Equatorial Rossby waves at different depths are studied, and it is found that the Rossby waves are tilted retrograde with depth rather than being a columnar structure. The tilt remains relatively stable through the solar cycle without being consistently modulated by magnetic activity.
Equatorial Rossby waves are detected using the HMI’s time-distance subsurface flow fields. It is also found that the power of the Rossby waves show a positive correlation with the sunspot number, while the frequency of the waves shows an anti-correlation with the sunspot number.
HMI magnetic field synoptic maps are used to evaluate the magnetic field structures’ organization and propagation as a function of time and latitude. It is demonstrated that the organization of longitudinal structures observed on synoptic maps is proportional to the level of activity at given latitudes.
Power-spectrum analysis is applied on the time-distance measured travel-time shifts in the Sun’s north-south direction along the equatorial area, and the existence of Rossby waves is confirmed.