|Title||Cross-shore deformation of a surfzone-released dye plume by an internal tide on the inner shelf|
|Publication Type||Journal Article|
|Year of Publication||2020|
|Authors||Grimes D.J, Feddersen F, Giddings S.N, Pawlak G.|
|Type of Article||Article|
|Keywords||Coastal flows; dispersion; driven; exchange; internal waves; model; ocean; oceanography; solitary waves; stokes drift; tracers; transient rip currents; transport; wind|
An inner-shelf (IS) dye plume that formed following a 3.84-h early morning surfzone (SZ) dye release off of Imperial Beach, California, is analyzed with in situ and aerial remotely sensed observations. Midmorning, 5 h after release start, the IS plume extended 800 m offshore (or approximate to 8L(sz), where L-sz is the surfzone width) and was surface intensified. Over the next approximate to 2 h, the IS plume deformed (narrowed) cross-shore with the offshore front progressing onshore at approximate to 5 cm s(-1), deepened by up to 3 m, and elongated alongshore at approximate to 4.5 cm s(-1) km(-1) (at approximate to 2.5L(sz)). Coincident with IS plume deformation and deepening, IS isotherms also deepened, with relatively stable IS plume joint dye and temperature statistics. Offshore tracer transport and subsequent IS plume deformation and deepening likely resulted from two phases of the diurnal internal tide (DIT). During and after deformation, the IS plume did not reenter the warm surfzone, which potentially acted as a thermal barrier. High-frequency internal waves (HF IWs) propagated through the IS plume at approximate to 9 cm s(-1) and dissipated onshore of 4L(sz). Surface HF IW signal was elevated in the plume elongation region, suggesting a linkage between plume elongation and either the DIT or HF IW. This IS plume evolution differs from previous SZ tracer releases, highlighting the effects of release timing relative to the solar cycle or the internal tide.