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Craig Lee

Senior Principal Oceanographer

Professor, Oceanography

Email

craig@apl.washington.edu

Phone

206-685-7656

Research Interests

Upper Ocean Dynamics, Coastal Ocean Processes, Internal Waves, Fronts, Dynamics and Biological Process Interactions

Biosketch

Dr. Lee is a physical oceanographer specializing in observations and instrument development. His primary scientific interests include: (1) upper ocean dynamics, especially mesoscale and submesocale fronts and eddies, (2) interactions between biology, biogeochemistry and ocean physics and (3) high-latitude oceanography.

With partner Dr. Jason Gobat, Lee founded and leads a team of scientists and technologists that pursues a wide range of oceanographic field programs, including intensive studies of the Kuroshio Current, coupled physical–biogeochemical studies such as the recent patch-scale investigation of the North Atlantic spring phytoplankton bloom and studies aimed at quantifying and understanding Arctic change. An important component of this work involves identifying advances that could be achieved through novel measurements and developing new instruments to meet these needs.

The team's accomplishments include autonomous gliders capable of extended operation in ice-covered waters, high-performance towed vehicles and light-weight, inexpensive mooring technologies. The team also pursues K-12 educational outreach and routinely employs undergraduate research assistants. Within the community, Lee provides leadership through service on the science steering committees for several large research programs and by serving on and chairing advisory panels for U.S. Arctic efforts. Lee supports and advises masters and doctoral students and teaches graduate level courses on observations of ocean circulation and instruments, methods and experimental design.

Department Affiliation

Ocean Physics

Education

B.S. Electrical Engineering and Computer Science, University of California, Berkeley, 1987

Ph.D. Physical Oceanography, University of Washington, 1995

Projects

Stratified Ocean Dynamics of the Arctic — SODA

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31 Oct 2016

Vertical and lateral water properties and density structure with the Arctic Ocean are intimately related to the ocean circulation, and have profound consequences for sea ice growth and retreat as well as for prpagation of acoustic energy at all scales. Our current understanding of the dynamics governing arctic upper ocean stratification and circulation derives largely from a period when extensive ice cover modulated the oceanic response to atmospheric forcing. Recently, however, there has been significant arctic warming, accompanied by changes in the extent, thickness distribution, and properties of the arctic sea ice cover. The need to understand these changes and their impact on arctic stratification and circulation, sea ice evolution, and the acoustic environment motivate this initiative.

The Submesoscale Cascade in the South China Sea

This research program is investigating the evolution of submesoscale eddies and filaments in the Kuroshio-influenced region off the southwest coast of Taiwan.

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26 Aug 2015

Science questions:
1. What role does the Kuroshio play in generating mesoscale and submesoscale variability modeled/observed off the SW coast of Taiwan?
2. How does this vary with atmospheric forcing?
3. How do these features evolve in response to wintertime (strong) atmospheric forcing?
4. What role do these dynamics play in driving water mass evolution and interior stratification in the South China Sea?
5. What role do these dynamics/features have on the transition of water masses from northern SCS water into the Kuroshio branch water/current and local flow patterns?

Salinity Processes in the Upper Ocean Regional Study — SPURS

The NASA SPURS research effort is actively addressing the essential role of the ocean in the global water cycle by measuring salinity and accumulating other data to improve our basic understanding of the ocean's water cycle and its ties to climate.

15 Apr 2015

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Videos

EXPORTS: Export Processes in the Ocean from RemoTe Sensing

The EXPORTS mission is to quantify how much of the atmospheric carbon dioxide fixed during primary production near the ocean surface is pumped to the deep twilight zone by biological processes, where it can be sequestered for months to millennia.

An integrated observation strategy leverages the precise, intense measurements made on ships, the persistent subsurface data collected by swimming and floating robots, and the global surface views provided by satellites.

18 Sep 2018

Eddies Drive Particulate Carbon Deep in the Ocean During the North Atlantic Spring Bloom

The swirling eddies that create patches of stratification to hold phytoplankton near the sunlit surface during the North Atlantic spring bloom, also inject the floating organic carbon particles deep into the ocean. The finding, reported in Science, has important implications for the ocean's role in the carbon cycle on Earth: phytoplankton use carbon dioxide absorbed by the ocean from the atmosphere during the bloom and the resulting organic carbon near the sea surface is sequestered in the deep ocean.

27 Mar 2015

Seaglider: Autonomous Undersea Vehicle

APL-UW scientists continually expand Seaglider's hardware/software systems, and sensor packages. First developed for oceanographic research, it is also used by the U.S. Navy to detect and monitor marine mammals. Recently, the manufacture and marketing of Seaglider has been licensed to Kongsberg Underwater Technology, Inc., which will push the vehicle to emerging markets in offshore environmental monitoring for the oil and gas industry.

14 Aug 2013

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Publications

2000-present and while at APL-UW

Observations of cross-frontal exchange associated with submesoscale features along the North Wall of the Gulf Stream

Sanchez-Rios, A., R.K. Sherman, J. Klymak, E. D'Asaro, and C. Lee, "Observations of cross-frontal exchange associated with submesoscale features along the North Wall of the Gulf Stream," Deep Sea Res., 163, doi:10.1016/j.dsr.2020.103342, 2020.

