Vertical mixing at intermediate depths in the Arctic boundary current

• Published in: Geophysical Research Letters
• Main Authors: Lenn, Y.D., Wiles, P.J., Torres-Valdes, S., Abrahamsen, E.P., Rippeth, T.P., Simpson, J.H., Bacon, S., Laxon, S.W., Polyakov, I., Ivanov, V., Kirillov, S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Geophysical Union 2009
• Subjects: Marine Sciences; Arctic
• Online Access: http://nora.nerc.ac.uk/id/eprint/5919/; https://nora.nerc.ac.uk/id/eprint/5919/5/2008GL036792.pdf; https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2008GL036792; https://doi.org/10.1029/2008GL036792

Microstructure and hydrographic observations, during September 2007 in the boundary current on the East Siberian continental slope, document upper ocean stratification and along-stream water mass changes. A thin warm surface layer overrides a shallow halocline characterized by a ~40-m thick temperature minimum layer beginning at ~30 m depth. Below the halocline, well-defined thermohaline diffusive staircases extended downwards to warm Atlantic Water intrusions found at 200-800 m depth. Observed turbulent eddy kinetic energy dissipations are extremely low (epsilon <10^-6 W m^-3), such that double diffusive convection dominates the vertical mixing in the upper-ocean. The diffusive convection heat fluxes F^dc_H ~1 W m^-2, are an order of magnitude too small to account for the observed along-stream cooling of the boundary current. Our results implicate circulation patterns and the influence of shelf waters in the evolution of the boundary current waters.