MPDATA and grid adaptivity in geophysical fluid flow models

Abstract

AbstractGeophysical flows can profoundly affect human activities. Often characterized by an astonishing range of significant scales and a rich assortment of physical processes, the complexity of such flows generally precludes all but numerical simulation for prediction and understanding—yet even state of the art computational models may be severely challenged by problems such as hurricane intensification. Although a number of significant issues are involved, a major factor is often grid resolution, for which grid adaptivity (GA) can be useful. Our experience has been that MPDATA is particularly well suited for GA. This paper sketches general details of a model that blends MPDATA with continuous GA; highlights a tensor viewpoint of the geometric conservation law; and presents results for both global and regional atmospheric applications. Together, the examples demonstrate the advantages of using GA with MPDATA to resolve fine‐scale features—explicit gravity waves generated by flow over orography. Resolution of these waves (or lack thereof) are shown to affect global climate; furthermore, wave resolution is shown to depend upon the regional atmospheric environment. Finally the regional simulations show a surprising increase in the complexity of the wavefields as resolution is increased to the point of resolving nonhydrostatic effects. Copyright © 2005 John Wiley & Sons, Ltd.