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John Mickett

Senior Oceanographer

Email

jmickett@apl.washington.edu

Phone

206-897-1795

Department Affiliation

Ocean Physics

Education

B.S. Marine Science, U.S. Coast Guard Academy, 1994

M.S. Physical Oceanography, University of Washington - Seattle, 2002

Ph.D. Physical Oceanography, University of Washington - Seattle, 2007

Projects

Submesoscale Mixed-Layer Dynamics at a Mid-Latitude Oceanic Front

SMILE: the Submesoscale MIxed-Layer Eddies experiment

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1 Mar 2017

This experiment is aimed at increasing our understanding of the role of lateral processes in mixed-layer dynamics through a series of ship surveys and Lagrangian array deployments. Instrument deployments and surveys target the upper ocean's adjustment to winter atmospheric forcing events in the North Pacific subtropical front, roughly 800 km north of Hawaii.

This study will improve understanding of 1–10-km scale lateral processes in three-dimensional mixed-layer dynamics in a region of above-average atmospheric forcing, typical mid-ocean mesoscale advection and straining, and typical submesoscale activity. The results will improve the physical basis of mixed-layer parameterizations, leading to better model predictions of air-sea fluxes, gas transfer, and biological productivity.

Tasmania Internal Tide Experiment

The Tasmanian continental slope will be instrumented with a range of tools including moored profiler, chi-pods, CTDs, and gliders to understand the process, strength, and distribution of ocean mixing from breaking internal waves.

27 Nov 2011

Samoan Passage Abyssal Mixing

The Samoan Passage, 5500 m beneath the sea surface, is one of the "choke points" in the abyssal circulation. A veritable river of Antarctic Bottom water flows through it on its way into the North Pacific. As it enters the constriction, substantial turbulence, hydraulic processes and internal waves must occur, which modify the water. The overall goal is to understand these deep processes and the way they impact the flow, and to develop a strategy for eventually monitoring the flow through the Passage.

27 Sep 2011

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Videos

Environmental Sample Processor: A Sentry for Toxic Algal Blooms off the Washington Coast

An undersea robot that measures harmful algal species has been deployed by APL, UW, and NOAA researchers off the Washington coast near La Push. Algal bloom toxicity data are relayed to shore in near-real time and displayed through the NANOOS visualization system. The Environmental Sample Processor, or ESP, is taking measurements near the Juan de Fuca eddy, which is a known incubation site for toxic blooms that often travel toward coastal beaches, threatening fisheries and human health.

22 Jun 2016

ORCA Tracks the 'Blob'

A 'blob' of very warm surface water developed in the northeastern Pacific Ocean in 2014–2015 and its influence extended to the inland waters of Puget Sound throughout the summer of 2015. The unprecedented conditions were tracked by the ORCA (Oceanic Remote Chemical Analyzer) buoy network — an array of six heavily instrumented moored buoys in the Sound. ORCA data provided constant monitoring of evolving conditions and allowed scientists to warn of possible fish kill events in the oxygen-starved waters of Hood Canal well in advance.

The ORCA network is maintained by a partnership among APL-UW, the UW College of the Environment, and the UW School of Oceanography.

3 Nov 2015

ArcticMix 2015

APL-UW physical oceanographers John Mickett and Mike Gregg joined SIO colleagues during September 2015 in the Beaufort Sea aboard the R/V Sikuliaq to measure upper ocean mixing that billows heat from depth to the surface. These mixing dynamics may be an important factor in hastening sea ice melt during summer and delaying freeze-up in the fall.

14 Oct 2015

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Publications

2000-present and while at APL-UW

A spatial geography of abyssal turbulent mixing in the Samoan Passage

Carter, G.S., G. Voet, M.H. Alford, J.B. Girton, J.B. Miskent, J.M. Kaymak, L.J. Pratt, K.A. Pearson-Potts, J.M. Cusack, and S. Tan, "A spatial geography of abyssal turbulent mixing in the Samoan Passage," Oceanography, 32, 194-203, doi:10.5670/oceanog.2019.425, 2019.

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1 Dec 2019

High levels of turbulent mixing have long been suspected in the Samoan Passage, an important topographic constriction in the deep limb of the Pacific Meridional Overturning Circulation. Along the length of the passage, observations undertaken in 2012 and 2014 showed the bottom water warmed by ~55 millidegrees Celsius and decreased in density by 0.01 kg m-3. Spatial analysis of this first-ever microstructure survey conducted in the Samoan Passage confirmed there are multiple hotspots of elevated abyssal mixing. This mixing was not just confined to the four main sills — even between sills, the nature of the mixing processes appeared to differ: for example, one sill is clearly a classical hydraulically controlled overflow, whereas another is consistent with mode-2 hydraulic control. When microstructure casts were averaged into 0.1°C conservative temperature classes, the largest dissipation rates and diapycnal diffusivity values (>10-7 W kg-1 and 10-2 m2 s-1, respectively) occurred immediately downstream of the northern sill in the eastern and deepest channel. Although topographic blocking is the primary reason that no water colder than Θ = 0.7°C is found in the western channel, intensive mixing at the entrance sills appeared to be responsible for eroding an approximately 100 m thick layer of Θ < 0.7°C water. Three examples highlighting weak temporal variability, and hence suggesting that the observed spatial patterns are robust, are presented. The spatial variability in mixing over short lateral scales suggests that any simple parameterization of mixing within the Samoan Passage may not be applicable.

