Abstract:Using monthly data for the period 1979-2010, we study the dynamics and strength of land surface-atmosphere feedbacks (LAFs) among variables involved in the heat and moisture fluxes, at interannual timescales in Tropical South America (TropSA). The variables include precipitation, surface air temperature, specific humidity at 925 hPa, evaporation, and estimates of volumetric soil water content. We use a Maximum Covariance Analysis (MCA) to reduce the dimensionality and to rank the relative contributions to LAFs and group the time series into Maximum Covariance States (MCS) with common mechanisms among variables. We estimate linear (Pearson correlations) and non-linear association (information transfer or causality) metrics among pairs of variables to configure the structure of linkages. The main MCS associated with LAFs over TropSA are strongly influenced by ENSO, and the meridional and equatorial SSTs modes over the Atlantic and Indian Oceans. ENSO favors a unimodal behavior, with center of action in the Amazon River basin, while the SSTs mode over the Tropical North Atlantic (TNA) results in a dipole between northern and southern TropSA. Our results show that soil moisture plays a leading role in regulating heat and water anomalies, and provides the memory of the LAFs and their subsequent influence. Thus, volumetric soil water becomes a fundamental variable leading up to 9 month-lags. ENSO enhances the interannual connectivity and memory inside LAF mechanisms with respect to other modes. Within the identified multivariate structure, evaporation and soil moisture enhance the interannual connectivity of the whole set of variables since both variables exhibit more frequent two-way feedbacks with the remaining variables.