The Role of Argus in the NCEX Field Experiment

Rob HolmanSECNAV/CNO Chair in Oceanography

Argus I

Argus II

Argus III

Pixel Instrument Coverage (early test example)

shoreline

NCEX Tessellation Array

Resolution limited (5 m)

1842 pixels

tile

Tessellation Array Locations

Example Directional Spectra

Example Directional Spectra

Example Directional Spectra

Tessellation Arrays

• Produce wave directional “spectrum” at any location

• Extract simple statistics (peak direction?)

• Use same lag array for depth estimation

NCEX Array, 09/03

NCEX Array, 09/03 (blow-up)

Runup

“Old” Bathy Line

Vbar

Tess(alpha and bathy

Longshore Currents(Chris Chickadel)

Orientation for Next Slide

10/31/03, 0700 Variance Image

Happy Halloween

Rip current

Radiation Stress Gradients

cx

Sxy αε sin><=

∂∂

where:

Sxy = Radiation Stress

<ε> = mean dissipation due to wave breaking

α = local incident wave angle

c = celerity

•Components in both the longshore and cross-shore directions

•Concentration on diagonal component Sxy

•Optical techniques necessary for all parameters to allow remote sensing

Work of Jason Killian

Fusion with Numerical Models

Based on:• Wave direction• Surf zone width

California Fires, 10/28/03

Mid-afternoon view

Southern California

Estimation of Swash Velocities

Runup transect from NCEX exp’t, 2004

Two-minute Time Stack

NCEX stack, 2003

Band-pass Isolation of Foam

Consecutive Intensity Transects

Analysis

•Band-pass to isolate foam

•Hilbert transform to extract phase and wavenumber

•U = d(phase)/dt * 1/k

Example Sub-stack Results

Example Sub-stack

Example Sub-stack Overlay

Two-minute Sub-stack Example

17 minute run takes 9 seconds

Application of Hilbert Approach to Longshore Currents?(and rips?)

Longshore velocity = = 0.60 m/ secyt

Duck, NC

0

40

Tim

e (s

ec)

t =

18.

7 s

y =11.3 m

-20 20Longshore Distance (m)

Questions?

Dr. AarninkhofDistinguished Argus Scientist

Costas Synolakis

Oregon State University Wave Tank, 2003