Variations in the Sun's meridional flow over a solar cycle

Area of Science:

• Solar Physics
• Heliophysics
• Plasma Physics

Background:

• The Sun's meridional flow, a surface current from equator to poles, influences polar magnetic field strength and sunspot cycle intensity.
• Understanding this flow is key to predicting solar activity and its impact.

Purpose of the Study:

• To determine the speed of the Sun's meridional flow using magnetic features.
• To analyze how flow speed varies with latitude and solar cycle phase.

Main Methods:

• Utilized data from the Solar and Heliospheric Observatory (SOHO).
• Tracked magnetic features to measure surface flow speeds across various latitudes.
• Compared flow speeds at solar maximum and minimum.

Main Results:

• The meridional flow is poleward at all measured latitudes up to 75 degrees.
• Flow speed was greater during solar cycle minimum compared to solar cycle maximum.
• The approach to the current solar minimum showed a substantially faster flow than the previous minimum.

Conclusions:

• The Sun's meridional flow extends to high latitudes, likely reaching the poles.
• Variations in meridional flow speed correlate with solar cycle phases.
• The accelerated flow near the current minimum may explain its unusual characteristics.