  Compositional convection is atmospheric mixing driven by density variations
caused by compositional gradients. Previous studies have suggested that
compositional gradients of atmospheric trace species within planetary
atmospheres can impact convection and the final atmospheric temperature
profile. In this work, we employ 3D convection resolving simulations using
Cloud Model 1 (CM1) to gain a fundamental understanding of how compositional
variation influences convection and the final atmospheric state of exoplanet
atmospheres. We perform 3D initial value problem simulations of non-condensing
compositional convection for Earth-Air, $\rm H_2$, and $\rm CO_2$ atmospheres.
Conventionally, atmospheric convection is assumed to mix the atmosphere to a
final, marginally stable state defined by a unique temperature profile.
However, when there is compositional variation within an atmosphere, a
continuous family of stable end states is possible, differing in the final
state composition profile. Our CM1 simulations are used to determine which of
the family of possible compositional end states is selected. Leveraging the
results from our CM1 simulations, we develop a dry convective adjustment scheme
for use in General Circulation Models (GCMs). This scheme relies on an energy
analysis to determine the final adjusted atmospheric state. Our convection
scheme produces results that agree with our CM1 simulations and can easily be
implemented in GCMs to improve modelling of compositional convection in
exoplanet atmospheres.
