Speaker
Description
The Els ̈asser variables have been widely used in magnetohydrodynamics (MHD) to describe Alfv ́en waves. However, Els ̈asser variables are less suited for other wave modes, such as fast and slow magnetosonic waves, which require mixed components. To address this limitation, Q-variables were introduced as a generalisation of the Els ̈asser formalism, which allows for tracking waves with phase speeds different from the Alfv ́en speed. This extension provides a new framework for studying MHD wave dynamics. In this work, we extend the Q-variable framework by analytically deriving the dispersion relation for magnetosonic waves. We demonstrate that the Q-formalism is complete and consistent for compressive waves, and we obtain an explicit expression for the parameter α required to separate wave modes in a reference frame. These results provide the theoretical foundation for incorporating compressive wave drivers in solar wind models such as UAWSOM (Uniturbulence and Alfv ́en Wave SOlar Models).
