  Turbulent superstructures, i.e. large-scale flow structures in turbulent
flows, play a crucial role in many geo- and astrophysical settings. In
turbulent Rayleigh-B\'{e}nard convection, for example, horizontally extended
coherent large-scale convection rolls emerge. Currently, a detailed
understanding of the interplay of small-scale turbulent fluctuations and
large-scale coherent structures is missing. Here, we investigate the resolved
kinetic energy and temperature variance budgets by applying a filtering
approach to direct numerical simulations of Rayleigh-B\'{e}nard convection at
high aspect ratio. In particular, we focus on the energy transfer rate between
large-scale flow structures and small-scale fluctuations. We show that the
small scales primarily act as a dissipation for the superstructures. However,
we find that the height-dependent energy transfer rate has a complex structure
with distinct bulk and boundary layer features. Additionally, we observe that
the heat transfer between scales mainly occurs close to the thermal boundary
layer. Our results clarify the interplay of superstructures and turbulent
fluctuations and may help to guide the development of an effective description
of large-scale flow features in terms of reduced-order models.
