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Eric D'Asaro

Senior Principal Oceanographer

Professor, Oceanography





Research Interests

Physical oceanography, internal waves, air-sea interaction, upper ocean dynamics, Arctic oceanography, ocean instrumentation


Dr. D'Asaro's research spans a wide number of environments from upper ocean mixed layers to nearshore coastal fronts to fjords to deep convection. It retains studies of turbulence and internal waves, but has increasingly moved toward understanding the role of these ocean mixing processes in controlling biochemical processes in the ocean, especially gas exchange and biological productivity. By measuring big signals, like hurricanes or major blooms, it is easier to unravel the underlying processes because the signal to noise is high.

For the past 20 years, D'Asaro has focused on exploiting the unique capabilities of "Lagrangian Floats", a class of instruments that try to accurately follow the three dimensional motion of water parcels particularly in regions of strong mixing. This turns out to be a novel but effective way to measure turbulence in regions of strong mixing.

Lagrangian techniques have not been used very much in measuring mixing and turbulence. Accordingly one of the more exciting aspects of this work is learning how to use Lagrangian floats in the ocean. This understanding draws both upon basic ideas in fluid mechanics and upon understanding of mixing in the ocean. It strongly influences float design, use, and the oceanographic problems studied. The work thus spans a wide range of topics, from fluid mechanics to oceanography to engineering. That makes it particularly fun and interesting.

Chemical species in the ocean and many microbial plants and animals drift with the ocean currents. Floats mimic this behavior, making them excellent platforms for studying aspects of ocean chemistry and biology. There is an ongoing revolution in these fields as electronic sensors become capable of making measurements formerly possible only in the laboratory. Floats equipped with such sensors are potentially very powerful tools. Dr. D'Asaro works to realize this potential, which is especially challenging and interesting as he collaborates with ocean biologists and chemists to design and operate multidisciplinary floats.

Department Affiliation

Ocean Physics


B.A. Physics, Harvard University, 1976

M.S. Applied Physics, Harvard University, 1976

Ph.D. Oceanography, MIT/WHOI, 1980


Wave Measurements at Ocean Weather Station PAPA

As part of a larger project to understand the impact of surface waves on the ocean mixed layer, APL-UW is measuring waves at Ocean Weather Station Papa, a long-term observational site at N 50°, W 145°.

29 Aug 2019

Air–Sea Momentum Flux in Tropical Cyclones

The intensity of a tropical cyclone is influenced by two competing physical processes at the air–sea interface. It strengthens by drawing thermal energy from the underlying warm ocean but weakens due to the drag of rough ocean surface. These processes change dramatically as the wind speed increases above 30 m/s.

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30 Mar 2018

The project is driven by the following science questions: (1) How important are equilibrium-range waves in controlling the air-sea momentum flux in tropical cyclones? We hypothesize that for wind speeds higher than 30 m/s the stress on the ocean surface is larger than the equilibrium-range wave breaking stress. (2) How does the wave breaking rate vary with wind speed and the complex surface wave field? At moderate wind speeds the wave breaking rate increases with increasing speed. Does this continue at extreme high winds? (3) Can we detect acoustic signatures of sea spray at high winds? Measurements of sea spray in tropical cyclones are very rare. We will seek for the acoustic signatures of spray droplets impacting the ocean surface. (4) What are the processes controlling the air-sea momentum flux?

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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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

Lagrangian Submesoscale Experiment — LASER

A science team led by Eric D'Asaro conducted a unique mission to deploy over 1,000 ocean drifters in a small area of the Gulf of Mexico. The real-time data collected from the biodegradable drifters recalibrated understanding of ocean currents.

22 Jan 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

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2000-present and while at APL-UW

LC–DRI Field Experiment and Data Calibration Report

Ma, B., E. D'Asaro, T. Sanford, J. Thomson, "LC–DRI Field Experiment and Data Calibration Report," Technical Report, APL-UW TR 2002, Applied Physics Laboratory, University of Washington, Seattle, March 2020.

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10 Mar 2020

The goal of the Waves, Langmuir Cells and the Upper Ocean Boundary Layer Departmental Research Initiative (LC–DRI) is to explore the upper ocean physics necessary to advance our understanding of the fluxes into and across the ocean mixed layer, including surface waves and wave breaking, Langmuir cells, and wave–current interaction. A set of comprehensive observational data was collected during the LC–DRI field experiment from various platforms including autonomous floats, drifter, buoys, and shipboard observations. The field campaign was conducted on the coast of Southern California 21 March – 5 April 2017. The fieldwork, including the event log and instrument deployment, is described in Part I. The inter-calibration between observed CTD data from EM-APEX and MLF floats, SWIFT drifters and R/V Sproul are described in Part II. For the MLF vs. EM-APEX calibration, the average salinity of MLF #82 and #83 top and bottom sensors is used as a reference. The calculated salinity offset for EM-APEX #6667, #6672, and #6678 is ~ 0.004 psu, for EM-APEX #6671 and #6674 is ~0.001 psu, and for EM-APEX #6675 is ~–0.001 psu. For seven SWIFT drifters at 0.2, 0.5, and 1.2 m, the calculated temperature offset varies from –0.1 to 0.1°C and the salinity offset varies from –0.003 to 0.2 psu. The salinity data from SWIFT #16 and #17 at 0.2 m exhibited large offsets, which suggest data bias. The comparison of wave energy measurements between SWIFT drifters and a Datawell Waverider buoy moored at CDIP station 299 are described in Part III. Excluding the periods when the mean separation distance was greater than 30 km (periods 3−1, 3, 5, 6, 8, 12), the root-mean-square error (RMSE) of significant wave height (Hs) is 0.25 ± 0.08 m, the RMSE of integrated wave energy is 0.057 ± 0.029 m2, and the average percent error of Hs is ~13%. In general, given the temporal, spatial, and spectral differences in the sampling strategy of SWIFTdrifters and the CDIP buoy, the comparison suggests no significant bias in either dataset.

