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Finescale variability in salinity fronts in the northwest Atlantic reconstructed through Lagrangian techniques

Finescale salinity variability was reconstructed through Lagrangian techniques applied to satellite salinity measurements made by the Soil Moisture Active Passive (SMAP) satellite in the northwest Atlantic Ocean.

Oceanic structures at scales smaller than ∼100 km (such as fronts, eddies, and filaments) have an important contribution to ocean circulation, air-sea interactions, climate variability, and marine biogeochemistry. In many regions, the contribution of salinity dominates that of temperature in generating density fronts. 

Despite its importance, measurements of ocean salinity are limited to relatively sparse in-situ observations from different platforms and global remote sensing surface observations with low resolution from satellites. Satellites that measure sea surface salinity (SSS) from space have a resolution lower than 40 km and do not allow the observation of small-scale structures (<25 km). 

The paper Lagrangian Reconstruction to Extract Small-Scale Salinity Variability From SMAP Observations developed techniques to exploit satellite salinity measurements made by the Soil Moisture Active Passive (SMAP) satellite in the northwest Atlantic Ocean so to extract signals at the highest possible spatial resolution. Reconstructed fields were compared to in-situ observations and revealed a marked improvement in the reproduction of observed salinity fronts when compared to SMAP fields. The paper found that enhanced small-scale salinity variability is concentrated in two bands: a northern band aligned with the continental shelf break, and a southern band aligned with the Gulf Stream mean position. Seasonal differences in the small-scale salinity variability are mainly driven by the seasonal cycle of the large-scale SSS induced by the freshening of the coastal waters due to river outflow. 

The next generation of satellite missions, such as SWOT will provide surface horizontal velocities with high-spatial resolution that may increase the accuracy of the finescale salinity variability reconstructed from SMAP.       

FOR MORE INFORMATION

Bàrbara Barceló-Llull, Kyla Drushka, Peter Gaube (2021). Lagrangian Reconstruction to Extract Small-Scale Salinity Variability From SMAP Observations. Journal of Geophysical Research: Ocean. https://doi.org/10.1029/2020JC016477