Scaling for the Nontraditional Coriolis Term in Diabatic-Forced Dynamics

This paper introduces a nondimensional measure, Ong number. Regarding the Ertel potential vorticity (EPV) equation in a flux form, this number is defined as the diabatic flux convergence associated with the nontraditional Coriolis term (NCT), divided by the advective flux convergence. NCT-diabatic EPV transport is negligible when Ong ≪ 1 but becomes considerable on the level of heating maximum in the tropical atmosphere for an intraseasonal timescale, where Ong ≅ 0.3. Accordingly, for dynamic understanding, analysis demonstrates that NCT-coupled diabatic heating yields southward EPV transport that could correspond to a zonal wind change of 5 m s^-1 in a month. Moreover, for modeling advances, results suggest that the quasi-hydrostatic equations may be adequate for large-scale long-term global atmospheric simulations.