Flow-topography interactions in the Samoan Passage

Girton, J.B., J.B. Mickey, Z.X. Zhao, M.H. Alford, G. Voet, J.M. Cusack, G.S. Carter, K.A. Pearson-Potts, L.J. Pratt, S. Tan, and J.M. Klymak, "Flow-topography interactions in the Samoan Passage," Oceanography, 32, 184-193, doi:10.5670/oceanog.2019.424, 2019.

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1 Dec 2019

Mixing in the Samoan Passage has implications for the abyssal water properties of the entire North Pacific — nearly 20% of the global ocean's volume. Dense bottom water formed near Antarctica encounters the passage — a gap in a ridge extending from north of Samoa eastward across the Pacific at around 10°S — and forms an energetic cascade much like a river flowing through a canyon. The 2011–2014 Samoan Passage Abyssal Mixing Experiment explored the importance of topography to the dense water flow on a wide range of scales, including (1) constraints on transport due to the overall passage shape and the heights of its multiple sills, (2) rapid changes in water properties along particular pathways at localized mixing hotspots where there is extreme topographic roughness and/or downslope flow acceleration, and (3) diversion and disturbance of flow pathways and density surfaces by small-scale seamounts and ridges. The net result is a complex but fairly steady picture of interconnected pathways with a limited number of intense mixing locations that determine the net water mass transformation. The implication of this set of circumstances is that the dominant features of Samoan Passage flow and mixing (and their responses to variations in incoming or background properties) can be described by the dynamics of a single layer of dense water flowing beneath a less-dense one, combined with mixing and transformation that is determined by the small-scale topography encountered along flow pathways.

Tracking icebergs with time-lapse photography and sparse optical flow, LeConte Bay, Alaska, 2016–2017

Kienholz, C., and 9 others including J.B. Mickett, "Tracking icebergs with time-lapse photography and sparse optical flow, LeConte Bay, Alaska, 2016–2017," J. Glaciol., 250, 195-211, doi:10.1017/jog.2018.105, 2019.

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1 Apr 2019

We present a workflow to track icebergs in proglacial fjords using oblique time-lapse photos and the Lucas–Kanade optical flow algorithm. We employ the workflow at LeConte Bay, Alaska, where we ran five time-lapse cameras between April 2016 and September 2017, capturing more than 400 000 photos at frame rates of 0.5–4.0 min-1. Hourly to daily average velocity fields in map coordinates illustrate dynamic currents in the bay, with dominant downfjord velocities (exceeding 0.5 m s-1 intermittently) and several eddies. Comparisons with simultaneous Acoustic Doppler Current Profiler (ADCP) measurements yield best agreement for the uppermost ADCP levels (~ 12 m and above), in line with prevalent small icebergs that trace near-surface currents. Tracking results from multiple cameras compare favorably, although cameras with lower frame rates (0.5 min-1) tend to underestimate high flow speeds. Tests to determine requisite temporal and spatial image resolution confirm the importance of high image frame rates, while spatial resolution is of secondary importance. Application of our procedure to other fjords will be successful if iceberg concentrations are high enough and if the camera frame rates are sufficiently rapid (at least 1 min-1 for conditions similar to LeConte Bay).

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In The News

Ocean trash: What you need to know

KCTS9/EarthFix , Ken Christensen

Ocean currents carry man-made debris to remote corners of the planet—even to places mostly untouched by people. And that makes it difficult to clean up, as APL-UW's Senior Oceanographer John Mickett demonstrates during his recent sojourn to Vancouver Island, B.C. to recover a wayward research buoy.

11 Dec 2017

UW, NOAA deploy ocean robot to monitor harmful algal blooms off Washington coast

UW News and Information, Hannah Hickey

John Mickett, an oceanographer at the UW Applied Physics Laboratory, led the deployment of the new instrument with Stephanie Moore, a scientist at NOAA’s Northwest Fisheries Science Center, as part of a larger collaborative project.

25 May 2016

Buoy deployed in Bellingham Bay to chart health of Puget Sound

KING 5 News, Alison Morrow

Oceanographers deployed a buoy in Bellingham Bay on Thursday that will chart the health of Puget Sound. It joins a half-dozen other buoys, but this is the only one in the north Puget Sound. It is equipped with several pieces of advanced technology that will monitor everything from salinity, temperature and weather changes.

11 Feb 2016

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Inventions

Real-time Ocean Mooring for the Environmental Sample Processor

Record of Invention Number: 48554

John Mickett, Nick Michel-Hart

Disclosure

20 Feb 2019

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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