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Ed Zaron
Research Associate Professor
Department of Civil and Environmental Engineering
Portland State University
P.O. Box 751
Portland, OR 972070751
Phone: (503) 7252435
Email: ezaron at pdx.edu
CoI's: Shane Elipot, University of Miami, & Rick Lumpkin, NOAA
PI: Sophie Nowicki, NASA/GSFC
My role in this project involves simultaneous mapping of steric and nonsteric sea level changes from satellite altimetry.
PI: Richard D. Ray, NASA/GSFC; CoI's: Gary D. Egbert and Zaron.
The Surface Water Ocean Topography (SWOT) mission is planned for launch in 2020.
PI: Richard D. Ray, NASA/GSFC; CoI's: Gary D. Egbert and Zaron.
The objective of this project is an improved understanding of surface and internal tides, and their relationship to nontidal phenomena.
PI: Liang Xu, NRLMonterey
I have been working with students to measure the velocity of a flowing soap water film with a laser Doppler sensor from a highend gaming mouse, as described in this short manuscript. This project is supported by the PSU PI Research Incentive Program.
PI: Zaron; CoI: MarieAude Pradal, Johns Hopkins University.
We are developing techniques to use knowledge of the ocean surface tide to improve maps of seafloor bathymetry. Our approach is to use inverse methods with a data assimilative hydrodynamic model to simultaneously infer both tides and bathymetry.
PI: Zaron
I am collaborating with the group at Arete Associates to develop algorithms for bottom topography mapping using remotelysensed data in a project supported by the NGA.
PI: David T. Sandwell, SIO/UCSD; CoI: Zaron.
Uncertainties in tides near the coastline contribute errors to marine gravity models derived from satellite altimetry. I am developing new techniques for highresolution empirical mapping of tides that utilize data from nonrepeat altimeter missions.
PI: Christopher N. K. Mooers.
This project is evaluating prototype operational numerical ocean models of the Gulf of Mexico. My role is the development of software and evaluation of metrics for analysis of models.
David Jay of PSU recently discovered that tides are changing in the North Pacific. This project aims to follow up on his initial data analysis and identify the causes of the change. Although the observed rate of change is small, approximately 1% per century, it is a puzzle when we consider the processes which could interact with tides on large, oceanbasin, scales. Using numerical models of the ocean we are assessing a number of possible dynamical causes, and also developing new approaches to tidal analysis which make better use of long, sparse, time series.
Together with collaborators at the Naval Research Lab, Stennis, MS, I am building an improved and automated version of the OTIS software for dataassimilative tidal modeling. Emphasis is on shallowwater modeling, with the goal of automatically tuning the representation of the model forcing error covariance.
I have been working with student volunteers and a graduate student to develop lowcost equipment for studying turbulence in flowing soapwater films. Present efforts are aimed at using modified phonograph cartidges as transducers to measure the dynamic pressure of the turbulent flow.
I am collaborating with Alan Blumberg's group at the Stevens Institute of Technology to develop an efficient means of inverting surface velocity for bottom depth. This is an interesting and strongly nonlinear estimation problem with many practical applications.
Gary Egbert (Oregon State University) and I have a project to assimilate satellite altimetry data into a threedimensional primitive equations model in order to better quantify the energy flux of tidal internal waves, and infer the mechanisms responsible for dissipating these waves. The ultimate objective of this project is to test the hypothesis that tidal energy drives much of the global thermohaline overturning circulation, a quantity of central importance to climate change studies.
Together with Jim Moum at Oregon State University, I analyzed a widelyused parameterization of sheardriven turbulence in stratified flows. We found a new empirical relationship between turbulence diffusivity and gradient Richardson number using basic principles of dimensional analysis. The relationship collapses the turbulence data within a factor of 2, which is much improved over previous Richardsonnumberbased schemes, but we also demonstrate the lack of universality of these approaches. Essentially, the nonlinear dependence of diffusivity on Richardson number causes the relationship between mean quantities to deviate strongly from the relationship between the instantaneous quantities, leading to a Landautype argument against universality.
I am involved in a project with David Jay (Portland State University) looking at the Columbia River Estuary and Plume (River Influences on Coastal Ecosystems, RISE). We are looking at the currents and mixing associated with the tidal plume, and the larger subtidal plume, using ADCP and CTD data from a towed, undulating platform.
PEZHAT is the dataassimilating primitive equation model I have been developing and using for our analyses of satellite altimetry. The model and its adjoint are designed to execute efficiently on computer clusters using domain decomposition via MPI. The model equations and finitedifference methods are based on MOM3, with some minor changes specific to tidal applications.
The Inverse Ocean Model (IOM) is an advanced software system for data assimilative modeling, developed by Andrew Bennett (Oregon State University) and colleagues under NSFITR funding. It uses advanced program generation tools to create a custom data assimilation system for any numerical model and observing system. I participated as a postdoc on this project and developed the tidal applications with PEZHAT.