The dynamics of mixed layer deepening during open-ocean convection

Sohail, T and Gayen, B and Hogg, AM (2020) The dynamics of mixed layer deepening during open-ocean convection. In: Journal of Physical Oceanography, 50 (6). pp. 1625-1641.

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Abstract

Open-ocean convection is a common phenomenon that regulates mixed layer depth and ocean ventilation in the high-latitude oceans. However, many climate model simulations overestimate mixed layer depth during open-ocean convection, resulting in excessive formation of dense water in some regions. The physical processes controlling transient mixed layer depth during open-ocean convection are examined using two different numerical models: a high-resolution, turbulence-resolving nonhydrostatic model and a large-scale hydrostatic ocean model. An isolated destabilizing buoyancy flux is imposed at the surface of both models and a quasi-equilibrium flow is allowed to develop. Mixed layer depth in the turbulence-resolving and large-scale models closely aligns with existing scaling theories. However, the large-scale model has an anomalously deep mixed layer prior to quasi-equilibrium. This transient mixed layer depth bias is a consequence of the lack of resolved turbulent convection in the model, which delays the onset of baroclinic instability. These findings suggest that in order to reduce mixed layer biases in ocean simulations, parameterizations of the connection between baroclinic instability and convection need to be addressed. © 2020 American Meteorological Society.

Item Type:	Journal Article
Publication:	Journal of Physical Oceanography
Additional Information:	cited By 0
Keywords:	Oceanography; Turbulence, Baroclinic instability; Climate model simulations; Large-scale modeling; Mixed layer deepening; Mixed layer depths; Nonhydrostatic model; Ocean ventilations; Turbulent convection, Climate models, baroclinic instability; buoyancy; climate modeling; computer simulation; mixed layer; numerical model; oceanic convection; open ocean; turbulence; ventilation
Department/Centre:	Division of Mechanical Sciences > Centre for Atmospheric & Oceanic Sciences
Date Deposited:	22 Sep 2021 10:01
Last Modified:	22 Sep 2021 10:01
URI:	http://eprints.iisc.ac.in/id/eprint/65774

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