Challenges and opportunities in modeling of the global atmosphere

Abstract

Issues relevant for modeling of the atmosphere on the global scale are discussed in the light of the advancements in computer technology. It should be noted, however, that the prediction of future computer developments over the next few decades is difficult, and that some of the current projections may not materialize. The problem of spherical geometry is addressed first. Several possible approaches are reviewed, including those that have been historically most popular, and those that are currently considered most promising in terms of computational efficiency and scalability. Also, implementation of global nonhydrostatic NWP models has been considered a priority at several meteorological centers. Having in mind the sensitivity of extended deterministic forecasts to small disturbances in initial data and model parameters, it is argued that we may need global nonhydrostatic models et even lower resolutions than in short-range regional runs, and that this is likely to bring additional problems with computational efficiency. As an example of a global model, the unified Nonhydrostatic Multiscale Model on the Arakawa B grid (NMMB) is presented. This model is being developed at National Centers for Environmental Predictions (NCEP) for spatial scales ranging from meso to global.