| Summary: | Results of four different coupled atmosphere-ocean general circulation model runs for South America and surrounding oveans are examined. The mean response of the simulated climate system to a gradual increase of greenhouse gases is presented. The transient coupled experiment data provide for the Intergovernmental Panel on Climate Change (IPCC) were the most recent available to us at the time of this study, from the following research centres in Europe and USA: the UK Meteorollogical Office (UKMO), the Max-Planck Institute for meteorology (MPI), the Geophysical Fluid Dynamic Laboratory (GFDL) and the National Centre for Atmospheric Research (NCAR). The regional performance of the control simulations (with fixed CO2 concentration) is determined by comparing sea-level pressure, near-surface zonal wind, precipitation and surface air temperature from the models, against observed climatological fields. The response of the climate system to the enhanced emission scenarios is established comparing the control experiments with the respective transient experiments around the time of doubling CO2. To assist in estimating likely future climate change in the South American region, only the rusults of those model experiments with the best control simulatin of current climate in the region are considered: the UKMO and MPI models. A maximum warming over the continent and a minimum warming in the extratropical oceans, a slight intensification and south ward migration of the subtropical ridge, a deepening of the sub-Antarctic trough, an intensification of the westerly winds, and increasing precipitation in the tropics and in the mid-latitude oceans are the most important potential changes simulated by both models for the increased CO2 scenarios. © 1997 royal Meteorological Society.
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