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The dynamical core of the Department of Energy global climate model is used to understand the role of non‐hydrostatic dynamics in the simulation of dry and moist baroclinic waves. To reduce computational cost, the Diabatic Acceleration and REscaling approach is adopted. Scale analysis and numerical simulations suggest that the model solution is not distorted by the change of spherical metric terms due to the change of Earth radius, neither are the inter‐scale interactions strongly altered as indicated by the analysis of spectral flux. Compared with hydrostatic simulations, the onset of baroclinic instability is delayed under non‐hydrostatic dynamics as the associated weaker vertical motions tend to increase the critical wavelength and narrow the range of waves that can be baroclinically unstable. During the development of baroclinic waves, non‐hydrostatic dynamics tends to induce vertical motions in the upper troposphere, accelerating the eastward propagation of upper‐level ridges through their impact on local vorticity tendency. These processes reduce the westward tilt of the vertical ridge axes and suppress the conversion of mean flow available potential energy to eddy kinetic energy, leading to weaker baroclinic eddies than in hydrostatic simulations. The contrasts between hydrostatic and non‐hydrostatic settings hold in supplemental experiments that vary the background flow Rossby number, the amount of water vapor content and vertical resolution. We also find that mesoscale and smaller‐scale activities can be considerably under‐represented when the vertical resolution is limited to that typically used in global climate models. Plain Language Summary: Limited by computational resources, comprehensive climate simulations are usually conducted with a horizontal grid spacing of 50–100 km. At such coarse resolutions, vertical motions can be approximated using hydrostatic balance in which the gravity force is balanced by the vertical component of the pressure gradient force. In high‐resolution simulations that aim at improving the representation of the Earth′s climate, this approximation breaks down, and one has to solve the complete vertical momentum equation to address non‐hydrostatic effects. Here, we examine the role of non‐hydrostatic dynamics in the simulation of baroclinic instability that is responsible for much of the weather in the midlatitudes. Our results show that non‐hydrostatic dynamics tends to delay the onset of baroclinic instability and reduce the amplitude of simulated baroclinic waves. We also find that mesoscale and smaller‐scale activities can be considerably under‐represented when the vertical resolution is limited to that typically used in global climate models. Besides illustrating the underlying physical mechanisms associated with non‐hydrostatic effects, this study implies the importance of including non‐hydrostatic dynamics in modeling midlatitude weather and climate in global high‐resolution simulations that are becoming affordable in the foreseeable future. Key Points: Non‐hydrostatic dynamics tends to delay the onset of baroclinic instability and reduce the amplitude of the simulated baroclinic wavesMesoscale and smaller‐scale processes are under‐represented with limited vertical resolution as typically used in global climate models [ABSTRACT FROM AUTHOR]

The classic baroclinic, wind-driven, double gyre problem is considered over a range of deformation radii, wind stress amplitudes, and bottom friction coefficients with the aim of better understanding the transfer of energy across scales. In this β-plane basin setting, significant differences are found with respect to classic studies of geostrophic turbulence, which generally assume zonal periodicity and for which the β term does not play a direct role in the energy transfers. In a basin geometry, the β term can play a direct role in the transfers; for example, it can be the dominant term allowing for energy transfer between the basin scale and the baroclinic mesoscale. It is also found that barotropization of baroclinic energy forces the barotropic mode near scales at which bottom drag damps this mode. Associated with this, the barotropic, nonlinear, inverse energy cascade does not extend between mesoscale injection and large-scale dissipation wavenumbers, as is often assumed. Instead, it is part of a 'double cascade' of barotropic energy in which the nonlinear inverse cascade is nearly offset by a forward cascade associated with the β term. This is particularly evident in weak bottom drag simulations, for which a time eddy-mean decomposition of the flow reveals the double cascade to be associated with the eddy-only terms. [ABSTRACT FROM AUTHOR]