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