The proposed effort will determine the contribution of subsurface flows of active regions (especially inflows and outflows) on flux cancellation at low latitudes and thus on the resulting poleward…

This federal contract award, valued at $523,995.00, was granted by the National Aeronautics and Space Administration (NASA) Shared Services Center to the Association of Universities for Research in Astronomy, Inc. (AURA), a non-profit organization that manages and operates major astronomical observatories and facilities. The proposed effort will determine the contribution of subsurface flows of active regions on flux cancellation at low latitudes and the resulting poleward migration of magnetic activity of opposite polarity. This will be carried out through a statistical study of the subsurface flows near active regions and the corresponding magnetic flux during Solar Cycles 24 and 25. The goal is to derive the role of these subsurface flows in magnetic flux transport and improve surface flux transport models. This grant award does not have a set-aside designation and is intended to support cutting-edge astronomical research that is relevant to the Solar Dynamics Observatory (SDO) project and the Heliophysics Decadal Survey.

The proposed effort will determine the contribution of subsurface flows of active regions (especially inflows and outflows) on flux cancellation at low latitudes and thus on the resulting poleward migration of magnetic activity of opposite polarity. This will be carried out through a statistical study of the subsurface flows near active regions and the corresponding magnetic flux during solar cycles 24 and 25. The study will investigate if such flows should be included as key ingredients in surface flux transport models and, as a consequence, in solar cycle predictions. The goal is to derive the role of these subsurface flows in magnetic flux transport. Surface flux transport models already include information about poleward meridional flow and diffusion to model the evolution of the magnetic field and activity cycle. Some of these models explain the amplitude variability of the solar cycle with inflows toward active regions and rare events, such as cross-equatorial flux plumes. Cross-equatorial meridional flow is one of the processes that may lead to magnetic flux cancellation late in the solar cycle where fields with opposite polarity come in close proximity and cancel each other across the equator. Simulations have shown that even single big active regions not following JOY's law emerging very near or across the solar equator can significantly affect the amplitude of the polar field. While subsurface flows of active regions and large-scale flows have been studied before, their specific role in magnetic flux transport have not yet been explored. Proposed study will lead to a better understanding of the interconnection between subsurface flow patterns near active regions and surface flux transport. The proposal is thus relevant to the following goal of the SDO project: how is active region magnetic flux synthesized, concentrated, and dispersed across the solar surface? The proposal also addresses the goal determine the origins of the sun's activity and predict the variations in the space environment from the heliophysics decadal survey.