Rain and sun create slippery layers in the Eastern Pacific Fresh Pool

Shcherbina, A.Y., E.A. D'Asaro, and R.R. Harcourt, "Rain and sun create slippery layers in the Eastern Pacific Fresh Pool," Oceanography, 32, 98-107, doi:10.5670/oceanog.2019.217, 2019.

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14 Jun 2019

An autonomous Lagrangian float equipped with a high-resolution acoustic Doppler current profiler observed the evolution of upper-ocean stratification and velocity in the Eastern Pacific Fresh Pool for over 100 days in August–November 2016. Although convective mixing homogenized the water column to 40 m depth almost every night, the combination of diurnal warming on clear days and rainfall on cloudy days routinely produced strong stratification in the upper 10 m. Whether due to thermal or freshwater effects, the initial strong stratification was mixed downward and incorporated in the bulk of the mixed layer within a few hours. Stratification cycling was associated with pronounced variability of ocean surface boundary layer turbulence and vertical shear of wind-driven (Ekman) currents. Decoupled from the bulk of the mixed layer by strong stratification, warm and fresh near-surface waters were rapidly accelerated by wind, producing the well-known "slippery layer" effect, and leading to a strong downwind near-surface distortion of the Ekman profile. A case study illustrates the ability of the new generation of Lagrangian floats to measure rapidly evolving temperature, salinity, and velocity, including turbulent and internal wave components. Quantitative interpretation of the results remains a challenge, which can be addressed with high-resolution numerical modeling, given sufficiently accurate air-sea fluxes.

Response of the salinity-stratified Bay of Bengal to Cyclone Phailin

Chaudhuri, D., D. Sengupta, E. D'Asaro, R. Venkatesan, and M. Ravichandran, "Response of the salinity-stratified Bay of Bengal to Cyclone Phailin," J. Phys. Oceanogr., 49, 1121-1140, doi:10.1175/JPO-D-18-0051.1, 2019.

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1 May 2019

Cyclone Phailin, which developed over the Bay of Bengal in October 2013, was one of the strongest tropical cyclones to make landfall in India. We study the response of the salinity-stratified north Bay of Bengal to Cyclone Phailin with the help of hourly observations from three open-ocean moorings 200 km from the cyclone track, a mooring close to the cyclone track, daily sea surface salinity (SSS) from Aquarius, and a one-dimensional model. Before the arrival of Phailin, moored observations showed a shallow layer of low-salinity water lying above a deep, warm "barrier" layer. As the winds strengthened, upper-ocean mixing due to enhanced vertical shear of storm-generated currents led to a rapid increase of near-surface salinity. Sea surface temperature (SST) cooled very little, however, because the prestorm subsurface ocean was warm. Aquarius SSS increased by 1.5–3 psu over an area of nearly one million square kilometers in the north Bay of Bengal. A one-dimensional model, with initial conditions and surface forcing based on moored observations, shows that cyclone winds rapidly eroded the shallow, salinity-dominated density stratification and mixed the upper ocean to 40–50-m depth, consistent with observations. Model sensitivity experiments indicate that changes in ocean mixed layer temperature in response to Cyclone Phailin are small. A nearly isothermal, salinity-stratified barrier layer in the prestorm upper ocean has two effects. First, near-surface density stratification reduces the depth of vertical mixing. Second, mixing is confined to the nearly isothermal layer, resulting in little or no SST cooling.

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In The News

NASA, NSF expedition to study ocean carbon embarks in August from Seattle

UW News, Hannah Hickey

Dozens of scientists, as well as underwater drones and other high-tech ocean instruments, will set sail from Seattle in mid-August. Funded by NASA and the National Science Foundation, the team will study the life and death of the small organisms that play a critical role in removing carbon dioxide from the atmosphere, and in the ocean’s carbon cycle.

21 Jun 2018

Scientists watch ocean plastic hotspots form in real time

NewsDeeply, Erica Cirino

Researchers tracked hundreds of buoys deployed in the Gulf of Mexico. Not only did the buoys not spread out – many concentrated into an area the size of a football stadium. The findings may help scientists pinpoint areas for plastic or oil-spill cleanup.

6 Feb 2018

Temporary 'bathtub drains' in the ocean concentrate flotsam

UW News, Hannah Hickey

An experiment featuring the largest flotilla of sensors ever deployed in a single area provides new insights into how marine debris, or flotsam, moves on the surface of the ocean.

18 Jan 2018

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Open Water Detection from Beneath Sea Ice

Record of Invention Number: 47655

Eric D'Asaro, Andrey Shcherbina


16 Mar 2016

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