The 2005 Amazon Drought Legacy Effect Delayed the 2006 Wet Season Onset

Abstract

While the long-term drought effect on tropical forests has been observed in ground-based and remote sensing measurements, the feedback of reduced forest biomass on subsequent rainfall is not well understood. We evaluate the impact of slow forest recovery after the 2005 Amazonian drought on local evapotranspiration (ET) and wet season onset (WSO) using remotely sensed precipitation, deuterium retrievals, reanalysis data, and a new ET product. A comparison to the 2009 rainy season, which exhibits similar large-scale moisture flux convergence, shows that 2006 experienced a 25% ET reduction and 20 days of postponed WSO in the dry-to-wet transition. Our results imply that ET reduction due to drought-driven legacy effect on the Amazon rainforest could be a crucial factor triggering WSO delay in the transitional season following drought events.