A review of atmosphere-biosphere interactions in Amazonia (Invited Presentation)

bal climate.The current knowledge about the water, energy and carbon cycles in Amazonia will be reviewed as well as the effect of land cover changes on these cycles.

With respect to the water and energy cycles, the forest cover is thought to be conducive to higher water recycling and precipitation rates in comparison to the short vegetation cover which tipically replaces forest after deforestation, that is, degraded pastures. Large scale deforestation may reduce rainfall with regional and remote consequences. That is even more important because the SH summer Amazonian atmospheric heat source is the dominant forcing for the South Atlantic Convergence Zone (SACZ) and for other large scale features of the upper level circulation over South America.

Biomass burning in Amazonia throughout the dry season emits significant amounts of aerosols to the troposphere. That aerosol load is both chemically and radiatively important to the atmosphere locally and long range transports are likely to make them significant globally.

Biomass burning and decay of felled forests also represent large emissions of greenhouse gases to the atmosphere, mostly CO2 and CH4, with global significance. However, recent measurements have indicated that the undisturbed rainforest may be a large sink of carbon. Therefore, it is unclear whether Amazonia is a source or a sink of carbon to the global atmosphere.

Finally, the Large Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) will be discussed and preliminary results will be shown as a way to indicate how LBA will help reducing uncertainties about the role of Amazonia for the regional and glo