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1 Sep 2020

Using high-resolution measurements of the Gulf Stream North Wall (GSNW), we investigated whether detachments from the warm current at the edge of the front, known as streamers, affect the overall heat and salt content of the region. Temperature, salinity, and velocity data were collected across the front from towed CTDs, shipboard ADCPs, and gliders following a Lagrangian drifter that was deployed at the GSNW during winter 2012. Four streamers were identified, all of which expanded laterally 10–15 km, with vertical salinity interleaving down to a 200 m depth. We observed that temperature and salinity (T/S) increased along the trajectory of the Lagrangian float. These trends were density compensated and ranged from the surface down to a 200 m depth and across a 5 km band. The heat and salt budget analysis showed that surface fluxes, advection due to large-scale circulation, and diapycnal mixing could not explain the observed increase in T/S in the mixed layer and in the subsurface area. The only possible source that could explained the increase in T/S was along-isopycnal mixing. Estimates of the Reynolds transport supported this conclusion, although the low number of realizations meant these estimates were not statistically significant. From the heat and salt budgets, we observed that an along-isopycnal diffusivity, ki, of 110 ± 30 m2s-1 accounted for the estimated residual and matched the Reynolds transport estimates. This value of is consistent with other studies that assert that lateral mixing is required for the production of Eighteen Degree Water (EDW) subtropical mode water.

Enhanced mixing across the gyre boundary at the Gulf Stream front

Wenegrat, J.O., L.N. Thomas, M.A. Sundermeyer, J.R. Taylor, E.A. D'Asaro, J.M. Klymak, R. Kipp Shearman, and C.M. Lee, "Enhanced mixing across the gyre boundary at the Gulf Stream front," Proc. Nat. Acad. Sci. USA, 117, 17,607-17,614, doi:10.1073/pnas.2005558117, 2020.

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28 Jul 2020

The Gulf Stream front separates the North Atlantic subtropical and subpolar ocean gyres, water masses with distinct physical and biogeochemical properties. Exchange across the front is believed to be necessary to balance the freshwater budget of the subtropical gyre and to support the biological productivity of the region; however, the physical mechanisms responsible have been the subject of long-standing debate. Here, the evolution of a passive dye released within the north wall of the Gulf Stream provides direct observational evidence of enhanced mixing across the Gulf Stream front. Numerical simulations indicate that the observed rapid cross-frontal mixing occurs via shear dispersion, generated by frontal instabilities and episodic vertical mixing. This provides unique direct evidence for the role of submesoscale fronts in generating lateral mixing, a mechanism which has been hypothesized to be of general importance for setting the horizontal structure of the ocean mixed layer. Along the Gulf Stream front in the North Atlantic, these observations further suggest that shear dispersion at sharp fronts may provide a source of freshwater flux large enough to explain much of the freshwater deficit in the subtropical-mode water budget and a flux of nutrients comparable to other mechanisms believed to control primary productivity in the subtropical gyre.

Restratification at a California Current upwelling front. Part I: Observations

Johnson, L., C.M. Lee, E.A. D'Asaro, L. Thomas, and A. Shcherbina, "Restratification at a California Current upwelling front. Part I: Observations," J. Phys. Oceanogr., 50, 14-55-1472, doi:10.1175/JPO-D-19-0203.1, 2020.

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6 May 2020

A coordinated survey between a subsurface Lagrangian float and a ship-towed Triaxus profiler obtained detailed measurements of a restratifying surface intensified front (above 30 m) within the California Current System. The survey began as downfront winds incited mixing in the boundary layer. As winds relaxed and mixing subsided, the system entered a different dynamical regime as the front developed an overturning circulation with large vertical velocities that tilted isopycnals and stratified the upper ocean within a day. The horizontal buoyancy gradient was 1.5 x 10-6 s-2 and associated with vorticity, divergence, and strain that approached the Coriolis frequency. Estimates of vertical velocity from the Lagrangian float reached 1.2 x 10-3 m s-1. These horizontal gradients and vertical velocities were consistent with submesoscale dynamics that are distinct from the classic quasigeostrophic framework used to describe larger-scale flows. Vertical and horizontal gradients of velocity and buoyancy in the vicinity of the float revealed that sheared currents differentially advected the horizontal buoyancy gradient to increase vertical stratification. This was supported by analyses of temperature and salinity gradients that composed the horizontal and vertical stratification. Potential vorticity was conserved during restratification at 16 m, consistent with adiabatic processes. Conversely, potential vorticity near the surface (8 m) increased, highlighting the role of friction in modulating near-surface stratification. The observed increase in stratification due to these submesoscale processes was equivalent to a heat flux of 2000 W m-2, which is an order-of-magnitude larger than the average observed surface heat flux of 100 W m-2.

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In The News

During a pandemic, is oceangoing research safe?

Eos, Jenessa Duncombe

Postponing cruises. Cancelling cruises. UNOLS has extended its halt on vessel operations until July. UNOLS Chair Craig Lee explains why onboard mitigation of COVID-19 is "difficult to impossible."

1 Apr 2020

Coronavirus is wreaking havoc on scientific field work

The Washington Post, Maddie Stone

As the novel coronavirus pandemic continues to upend life around the world, scientific research is beginning to suffer. Over the past several weeks, major Earth science field campaigns, some years in the making, have been called off or postponed indefinitely. Craig Lee, APL-UW Senior Principal Oceanographer and UNOLS Council Chair, comments on impacts to at-sea research.

27 Mar 2020

These ocean robots spent a year collecting data under Antarctic ice

Geek.com, Genevieve Scarano

Studying Antarctic areas can be tough for scientists, but ocean robots are here to help: A group of autonomous subs have successfully collected data beneath the Dotson Ice Shelf in West Antarctica.

24 Jan 2019

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Inventions

Ogive Fairing, Cover Hatch, and Wing Drawings

Record of Invention Number: 4149-Reg-0009

Jason Gobat, Adam Huxtable, Craig Lee, Charles Eriksen, Jim Osse

Disclosure

25 Mar 2010

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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