A thermodynamic formulation of the equations of motion and buoyancy frequency for Earth's fluid outer core (Q1915496)

This work presents a precise formulation of the balance and constitutive relations appropriate to the modeling of the motion of the fluid outer core, including a full thermodynamic analysis and derivation of the buoyancy frequency, its role in the equations of motion for the fluid outer core, and the dependence of this equation on the thermodynamic state of the outer core. It is shown that the equation of motion is controlled by a single parameter, the buoyancy frequency. By appropriate scaling, a variety of different approximations arise from this formulation using the thermodynamic definition of the buoyancy frequency. Special interest is put on the scaling for the outer core eigenmodes yielding consistent formulations for the Boussinesq- and the subseismic approximation.