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Bill Plant

Hourly Retiree

Email

plant@apl.washington.edu

Phone

206-221-7623

Biosketch

Dr. Plant's expertise is in remote sensing, air-sea interaction, and streamgaging. The primary objectives of his research group are to investigate microwave scattering from rough water surfaces and to develop techniques to obtain geophysical information from such scattering.

Bill Plant received his bachelor's degree in physics from Kansas State University, and the M.S. and Ph.D. degrees from Purdue University. He is also an Adjunct Professor in the Division of Applied Marine Physics at the University of Miami.

Education

B.S. Physics, Kansas State University, 1966

M.S. Physics, Purdue University, 1968

Ph.D. Physics, Purdue University, 1972

Projects

Radar Measurements of Shoaling Waves and Longshore Currents at the Corps of Engineers Field Research Facility

We have operated our coherent, X-band radar, RiverRad, at the Corps of Engineers Field Research Facility in Duck, NC in order to compare our measured return with that obtained by Merrick Haller of Oregon State University using a non-coherent, X-band, marine radar and with video images obtained by Rob Holman of the same institution. OSU graduate student Patricio Catalan is coordinating this comparison.

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We have operated our coherent, X-band radar, RiverRad, at the Corps of Engineers Field Research Facility in Duck, NC in order to compare our measured return with that obtained by Merrick Haller of Oregon State University using a non-coherent, X-band, marine radar and with video images obtained by Rob Holman of the same institution. OSU graduate student Patricio Catalan is coordinating this comparison. The purpose of this experiment was be three fold: 1) to calibrate the marine radar against RiverRad, which is calibrated on our test range, 2) to examine the differences in HH and VV return from breaking waves, and 3) to attempt to obtain along shore currents from the Doppler shifts in the VV return. All of these measurements will augment the marine radar, which operates only at HH and is presently uncalibrated. They will not provide the spatial wave images possible with the marine radar, however.

Optimum Vessel Performance in Evolving Nonlinear Wave Fields

Measuring phase-resolved waves around a ship is APL-UW's involvement in this four-part project by demonstrating wave height retrievals from both cross sections and Doppler shifts along a line.

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This project has four parts:

1. Measure phase-resolved waves around a ship.
2. Predict the evolution of these waves a few minutes into the future.
3. Determine the ship response to the waves and the optimum path through the waves.
4. Automatically guide the ship through the wave field.

APL/UW is pursuing the first of these four objectives.

We have been able to demonstrate wave height retrievals from both cross sections and Doppler shifts, but only along a line. The wave heights retrieved by the two methods agree fairly well with each other and both indicate that retrieving wave heights in directions parallel to wave crests will be problematic. Nevertheless, this year we will produce maps of wave height around the ship to the best of our ability using cross sections and Doppler shifts. We will then work with the modelers to utilize these maps in the models.

Developing Techniques for Non-Contact Streamgaging

We are developing techniques for the long-term monitoring of surface velocity at the mouth of the Columbia River with microwave Doppler radars.

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We are developing techniques for the long-term monitoring of surface velocity at the mouth of the Columbia River with microwave Doppler radars. Through our past efforts with the USGS and ONR, we have developed an X-band Doppler radar which we call RiverRad that has proven valuable for the long-term monitoring of river surface currents and for determining discharge in stable streams. Our recent work with a similar CW microwave system called Riverscat has strongly suggested that discharge can also be determined on unstable streams, those with frequently changing beds, using microwave Doppler sensors.

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Publications

2000-present and while at APL-UW

Directional surface wave spectra from point measurements of height and slope

Plant, W.J., and M.A. Donelan, "Directional surface wave spectra from point measurements of height and slope," J. Atmos. Ocean. Technol., 37, 67–83, doi:10.1175/JTECH-D-19-0128.1, 2020.

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23 Jan 2020

We describe here a method for recovering directional ocean surface wave spectra obtained from height and slope measurements made over a small area, the iterative deconvolution method (IDM). We show that IDM is a more reliable method for estimating directional wave spectra than more common spectral estimation techniques by comparing it with the widely used maximum entropy method (MEM). IDM is based on the observation that pitch–roll buoys produce directional spectra that are the true spectra convolved with an angular windowing function and are therefore much broader than the true spectra. We test IDM against simulated data and find that it does a better job of retrieving the known input spectra than does MEM, which often produces false double peaks or incorrect angular widths. We compare IDM recoveries to spectra obtained using a nonstandard processing technique, the wavelet directional method (WDM) on data from a compact array of wave staffs on Lake Ontario. We find that IDM produces directional wave spectra very nearly identical to those obtained using WDM, verifying both techniques. Finally, we processed standard NDBC buoy directional spectra and showed that IDM recovers ocean wave spectra that narrow in the Strait of Juan de Fuca and that follow a changing wind in the expected manner. Neither of these phenomena are reliably obtained using MEM due to its tendency to produce false bimodal peaks and peaks that are too narrow.

A joint active/passive physical model of sea surface microwave signatures

Plant, W.J., and V. Irisov, "A joint active/passive physical model of sea surface microwave signatures," J. Geophys. Res., 122, 3219-3239, doi:10.1002/2017JC012749, 2017.

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1 Apr 2017

Active and passive microwave signatures of the ocean can only depend on the ocean wave spectrum if bound and breaking waves are neglected. However, history has not been kind to attempts to explain both radiometer brightness temperatures (Tb) and normalized radar cross sections (σo) of the sea using the same ocean wave spectrum without bound and breaking waves. In this paper, we show that if bound and breaking waves are included in physical models of radiometer and scatterometer microwave signatures of the ocean, a single wave spectrum can explain both Tb and σo to reasonable accuracy. Bound waves are the roughness produced by gently breaking, or crumpling, waves that travel near the speed of the parent wave. Bound wave modeling is based on earlier work by Plant (1997) but using additional information about the slope probability distributions of the bound waves' parents. Breaking wave and foam modeling both build on the function λ(cb) introduced by Phillips (1985), which describes the average length of breaking wavefronts on the ocean per unit area as a function of breaker velocity, cb. We model λ(cb) as documented in Irisov and Plant (2016) where we show that the wave spectrum completely determines λ(cb). We thus show here that the result of including bound and breaking waves in radiometer and scatterometer models of oceanic signatures is a much closer fit to data over a wide range of microwave frequencies and incidence angles using a single wave spectrum.

Phillips' lambda function: Data summary and physical model

Irisov, V., and W. Plant, "Phillips' lambda function: Data summary and physical model," Geophys. Res. Lett., 43, 2053-2058, doi:10.1002/2015GL067352, 2016.

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16 Mar 2016

Measurements of Phillips' Lambda function describing the average length of breakers on the ocean per unit area at speed cb are summarized. An expression is developed that fits these data within reasonable bounds. A physical model for the Lambda function is derived based on the assumption that breaking occurs when the surface steepness exceeds a threshold value. The energy contained in the breaking region is related to the fifth power of the breaker speed, as Phillips showed, and from this the probability of finding a breaker with a speed cb may be determined from a simulation of the long-wave surface based on a linear superposition of Fourier components. This probability is directly related to the Lambda function so that a form for this function can be determined. The Lambda function so determined agrees in both shape and intensity with the fit to the measured Lambda functions.

More Publications

Inventions

Shipborne Ocean Wave Measurement System

Record of Invention Number: 46763

Gordon Farquharson, Bill Plant

Disclosure

11 Dec 2013

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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