Adapting the MPAS dynamical core for applications extending into the thermosphere

The split-explicit numerical integration techniques in MPAS remain stable in idealized test cases for atmospheric domains extending into the upper thermosphere and continue to provide an efficient numerical framework for nonhydrostatic simulations.

Variations in the atmospheric constituents influence the dynamical equations by altering the heat capacity and ideal gas constants. These feedbacks require little alteration of the dynamical equations although our testing reveals that the amplitude of disturbances may be sensitive to even small variations in the thermodynamic coefficients. Although the potential temperature is no longer formally conserved for adiabatic flow, it remains effective as a prognostic thermodynamic variable in the model equations.