On the reflection of Alfvén waves and its implication for Earth's core modelling

摘要: SUMMARY Alfven waves propagate in electrically conducting fluids the presence of a magnetic field. Their reflection properties depend on ratio between kinematic viscosity and diffusivity fluid, also known as Prandtl number Pm. In special case, Pm = 1, there is no an insulating, no-slip boundary, incoming wave energy entirely dissipated boundary layer. We investigate consequences this remarkable behaviour for numerical modelling torsional Alfven (also oscillations), which represent class waves, rapidly rotating spherical shells. They consist geostrophic motions are thought to exist fluid cores planets with internal geophysical limit ≪ these reflected at core equator, but they absorbed 1. Our calculations show that coefficient equator remains below 0.2 ≥ 0.3, range values geodynamo models operate. As result, conditions cannot exhibit oscillation normal modes.