Schematic illustrating the several steps from incident stellar wind energy flux toward auroral radio emission. The transfer function, T_a (see Sect. 4.1.1) describes the conversion from incident stellar energy to auroral Poynting fluxes. The conversion efficiency from auroral Poynting fluxes (Eq. (12)) to radio emission, ϵ_a, implicitly includes the efficiency of electron acceleration and the ECMI mechanism. The steps within the pink shaded area are not included in our model. Brown arrows indicate physical processes, blue arrows denote model parameters that quantify energy conversion, and the magenta arrow the radiometric scaling law.