Detection of salinity fronts from satellite observations

Small-scale variability is fundamental to ocean circulation, air-sea interactions, and biogeochemical processes. In many locations, salinity variations play a more significant role than temperature in shaping density fronts. Unfortunately, current satellite data on sea surface salinity (SSS) can only capture features down to 40 km. This study focuses on analysing mesoscale variability (≤25 km) by reconstructing SSS data from satellite observations in the southwest Atlantic, in particular at the Brazil-Malvinas Confluence (BMC). This region is characterised with strong mesoscale structures and high biological activity due to the interaction of western boundary currents and cross-shelf activity. The numerical advection of satellite SSS fields using altimetric geostrophic currents produces a Lagrangian reconstruction that captures finer-scale details. These reconstructed fields are then validated with in-situ salinity measurements obtained via thermosalinograph. Results show that reconstructed SSS fields capture mesoscale structures detected by in-situ observations at the region and improves the effective resolution of SSS satellite observations.