Consequences of Using the Splitting Method for Implementing Physical Forcings in a Semi-Implicit Semi-Lagrangian Model

Any comprehensive numerical model is composed of two parts: a dynamical kernel solving for the fluid mechanical field equations and a physical package to parameterize the ensemble effect of subgrid-scale processes upon the resolved scales of the model. There are a number of techniques that can be used for combining the dynamics and physics contributions. One such method called “splitting” is used in some models because of its simplicity and stability property. In this article the authors demonstrate that the splitting method may introduce serious truncation errors when used in conjunction with long time steps that are permitted by semi-implicit and semi-Lagrangian marching algorithms.