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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

More Info

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

Arctic Mediterranean exchanges: A consistent volume budget and trends in transports from two decades of observations

Østerhus, S., and 16 others including R. Woodgate, C.M. Lee, and B. Curry, "Arctic Mediterranean exchanges: A consistent volume budget and trends in transports from two decades of observations," Ocean Sci., 15, 379-399, doi:10.5194/os-15-379-2019, 2019.

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12 Apr 2019

The Arctic Mediterranean (AM) is the collective name for the Arctic Ocean, the Nordic Seas, and their adjacent shelf seas. Water enters into this region through the Bering Strait (Pacific inflow) and through the passages across the Greenland–Scotland Ridge (Atlantic inflow) and is modified within the AM. The modified waters leave the AM in several flow branches which are grouped into two different categories: (1) overflow of dense water through the deep passages across the Greenland–Scotland Ridge, and (2) outflow of light water — here termed surface outflow — on both sides of Greenland. These exchanges transport heat and salt into and out of the AM and are important for conditions in the AM. They are also part of the global ocean circulation and climate system. Attempts to quantify the transports by various methods have been made for many years, but only recently the observational coverage has become sufficiently complete to allow an integrated assessment of the AM exchanges based solely on observations. In this study, we focus on the transport of water and have collected data on volume transport for as many AM-exchange branches as possible between 1993 and 2015. The total AM import (oceanic inflows plus freshwater) is found to be 9.1 Sv (sverdrup, 1 Sv =106 m3 s-1) with an estimated uncertainty of 0.7 Sv and has the amplitude of the seasonal variation close to 1 Sv and maximum import in October. Roughly one-third of the imported water leaves the AM as surface outflow with the remaining two-thirds leaving as overflow. The overflow water is mainly produced from modified Atlantic inflow and around 70% of the total Atlantic inflow is converted into overflow, indicating a strong coupling between these two exchanges. The surface outflow is fed from the Pacific inflow and freshwater (runoff and precipitation), but is still approximately two-thirds of modified Atlantic water. For the inflow branches and the two main overflow branches (Denmark Strait and Faroe Bank Channel), systematic monitoring of volume transport has been established since the mid-1990s, and this enables us to estimate trends for the AM exchanges as a whole. At the 95 % confidence level, only the inflow of Pacific water through the Bering Strait showed a statistically significant trend, which was positive. Both the total AM inflow and the combined transport of the two main overflow branches also showed trends consistent with strengthening, but they were not statistically significant. They do suggest, however, that any significant weakening of these flows during the last two decades is unlikely and the overall message is that the AM exchanges remained remarkably stable in the period from the mid-1990s to the mid-2010s. The overflows are the densest source water for the deep limb of the North Atlantic part of the meridional overturning circulation (AMOC), and this conclusion argues that the reported weakening of the AMOC was not due to overflow weakening or reduced overturning in the AM. Although the combined data set has made it possible to establish a consistent budget for the AM exchanges, the observational coverage for some of the branches is limited, which introduces considerable uncertainty. This lack of coverage is especially extreme for the surface outflow through the Denmark Strait, the overflow across the Iceland–Faroe Ridge, and the inflow over the Scottish shelf. We recommend that more effort is put into observing these flows as well as maintaining the monitoring systems established for the other exchange branches.

Interruption of two decades of Jakobshavn Isbrae acceleration and thinning as regional ocean cools

Khazendar, A., and 13 others including C.M. Lee, "Interruption of two decades of Jakobshavn Isbrae acceleration and thinning as regional ocean cools," Nat. Geosci., 12, 277-283, doi:10.1038/s41561-019-0329-3, 2019.

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1 Apr 2019

Jakobshavn Isbrae has been the single largest source of mass loss from the Greenland Ice Sheet over the last 20 years. During that time, it has been retreating, accelerating and thinning. Here we use airborne altimetry and satellite imagery to show that since 2016 Jakobshavn has been re-advancing, slowing and thickening. We link these changes to concurrent cooling of ocean waters in Disko Bay that spill over into Ilulissat Icefjord. Ocean temperatures in the bay’s upper 250 m have cooled to levels not seen since the mid 1980s. Observations and modelling trace the origins of this cooling to anomalous wintertime heat loss in the boundary current that circulates around the southern half of Greenland. Longer time series of ocean temperature, subglacial discharge and glacier variability strongly suggest that ocean-induced melting at the front has continued to influence glacier dynamics after the disintegration of its floating tongue in 2003. We conclude that projections of Jakobshavn’s future contribution to sea-level rise that are based on glacier geometry are insufficient, and that accounting for external forcing is indispensable.

Subannual and seasonal variability of Atlantic-origin waters in two adjacent West Greenland fjords

Carroll, D., D.A. Sutherland, B. Curry, J.D. Nash, E.L. Shroyer, G.A. Catania, L.A. Stearns, J.P. Grist, C.M. Lee, and L. de Steur, "Subannual and seasonal variability of Atlantic-origin waters in two adjacent West Greenland fjords," J. Geophys. Res., 123, 6670-6687, doi:10.1029/2018JC014278, 2018.

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1 Sep 2018

Greenland fjords provide a pathway for the inflow of warm shelf waters to glacier termini and outflow of glacially modified waters to the coastal ocean. Characterizing the dominant modes of variability in fjord circulation, and how they vary over subannual and seasonal time scales, is critical for predicting ocean heat transport to the ice. Here we present a 2‐year hydrographic record from a suite of moorings in Davis Strait and two neighboring west Greenland fjords that exhibit contrasting fjord and glacier geometry (Kangerdlugssuaq Sermerssua and Rink Isbrae). Hydrographic variability above the sill exhibits clear seasonality, with a progressive cooling of near‐surface waters and shoaling of deep isotherms above the sill during winter to spring. Renewal of below‐sill waters coincides with the arrival of dense waters at the fjord mouth; warm, salty Atlantic‐origin water cascades into fjord basins from winter to midsummer. We then use Seaglider observations at Davis Strait, along with reanalysis of sea ice and wind stress in Baffin Bay, to explore the role of the West Greenland Current and local air‐sea forcing in driving fjord renewal. These results demonstrate the importance of both remote and local processes in driving renewal of near‐terminus waters, highlighting the need for sustained observations and improved ocean models that resolve the complete slope‐trough‐fjord‐ice system.

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In The News

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

Autonomous subs spend a year cruising under Antarctic ice

TechCrunch, Devin Coldewey

The freezing waters underneath Antarctic ice shelves and the underside of the ice itself are of great interest to scientists. A pair of autonomous subs have been nosing around the ice for a full year now, producing data unlike any other expedition ever has.

23 Jan 2019

One year into the mission, autonomous ocean robots set a record in survey of Antarctic ice shelf

UW News, Hannah Hickey

A team of ocean robots deployed in January 2018 have, over the past year, been the first self-guided ocean robots to successfully travel under an ice sheet and return to report long-term observations.

23 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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