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Observation of Sediment Mobilization by an Internal Solibore on the California Inner Shelf
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  • Joseph Darryl Jefferson,
  • Julian A Simeonov,
  • Joseph Calantoni,
  • Alex Sheremet
Joseph Darryl Jefferson
University of Florida

Corresponding Author:[email protected]

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Julian A Simeonov
Naval Research Laboratory
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Joseph Calantoni
U.S. Naval Research Laboratory
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Alex Sheremet
University of Florida
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Abstract

Acoustic backscatter, velocimetry measurements of the nearbed velocity profiles, and thermistor chain measurements of the temperature stratification were used to understand the bottom boundary layer flows and associated sediment transport processes in 35 meters water depth on the California shelf off of Point Sal where the bottom sediment consist of fine sand with median grain size diameter of $d_{50}=0.1$ mm. The observations show that the nearbed flow is dominated by the bore of a shoaling internal tide whose steepening front generated a series of internal solitary waves (ISW) with a 15-min period superposed on the tail of the bore. The bore-induced nearbed flow was strongly asymmetric with 20 cm/s seaward directed flow under the bore trough that exceeded the bottom stress threshold for mobilization of the 0.1 mm sand, and 5-10 cm/s onshore flow during the tail of the bore that produced only subcritical bottom stress. The ISWs induced symmetric 5-10 cm/s nearbed velocity which however combined with the bore tail to produce onshore flows under the wave crests with bottom stress that also exceeded the sediment mobilization threshold.
19 Jun 2023Submitted to ESS Open Archive
22 Jun 2023Published in ESS Open Archive