Science Meetings

Quantifying the Impact of Mesoscale Signature on SSS Changes in the Tropical Pacific
Delcroix T., D. Soviadan, A. Chaigneau, and J. Boutin (25-Apr-17)

High-resolution ocean model results as well as sporadic observations collected in different regions indicate that mesoscale eddies imprint distinguishable changes in collocated Sea Surface Salinity (SSS) and/or precipitation (P) distribution. This presentation shows this is indeed the case for the tropical Pacific, by collocating 6 years (2010-2016) of SMOS-derived SSS, TRMM-derived P and AVISO-derived sea level anomalies. The main characteristics of 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 for the whole tropical Pacific first reveals a physically-realistic relationship between mesoscale eddies and SSS and P changes. The overall tropical Pacific relationship is then stratified as a function of cyclonic and anticyclonic eddies, their amplitude, size, location, kinetic energy (EKE), as well as their SSS and P signatures. For example, in the central basin and near the intertropical convergence zone (where eddy activity dominates and precipitation largely exceeds evaporation), we found that mesoscale eddies can strongly modulate P (± 5 mm/day), probably in line with SST changes, that in turn impacts SSS (± 0.3) with the largest changes found near the eddy center decaying radially to reach minimum values outside. The role of mesoscale eddies in the mixed layer salinity budget is finally discussed.