Surging Non-Linear Internal Waves Deliver Cold Inner-Shelf Water to the Surfzone
Gregory Sinnett1, Andrew Lucas1, Geno R Pawlak2, Eric J Terrill3 and Falk Feddersen2, (1)Scripps Institution of Oceanography, La Jolla, CA, United States, (2)University of California San Diego, La Jolla, CA, United States, (3)SIO, UCSD, La Jolla, CA, United States
Abstract:
Non-linear internal waves (NLIW) are a significant mechanism for cross-shelf transport of important physical and biological properties. Here, we report new observations of NLIWs delivering cold inner-shelf water all the way to the surfzone. A heavily instrumented cross-shore array with 75 thermistors and 5 ADCPs (spanning depths from 0 to 15 m and cross-shore distances from 0 to 700 m) deployed for 30 days tracked NLIW events as they propagated through the inner-shelf. These observations are used to determine the impact internal waves have on the coupled surfzone/inner-shelf system. Internal wave events in the inner-shelf caused large temperature fluctuations, as high as 6.5 oC in less than 5 hours, causing vertical velocity shear and vertical temperature gradients as high as 1.6 oC/m. Often, NLIWs were observed to propagate all the way to the surfzone, leaving a residual cooling signature in the surfzone, indicative of mixing. The resulting cross-shore temperature gradient persisted long after the end of the internal wave event. Here, we report on these coupled inner- shelf/surfzone NLIW events and explore the associated transport and mixing.
