2017).…”

Coronal Mass Ejections over Solar Cycles 23 and 24

“…Note that the reference value of 0.86 (solid black line) corresponds to the ratio of the radio fluxes separately calculated over the two cycles. North-South asymmetry of solar activity and the associated phase asynchrony, in particular those of the sunspots, have been known for a long time and recent studies include for example Zolotova and Ponyavin (2006), Carbonell et al (2007), Donner and Thiel (2007), Li et al (2009a), McIntosh et al (2013, Deng et al (2017). It is beyond the scope of this article to discuss the underlying processes invoked to explain them, but it is considered that the mechanisms which create and transport the magnetic flux from the interior of the Sun to its surface are slowly evolving with time, further loosing coupling across the equator such that those asymmetries can persist for several years.…”

North-South Distribution and Asymmetry of GOES SXR Flares during Solar Cycle 24

“…The solar N-S asymmetry is considered as one of the most interesting properties of solar activity and studied in many manifestations of solar activity such as flares, prominences, sunspots, filaments, etc. (Howard 1974;Roy 1977;Yadav et al 1980;Swinson et al 1986;Ballester 1987, 1990;Carbonell et al 1993;Oliver and Ballester 1994;Joshi 1995;Javaraiah and Gokhale 1997;Verma 2000;Ataç and Özgüç 2001;Temmer et al 2002;Joshi and Joshi 2004;Ballester et al 2005;Javaraiah and Ulrich 2006;Zaatri et al 2006;Temmer et al 2006;Carbonell et al 2007;Li et al 2009a,b;Gigolashvili et al 2011;Chowdhury et al 2013;Chandra et al 2013;Obridko et al 2014;Joshi et al 2015;Zhang et al 2015;Javaraiah 2016;Bruevich and Yakunina 2017;Deng et al 2017;Gurgenashvili et al 2017;Xie et al 2018;El-Borie et al 2019;Li et al 2019).…”