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Caitlin Whalen

Senior Oceanographer

Affiliate Assistant Professor, Oceanography

Email

cwhalen@apl.uw.edu

Research Interests

Small-scale oceanic processes as viewed from global and regional scales including diapycnal mixing, internal waves, submesoscale dynamics, air–sea interactions, and mesoscale–internal wave interactions

Education

B.A. Physics, Reed College, 2008

Ph.D. Physical Oceanography, University of California at San Diego, 2015

Publications

2000-present and while at APL-UW

A parameterization of local and remote tidal mixing

de Lavergne, C., and 9 others including C.B. Whalen, "A parameterization of local and remote tidal mixing," J. Adv. Model. Earth Syst., EOR, doi:10.1029/2020MS002065, 2020.

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20 Apr 2020

Vertical mixing is often regarded as the Achilles' heel of ocean models. In particular, few models include a comprehensive and energy‐constrained parameterization of mixing by internal ocean tides. Here, we present an energy‐conserving mixing scheme which accounts for the local breaking of high‐mode internal tides and the distant dissipation of low‐mode internal tides. The scheme relies on four static two‐dimensional maps of internal tide dissipation, constructed using mode‐by‐mode Lagrangian tracking of energy beams from sources to sinks. Each map is associated with a distinct dissipative process and a corresponding vertical structure. Applied to an observational climatology of stratification, the scheme produces a global three‐dimensional map of dissipation which compares well with available microstructure observations and with upper‐ocean finestructure mixing estimates. This relative agreement, both in magnitude and spatial structure across ocean basins, suggests that internal tides underpin most of observed dissipation in the ocean interior at the global scale. The proposed parameterization is therefore expected to improve understanding, mapping and modelling of ocean mixing.

Large-scale impacts of the mesoscale environment on mixing from wind-driven internal waves

Whalen, C.B., J.A. MacKinnon, and L.D. Talley, "Large-scale impacts of the mesoscale environment on mixing from wind-driven internal waves," Nat. Geosci., 11, 842-847, doi:10.1038/s41561-018-0213-6, 2018.

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17 Sep 2018

Oceanic mesoscale structures such as eddies and fronts can alter the propagation, breaking and subsequent turbulent mixing of wind-generated internal waves. However, it has been difficult to ascertain whether these processes affect the global-scale patterns, timing and magnitude of turbulent mixing, thereby powering the global oceanic overturning circulation and driving the transport of heat and dissolved gases. Here we present global evidence demonstrating that mesoscale features can significantly enhance turbulent mixing due to wind-generated internal waves. Using internal wave-driven mixing estimates calculated from Argo profiling floats between 30° and 45°N, we find that both the amplitude of the seasonal cycle of turbulent mixing and the response to increases in the wind energy flux are larger to a depth of at least 2,000 m in the presence of a strong and temporally uniform field of mesoscale eddy kinetic energy. Mixing is especially strong within energetic anticyclonic mesoscale features compared to cyclonic features, indicating that local modification of wind-driven internal waves is probably one mechanism contributing to the elevated mixing observed in energetic mesoscale environments.

Climate process team on internal-wave driven ocean mixing

MacKinnon, J.A., Z. Zhao, C.B. Whalen, and 32 others "Climate process team on internal-wave driven ocean mixing," Bull. Amer. Meteor. Soc., 98, 2429-2454, doi:10.1175/BAMS-D-16-0030.1, 2017.

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1 Nov 2017

Recent advances in our understanding of internal-wave driven turbulent mixing in the ocean interior are summarized. New parameterizations for global climate ocean models, and their climate impacts, are introduced.

Diapycnal mixing plays a primary role in the thermodynamic balance of the ocean and, consequently, in oceanic heat and carbon uptake and storage. Though observed mixing rates are on average consistent with values required by inverse models, recent attention has focused on the dramatic spatial variability, spanning several orders of magnitude, of mixing rates in both the upper and deep ocean. Away from ocean boundaries, the spatio-temporal patterns of mixing are largely driven by the geography of generation, propagation and dissipation of internal waves, which supply much of the power for turbulent mixing. Over the last five years and under the auspices of US CLIVAR, a NSF- and NOAA-supported Climate Process Team has been engaged in developing, implementing and testing dynamics-based parameterizations for internal-wave driven turbulent mixing in global ocean models. The work has primarily focused on turbulence 1) near sites of internal tide generation, 2) in the upper ocean related to wind-generated near inertial motions, 3) due to internal lee waves generated by low-frequency mesoscale flows over topography, and 4) at ocean margins. Here we review recent progress, describe the tools developed, and discuss future directions.

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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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