Characterizing turbulence in the presence of coherent structures in an estuary Book uri icon

abstract

  • As part of the COHerent STructures in Rivers and Estuaries eXperiment, (COHSTREX), we investigate the effect that vortices and "boils" have on the flow field and turbulent kinetic energy (TKE) immediately downstream of a rocky sill. The field site is located in the Snohomish estuary near Everret, WA, a macrotidal estuary (4 m tidal range) characterized by large, intermittent density stratification over a tidal cycle. Turbulence statistics are estimated using velocity data from a bottom-mounted Acoustic Doppler Velocity Profiler (ADCP) located immediately downstream of the sill and from a vessel-mounted array of acoustic Doppler velocimeters (ADVs) moored within the boil field. These data are compared with data from calibrated thermal (longwave infrared, IR) images of the flow over the sill acquired from an aerial platform. Differences in water temperature measured with the IR platform, as well as data from an echo sounder, are used to determine the presence and intensity of coherent structures. These data are used to determine the boil onset time and are compared with fluctuations in the measured TKE and flow field in order to investigate the modification of the turbulence field by the boils.

publication date

  • October 2007