Dynamics of the subtidal transport through the Guafo Mouth connecting the open ocean and the Chilean Inland Sea in southern Chile

The Chilean Inland Sea (CIS) and the fjords region in Southern Chile host human activities such as salmon aquaculture. During the productive austral summer, the CIS exchanges heat, salt, dissolved oxygen, and nutrients with the Southern Pacific Ocean via the Guafo Mouth, a very shallow strait. Tides influence the productivity of the CIS, a high-frequency forcing typically not considered in circulation models when estimating exchange fluxes. In this work, the inflow, outflow, net, mass, and nutrient fluxes through the Guafo Mouth are evaluated using a high-resolution regional model forced by tides. Model output (temperature, salinity, and currents) is compared to hydrodynamic data. The impact of tidal forcing on summer-mean currents and transports is quantified. These findings are compared with results from a lower-resolution, commonly used, general circulation model. A Lagrangian modeling approach highlights that the water masses transiting from the open ocean through the Guafo Mouth mainly originate from the region south of the mouth.