Publications
Following publication has been announced by our department Small-Scale Physics and Turbulence. For further information please contact Dr. Jeffrey Carpenter, author of the publication:
Carpenter, J.R., Waterman, S., & Scheifele, B. (2022): Enhanced mixing of heat in the Arctic Ocean halocline in weakly turbulent conditions. Geophysical Research Letters, 49, e2022GL100450, doi:10.1029/2022GL100450
Abstract:
In the low-energy mixing environment of the Arctic Ocean halocline, a unique mixing mechanism of temperature is present. It consists of the formation of small-vertical-scale (∼1 m) intrusive features, with temperature anomalies up to ∼0.1°C, that create mean-square vertical temperature gradients that are orders of magnitude greater than the background. This finescale temperature structure results in enhanced heat fluxes in conditions of extremely weak turbulence and is responsible for an irreversible mixing of heat into cold halocline waters. The rates of thermal variance dissipation and heat transport are comparable to turbulent mechanisms in the Arctic Ocean, such as internal wave-driven mixing and double diffusive convection. We propose that in conditions of low turbulence, and in the presence of lateral thermal variability, the temperature field displays a self-regulating mechanism by which it is able to enhance its finescale structure to generate enhanced mixing, thus compensating for the lack of turbulent fluxes.
Plain Language Summary:
Understanding the causes of the ongoing reductions in Arctic sea ice cover requires knowledge of the processes controlling ocean heat transport. The transport caused by ocean turbulence is particularly important since it provides a mechanism by which significant heat that is stored in the Arctic Ocean water column may cause ice melt. However, this turbulent transport is hindered by an extremely stable, near-surface layer, the halocline, that acts to damp ocean turbulence. In this study, we describe observations made using an autonomous underwater glider of a process within the halocline that is able to transport heat while bypassing the generation of ocean turbulence. We argue that this transport mechanism is a result of the highly stable, low-turbulence conditions in the halocline, and is thus able to partially self-regulate the transport of heat in such a stable environment.
