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Chris Chickadel

Chair, AIRS Department & Senior Principal Oceanographer

Affiliate Associate Professor, Civil and Environmental Engineering






B.S. Oceanography, University of Washington, 1997

M.S. Oceanography, Oregon State University, 2003

Ph.D. Oceanography, Oregon State University, 2007


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.



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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2000-present and while at APL-UW

Thermal infrared shadow-hiding in GOES-R ABI imagery: Snow and forest temperature observations from the SnowEx 2020 Grand Mesa field campaign

Pestana, S.J., C.C. Chickadel, and J.D. Lundquist, "Thermal infrared shadow-hiding in GOES-R ABI imagery: Snow and forest temperature observations from the SnowEx 2020 Grand Mesa field campaign," Cryosphere, 18, 2257-2276, doi:10.5194/tc-18-2257-2024, 2024.

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7 May 2024

The high temporal resolution of thermal infrared imagery from the Geostationary Operational Environmental Satellites R-series (GOES-R) presents an opportunity to observe mountain snow and forest temperatures over the full diurnal cycle. However, the off-nadir views of these imagers may impact or bias temperature observations, especially when viewing a surface composed of both snow and forests. We used GOES-16 and -17 thermal infrared brightness temperature observations of a flat snow- and forest-covered study site at Grand Mesa, Colorado, USA, to characterize how forest coverage and view angle impact these observations. These two geostationary satellites provided views of the study area from the southeast (134.1° azimuth, 33.5° elevation) and southwest (221.2° azimuth, 35.9° elevation), respectively. As part of the NASA SnowEx field campaign in February 2020, coincident brightness temperature observations from ground-based and airborne IR sensors were collected to compare with those from the geostationary satellites. Observations over the course of 2 cloud-free days spanned the entire study site. The brightness temperature observations from each dataset were compared to find their relative differences and how those differences may have varied over time and/or as a function of varying forest cover across the study area. GOES-16 and -17 brightness temperatures were found to match the diurnal cycle and temperature range within ~ 1 h and ± 3 K of ground-based observations. GOES-16 and -17 were both biased warmer than nadir-looking airborne IR and ASTER observations. The warm biases were higher at times when the sun–satellite phase angle was near its daily minimum. The phase angle, the angle between the direction of incoming solar illumination and the direction from which the satellite is viewing, reached daily minimums in the morning for GOES-16 and afternoon for GOES-17. In morning observations, warm biases in GOES-16 brightness temperature were greater for pixels that contained more forest coverage. The observations suggest that a 'thermal infrared shadow-hiding' effect may be occurring, where the geostationary satellites are preferentially seeing the warmer sunlit sides of trees at different times of day. These biases are important to understand for applications using GOES-R brightness temperatures or derived land surface temperatures (LSTs) over areas with surface roughness features, such as forests, that could exhibit a thermal infrared shadow-hiding effect.

Two-dimensional inverse energy cascade in a laboratory surf zone for varying wave directional spread

Baker, C.M., M. Moulton, C.C. Chickadel, E.S. Nuss, M.L. Palmsten, and K.L. Brodie, "Two-dimensional inverse energy cascade in a laboratory surf zone for varying wave directional spread," Phys. Fluids, 35, doi:10.1063/5.0169895, 2023.

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1 Dec 2023

Surfzone eddies enhance the dispersion and transport of contaminants, bacteria, and larvae across the nearshore, altering coastal water quality and ecosystem health. During directionally spread wave conditions, vertical vortices (horizontal eddies) are injected near the ends of breaking crests. Energy associated with these eddies may be transferred to larger-scale, low-frequency rotational motions through an inverse energy cascade, consistent with two-dimensional turbulence. However, our understanding of the relationships between the wave conditions and the dynamics and energetics of low-frequency surfzone eddies are largely based on numerical modeling. Here, we test these relationships with remotely sensed and in situ observations from large-scale directional wave basin experiments with varying wave conditions over alongshore-uniform barred bathymetry. Surface velocities derived with particle image velocimetry were employed to assess the spatial scales of low-frequency surfzone eddies and compute structure functions with alongshore velocities. Second-order structure functions for directionally spread waves (σθ ≥ 10°) are consistent with energy flux to larger or smaller length scales, while normally incident, unidirectional waves do not display this behavior. Third-order structure functions suggest that the surfzone flows exhibit a bidirectional energy cascade — a direct cascade to smaller and inverse cascade to larger length scales — during large directional spreads waves (σθ ≥ 18°). However, there is not decisive evidence of an inverse energy cascade for moderate directional spreads (σθ ≥ 10°). Energy flux varies by cross-shore location and increases with increasing directional spread and wave height. Eddy decorrelation length scales weakly depend on wave directional spread. These findings advance our understanding of the dynamics linking wave breaking to large-scale rotational motions that enhance mixing and lead to rip currents, important conduits for cross-shore material exchange.

Remotely sensed short-crested breaking waves in a laboratory directional wave basin

Baker, C.M., M. Moulton, M.L. Palmsten, K. Brodie, E. Nuss, and C.C. Chickadel, "Remotely sensed short-crested breaking waves in a laboratory directional wave basin," Coastal Eng., 183, doi:10.1016/j.coastaleng.2023.104327, 2023.

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1 Aug 2023

Short-crested breaking waves that result from directionally spread wave conditions dissipate energy and generate turbulence within the surf zone, altering sediment transport processes, wave runup, and forces on structures. Additionally, vertical vorticity generated near crest ends during breaking, which depends on the gradient in wave height along a crest, may enhance nearshore dispersion of pollutants, nutrients, and larvae. Although directionally spread irregular wave fields are ubiquitous on ocean and large lake coastlines, the dependence of short-crested breaking wave characteristics (including the along-crest length and number of crest ends) on offshore wave conditions is not well established. To assess this relationship, laboratory experiments with alongshore-uniform barred bathymetry were performed in a large-scale directional wave basin. A three-dimensional scanning lidar, trinocular camera stereo processing methods, and in situ measurements were used to study short-crested wave field breaking characteristics in the laboratory, yielding a dataset with dense spatio-temporal coverage relative to prior laboratory or field measurements. Wave height estimates are similar for remotely sensed and in situ observations, except in the outer surf zone where plunging breaking occurred. Directional wave properties estimated with an array of in situ or remotely sensed sea-surface elevation estimates are similar and yield smaller directional spreads than single-point colocated pressure and velocity based in situ estimates when waves are less directionally spread. Using a breaking crest identification procedure combining visible imagery and stereo sea-surface elevation, we find that the average along-crest length of breaking waves decreases and the average number of crest ends increases with increasing directional spread. Relative to observations, a parameterized relationship between directional spread and crest characteristics based on theory for non-breaking, refracting waves generally over-estimates breaking crest lengths and is similar to or underestimates the total number of crest ends observed in the surf zone. The wave-field-dependent breaking-wave characteristics examined in the laboratory with remote sensing techniques can inform future investigations of depth-limited short-crested wave breaking and resulting surfzone eddy processes.

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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