Sistemas convectivos de mesoescala e sua influência na precipitação e nos desastres naturais no sul do Brasil

Abstract

Natural Disasters (ND) are characterized as the result of adverse events, such as extreme precipitation or droughts, mass movements, among others, which in turn cause damage to humans, materials, and/or the environment, consequently leading to both economic and social losses. In Brazil, there has been a growing increase in the number of disasters related to extreme precipitation, especially in the Southern Brazil (SB) region. Mesoscale Convective Systems (MCS), particularly Mesoscale Convective Complexes (MCC), are organized meteorological systems that generate intense and prolonged precipitation, playing a key role in the rainfall regime of the La Plata Basin region. This study aimed to understand the dynamics of these systems, from their formation to dissipation, and assess how they contribute to extreme precipitation events that trigger natural disasters. Data from the International Satellite Cloud Climatology Project (ISCCP) and ERA5 reanalysis were used to analyze the mesoscale environments that favor the lifespan of MCCs. To investigate the relationship between MCS and landslides, data from Forecast and Tracking the Evolution of Cloud Clusters (FORTRACC) were used for MCS tracking, along with disaster records and precipitation data provided by the National Center for Monitoring and Early Warning of Natural Disasters (Cemaden). The research identified that longer-lasting MCCs (D3) are associated with more favorable atmospheric conditions, such as greater low-level moisture convergence, upper-level divergence, and high values of Equivalent Potential Temperature (EPT) and Convective Available Potential Energy (CAPE). These systems tend to travel longer distances and persist for extended periods. Additionally, it was found that most landslides occurred during the Pre-Maturation phase of MCS, when the systems are intensifying and producing more intense rainfall. Furthermore, antecedent precipitation (accumulated in the days prior to the disaster) played a crucial role in soil saturation, increasing susceptibility to landslides.