Regional Climate Models

Abstract

Regional climate models are numerical models that simulate the climate of geographic regions typically covering a few thousand square kilometers to a continent. Most regional climate models include models that describe the atmosphere and the underlying land surface, but a few also include models of ocean and sea ice and atmospheric aerosols and chemistry. Given the atmospheric state at the lateral boundaries, regional climate models simulate regional climate in the context of the evolving global climate. Because regional domains cover only a fraction of the globe, it is computationally more feasible to apply regional climate models at higher grid resolution compared to global climate models to better resolve atmospheric and terrestrial processes and how they respond to regional forcings such as topography and land cover/land use. While global climate models are generally applied at grid resolution of a few hundred kilometers, regional climate models have been more commonly applied at grid resolution of a few tens of kilometers. Therefore, a common application of regional climate models is the dynamical downscaling of global climate simulations to provide regional climate information related to climate change projections or climate predictions. As such, regional climate models have served an important function of providing regional climate scenarios needed to assess a wide range of societal relevant climate impacts such as climate change effects on water resources and ecosystems. Regional climate models are also used to study regional climate processes, particularly those that are related to the water cycle that is inherently multi-scale; so explicitly representing finer scale processes is important to simulate its variations at multiple time and space scales.