Publications

Export 2 results:
Sort by: Author Title Type [ Year  (Desc)]
2018
Fine, EC, MacKinnon JA, Alford MH, Mickett JB.  2018.  Microstructure observations of turbulent heat fluxes in a warm-core Canada Basin eddy. Journal of Physical Oceanography. 48:2397-2418.   10.1175/jpo-d-18-0028.1   AbstractWebsite

An intrahalocline eddy was observed on the Chukchi slope in September of 2015 using both towed CTD and microstructure temperature and shear sections. The core of the eddy was 6 degrees C, significantly warmer than the surrounding -1 degrees C water and far exceeding typical temperatures of warm-core Arctic eddies. Microstructure sections indicated that outside of the eddy the rate of dissipation of turbulent kinetic energy epsilon was quite low . Three different processes were associated with elevated epsilon. Double-diffusive steps were found at the eddy's top edge and were associated with an upward heat flux of 5 W m(-2). At the bottom edge of the eddy, shear-driven mixing played a modest role, generating a heat flux of approximately 0.5 W m(-2) downward. Along the sides of the eddy, density-compensated thermohaline intrusions transported heat laterally out of the eddy, with a horizontal heat flux of 2000 W m(-2). Integrating these fluxes over an idealized approximation of the eddy's shape, we estimate that the net heat transport due to thermohaline intrusions along the eddy flanks was 2 GW, while the double-diffusive flux above the eddy was 0.4 GW. Shear-driven mixing at the bottom of the eddy accounted for only 0.04 GW. If these processes continued indefinitely at the same rate, the estimated life-span would be 1-2 years. Such eddies may be an important mechanism for the transport of Pacific-origin heat, freshwater, and nutrients into the Canada Basin.

2016
Alford, MH, MacKinnon JA, Simmons HL, Nash JD.  2016.  Near-inertial internal gravity waves in the ocean. Annual Review of Marine Science, Vol 8. 8( Carlson CA, Giovannoni SJ, Eds.).:95-123., Palo Alto: Annual Reviews   10.1146/annurev-marine-010814-015746   Abstract

We review the physics of near-inertial waves (NIWs) in the ocean and the observations, theory, and models that have provided our present knowledge. NIWs appear nearly everywhere in the ocean as a spectral peak at and just above the local inertial period f, and the longest vertical wavelengths can propagate at least hundreds of kilometers toward the equator from their source regions; shorter vertical wavelengths do not travel as far and do not contain as much energy, but lead to turbulent mixing owing to their high shear. NIWs are generated by a variety of mechanisms, including the wind, nonlinear interactions with waves of other frequencies, lee waves over bottom topography, and geostrophic adjustment; the partition among these is not known, although the wind is likely the most important. NIWs likely interact strongly with mesoscale and submesoscale motions, in ways that are just beginning to be understood.