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Chris Chickadel

Chair, AIRS Department & 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.

 

Videos

IRISS — InfraRed In situ Skin and Subskin — Experiments

Infrared radiometers are used to take the temperature of the very surface of the ocean. In this project 'gold standard' radiometers used to measure the ocean skin temperature are compared alongside simplified and miniaturized infrared systems. The goal is to deploy these small, lightweight, and comparatively inexpensive sensing systems on uncrewed surface vehicles to increase data coverage of the global ocean.

12 Oct 2021

APL-UW Remote Sensing Measurements of the Oso Mudslide

Days after the devastating natural disaster in Oso, WA, APL-UW scientists outfitted a small plane with synthetic aperture radar, and thermal and visual radars to gather baseline data of the site conditions. These may help pinpoint the causes of the slide as the investigation continues and represent methods that could be used to monitor landslide prone slopes.

4 Apr 2014

DARLA: Data Assimilation and Remote Sensing for Littoral Applications

Investigators completed a series of experiments in April 2013 at the mouth of the Columbia River, where they collected data using drifting and airborne platforms. DARLA's remote sensing data will be used to drive representations of the wave, circulation, and bathymetry fields in complex near-shore environments.

5 Dec 2013

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Publications

2000-present and while at APL-UW

Laboratory heat flux estimates of seawater foam for low wind speeds

Chickadel, C.C., R. Branch, W.E. Asher, and A.T. Jessup, "Laboratory heat flux estimates of seawater foam for low wind speeds," Remote Sens., 14, doi:10.3390/rs14081925, 2022.

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15 Apr 2022

Laboratory experiments were conducted to measure the heat flux from seafoam continuously generated in natural seawater. Using a control volume technique, heat flux was calculated from foam and foam-free surfaces as a function of ambient humidity (ranged from 40% to 78%), air–water temperature difference (ranged from –9°C to 0°C), and wind speed (variable up to 3 m s-1). Water-surface skin temperature was imaged with a calibrated thermal infrared camera, and near-surface temperature profiles in the air, water, and foam were recorded. Net heat flux from foam surfaces increased with increasing wind speed and was shown to be up to four times greater than a foam-free surface. The fraction of the total heat flux due to the latent heat flux was observed for foam to be 0.75, with this value being relatively constant with wind speed. In contrast, for a foam-free surface the fraction of the total heat flux due to the latent heat flux decreased at higher wind speeds. Temperature profiles through foam are linear and have larger gradients, which increased with wind speed, while foam free surfaces show the expected logarithmic profile and show no variation with temperature. The radiometric surface temperatures show that foam is cooler and more variable than a foam-free surface, and bubble-resolving thermal images show that radiometrically transparent bubble caps and burst bubbles reveal warm foam below the cool surface layer, contributing to the enhanced variability.

Internal bore evolution across the shelf near Pt. Sal CA interpreted as a gravity current

Spydell, M.S., and 15 others including C. Chickadel, M. Moulton, and J. Thomson, "Internal bore evolution across the shelf near Pt. Sal CA interpreted as a gravity current," J. Phys. Oceanogr., 51, 3629-3650, doi:10.1175/JPO-D-21-0095.1, 2021.

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11 Nov 2021

Off the central California coast near Pt. Sal, a large amplitude internal bore was observed for 20 h over 10 km cross-shore, or 100 m to 10 m water depth (D), and 30 km alongcoast by remote sensing, 39 in situ moorings, ship surveys, and drifters. The bore is associated with steep isotherm displacements representing a significant fraction of D. Observations were used to estimate bore arrival time tB, thickness h, and bore and non-bore (ambient) temperature difference ΔT, leading to reduced gravity g'. Bore speeds c, estimated from mapped tB, varied from 0.25 m s-1 to 0.1 m s-1 from D = 50 m to D = 10 m. The h varied from 5 to 35 m, generally decreased with D, and varied regionally alongisobath. The bore ΔT varied from 0.75 to 2.15°C. Bore evolution was interpreted from the perspective of a two-layer gravity current. Gravity current speeds U, estimated from the local bore h and g compared well to observed bore speeds throughout its cross-shore propagation. Linear internal wave speeds based on various stratification estimates result in larger errors. On average bore thickness h = D/2, with regional variation, suggesting energy saturation. From 50–10 m depths, observed bore speeds compared well to saturated gravity current speeds and energetics that depend only on water depth and shelf-wide mean g'. This suggests that this internal bore is the internal wave analogue to a saturated surfzone surface gravity bore. Alongcoast variations in pre-bore stratification explain variations in bore properties. Near Pt. Sal, bore Doppler shifting by barotropic currents is observed.

Surface turbulence reveals riverbed drag coefficient

Branch, R.A., A.R. Horner-Devine, C.C. Chickadel, S.A. Talke, D. Clark, and A.T. Jessup, "Surface turbulence reveals riverbed drag coefficient," Geophys. Res. Lett., 48, doi:10.1029/2020GL092326, 2021.

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28 May 2021

Flow in rivers and the coastal ocean is controlled by the frictional force exerted on the water by riverbed or seabed roughness. The frictional force is typically characterized by a drag coefficient Cd, which is estimated from bulk measurements and often assumed constant. Here, we demonstrate a relationship between bed roughness and water surface turbulence that can be used to make remote estimates of CdCd, and validate this relationship by comparing remotely sensed estimates of Cd to those from in situ measurements. Thus, our results provide an approach for estimating bottom roughness and Cd based entirely on remotely sensed data, including their spatial variability, which can improve modeling of river discharge and morphodynamics in data-poor regions.

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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