A three-dimensional, adaptive, Godunov-type model for global atmospheric flows

In this paper a Godunov-type methodology is applied to three-dimensional global atmospheric modeling. Numerical issues are addressed regarding the formulation of the tracer advection problem, the application of dimensional splitting, and the implementation of a Godunov-type scheme, based on the WAF approach, on spherical geometries. Particular attention is paid to addressing the problems that arise because of the convergence of the grid lines toward the Poles. A three-dimensional model is then built on the sphere that is based on a uniform longitude-latitude-height grid. This provides the framework within which an adaptive mesh refinement (AMR) algorithm is applied, to enhance the efficiency and accuracy with which results are obtained. These methods are not commonly used in the area of atmospheric modeling, but AMR in particular is commonly used with great success in other areas of computational fluid dynamics. The model is initially validated using a series of idealized case studies that have exact solutions, but is then developed into an offline model of tracer advection, forced by data from meteorological analyses, suitable to study the evolution of trace chemical species in the atmosphere.