  Several recent studies utilizing different helioseismic methods have
confirmed the presence of large-scale vorticity waves known as solar Rossby
waves within the Sun. Rossby waves are distinct from acoustic waves, typically
with longer periods and lifetimes; and their general properties, even if only
measured at the surface, may be used to infer properties of the deeper
convection zone, such as the turbulent viscosity and entropy gradients which
are otherwise difficult to observe. In this study, we utilize $12~$years of
inverted subsurface velocity fields derived from the SDO/HMI's time--distance
and ring-diagram pipelines to investigate the propoerty of the solar equatorial
Rossby waves. By covering the maximum and the decline phases of Solar Cycle 24,
these datasets enable a systematic analysis of any potential cycle dependence
of these waves. Our analysis provides evidence of a correlation between the
average power of equatorial Rossby waves and the solar cycle, with stronger
Rossby waves during the solar maximum and weaker waves during the minimum. Our
result also shows that the frequency of the Rossby waves is lower during the
magnetic active years, implying a larger retrograde drift relative to the solar
rotation. Although the underlying mechanism that enhances the Rossby wave power
and lowers its frequency during the cycle maximum is not immediately known,
this observation has the potential to provide new insights into the interaction
of large-scale flows with the solar cycle.
