Impact of wind variations on surface variability over the Patagonian Continental Shelves

Abstract. We study the impact of wind variability on sea surface temperature (SSTa), sea surface salinity (SSSa), and sea level anomaly (SLAa) over the Patagonian shelves around southern South America using satellite observations and the ERA5 reanalysis. Using Empirical Orthogonal Function (EOF) analysis, we identify the dominant patterns of variability in surface ocean properties and winds and assess their interconnections through correlation and composite maps. Zonal and meridional wind anomalies modulate the variability of sea level anomaly with distinct spatial signatures. Meridional wind variability emerges as the dominant driver, exerting a strong influence on sea surface temperature, salinity, and sea level, generating coherent patterns across the southeast South Pacific and southwest South Atlantic continental shelves. Specifically, the leading mode of meridional wind is significantly correlated with the dominant modes of variability of SSTa, SSSa, and SLAa. Moreover, the spatial patterns emerging from the composites associated with the leading meridional wind mode are consistent with the dominant SSTa, SSSa, and SLAa variability patterns. These results suggest that southerly winds promote upwelling and offshore flow of low salinity waters over the Pacific shelf, weaken the southward flowing Cape Horn Current along the shelf break, and strengthen the northward transport of cold-salty subantarctic water over the Atlantic shelf. Northerly winds reverse these dynamics. This study provides evidence of wind-driven coupling of the shelf circulation on both sides of South America and the interocean exchanges between the Pacific and Atlantic continental shelves.