Regional simulation with the PRECIS Model

Abstract

During 2006 the Geophysics Department of the University of Chile conducted a series of high resolution regional climate model (RCM) simulations for Chile’s National Environmental Commission (CONAMA). The study employed a dynamical model (PRECIS) to produce spatially detailed climate projections for Chile under two different emissions scenarios. The results of the simulations were made freely available for use by the scientific community, industry and policy makers. Today the PRECIS database remains an im-portant resource for the analysis of climate change in Chile, especially in areas such as Patagonia where observations are sparse and climate variables such as temperature and precipitation exhibit extremely sharp spatial gradients that are not resolved by global models. In this presentation we provide an overview of the PRECIS project. We begin with a brief discus-sion of the motivation (section 2) and configuration (section 3) for the regional simulations. In section 4 selected PRECIS results are shown focusing on temperature and precipitation predictions in the Magellan region.MOTIVATIONMost current knowledge about how the world’s climate is likely to change as a result of increasing greenhouse gas emissions is based on numerical simulations using global climate models (GCMs). GCMs describe important physical elements and processes in the atmosphere, oceans and land surface that make up the climate system. The conclusions of the latest IPCC Assessment report were based on simulations from over 20 different global models operated by a similar number of scientific agencies worldwide. A major disadvantage of GCMs is their spatial scale, which is typically a few hundred kilo-meters in resolution. In order to study the impacts of climate change, it is necessary to predict changes on much finer scales. One of the techniques for doing so is through the use of Regional Climate Models (RCMs), which have the potential to improve the representation of the climate information used to assess vulnerability to climate change.The need for RCM’s is especially evident in Chile where, due to the sharp differences in eleva-