A mixed finite-element, finite-volume, semi-implicit discretisation for atmospheric dynamics: Spherical geometry

TL;DR

This paper extends a semi-implicit mixed finite-element and finite-volume discretisation for atmospheric dynamics to spherical geometries using a cubed-sphere mesh, improving accuracy for weather and climate modeling.

Contribution

It updates the semi-implicit formulation to accommodate spherical domains and non-uniform meshes, enhancing the dynamical core for operational weather prediction.

Findings

Model performs well on standard dry dynamical core tests.

Compared favorably to existing semi-Lagrangian core.

Handles non-orthogonal, non-uniform meshes effectively.

Abstract

The reformulation of the Met Office's dynamical core for weather and climate prediction previously described by the authors is extended to spherical domains using a cubed-sphere mesh. This paper updates the semi-implicit mixed finite-element formulation to be suitable for spherical domains. In particular the finite-volume transport scheme is extended to take account of non-uniform, non-orthogonal meshes and uses an advective-then-flux formulation so that increment from the transport scheme is linear in the divergence. The resulting model is then applied to a standard set of dry dynamical core tests and compared to the existing semi-implicit semi-Lagrangian dynamical core currently used in the Met Office's operational model.