Circulation Patterns and Associated Rainfall Over South Tropical South America: GCMs Evaluation During the Dry‐To‐Wet Transition Season

International audienceSouth Tropical South America (STSA), extended approximately between 10°N-30°S and 90°W-30°W, is a wide region where diverse interactions among biomass, land surface processes and atmospheric convection take place. These interactions modulate the local and regional climate and directly impact on the socio-environmental activities (Fu et al., 2013; Reis et al., 2018; Zhang et al., 2015). STSA hosts the Amazonia-the world's largest rainforest and one of the major sources of evapotranspiration-playing a critical role in the global balances of energy, water, moisture and carbon (Gatti et al., 2021; Llopart et al., 2020). The region presents unique biodiversity and geographical patterns, mainly due to the interaction of the Amazonia and the Andes mountain range, which have deep implications in the atmospheric dynamics, moisture transport and river discharge not only throughout STSA but also in remote regions of the continent (Arias, Garreaud, et al., 2021; Espinoza et al., 2020; Sierra et al., 2021). Precipitation (PP) over STSA presents a marked spatio-temporal variability, strongly controlled by the South American Monsoon System (SAMS), with rainfall maxima during its active phase during the austral summer (Marengo et al., 2012; Vera et al., 2006). The monsoonal circulation-which develops in response to seasonal changes in thermal land-sea contrasts-is connected to different documented atmospheric features, including a NW-SE band of convergence and convective activity over the southeast of South America and the adjacent South Atlantic ocean known as the South Atlantic Convergence Zone (SACZ), an anticyclonic center locate