Applied Physical Sciences Corp. 475 Bridge Street, Suite 100, Groton, CT 06340 (860) 448-3253 β www.aphysci.com DISTRIBUTION A. Approved for public release: distribution unlimited. Wave Sensing Radar and Wave Reconstruction Gordon Farquharson, John Mower, and Bill Plant (APL-UW) Jason Rudzinsky, John Kusters, Kevin Cockrell, Brad Frazer, and Ben Connell (APS)
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Applied Physical Sciences Corp.
475 Bridge Street, Suite 100, Groton, CT 06340
(860) 448-3253 β www.aphysci.com
DISTRIBUTION A. Approved for public release: distribution unlimited.
Wave Sensing Radar and Wave Reconstruction
Gordon Farquharson, John Mower, and Bill Plant (APL-UW)
Jason Rudzinsky, John Kusters, Kevin Cockrell, Brad Frazer, and Ben Connell (APS)
Slide 2DISTRIBUTION A. Approved for public release: distribution unlimited.
Group speed determines sensing range for forecasting
Slide 9DISTRIBUTION A. Approved for public release: distribution unlimited.
Observation point
Extraction Region (in 1 Dimension)
Reconstruction point
Time
Range
Blind zone
π max
ππ
ππΈ
β’ To reconstruct waves at the buoy, we
have to go back into the radar data
records a minimum of ππ seconds.
β’ The oldest measurement we need to
consider is ππΈ seconds in the past.
β’ π max must be sufficiently large to
ensure that enough modal coefficients
are represented in π-π space.
β’ If π max is too large, low SNR data will
be used in the reconstruction.
Observation area
Slide 10DISTRIBUTION A. Approved for public release: distribution unlimited.
Buoy Measurement Reconstruction
Buoy measurement reconstruction allows us to debug the wave retrieval algorithm
The following conditions must be imposed when doing buoy measurement reconstruction:
Β» Waves propagating towards the buoy must be visible from the point of view of the radar β this can make buoy measurement reconstruction in bimodal seas difficult
Ship
ShipBuoy
Ship motion forecasting Buoy reconstruction
Slide 11DISTRIBUTION A. Approved for public release: distribution unlimited.
R/V Melville Test
September 2013
Wave buoys deployed to measure waves
AWSR #2AWSR #1
Slide 12DISTRIBUTION A. Approved for public release: distribution unlimited.
Melville 2013-09-17 Run 1
β’ In all cases, waves are from the north east, and the buoy was drifting south.
β’ Record length shown is 120 s.
β’ Buoy within, but on the edge of the extraction region until around half way through the record.
β’ Ship comes within 40 m of the buoy.
Slide 13DISTRIBUTION A. Approved for public release: distribution unlimited.
Melville 2013-09-17 Run 2
β’ Buoy well located for wave retrieval.
β’ In this case, buoy measurement reconstruction is very much like reconstruction of waves at the ship.
β’ Why arenβt we getting better correlations?
Slide 14DISTRIBUTION A. Approved for public release: distribution unlimited.
Melville 2013-09-17 Run 3
β’ Outbound waves case β havenβt studied how to set up wave retrieval for this case.
β’ Could set up extraction region on opposite side of track, but distance to buoy is large, so ππΈ would be large.
β’ Radar partially blanked in extraction region.
Slide 15DISTRIBUTION A. Approved for public release: distribution unlimited.
Melville 2013-09-17 Run 4
β’ Radar blanked in extraction region
β’ Extraction region not optimal for first half of record.
β’ Buoy within extraction region for latter half of record.
Slide 16DISTRIBUTION A. Approved for public release: distribution unlimited.
Wave Reconstruction Debugging
Wave reconstruction at buoy for September 11, 2013
Investigating the causes for why we are not reconstructing the wave perfectly all of the time
Slide 17DISTRIBUTION A. Approved for public release: distribution unlimited.
Comparison with Airborne Lidar
Lidar Reconstructed
Lidar data provided by Scripps Institute of Oceanography
Can reconstruct wave field for (π₯, π¦, π‘), which provides us with a natural way to compare with lidar point cloud data
Slide 18DISTRIBUTION A. Approved for public release: distribution unlimited.
Conclusions
Introduced a radar designed for wave measurements
New approach to wave reconstruction from radar data
Wave retrievals compared with buoy data
Topics not covered in this presentation
Β» This algorithm runs in real time, and has been used for wave forecasting
Β» Wave reconstruction technique naturally handles reconstruction using multiple radars (possibly on different ships)
Β» Successfully applied wave retrieval algorithm to data collected by the coherent on receive radar built by University of Michigan / Ohio State University