Inflows towards active regions and the modulation of the solar cycle: a parameter study

Abstract

Aims: We aim to investigate how converging flows towards active regions affect the surface transport of magnetic flux, as well as their impact on the generation of the Sun's poloidal field. The inflows constitute a potential non-linear mechanism for the saturation of the global dynamo and may contribute to the modulation of the solar cycle in the Babcock-Leighton framework. Methods: We build a surface flux transport code incorporating a parametrized model of the inflows and run simulations spanning several cycles. We carry out a parameter study to assess how the strength and extension of the inflows affect the build-up of the global dipole field. We also perform simulations with different levels of activity to investigate the potential role of the inflows in the saturation of the global dynamo. Results: We find that the interaction of neighbouring active regions can lead to the occasional formation of single-polarity magnetic flux clumps inconsistent with observations. We propose the darkening caused by pores in areas of high magnetic field strength as a plausible mechanism preventing this flux-clumping. We find that inflows decrease the amplitude of the axial dipole moment by a $\sim 30\%$, relative to a no-inflows scenario. Stronger (weaker) inflows lead to larger (smaller) reductions of the axial dipole moment. The relative amplitude of the generated axial dipole is about $9\%$ larger after very weak cycles than after very strong cycles. This supports the inflows as a non-linear mechanism capable of saturating the global dynamo and contributing to the modulation of the solar cycle within the Babcock-Leighton framework.

References in corpus (12)

• The Solar Cycle
• The crucial role of surface magnetic fields for the solar dynamo
• Solar Cycle Propagation, Memory, and Prediction: Insights from a Century of Magnetic Proxies
• Origin of the torsional oscillation pattern of solar rotation
• Surface flux transport modeling for solar cycles 15--21: effects of cycle-dependent tilt angles of sunspot groups
• The effect of activity-related meridional flow modulation on the strength of the solar polar magnetic field
• Are the strengths of solar cycles determined by converging flows towards the activity belts?
• Coronal Magnetic Field Evolution from 1996 to 2012: Continuous Non-Potential Simulations
• Observation and Modeling of the Solar-Cycle Variation of the Meridional Flow
• Migration of Ca II H bright points in the internetwork
• Surface flux transport simulations: Effect of inflows toward active regions and random velocities on the evolution of the Sun's large-scale magnetic field
• A mechanism for the dependence of sunspot group tilt angles on cycle strength

Cited by in corpus (14)

• Solar cycle prediction
• Predictability of the solar cycle over one cycle
• Models for the long-term variations of solar activity
• Surface Flux Transport on the Sun
• Improvement of solar cycle prediction: Plateau of solar axial dipole moment
• Nonlinear mechanisms that regulate the solar cycle amplitude
• Predicting solar surface large-scale magnetic field of Cycle 24
• A New Formula for Predicting Solar Cycles
• Comparison of physics-based prediction models of solar cycle 25
• Flows around Averaged Solar Active Regions
• Supercriticality of the dynamo limits the memory of the polar field to one cycle
• Testing solar surface flux transport models in the first days after active region emergence
• Effect of Nonlinear Surface Inflows into Activity Belts on Solar Cycle Modulation
• Evolution of solar surface inflows around emerging active regions