The Amazon River discharges into the tropical Atlantic ocean an enormous flow of fresh, nutrient-rich waters, with a noticeable effect on the ocean. Moreover, a shallow continental shelf borders South America, where tides are important. However, the salty ocean water does not manage to get into the river mouth, so strong is the Amazon river flow. So is there any impact of tides on the Amazon plume dispersion in the Atlantic?
 
To better understand the effects of tides in the region, a high-resolution, tide-resolving numerical modeling of the western tropical Atlantic was implemented, and two sensitivity experiments were conducted: one with tides, another without tides. This enables comparisons and analysis of what is happening, and understanding of what is the contribution of tides on the observed parameters of the ocean. It appears that the vigorous tidal flow vertically mixes the water column in the shallow shelf off the Amazon mouth, thus leading to less stratified waters. This in turn leads to less salty waters near the river mouth, a plume more extended in the cross-shore direction, favouring its export in the North Brazil Current at the shelf break.
 
Altimetry brought a better knowledge of tides all around the world, close to the coasts and in the open ocean. Even now, the tidal models are improved, and are used in various contexts, including to better understand some general ocean circulation phenomena.