Variations of Solar Non-axisymmetric Activity

TL;DR

This study analyzes the migration patterns of solar active longitudes using sunspot data, revealing preferred zones, their migration behaviors, and potential links to deep convection zone dynamics.

Contribution

It provides new insights into the migration patterns of active longitudes and their possible connection to the solar convection zone, based on detailed analysis of sunspot data from two catalogs.

Findings

Active longitudes show preferred zones and migration patterns.

Migration paths exhibit alternating prograde/retrograde motions.

Sunspot emergence rates have a ~1.3-year periodicity.

Abstract

The temporal behaviour of solar active longitudes has been examined by using two sunspot catalogues, the Greenwich Photoheliographic Results (GPR) and the Debrecen Photoheliographic Data (DPD). The time-longitude diagrams of the activity distribution reveal the preferred longitudinal zones and their migration with respect to the Carrington frame. The migration paths outline a set of patterns in which the activity zone has alternating prograde/retrograde angular velocities with respect to the Carrington rotation rate. The time profiles of these variations can be described by a set of successive parabolae. Two similar migration paths have been selected from these datasets, one northern path during cycles 21 - 22 and one southern path during cycles 13 - 14, for closer examination and comparison of their dynamical behaviours. The rates of sunspot emergence exhibited in both migration paths similar periodicities, close to 1.3 years. This behaviour may imply that the active longitude is connected to the bottom of convection zone.