THE EFFECTS OF CONVECTION ZONE TURBULENCE ON THE TILT ANGLES OF MAGNETIC BIPOLES

Bipolar magnetic regions are believed to form when flux originating be low the solar convection zone rises to the surface in the form of long thin loops. Numerical models of rising flux tubes have been able to e xplain many observed features of these bipoles, including their angle of tilt relative to the east-west direction. Observations reveal that the mean tilt angle, alpha, varies with both latitude of emergence and with flux, in agreement with simulations. However, observed bipoles a lso exhibit a considerable fluctuation, Delta alpha, about the mean ti lt angle. Here we show that tilt angle fluctuations can arise in model calculations from interactions with hydrodynamic turbulence during th e tube's rise. Numerical simulations indicate that both the magnitude of these fluctuations, and their scaling with footpoint separation (De lta alpha similar to d(-1)), are consistent with observations. Best ag reement with observations occurs for flux tubes whose magnetic field s trength is similar to those used in other numerical investigations, B- 0 similar to 30 kG. Furthermore, the agreement with observation sugges ts that turbulent velocities throughout the convection zone are consis tent with those derived from mixing-length convection models.