Energy-Conserving Physics for Nonhydrostatic Dynamics in Mass Coordinate Models
The plot shows time evolution of a thermal bubble under three different coupling strategies.
Image by paper authors.
We investigate thermodynamic mechanisms that couple moist processes in the atmosphere with the processes that govern air circulation. The goal is to reduce errors in the moist energy budget in numerical atmospheric models. We provide a few approaches that are consistent with conservation principles and accurately represent energy budgets.
This study aims to increase the fidelity of moist thermodynamic processes in global atmospheric models by investigating consistent and physically accurate implementations of moist thermodynamics in atmospheric models.
Motivated by reducing errors in the energy budget related to enthalpy fluxes within the Energy Exascale Earth System Model (E3SM), we study several physics–dynamics coupling approaches. Using idealized physics, a moist rising bubble test case, and the E3SM's nonhydrostatic dynamical core, we consider unapproximated and approximated thermodynamics. Using time-step convergence studies, we show that commonly used coupling mechanisms converge but to slightly different solutions. We reproduce the large inconsistencies between the energy flux internal to the model and the energy flux of precipitation when using approximate thermodynamics, which can only be removed by considering unapproximated thermodynamics. Finally, we derive a new coupling mechanism for physics and a nonhydrostatic dynamical core.