Análisis de retroalimentaciones suelo-atmósfera en América del Sur empleando un nuevo modelo climático regional

The primary objective of the present thesis is to contribute to the understanding of the soil moisture – atmosphere interaction during the development and mature phases of the South American monsoon system. A set of dynamical downscaling experiments over the continent are developed and analyzed for this purpose, using the Rossby Centre Atmospheric regional model (RCA). The primary objective leads directly to secondary objectives related to the tool employed for these experiments, the regional model RCA. RCA was developed at Rossby Centre in Sweden to study European and Nordic climate, and for the implementation of the model over South America the model version employed for the thesis work, RCA3-E, was developed and evaluated. A third objective is to quantify the importance of the land surface parameterizations for the simulated climate of South America. The development of the regional model is one of the most important results of this thesis. Many of the biases in the original version employed over Europe (RCA3) could be corrected by changing the surface database and the parameterizatios of convection, microphysics and cloud cover. This thesis also contributed to the understanding of the interactions between soil moisture and atmosphere during the South American monsoon. The influence of a dry winter on the SAMS can have implications for the development of the monsoon both in the Amazon region and in the subtropics through alternations in the continental winds and by direct evapotranspiration recycling. The coupling between soil moisture and precipitation is connected to the coupling between soil moisture and evapotranspiration during the mature SAMS. The La Plata Basin, North Eastern Brazil and parts of the SACZ region were identified as regions with strong soil moisture – precipitation coupling. The sensitivity of the model to land surface parameterizations was found to have a maximum during spring.