Structure and position of the bottom salinity fron

Authors: Ernesto Molinas Susana Beatriz Vinzon Carla de Paula Xavier Vilela Marcos Nicolas Gallo

Publish Date: 2014/09/12

Volume: 64, Issue: 11, Pages: 1583-1599

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Abstract

This paper aims to study the spatial and temporal variability of the haline structure in the Amazon River mouth A baroclinic threedimensional numerical model Delft3D is configured in order to obtain a yearlong data set of salinity for the domain of interest The results are analyzed along a crossshore transect at the Amazon North Channel A modelbased system description is presented considering the differences between average modeled salinities for different scenarios dry/wet for river discharge neap/spring for tides and windy/calm for wind forcing These results are also presented as Hovmöller graphics evidencing their relation with forcings A statistical model is fitted in order to quantify the importance of the three main forcings—namely river discharge tide and wind—in the bottom salinity front position The main conclusions are as follows i Neap tides favor stratification estuarine circulation and the landward displacement of the front River discharge has low influence on bottom salinities Landward winds promote an increase in surface salinity and reduction at the bottom ii From a maximum displacement of ∼100 km the bottom salinity front position presents astronomical ranges of 232 km for semidiurnal constituents and 668 km for longterm constituents iii Time lags in days found between forcings and the bottom salinity front position were 25 for tidal range null for discharge and 625 for NE–SW winds iv The statistical model confirmed the major relevance of the astronomic tidal effect over the salinity front dynamics r 2 = 80  surpassing the partial influence of winds r 2 = 30  and river discharges r 2 = 21 This study was made possible through grants by FINEP 554616/20106 and CNPq 309288/20118 and 490410/20103 Gail Kineke is acknowledged for making available a data set from AmasSeds project The first and third authors were supported by CAPES Foundation Ministry of Education

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