CoAuthors

Alexis Chaigneau (IRD/LEGOS, France); Thierry Delcroix (IRD/LEGOS, France); Jacqueline Boutin (LOCEAN, France)

High-resolution model results and sporadic in situ observations suggest that mesoscale activity has to be considered to properly close the mixed-layer salinity budget. By collocating 6 years (2010–2016) of remotely sensed validated sea-surface salinity (SMOS-CATDS CEC LOCEAN debiased product), precipitation (TRMM-3B42) and satellite altimetry data (AVISO+), we investigate the impact of oceanic mesoscale eddies on sea-surface salinity (SSS) and freshwater fluxes (P) in the tropical Pacific. Mesoscale eddies are first identified in sea-level altimetry maps and their signature is then determined using concomitant satellite-derived SSS and P data. A composite analysis over the whole tropical Pacific first reveals a likely relationship between mesoscale eddies and SSS and P changes. The relationship is then stratified as a function of cyclonic and anticyclonic eddy amplitude, size, location and EKE. We found, for example, that near the intertropical convergence zone, where eddy activity dominates and precipitation largely exceeds evaporation, mesoscale eddies can strongly modulate precipitation (± 5 mm/day) that in turn impacts SSS (± 0.3). There, anticyclonic (cyclonic, respectively) eddies are mainly associated with positive (negative) P anomalies that tend to decrease (increase) SSS. In addition, the SSS anomalies are found stronger near the eddy center, decaying radially to reach minimum values outside. The role of mesoscale eddies in closing the mixed layer salinity budget is finally discussed.