Other Scholarly Content

 

Turbulent mixing in a strongly forced salt wedge estuary Public Deposited

Downloadable Content

Download PDF
https://ir.library.oregonstate.edu/concern/defaults/1831cm425

Descriptions

Attribute NameValues
Creator
Abstract
  • Turbulent mixing of salt is examined in a shallow salt wedge estuary with strong fluvial and tidal forcing. A numerical model of the Merrimack River estuary is used to quantify turbulent stress, shear production, and buoyancy flux. Little mixing occurs during flood tides despite strong velocities because bottom boundary layer turbulence is dislocated from stratification elevated in the water column. During ebbs, bottom salinity fronts form at a series of bathymetric transitions. At the fronts, near-bottom velocity and shear stress are low, but shear, stress, and buoyancy flux are elevated at the pycnocline. Internal shear layers provide the dominant source of mixing during the early ebb. Later in the ebb, the pycnocline broadens and moves down such that boundary layer turbulence dominates mixing. Mixing occurs primarily during ebbs, with internal shear mixing accounting for about 50% of the total buoyancy flux. Both the relative contribution of internal shear mixing and the mixing efficiency increase with discharge, with bulk mixing efficiencies between 0.02 and 0.07. Buoyancy fluxes in the estuary increase with discharge up to about 400 m³ s⁻¹ above which a majority of the mixing occurs offshore. Observed buoyancy fluxes were more consistent with the k-ɛ turbulence closure than the Mellor-Yamada closure, and more total mixing occurred in the estuary with k-ɛ. Calculated buoyancy fluxes were sensitive to horizontal grid resolution, as a lower resolution grid yielded less integrated buoyancy flux in the estuary and exported lower salinity water but likely had greater numerical mixing.
Resource Type
Date Available
Date Issued
Citation
  • Ralston, D. K., W. R. Geyer, J. A. Lerczak, and M. Scully (2010), Turbulent mixing in a strongly forced salt wedge estuary, Journal of Geophysical Research, 115, C12024
Series
Rights Statement
Funding Statement (additional comments about funding)
  • This research was funded by National Science Foundation Grant OCE‐0452054. Ralston also received support from The Penzance Endowed Fund in Support of Assistant Scientists and The John F. and Dorothy H. Magee Fund in Support of Scientific Staff at Woods Hole Oceanographic Institution.
Publisher
Language
Replaces
Additional Information
  • description.provenance : Submitted by Deborah Campbell (deborah.campbell@oregonstate.edu) on 2012-04-18T20:02:12Z No. of bitstreams: 1 LerczakJamesA.CEOAS.Turbulentmixingstrongly.pdf: 2524667 bytes, checksum: 1fa4bea574a3ee9811e97003d511a844 (MD5)
  • description.provenance : Made available in DSpace on 2012-04-18T20:02:12Z (GMT). No. of bitstreams: 1 LerczakJamesA.CEOAS.Turbulentmixingstrongly.pdf: 2524667 bytes, checksum: 1fa4bea574a3ee9811e97003d511a844 (MD5) Previous issue date: 2010

Relationships

Parents:

This work has no parents.

Items