Active Region Flows and their Contribution to Varying Global Dynamics
Abstract
We explore the general properties of the near-surface dynamics of solar active regions (ARs) and show how AR flows may contribute to longitudinally averaged measurements of global properties such as meridional circulation and torsional oscillations. Helioseismic holography is applied to HMI Dopplergrams yielding about 5000 flow measurements of 336 ARs observed by SDO between 2010 and 2014. Ensemble averages of the AR flows are presented, binned into subsets based on total magnetic flux. These averages show converging flows, with speeds about 10 m/s and spanning 10 degrees from the active region centers, which are apparent for most ARs above the flux limit of our survey at 1021 Mx. Retrograde flows are also detected, with amplitudes around 10 m/s, which predominantly, but not exclusively, flank the polar side of the ARs. The high signal-to-noise levels of these averages makes possible the assessment of individual AR contributions to time-varying global flows. We demonstrate this for several solar rotations, showing that individual active regions contribute substantially to these global flows.
This work is supported by the Solar Terrestrial program of the National Science Foundation (award AGS-1623844) and by the NASA Heliophysics Division (awards 80NSSC18K0066 and 80NSSC18K0068).- Publication:
-
American Astronomical Society Meeting Abstracts #234
- Pub Date:
- June 2019
- Bibcode:
- 2019AAS...23430210B