CONICET | Buscador de Institutos y Recursos Humanos

We present an analysis of climate change over Southern South America as simulated by a regional climate model. For the driven global model HadAM3P, a 10-year control run and two 10-year scenario runs (based on the SRES A2 and B2 emission scenarios) were made with MM5 regional model. There are few quantitative differences between both emission scenarios. The simulated changes are larger for the A2 than the B2 scenario, although with few qualitative differences. In the two scenario runs, the warming in southern Brazil, Paraguay, Bolivia and northeastern Argentina are larger in winter and mainly in spring. In Paraguay, southern Brazil and northern Argentina the warming peaks in spring when it locally reaches 5.5 ° C in the simulation for the A2 scenario. The B2 simulation shows a general increase in precipitation in southern Brazil, Paraguay, Bolivia, Uruguay, northern Argentina and northern Chile, with some decrease patches in precipitation southern Brazil, northern Chile, southern Peru, northwestern and northeastern Argentina and in the Patagonia. The A2 simulation shows a similar geographical pattern of the changes in precipitation, but with more extended areas with decrease in precipitation mainly in Chile. Both simulations show a general increase in precipitation in northern and central Argentina especially in summer and fall and a general decrease in precipitation in winter and spring. In fall the simulations agree on a general decrease in precipitation in southern Brazil. This reflects changes in the atmospheric circulation during winter and spring. Changes in mean sea level pressure show a cell of increasing pressure centered somewhere in the southern Atlantic Ocean and southern Pacific Ocean, mainly during summer and fall in the Atlantic and in spring in the Pacific. In relation to the pressure distribution in the control run, this indicates a southward extension of the summer mean Atlantic and Pacific subtropical highs.

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