Mean climate and annual cycle in a regional climate change experiment over southern South America II: Climate change scenarios (2081-2090).

MARIO N. NUÑEZ, SILVINA A. SOLMAN, MARÍA FERNANDA CABRÉ

Foz de Iguazú, Brasil

Conferencia; 8th International Conference on Southern Hemisphere Meteorology and Oceanography. (8ICSHMO). Octava Conferencia del Hemisferio Sur de Meteorología y Oceanografía.; 2006

American Meteorological Society.

We analyzed the climate changes simulated over Argentina and surrounding countries under two IPCC emission scenarios (A2 and B2) for the period 2081-2090 with respect to the reference period 1981-1990. The simulations are performed with the regional climate model MM5 using forcing lateral boundary conditions from time-slice simulations with the HAdAM3P global atmospheric model. Our primary conclusions can be summarized as follows:• The MM5 Regional Climate Model simulate current climate more realistically and project climate change with greater detail.• In all seasons, southern South America undergoes warming in both the A2 and B2scenarios. Minimum changes in the Mean Temperature are projected for summerand fall over the domain (2.5 - 3.5 ° C in the A2 simulation).• Maximum changes in the Mean Temperature are projected for winter and springover the domain (2.5 - 5.0 ° C).• The precipitation changes vary substantially from season to season and acrossregions in response to changes in large scale circulations. Seasonal changes inprecipitation in Argentina are projected for summer and fall seasons (west and humidPampas increase approximately 180 mm maximum per season in the A2 simulation).• Maximum monthly changes are found for February, March, April, November andDecember (not shown) in Precipitation.• B2 simulation shows a similar geographical pattern of the changes in temperatureand precipitation, with quantitative differences between both emission scenarios.• The broad patterns of change in the nested regional climate model MM5 anddriving HadAm3P fields are generally consistent each other, as can be expectedfrom the strong influence of the boundary forcing on the regional model simulation.In summer, however, significant differences in the temperature and precipitationchange can be found between the models. This could be due to the local physical processes.• Strongly changes in sea level pressure (SLP) along the year produced by a displacementof the Atlantic and Pacific Anticyclones toward South Pole.• Changes in high latitude circulation. Westerly winds in low levels will be less intense.• Comparing with present trends, the regional climate projections for 2080s showan increase in most of Argentina, as in the present observed climate.