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Caitlin Whalen

Senior Oceanographer

Affiliate Assistant Professor, Oceanography

Email

cwhalen@apl.uw.edu

Phone

206-897-1739

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

Decreased stratification in the abyssal southwest Pacific basin and implication for the energy budget

Zhang, H.J., C.B. Whalen, N. Kumar, and S.G. Purkey, "Decreased stratification in the abyssal southwest Pacific basin and implication for the energy budget," Geophys. Res. Lett., EOR, doi:10.1029/2021GL094322, 2021.

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25 Aug 2021

The large scale circulation of the ocean is primarily driven by density differences. As dense, heavy water sinks, it fills the deep ocean basins and aids in pushing water around the globe, cycling around the world over many centuries. A key location where this happens is around Antarctica. The ice and cold winds cool the water, making it denser. This cooled water sinks, displacing the deep water and pushing it northwards. As Antarctica warms, this water carries the extra heat into the rest of the world, causing the deep ocean to rapidly warm. In the Southwest Pacific Basin, we find that this bottom intensified warming has caused a significant reduction in the stratification of the deepest layer over the past three decades. This change can disrupt the global ocean conveyor belt, impacting the transport of heat, carbon dioxide, nutrients, and other dissolved matter around the world.

Spatial and temporal variability of diapycnal mixing in the Indian Ocean

Katsumata, K., L.D. Talley, T.A. Capuano, C.B. Whalen, "Spatial and temporal variability of diapycnal mixing in the Indian Ocean," J. Geophys. Res., 126, doi:10.1029/2021JC017257, 2021.

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1 Jul 2021

The rate of turbulent kinetic energy dissipation and diapycnal diffusivity are estimated along 10 hydrographic sections across the Indian Ocean from a depth of 500 m to the seabed. Six sections were occupied twice. On the meridional section, which is nominally along 95°E, spatial patterns were observed to persist throughout the three occupations. Since the variability in diffusivity exceeds the variability in the vertical gradients of temperature and salinity, we conclude that the diffusive diapycnal fluxes vary mostly with diffusivity. In high latitudes, diapycnal diffusion of both temperature and salinity contribute almost equally to density diffusion, particularly across isopycnals just above the salinity maximum, while mainly temperature contributes in other latitudes. The known zonal difference in turbulence is reproduced. Diffusivity from the seabed to 4000 m above the seabed has an exponential profile with a mode value of 4 x 10-4 m2s-1 at 1000 m above the seabed and is positively correlated with topographic roughness as reported previously. It is found that the diffusivity also correlates with wind power injected through the surface at near-inertial frequencies 10–80 days before the observations. These correlations were used to interpolate the observation-based turbulence quantities to the entire Indian Ocean. Although the dissipation averaged along selected neutral-density surfaces is less than the dissipation needed to explain the meridional overturning circulation evaluated across 32°S latitude, this may be explained by effects not captured by the ship-based observations and parameterization. These effects likely include unobserved high-mixing events, near bottom processes (e.g. hydraulic jumps), and deep equatorial jets.

Best practices for comparing ocean turbulence measurements across spatiotemporal scales

Whalen, C.B., "Best practices for comparing ocean turbulence measurements across spatiotemporal scales," J. Atmos. Ocean. Technol., 38, 837-841, doi:10.1175/JTECH-D-20-0175.1, 2021.

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1 Apr 2021

The turbulent energy dissipation rate in the ocean can be measured by using rapidly sampling microstructure shear probes, or by applying a finescale parametrization to coarser resolution density and/or shear profiles. The two techniques require measurements that are on different spatiotemporal scales and generate dissipation rate estimates that also differ in spatiotemporal scale. Since the distribution of the measured energy dissipation rate is closer to lognormal than normal and fluctuates with the strength of the turbulence, averaging the two approaches on equivalent spatiotemporal scales is critical for accurately comparing the two methods. Here, microstructure data from the 1997 Brazil Basin Tracer Release Experiment (BBTRE) is used to demonstrate that comparing averages of the dissipation rate on different spatiotemporal scales can generate spurious discrepancies of up to a factor of O10 in regions of strong turbulence and smaller biases of up to a factor of 2 in the presence of weaker turbulence.

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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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