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Abstract:
Quantifying ocean mixing rates in the Arctic Ocean is critical to our ability to predict upwards oceanic heat flux, freshwater distribution, and circulation. However, direct ocean mixing measurements in the Arctic are sparse and cannot characterize the high spatiotemporal variability typical of ocean mixing. Further, latitude, ice, and stratification make the Arctic Ocean mixing environment unique, with all of double-diffusive, internal wave-driven and non-turbulent mixing processes playing a role.
In this work, we use year-round observations of temperature and salinity from Ice-Tethered Profilers (ITPs), as well as an archived record of ship-based measurements, to 1. characterize the prevalence of various mixing regimes including non-turbulent, double-diffusive, and internal wave-driven regimes; 2. compute well-resolved, pan-Arctic maps of average effective vertical diffusivity for temperature and density that account for the varied contributions of each of these regimes; 3. map the pan-Arctic distributions of vertical heat and buoyancy fluxes; and 4. quantify the relative roles of each regime in setting net fluxes. Focusing on the water column segment directly above the Atlantic Water (AW) temperature maximum, we use these analyses to gain insight into the upward heat and buoyancy fluxes from the AW layer, specifically the regional patterns of the different processes’ contributions to upward heat transport, as well as the competition between the de-stratifying effects of internal wave-driven mixing vs. the re-stratifying effects of double diffusive and non-turbulent mixing processes.
