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Chris Chickadel

Principal Oceanographer

Affiliate Assistant Professor, Civil and Environmental Engineering

Email

chickadel@apl.washington.edu

Phone

206-221-7673

Education

B.S. Oceanography, University of Washington, 1997

M.S. Oceanography, Oregon State University, 2003

Ph.D. Oceanography, Oregon State University, 2007

Projects

Inner Shelf Dynamics

The inner shelf region begins just offshore of the surf zone, where breaking by surface gravity waves dominate, and extends inshore of the mid-shelf, where theoretical Ekman transport is fully realized. Our main goal is to provide provide improved understanding and prediction of this difficult environment. This will involve efforts to assess the influence of the different boundaries — surf zone, mid and outer shelf, air-water interface, and bed — on the flow, mixing and stratification of the inner shelf. We will also gain information and predictive understanding of remotely sensed surface processes and their connection to processes in the underlying water column.

15 Dec 2015

COHerent STructures in Rivers and Estuaries eXperiment

The experiment is a four-year collaborative project that couples state-of-the-art remote sensing and in situ measurements with advanced numerical modeling to characterize coherent structures in river and estuarine flows.

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Coherent structures are generated in rivers and estuaries when the flow interacts with bathymetric and coastline features or when density stratification causes a gradient in surface properties. These coherent structures produce surface signatures that can be detected and quantified using remote sensing techniques. A second objective of this project is to determine the extent to which these remotely sensed signatures can be used to initialize and guide predictive models.

The study site selected for Year 1 and Year 2 field operations was the Snohomish River in Everett, WA. Its annual mean flow of approximately 300 cubic meters per second is the third largest discharge into Puget Sound. The mouth of the river is defined by the city of Everett to the west (man-influenced) and Jetty Island to the east (natural). The river is dredged to a nominal depth of 5 m from the mouth at the south end of Jetty Island to approximately 12 km upstream, while the undredged depth is nominally 1-3 m. Thus the river profile is a compound channel, with the full 300 m width at Jetty Island containing the dredged channel of about 50 m width. The tidal forcing is strong, with the tidal range representing up to 2/3 of the river%u2019s mean depth. There is a bypass between the north end of Jetty Island and the mainland that connects to a mudflat area. During high tides, the river flow bifurcates between the main channel and this bypass, while at low tide very little flow occurs in the bypass. A sill extends from the north tip of Jetty Island to the southeast toward the opposite bank. The depth along this sill varies from 2 m to 5 m and terminates in a large scour hole in the middle of the channel with a depth of about 10 m.

This research is being conducted by a partnership of experts in remote sensing, numerical modeling, and estuarine dynamics from the University of Washington (Applied Physics Laboratory, Civil and Environmental Engineering, and Oceanography) and Stanford University (Environmental Fluid Mechanics Laboratory). The program is funded by a Multidisciplinary University Research Initiative (MURI) grant sponsored by the Office of Naval Research.

Tidal Flats

Under an ONR-sponsored Department Research Initiative researchers are studying thermal signatures of inter-tidal sediments. The goal is to understand how sediment properties feedback on morphology and circulation, and the extent to which such properties
can be sensed remotely.

 

Publications

2000-present and while at APL-UW

Sea state single optical images: A methodology to derive wind-generated ocean waves from cameras, drones and satellites

Almar, R., and 10 others including C. Chickadel, "Sea state single optical images: A methodology to derive wind-generated ocean waves from cameras, drones and satellites," Remote Sens., 13, doi:10.3390/rs13040679, 2021.

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13 Feb 2021

Sea state is a key variable in ocean and coastal dynamics. The sea state is either sparsely measured by wave buoys and satellites or modelled over large scales. Only a few attempts have been devoted to sea state measurements covering a large domain; in particular its estimation from optical images. With optical technologies becoming omnipresent, optical images offer incomparable spatial resolution from diverse sensors such as shore-based cameras, airborne drones (unmanned aerial vehicles/UAVs), or satellites. Here, we present a standalone methodology to derive the water surface elevation anomaly induced by wind-generated ocean waves from optical imagery. The methodology was tested on drone and satellite images and compared against ground truth. The results show a clear dependence on the relative azimuth view angle in relation to the wave crest. A simple correction is proposed to overcome this bias. Overall, the presented methodology offers a practical way of estimating ocean waves for a wide range of applications.

On the thermal signature of the residual foam in breaking waves

Masnadi, N., C.C. Chickadel, and A.T. Jessup, "On the thermal signature of the residual foam in breaking waves," J. Geophys. Res., 126, doi:10.1029/2020JC016511, 2021.

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18 Jan 2021

Quantifying energy dissipation due to wave breaking remains an essential but elusive goal for studying and modeling air‐sea fluxes of heat, gas, and momentum. Previous observations have shown that lifetimes of bubble plumes and surface foam are directly related to the dissipated energy. Specifically, the foam decay time can be used to estimate the timescale of the subsurface bubble plume and the energy dissipated in the breaking process. A mitigating factor is that the foam decay time can be significantly affected by the surfactant concentration. Here we present an experimental investigation of a new technique that exploits the thermal signature of cooling foam to infer wave breaking dynamics. The experiments were conducted in a laboratory wave tank using artificial seawater with and without the addition of a surfactant. We show that the time from the start of the breaking process to the onset of cooling scales with the bubble plume decay time and the dissipated energy, and is not significantly affected by the presence of additional surfactants. We confirm observations from the field of the spatial variability of the temperature of foam generated by an individual breaking event, which has implications for inferring the spatial variability of bubble plume depth.

The Inner-Shelf Dynamics Experiment

Kumar, N., and 49 others, including J. Thomson, M. Moulton, and C. Chickadel, "The Inner-Shelf Dynamics Experiment," Bull. Am. Meteorol. Soc., EOR, doi:10.1175/BAMS-D-19-0281.1, 2020.

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31 Dec 2020

The inner shelf, the transition zone between the surf zone and the mid shelf, is a dynamically complex region with the evolution of circulation and stratification driven by multiple physical processes. Cross-shelf exchange through the inner shelf has important implications for coastal water quality, ecological connectivity, and lateral movement of sediment and heat. The Inner-Shelf Dynamics Experiment (ISDE) was an intensive, coordinated, multi-institution field experiment from Sep.–Oct. 2017, conducted from the mid shelf, through the inner shelf and into the surf zone near Point Sal, CA. Satellite, airborne, shore- and ship-based remote sensing, in-water moorings and ship-based sampling, and numerical ocean circulation models forced by winds, waves and tides were used to investigate the dynamics governing the circulation and transport in the inner shelf and the role of coastline variability on regional circulation dynamics. Here, the following physical processes are highlighted: internal wave dynamics from the mid shelf to the inner shelf; flow separation and eddy shedding off Point Sal; offshore ejection of surfzone waters from rip currents; and wind-driven subtidal circulation dynamics. The extensive dataset from ISDE allows for unprecedented investigations into the role of physical processes in creating spatial heterogeneity, and nonlinear interactions between various inner-shelf physical processes. Overall, the highly spatially and temporally resolved oceanographic measurements and numerical simulations of ISDE provide a central framework for studies exploring this complex and fascinating region of the ocean.

More Publications

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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