  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.
