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John Mickett

Senior Oceanographer

Email

jmickett@apl.washington.edu

Phone

206-897-1795

Department Affiliation

Ocean Physics

Projects

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

SMILE: the Submesoscale MIxed-Layer Eddies experiment

More Info

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

More Projects

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

Warming and weakening of the abyssal flow through Samoan Passage

Voet, G., M.H. Alford, J.B. Girton, G.S. Carter, J.B. Mickett, and J.M. Klymak, "Warming and weakening of the abyssal flow through Samoan Passage," J. Phys. Oceanogr., 46, 2389–2401, doi:10.1175/JPO-D-16-0063.1, 2016.

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1 Aug 2016

The abyssal flow of water through the Samoan Passage accounts for the majority of the bottom water renewal in the North Pacific, thereby making it an important element of the meridional overturning circulation. Here the authors report recent measurements of the flow of dense waters of Antarctic and North Atlantic origin through the Samoan Passage. A 15-month long moored time series of velocity and temperature of the abyssal flow was recorded between 2012 and 2013. This allows for an update of the only prior volume transport time series from the Samoan Passage from WOCE moored measurements between 1992 and 1994. While highly variable on multiple time scales, the overall pattern of the abyssal flow through the Samoan Passage was remarkably steady. The time-mean northward volume transport of about 5.4 Sv (1 Sv = 106 m3 s−1) in 2012/13 was reduced compared to 6.0 Sv measured between 1992 and 1994. This volume transport reduction is significant within 68% confidence limits (±0.4 Sv) but not at 95% confidence limits (±0.6 Sv). In agreement with recent studies of the abyssal Pacific, the bottom flow through the Samoan Passage warmed significantly on average by 1 x 10−3°C yr−1 over the past two decades, as observed both in moored and shipboard hydrographic observations. While the warming reflects the recently observed increasing role of the deep oceans for heat uptake, decreasing flow through Samoan Passage may indicate a future weakening of this trend for the abyssal North Pacific.

A tale of two spicy seas

MacKinnon, J.A., and 18 others, including J.B. Mickett and C.B. Whalen, "A tale of two spicy seas," Oceanography 29, 50–61, doi:10.5670/oceanog.2016.38, 2016.

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1 Jun 2016

Upper-ocean turbulent heat fluxes in the Bay of Bengal and the Arctic Ocean drive regional monsoons and sea ice melt, respectively, important issues of societal interest. In both cases, accurate prediction of these heat transports depends on proper representation of the small-scale structure of vertical stratification, which in turn is created by a host of complex submesoscale processes. Though half a world apart and having dramatically different temperatures, there are surprising similarities between the two: both have (1) very fresh surface layers that are largely decoupled from the ocean below by a sharp halocline barrier, (2) evidence of interleaving lateral and vertical gradients that set upper-ocean stratification, and (3) vertical turbulent heat fluxes within the upper ocean that respond sensitively to these structures. However, there are clear differences in each ocean’s horizontal scales of variability, suggesting that despite similar background states, the sharpening and evolution of mesoscale gradients at convergence zones plays out quite differently. Here, we conduct a qualitative and statistical comparison of these two seas, with the goal of bringing to light fundamental underlying dynamics that will hopefully improve the accuracy of forecast models in both parts of the world.

Pathways, volume transport, and mixing of abyssal water in the Samoan Passage

Voet, G., J.B. Girton, M.H. Alford, G.S. Carter, J.M. Klymak, and J.B. Mickett, "Pathways, volume transport, and mixing of abyssal water in the Samoan Passage," J. Phys. Oceanogr., 45, 562-588, doi:10.1175/JPO-D-14-0096.1, 2015.

More Info

1 Feb 2015

The flow of dense water through the Samoan Passage accounts for the major part of the bottom water renewal in the North Pacific and is thus an important element of the Pacific meridional overturning circulation. A recent set of highly resolved measurements used CTD/LADCP, a microstructure profiler, and moorings to constrain the complex pathways and variability of the abyssal flow. Volume transport estimates for the dense northward current at several sections across the passage, calculated using direct velocity measurements from LADCPs, range from 3.9 x 106 to 6.0 x 106 ± 1 x 106 m3 s-1. The deep channel to the east and shallower pathways to the west carried about equal amounts of this volume transport, with the densest water flowing along the main eastern channel. Turbulent dissipation rates estimated from Thorpe scales and direct microstructure agree to within a factor of 2 and provide a region-averaged value of O(10-8) W kg-1 for layers colder than 0.8°C. Associated diapycnal diffusivities and downward turbulent heat fluxes are about 5 x 10-3 m2 s-1 and O(10) W m-2, respectively. However, heat budgets suggest heat fluxes 2–6 times greater. In the vicinity of one of the major sills of the passage, highly resolved Thorpe-inferred diffusivity and heat flux were over 10 times larger than the region-averaged values, suggesting the mismatch is likely due to undersampled mixing hotspots.

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In The News

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

Arctic research ship probes frigid depths and 4th-lowest sea ice extent on record

Mashable, Andrew Freedman

One of the mysteries of the sea ice loss of the past few decades, particularly this year, is how the heat distribution is changing in various regions of the Arctic. Right now, the National Science Foundation's R/V Sikuliaq is sailing in the Beaufort Sea, north of Alaska, to investigate the distribution of heat throughout the water column, as well as how layers of water are interacting with one another.

17 Sep 2015

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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
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