Research Information System
21ST INTERNATIONAL CONFERENCE ON THE PHYSICS OF ESTUARIES AND COASTAL SEAS, Bordeaux, France, 23 - 27 September 2024, pp.23-24, (Summary Text)
Structure and intensity of estuarine exchange flow depend significantly on the eddy viscosity Av profile which is
dynamically linked to various forces (e.g., gravitational, tidal, wind-driven). The impact of winds on the exchange flow
is complex due to its direct (local and remote changes in shear and density stratification) and indirect (modifications to
Av profiles) contributions (see Basdurak et al., 2021). This study aims (i) to include wind entrainment effects in the tidally
averaged Av parameterization (Fig. 1); (ii) to develop an analytical one-dimensional model for the wind driven exchange
flow by using this novel parameterization and assess the tidally averaged dynamics over a relevant physical parameter-
space, subdomains of which have not yet been explored numerically. This one-dimensional model is based on a balance
between frictional forces and pressure gradient, calibrated with a tidally-resolving one-dimensional water-column model
with second-moment closure. Structure and intensity of the resulting exchange flow profiles are analyzed with respect to
three dimensionless parameters (the unsteadiness of boundary layer mixing Un, scaled-directional wind stress W, and
horizontal stratification Si). While down-estuarine winds enhance the gravitational circulation, up-estuarine winds result
in either a two-layer inverted circulation opposing the gravitational circulation, or a three-layer flow (favored by relatively
strong Si, weak W, and moderate Un) that is up-estuarine at the surface with classical two-layer circulation underneath.
Relative thicknesses of surface and bottom boundary layers affect both the intensity and the inflection depth of the
exchange flow layers. Up-estuarine winds with W ≳0.5 yield unstable stratification and reduce the exchange flow intensity
with increasing W (see Basdurak et al., 2023).