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

TL;DR

This study investigates the phase and amplitude asymmetry of the quasi-biennial oscillation in solar Halpha flare activity across hemispheres using advanced analysis techniques, revealing complex phase relationships and a hemispheric lead in solar cycle mode.

Contribution

It introduces a detailed analysis of hemispheric asymmetries in solar QBO of Halpha flare activity using ensemble empirical mode decomposition, cross-correlation, and wavelet transform methods.

Findings

Hemispheric QBO of Halpha flare index shows complex phase relationships.

Northern hemisphere generally leads southern hemisphere by 9 months in solar cycle mode.

No systematic regularity found in phase relationship between hemispheres.

Abstract

Quasi-biennial oscillation (QBO) of solar magnetic activities is intrinsic to dynamo mechanism, but still far from fully understood. In this work, the phase and amplitude asymmetry of solar QBO of Halpha flare activity in the northern and southern hemispheres is studied by the ensemble empirical mode decomposition, the cross-correlation analysis, and the wavelet transform technique. The following results are found: (1) solar QBO of Halpha flare index in the two hemispheres has a complicated phase relationship, but does not show any systematic regularity; (2) the solar cycle mode of solar Halpha flare index in the northern hemisphere generally leads that in the southern one by 9 months for the time interval from 1966 to 2014. The possible origin of these results is discussed.