Moisture and temperature sources were key drivers of the anomalies for the record-breaking of 2023 Amazon drought

The record-breaking 2022–24 Amazon-drought, which extended into the Orinoco and Cerrado regions, was characterized by severe-dry conditions during the dry-to-wet transition-season of the 2023–24 hydrological years (September-November/2023). This situation was not driven by a moisture-deficit from either remote sources or the region itself, although oceanic moisture sources exhibited negative anomalies. It was caused by the prevailing atmospheric stability, which inhibited convection and therefore precipitation in this region, and by extremely high temperatures having as its main driver the transition from 2022–23 La Niña to 2023–24 El Niño, which amplified the anomalies in the variables. Although atmospheric moisture was anomalously high, it was insufficient to compensate for the high temperatures, which led to reduced relative humidity values and enhanced atmospheric evaporative demand. Moisture that did not precipitate in the region was transported to areas where there was sufficient instability for convection, resulting in high precipitation and floods in the Uruguay/Brazilian-South-Atlantic-Marginal river basins in September-October/2023. The temperature anomaly over the target region had two sources: a local one contributing to warming and an external one contributing to cooling. The results show the importance of adiabatic warming due to subsidence in the region itself and outside the region. The record-breaking 2022–24 Amazon-drought was caused by prevailing atmospheric stability and extremely high temperatures driven by the transition from 2022–23 La Niña to 2023–24 El Niño, according to the Lagrangian moisture and heat uptake computation with database spanning 1994–2023.