Tracing Amazon River water into the Caribbean Sea

Monthly Amazon River discharge is correlated to historical monthly sea surface salinity (SSS) in the western tropical Atlantic Ocean and the Caribbean Sea. At Barbados a very high inverse correlation (R-2 = 0.92) exists if the discharge is lagged by two months, which corresponds to the travel time from the Amazon mouth to Barbados. Due to its proximity to Barbados, a small amount of the correlation can also be attributed to the Orinoco River. Between Barbados and the central Caribbean Sea (75W) the peak correlation of Amazon River discharge and SSS occurs at progressively longer lag times, representing the longer travel time. The correlation is highest at Barbados and diminishes with distance downstream. Downstream of the central Caribbean Sea (75W) no correlation is evident, as the Amazon water becomes too diluted to be clearly defined by available data. The results of the analysis are used to calculate surface current speeds of 0.34 +/- 0.09 m/s from the Amazon mouth to Barbados and 0.10 +/- 0.02 m/s from Barbados to the central Caribbean Sea (75W). Downstream of Barbados a subsurface maximum in correlation develops. The correlation is eroded more strongly at shallower depths due to more intense surface processes (e.g., evaporation and precipitation).