The influence of river discharge and wind on Patos Lagoon, Brazil, Suspended Particulate Matter

Eight years (2008–2015) of reflectance data from the Moderate Resolution Imaging Spectroradiometer (MODIS) – Aqua sensor are used to quantify Suspended Particulate Matter (SPM) distribution and variability in Brazil’s Patos Lagoon. After application of an atmospheric correction suitable for extremely turbid coastal water and calculation of SPM concentrations from the reflectance values using an established algorithm, the daily remote sensing data were averaged into eight-day and monthly composites. The climatological patterns show a gradient from higher concentrations in the north to lower concentration in the south, with highest concentrations in austral spring and summer and lowest in autumn and winter. Strong interannual variability shows 2009 and 2012 to have the highest SPM concentrations and 2010 and 2014 to have the lowest. Time series of SPM were then compared with the main forces to the lagoon circulation (wind and river discharge). Peaks in SPM are associated with peaks in river discharge. Maximum SPM occurred following peaks in river discharge combined with strong northeast (NE) winds, suggesting that freshwater input and direction-specific winds are the major mechanisms of sediment transport in Patos Lagoon.