Sponsor
This research was funded by a MURI grant from the Office of Naval Research (ONR), award N00014-05-1-0485, and ONR grant N00014-12- 1-0219.
Published In
Journal of Geophysical Research
Document Type
Article
Publication Date
12-2013
Subjects
Snohomish River (wash.) -- Tidal currents, Snohomish River Estuary (wash.) -- Turbulence, Estuaries -- Remote sensing
Abstract
We investigate the relationship between turbulence statistics and coherent structures (CS) in an unstratified reach of the Snohomish River estuary using in situ velocity measurements and surface infrared (IR) imaging. Sequential IR images are used to estimate surface flow characteristics via a particle-image-velocimetry (PIV) technique, and are conditionally sampled to delineate the surface statistics of bottom-generated CS, or boils. In the water column, we find that turbulent kinetic energy (TKE) production exceeds dissipation near the bed but is less than dissipation in the midwater column and that TKE flux divergence closes a significant portion of the measured imbalance. The surface boundary leads to divergence in upwelling CS, and leads to the redistribution of vertical TKE to the horizontal. Very near the surface, statistical anisotropy is observed at length scales larger than the depth H (3–5 m), while boil-scale motions of O(1)m are nearly isotropic and exhibit a 25/3 turbulent cascade to smaller scales. Conditional sampling suggests that TKE dissipation in boils is approximately 2 times greater on average than dissipation in ambient flow. Similarly, surface boils are marked by significantly greater velocity variance, upwelling, divergence, and TKE flux divergence than ambient flow regions. Coherent structures and their surface manifestation, therefore, play an important role in the vertical transport of TKE and the water column distribution of dissipation, and are an important component of the TKE budget.
DOI
10.1002/2012JC008103
Persistent Identifier
http://archives.pdx.edu/ds/psu/11213
Citation Details
Talke, S. A., Horner-Devine, A. R., Chickadel, C. C., & Jessup, A. T. (2013). Turbulent kinetic energy and coherent structures in a tidal river. Journal Of Geophysical Research: Oceans, 118(C12), 6965-6981. doi:10.1002/2012JC008103
Description
This is the publisher's final PDF. Reproduced here with author and publisher permission.
Originally published in Journal of Geophysical Research.
Copyright 2013 by the American Geophysical Union.