Adiabatic and diabatic energy tendencies of the equatorial Kelvin wave

Kelvin waves play an important role in tropical circulation variability. Previous research has shown that the tropospheric Kelvin wave activity is associated with both tropical convection and dry dynamics, which can be connected to the extratropics. The relative importance of the adiabatic and diabatic processes for Kelvin wave energy tendencies has not yet been consistently evaluated in reanalysis data.
In this study, we investigate the Kelvin wave energy budget focusing on the relative contributions of physical and dynamical processes in ERA5 reanalysis data. Kelvin waves and their energy tendencies are identified by applying three-dimensional normal-mode function decomposition. A novel aspect of our method is that momentum and temperature tendencies are computed directly from the complex normal-mode function expansion coefficients. This allows to quantify the adiabatic energy tendencies as nonlinear interactions of Rossby and inertia-gravity waves and the zonal mean flow. The diabatic energy tendencies are determined from the momentum and temperature tendencies due to parametrizations in the short-term ERA5 forecasts. 
The most relevant results are that the advection of zonal momentum is on average a source of Kelvin wave energy, whereas Kelvin wave energy variability on diurnal and submonthly scales is mainly due to heating by shortwave radiation and latent heat forcing, respectively. The 3D normal-mode decomposition allows to reveal the roles of wave-wave and wave-mean flow interactions in dynamical processes, in particular in the tropics.