| The rainfall regime over Central America and tropical South America is the most important hydro-meteorological event in the tropics after the Asian-Australian monsoon system. Therefore, in this study we analyzed how the tropical rainfall over tropical South America is developed using a multiple time and space scale approach.It was found that the rainfall regime is affected mainly by the ENSO, showing two opposite phases not only in the precipitation, but also in the dynamics terms. Although, there is an advance understanding of the role of the intraseasonal mode of the global tropical precipitation, documentation of the role of the 12-24 day mode over this area of the world is not found. We were able to link rainfall perturbation systems with the 12-24 day mode, which seems to be the dominant intraseasonal but it is embedded and modulated by the 30-60 day mode. Thus, the intraseasonal (12-24 and 30-60 day modes) acts in a harmonic way to portray a quasi-periodic behavior of the rainfall and dynamics elements over the tropics in South America.Finally, a description of the weather systems embedded in these scenarios mainly affected by the warm and cold ENSO phase are presented. There it was found synoptic (eastward) and high-frequency (westward) moving disturbances interaction can help to understand the rainfall pattern under the influence of the ENSO in tropical South America. Thus, during the cold ENSO the positive anomalous precipitation is explained because the constructive interference of these two perturbations and during the warm ENSO the synoptic disturbance is suppressed over the tropics. |
