Desynchronization Events in Solar Indices as a Manifestation of the North-South Asymmetry

Abstract

We suggest the Kuramoto chain model with four coupled oscillators as a way to describe the phase evolution and departures from synchronization of solar indices at low and high latitudes in the northern and southern hemispheres. Our model simulates the basic properties of the phase differences between the near-equatorial sunspot areas and the polar facula series provided by the Pulkovo and Mount Wilson (MWO) observatories. Temporal variations of the meridional circulation are represented through slow, regular oscillations of natural frequencies. We consider the Gleissberg range (GR) oscillations to have the North-South asymmetry and the 22-year oscillation to be symmetric. The overall synchronization of polar and equatorial solar indices is confirmed. We use it to reconstruct model parameters from the phase difference of solar indices. The synchronization allows for reducing the space of model parameters to a 2D plane, where the eventual departures from the synchronization cut out a narrow zone of accurate estimates. We discuss revealed relations between the low-frequency variations of the solar meridional circulation, the North-South asymmetry, and the desynchronization events.