Evapotranspiration anomalies over the Pantanal region during the droughts 2018-2020

The Pantanal region is the largest continuous wetland on Earth and one of the most biodiverse regions in the world. Its unique ecology relies on a natural flood pulse that sustains a great biodiversity. However, in the last decade, this region experienced anomalous temperatures, dryness and wildfires. In particular, Pantanal underwent three consecutive drought episodes during the years 2018, 2019 and 2020, which were analyzed in this study. In this paper we assess water and thermal stress conditions during these drought episodes using latent and sensible heat fluxes from reanalysis (ERA5land and FLDAS) as well as satellite LST and LAI products. Our results show a progressive intensification of soil moisture deficit, leading to high surface temperature amplitude (AMP-LST) anomalies, as actual evapotranspiration fails to match the evaporative demand. Drought conditions reached their maximum intensity in the September-October-November of 2020 season (SON-2020), when the combination of low soil moisture and high AMP-LST, associated to low Evaporative Fraction (EF), leads to thermal and water stress, further diminishing the ecosystem’s capacity to recover from environmental disturbances. This study highlights the need for an integrated monitoring of land-atmosphere dynamics and the usefulness of satellite observations, with the aim to help and mitigate the impacts of extreme climatic events, such as drought episodes, over sensitive ecological areas, like Pantanal.