HR: 09:00h
AN: OS31O-03 [PDF]
TI: Modeling the lateral circulation in stratified estuaries
AU: * Lerczak, J A
EM: jlerczak@whoi.edu
AF: Woods Hole Oceanographic Institution, Department of Physical Oceanography, MS#21, Woods Hole, MA 02543
United States
AU: Geyer, W R
EM: rgeyer@whoi.edu
AF: Woods Hole Oceanographic Institution, Department of Physical Oceanography, MS#21, Woods Hole, MA 02543
United States
AB:
In this numerical study, we investigate the mechanisms which
drive lateral (cross-channel) circulations in idealized
estuaries with nonuniform cross-sectional profiles, and
determine how significantly the lateral circulation
contributes to the momentum budget and the dispersion of
tracers (e.g., salinity). Previous observational,
theoretical and numerical studies have shown that lateral
currents can be large (10-20\% of the longitudinal tidal
currents) in well-mixed estuaries. The lateral transport of momentum can have a significant impact on the longitudinal
momentum balance, and the lateral transport of salt can
enhance vertical mixing and horizontal dispersion of salt.
However, less is understood about the dynamics and
significance of lateral circulation in stratified estuaries,
where the occurence of lateral circulations appears to be
more complex due to the baroclinic response to the transverse
flow. Here, we explore the mechanisms which influence the
lateral circulation in stratified estuaries and, conversely,
how lateral circulation influences the stratification. We
use the Regional Ocean Modeling System (ROMS) hydrostatic
primitive equation model. The model is forced by a
semidiurnal barotropic tide. A freshwater flux is prescribed
at the head of the estuary and a salinity gradient is
prescribed at the mouth. We vary vertical mixing (controlled
by a spatially-uniform eddy viscosity and diffusivity), the
freshwater flux and the tidal amplitude in order to study the
lateral circulation under different conditions of
stratification, longitudinal salinity gradient and exchange
flow. We also explore the roles of curvature and rotation in
lateral circulation in stratified estuaries by allowing the
model estuary to meander and by varying the Coriolis
parameter, respectively.
DE: 4235 Estuarine processes
DE: 4255 Numerical modeling
DE: 4500 OCEANOGRAPHY: PHYSICAL
SC: OS
MN: 2002 Ocean Sciences Meeting