Science Meetings

A Numerical Study of the Amazon and Congo Plumes
Palma, E.D., Matano, R.P., and Nof, D. (12-Nov-13)

The combined freshwater discharge of the Amazon, Orinoco and Congo rivers is ~280,000 m3/s, which is more than twice the rainfall of the entire Atlantic ITCZ, even without evaporation. The dynamics of these freshwater plumes, therefore, is critical to the freshwater balance of the equatorial Atlantic. In spite of their importance there are very few observational studies on the spreading of the equatorial plumes and scarce modeling studies on their dynamics. In this presentation we use Aquarius data and the results of a suite of process-oriented numerical experiments to investigate the dynamical mechanisms controlling the spreading of the Amazon and Congo plumes. We discuss experiments conducted in highly idealized domains as well as experiments in realistic settings. Our experiments show that the dynamics of the unforced plumes is quite different from the dynamics of mid-latitude plumes on account of the dominance of Beta (the planetary vorticity gradient) over f (the Coriolis parameter). Experiments including realistic wind forcing and the river's inflow show a strong modification of the surface salinity signal as compared to the no-inflow case and a marked seasonality in its spatial distribution.