Mobile Rip Current and Nonlinear InternalWave Profiler: Currents, Temperature, Turbulence
Abstract
Feddersen~s objectives are to use field observations to study the physics of and validate numericalmodels of near-inner-shelf (< 8" m depth but seaward of surfzone) processes important to Navyoperations, including the transport, dispersion, and exchange of tracers such as turbidity, chlorophyll,and temperature. Over the past few years, the previous dominant inner-shelf paradigm of (i)weak cross-shore Ekman transport and (ii) cross-shore exchange of onshore wave-driven Stokesdrift and Eulerian return flow (Lentz and Fewings, 2012) has been demolished. Our work hasclearly shown that surfzone-generated rip currents (primarily transient rip currents, TRCs) and onshorepropagating nonlinear internal waves (NLIW) are the dominant exchange mechanisms in thenear-inner-shelf or the 200-500 m wide region just offshore of the surfzone, and they evolve onvery short time-scales (minutes to hours). Many unanswered questions remain: How much verticalmixing (turbulence) do these processes induce in the near-inner-shelf? How do TRC and NLIW interact?High spatial and temporal resolution observations of TRC and NLIW events are scarce, andtheir interaction non-existent Although models have inferred strong TRC-induced vertical mixing3 surfzone widths offshore, TRC or NLIW mixing observations do not exist.In order to obtain high-resolution observations of TRC and NLIW events in the near-innershelf,we propose to build an Mobile Rip Current and Nonlinear Internal Wave Profiler Systemthat will dramatically expand our field capability to agilely sample TRC and NLIW events in thenear-inner-shelf in water depths < 6 m where small boats cannot operate. Observations from thissystem will provide the basis for addressing the science questions above. The proposed elementsof the Mobile Rip Current and Nonlinear Internal Wave Profiler System include:Jetski-based mobile current, CTD, turbidity, and microstructure profiler: The jetski will beequipped with an Xylem ADCP, Biosonics Echosounder, a a winched boom with CTD andmicrostructure profiler, RTK GPS and a Toughpad tablet for real time data display. Thismobile instrument platform will allow for in situ rip current and NLIW sampling.Unmanned Aircraft System (UAS) with Thermal Infrared Imagery: A FLIR Zenmuse XT2LWIR camera will be mounted on a DJI Matrice 210 RTK V2 UAV with RTK GPS inorder to make real-time measurements of sea surface temperature (SST) in regions where ripcurrents and NLIW interact. The system will cover a 500 m by 500 m at pixel resolutionat 1 m with temperature accuracy of 0.1oC. Real-time data will allow our FAA certifiedoperator to guide the mobile jetski to sample regions of interest.Wirewalker Mooring with Realtime Telemetry: A Del Mar Ocean Wirewalker mooring in15-20 m depth will have a CTD with real time telemetry via cell phone network allowingnotification of NLIW events.The PI, students and post-doctoral researchers will utilize the requested instrumentation in thesisresearch, publications, and presen"tations. This instrumentation will also be available to other SIOyoung scientists. This abstract is publicly releasable.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 20, 2019
- Source ID
- N000141912651
Entities
People
- Falk Feddersen
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego