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Harper Simmons

Senior Principal Oceanographer

Email

hsimmons@apl.washington.edu

Department Affiliation

Ocean Physics

Education

B.A. Physics, University of Alaska, 1995

M.S. Coastal Hydrology, University of Alaska, 1996

Ph.D. Physical Oceanography, Florida State University, 2000

Publications

2000-present and while at APL-UW

Formation and circulation of newly ventilated winter water in the western Beaufort Sea

Lin, P.G., R.S. Pickart, T.J. Weingartner, H.L. Simmons, M. Itoh, and T. Kikuchi, "Formation and circulation of newly ventilated winter water in the western Beaufort Sea," Prog. Oceanogr., 216, doi:10.1016/j.pocean.2023.103068, 2023.

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1 Aug 2023

Newly ventilated winter water (NVWW) is a cold, salty, nutrient-rich water mass that is critical for supporting the ecosystem of the western Arctic Ocean. In this study, NVWW formation is documented using timeseries from an 8-mooring array deployed from 2008 to 2009 across the shelf and slope in the western Beaufort Sea near 150°W. The saltiest (densest) class of the winter water (salinity > 32.6), which is able to ventilate the cold halocline in the interior Canada Basin, was only observed on the inner shelf from December to May. The reasons for this are three-fold: (1) In mid- to late-fall the water on the outer shelf is largely influenced by fresher water in the vicinity of the shelfbreak, limiting the density of the winter product there; (2) during winter the variance in ice cover is significantly higher on the inner shelf than the outer shelf, and this enhanced presence of leads and polynyas results in more re-freezing and hence formation of saltier winter water; and (3) the cross-shelf velocities during the cold months (December–May) were negligible at the array site. To better understand the ultimate fate of the salty NVWW, the components of the western Beaufort Sea boundary current system were quantified using the array data plus additional mooring data to the west. It is argued that the salty NVWW can be fluxed off the shelf due to the convergence of the westward-flowing current on the shelf and the eastward-flowing outflow from Barrow Canyon.

Boundary layer energetics of rapid wind and wave forced mixing events

Skyllingstad, E.D., R.M. Samelson, H. Simmons, L. St. Laurent, S. Merrifield, T. Klenz, and L. Centuroni, "Boundary layer energetics of rapid wind and wave forced mixing events," J. Phys. Oceanogr., 53, 1887-1900, doi:10.1175/JPO-D-22-0150.1, 2023.

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5 May 2023

The observed development of deep mixed layers and the dependence of intense, deep-mixing events on wind and wave conditions are studied using an ocean LES model with and without an imposed Stokes-drift wave forcing. Model results are compared to glider measurements of the ocean vertical temperature, salinity and turbulence kinetic energy (TKE) dissipation rate structure collected in the Icelandic Basin. Observed wind stress reached 0.8 N m-2 with significant wave height of 4–6 m, while boundary layer depths reached 180 m. We find that wave forcing, via the commonly used Stokes drift vortex force parameterization, is crucial for accurate prediction of boundary layer depth as characterized by measured and predicted TKE dissipation rate profiles. Analysis of the boundary layer kinetic energy (KE) budget using a modified total Lagrangian-mean energy equation, derived for the wave averaged Boussinesq equations by requiring that the rotational inertial terms vanish identically as in the standard energy budget without Stokes forcing, suggests that wind work should be calculated using both the surface current and surface Stokes drift. A large percentage of total wind energy is transferred to model TKE via regular and Stokes drift shear production and dissipated. However, resonance by clockwise rotation of the winds can greatly enhance the generation of inertial current mean KE (MKE). Without resonance, TKE production is about 5 times greater than MKE generation, whereas with resonance this ratio decreases to roughly 2. The results have implications for the problem of estimating the global kinetic energy budget of the ocean.

Island Arc Turbulent Eddy Regional Exchange (ARCTERX): Science and Experiment Plan

The ARCTERX Team, "Island Arc Turbulent Eddy Regional Exchange (ARCTERX): Science and Experiment Plan," Technical Report, APL-UW TR 2201. Applied Physics Laboratory, University of Washington, July 2022, 49 pp.

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15 Jul 2022

Submesoscale flows such as fronts, eddies, filaments, and instabilities with lateral dimensions between 100 m and 10 km are ubiquitous features of the ocean. They act as an intermediary between the mesoscale and small-scale turbulence and are thought to have a critical role in closing the ocean's kinetic budget by facilitating a forward energy cascade, where energy is transferred to small scales and dissipated.

The initiative uses a suite of measurements from autonomous platforms and ships combined with regional simulations to characterize the submesoscale flows in the western Pacific Ocean between Luzon and Mariana Island arcs &$151; the ARCTERX region.

Program goals are to characterize the strength and spectral properties of the turbulent cascade of kinetic energy on the submesoscales in the ARCTERX study region and understand the processes that control energy transfers across scales and their seasonal variability.

More Publications

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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