Active Latitude Oscillations Observed on the Sun
A. Kilcik1, V. Yurchyshyn2,3, F. Clette4, A. Ozguc5, J. P. Rozelot6
¹Akdeniz University Faculty of Science, Department of Space Science and
Technologies, 07058, Antalya, Turkey
2
Big Bear Solar Observatory, Big Bear City, CA 92314, USA
3
Korea Astronomy and Space Science Institute, 776 Daedeok-daero, Yuseong-gu,
Daejeon, 305-348, South Korea
4
Royal Observatory of Belgium Av. Circulaire, 3 - B-1180 Brussels, Belgium
5
Kandilli Observatory and Earthquake Research Institute, Bogazici University,
34684 Istanbul, Turkey
6
Nice University (OCA), Bvd. de l’Observatoire, CS 34229, F-06304 Nice Cedex
4, France
We investigate periodicity of heliographic latitudes of sunspot groups for the last
three complete solar cycles (1976-2008). For this purpose the Multi Taper Method
and Morlet Wavelet analysis methods were used. We found the following. 1)
Solar rotation (26–38 days) periodicities are present in active latitudes of both
hemispheres for all the investigated cycles (cycle 21, 22, and 23). 2) Both northern
and southern hemisphere active latitudes shift toward the equator from the
beginning of the cycle until the end following an oscillating path. These motions
are well described by the second order polynomial fit. 3) There is no meaningful
periods between 55 and 142 day found in both hemispheres for all cycles except
the cycle 22; about 55 day periodicity only appears in the northern hemisphere of
all solar cycles. 4) 142 - 176 day Rieger’s period appears only in the southern
hemisphere during cycles 21 and 23. 5) 1.3 year periodicity (421 – 529 days)
appears in all solar cycles.