  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.
