Sensitivity of RegCM3 simulations to horizontal resolution

Abstract

Dynamic downscaling for climate studies utilises a regional climate model that is nested within a global climate model (GCM) or global reanalyses. The GCM or global reanalyses data is interpolated to the RCM's grid and used to drive the RCM as initial and time-dependent lateral boundary conditions. The basic idea behind regional climate modelling is that a GCM can provide correct large scale circulation in response to global climatic forcing and the RCM can represent sub-GCM grid scale forcings due to complex topography adequately. Most regional climate modelling studies used a 60 km resolution following the initial RCM studies. Regional climate modelling studies over South Africa that have been conducted have used resolutions of 100 km. The aim of this study is to investigate the influence of horizontal resolution on the RegCM3 simulations over Southern Africa. This study is important for determining the best resolution to use with this model for studies over the area of interest with the parameterisation scheme used for this study nested within 2.5 degrees resolution reanalyses.