Toroidal Flux Loss due to Flux Emergence Explains why Solar Cycles Rise Differently but Decay in a Similar Way

Area of Science:

• Solar physics
• Heliophysics
• Astrophysics

Background:

• The solar cycle exhibits migrating sunspot latitudes and variable activity levels.
• Stronger solar cycles show earlier activity and wider sunspot distributions.
• Late-stage solar cycle properties appear statistically similar regardless of cycle strength.

Purpose of the Study:

• To model key features of the solar cycle using a dynamo model.
• To investigate the role of nonlinearity in solar dynamo processes.
• To understand the influence of flux loss via magnetic buoyancy.

Main Methods:

• Utilized a Babcock-Leighton type dynamo model for simulations.
• Analyzed the statistical properties of sunspot number and butterfly wings.
• Incorporated magnetic buoyancy as a key nonlinearity.

Main Results:

• Modeled the observed migration of sunspot emergence toward the equator.
• Demonstrated that flux loss through magnetic buoyancy is a crucial nonlinearity.
• Identified the critical mean-field strength for efficient flux emergence.

Conclusions:

• Magnetic buoyancy-driven flux loss is essential for nonlinear solar dynamo behavior.
• The model successfully reproduces late-stage solar cycle properties.
• Nonlinearity becomes effective at specific magnetic field strengths in the convection zone.