Observing Multi-Scale Ocean Dynamics off Rough Rocky Coastlines: Wave, Current, & Turbulence Coherent Observational System
Abstract
This abstract is publicaly releasable. Feddersens objectives are to use field observations to study the physics of and validate models of coastal ocean dynamical processes important to Navy operations, in particular on rocky coastlines. About 75% of the world coastlines are rocky, limiting Naval accessibility. In contrast to well-studied sandy shores, rocky shores have complex three-dimensional geometries at scales of cm to 100s m, are often exposed to strong waves, and relatively little is known about their wave and circulation dynamics. Rocky shore ocean dynamics are inherently multi-scale. Multi-scale bottom variability (or roughness) has strong effects on wave processes such as scattering, reflection, nonlinear energy transfers, and dissipation that are dramatically different than on sandy beaches. Rocky shore wave processes also strongly affect water-column turbulence and wave-driven currents (rip currents, undertow). The accuracy of existing models developed for low-sloped beaches in predicting rocky shores wave propagation, circulation and turbulence is unknown, nor is what new physics must be included to make accurate predictions. Synchronous arrays with spatial lags from 1-1000 m are required to observe coherent wave processes, yet previously used methods are costly and logistically hazardous on complex rocky shores, requiring a new approach. This DURIP proposal is associated with a MURI Program, ONR Topic 3: Littoral ocean dynamics off of rocky coasts and shorelines submission by a PI team led by MacMahan (NPS), which proposes field experiments on representative rocky shores, and modeling of wave, circulation, and turbulence processes. We propose to develop a Rocky Shorelines Wave, Currents, & Turbulence Coherent Observing System to coherently measure these processes over 1-1000 m scales, advance rocky shores observational capability, and allow use of new statistical approaches. The PI, graduate students and post-doctoral researchers will utilize this system in research, publications, and presentations. The proposed system includes: Phoenix Lidar SCOUT-32 UAS lidar system with a Harris Aerial Carrier H6 UAS (US-made), an IMU, a 32-beam Velodyne HDL-32 lidar, and optical camera to coherently measure the 2D water surface elevation and wave breaking including swash over time. This enables observations in complex regions and slopes difficult to access; Spotter Buoy Synchronous Wave Sampling Array made up of 15 solar-powered Spotter directional wave buoys (with GPS & DoD Iridium) each with SMART cables, and RBR Coda bottom-mounted pressure sensors all on GPS time to coherently measure sea-swell and infragravity wave transformation (shoaling, scattering, nonlinear energy transfers, and dissipation). The lack of cross-buoy cabling allows for versatility in array design and reduces logistical costs for the multiple proposed MURI experiments; and Current Meter Wave/Current/Turbulence Array made up of 4 bottom-mounted Nortek Signature 1000 acoustic current profilers to measure directional wave transformation, wave-induced circulation patterns, and water column turbulence. These Signatures will also be GPS time-synced enabling coherent observations.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 05, 2021
- Source ID
- N000142112700
Entities
People
- Falk Feddersen
Organizations
- Office of Naval Research
- United States Navy
- University of California, San Diego