Investigating global convective dynamos with mean-field models: full\n spectrum of turbulent effects required

Abstract

The role of turbulent effects for dynamos in the Sun and stars continues to\nbe debated. Mean-field (MF) theory provides a broadly used framework to connect\nthese effects to fundamental magnetohydrodynamics. While inaccessible\nobservationally, turbulent effects can be directly studied using global\nconvective dynamo (GCD) simulations. We measure the turbulent effects in terms\nof turbulent transport coefficients, based on the MF framework, from an\nexemplary GCD simulation using the test-field method. These coefficients are\nthen used as an input into an MF model. We find a good agreement between the MF\nand GCD solutions, which validates our theoretical approach. This agreement\nrequires all turbulent effects to be included, even those which have been\nregarded as unimportant so far. Our results suggest that simple dynamo models,\nas are commonly used in the solar and stellar community, relying on very few,\nprecisely fine-tuned turbulent effects, may not be representative of the full\ndynamics of dynamos in global convective simulations and astronomical objects.\n