Variations in the amount of rain that feeds the Amazon River, ranked as the world’s largest river in terms of annual discharge, can profoundly impact the marine ecosystem in the region where the fresh river water enters the salty ocean (Amazon plume region) and influence the hydroclimate over the tropical Atlantic. Recent research has found that seasonality changes in Amazon precipitation, where the wet seasons have become wetter and the dry seasons drier, have intensified recently, but it's unclear if this has affected river discharge and salinity in the plume region. Supported in part by CPO’s Climate Variability and Predictability (CVP) Program, a new study in Nature Communications found that the amplified seasonal cycle of Amazonia precipitation correspondingly leads to enhanced seasonality for both river discharge and ocean salinity in the Amazon plume region. Notably, low salinity in the plume region leads to more heat trapped in the upper ocean, which could encourage hurricane genesis over the tropical western Atlantic regions. The findings have important implications for hurricane forecasting and suggest that the intensified seasonal precipitation cycle may favor more extreme terrestrial and marine conditions.
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