Jack Reeves-Eyre and Xubin Zeng
The Amazon river system has by far the largest runoff of any river on Earth. Annual mean rainfall of over 2000 mm/yr (Tucson receives ~300 mm/yr) is fed by atmospheric convergence of moisture from the tropical Atlantic, as well as recycling of evapotranspiration. A significant fraction of this precipitation runs off into river channels and is routed to the ocean. Amazon discharge into the Atlantic Ocean affects ocean salinity over a significant area, with consequent effects on sea surface temperature and ocean-atmosphere interactions.
Past studies have suggested that, perhaps surprisingly, interannual Amazon discharge variability has relatively little effect on interannual ocean salinity variability. However, these studies have typically used only a subset of available salinity information and have relied on inland river gauges. Here, we use a range of satellite, reanalysis and in-situ data to create a holistic picture of the Amazon water cycle and better understand the discharge-salinity relationship.