Land-atmosphere interactions over southern South America using a coupled plant and atmospheric model. Preliminary Results

Observations and modeling results have shown that human disturbances can affect both local and regional atmospheric conditions, which in turn, may affect ecosystem functioning and structure. A coupled atmospheric-vegetation model constitutes an appropriate tool to study the interactions and feedbacks between the biosphere and atmosphere. In the southern part of South America, land-surface changes has occurred similar to other regions of the world, due to human activities such as overgrazing, leading to desertification processes; increased of irrigation practices; deforestation/reforestation; urbanization and conversion to agriculture/animal husbandry of "natural areas". Seasonal and interannual variability of atmospheric variables (e.g., precipitation) represent a distinctive characteristic of the climate in this region. These biosphere-atmosphere interactions, that operate from diurnal to year time scales, have not been fully explored in this region. A climate version of the Regional Atmospheric Modeling System (ClimRAMS) coupled with a plant-scale model (GEMTM) was used to evaluate the regional sensitivity of meteorological and biological variables to land use changes, and biological and radiative effects of increased carbon dioxide concentrations. The model was integrated over a domain covering the southern part of South America . Preliminary results of the model simulations are shown.