  The atmospheres of brown dwarfs have been long observed to exhibit a
multitude of non-equilibrium chemical signatures and spectral variability
across the L, T and Y spectral types. We aim to investigate the link between
the large-scale 3D atmospheric dynamics and time-dependent chemistry in the
brown dwarf regime, and to assess its impact on spectral variability. We couple
the miniature kinetic chemistry module `mini-chem' to the Exo-FMS general
circulation model (GCM). We then perform a series of idealised brown dwarf
regime atmospheric models to investigate the dynamical 3D chemical structures
produced by our simulations. The GCM output is post-processed using a 3D
radiative-transfer model to investigate hemisphere-dependent spectral
signatures and rotational variability. Our results show the expected strong
non-equilibrium chemical behaviour brought on by vertical mixing as well as
global spacial variations due to zonal flows. Chemical species are generally
globally homogenised, showing variations of $\pm$10\% or less, dependent on
pressure level, and follow the dynamical structures present in the atmosphere.
However, we find localised storm regions and eddies can show higher contrasts,
up to $\pm$100\%, in mixing ratio compared to the background global mean. This
initial study represents another step in understanding the connection between
three-dimensional atmospheric flows in brown dwarfs and their rich chemical
inventories.
