Mesogranulation and small-scale dynamo action in the quiet Sun

摘要: Regions of quiet Sun generally exhibit a complex distribution small-scale magnetic field structures, which interact with the near-surface turbulent convective motions. Furthermore, it is probable that some these fields are generated locally by dynamo mechanism. In addition to well-known granular and supergranular scales, various observations have indicated there an intermediate scale convection, known as mesogranulation, vertical flux concentrations accumulating preferentially at mesogranular boundaries. Our aim investigate properties flow exhibits both granulation comparing our findings solar observations. Adopting idealised model for localised region Sun, we use numerical simulations compressible magnetohydrodynamics, in 3D Cartesian domain, parametric dependence this system (focusing particularly upon effects varying aspect ratio Reynolds number). purely hydrodynamic find mesogranulation robust feature provided domain wide enough accommodate large-scale The peak kinetic energy spectrum more pronounced higher number simulations. We kinematic nonlinear regimes always efficient larger domains, when present. filtering technique Fourier space demonstrate indeed scales motion primarily responsible driving dynamo. regime, compares very favourably observations, terms spatial measured strengths.