Rossby Wave Dynamics over South America Explored with Automatic Tropical–Extratropical Cloud Band Identification Framework

Abstract During austral summer, persistent tropical–extratropical cloud bands, such as the South Atlantic convergence zone (SACZ) over America (SAm), link tropical humid areas to subtropics. In this study, we utilize an automatic object-based methodology identify synoptic band events occurring SAm that are responsible for almost 60% of precipitation during rainy season (November–March). addition identifying SACZ bands persisting 4 or more days, framework also highlights relevance transient (i.e., 3 days less) climatology. The location and persistence modulated by propagation synoptic-scale extratropical disturbances interacting with intraseasonal variability in basic-state upper-level zonal wind. lasting days), westerly anomalies subtropics favor deeper into tropics. Conversely, occur when Bolivian high is displaced/expanded southeastward, bringing easterly winds subtropical latitudes blocking Rossby waves lower latitudes. Subsequent anomalous convection from result sources interact basic flow, resulting downwind enhancement damping disturbances. adopted proved be a powerful demonstrating interaction between scales, state influencing being modified