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Parameterized Inflows Around Active Regions for Flux-transport Models

Presentation #201.03 in the session Heliosiesmology.

Published onSep 18, 2023
Parameterized Inflows Around Active Regions for Flux-transport Models

Parameterized flows around active regions can serve as a crucial first order correction to global-scale velocity fields used in flux-transport models. In a previous study, we carefully measured near-surface background meridional flow and differential rotation of the quiet Sun. This allows us to measure the near-surface inflows around active regions in the proper frame of reference. These inflows obtained from time-distance helioseismic inversions, which may be impacted by the magnetic effects on helioseismic waves, are observed up to 30 degrees away from active region centroids and can have peak amplitudes upto 30 m/s. The inflow magnitude and extent is strongly correlated to the net unsigned flux in active regions, with little to no dependence on other active region properties. We, therefore, present a simple formulation for modeling the 2D structure of near-surface inflows around active regions based on their net unsigned flux. A forward model of the parameterized inflows applied to active regions of cycle 24 reproduces the variability in cross-equatorial component of meridional flow very well. This is evidence for the cross-equatorial flow being driven by a combination of inflows around active regions and hemispheric asymmetry in activity.

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