On the origins of the low-frequency sea surface height variability of the Patagonia shelf region

Abstract

In this study, we identify the drivers of the dominant mode of sea surface height interannual variability over the Patagonian shelf using a suite of process-oriented numerical experiments. Consistent with altimetry, the dominant mode of the model sea surface height interannual variability, which accounts for approximately 84% of the total variance, exhibits a robust deterministic low-frequency variability. The weak sea surface height gradients indicate that this mode has a weak dynamical effect, but the contribution of the steric effect is shown to be non significant. Here we demonstrate that the temporal variability of this mode is not driven by heat or freshwater fluxes but by the propagation of sea surface height perturbations generated in the Pacific. In particular, we show that sea surface height interannual variability over the Patagonian shelf is influenced by wind stress forcing in the offshore region of southern Chile and by the propagation of equatorial sea surface height anomalies.