the role of argus in the ncex field experiment rob holman secnav/cno chair in oceanography
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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
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