The ocean mixed-layer under Southern Ocean sea-ice: Seasonal cycle and forcing.

Pellichero, Violaine, Sallée, Jean-Baptiste, Schmidtko, Sunke , Roquet, Fabien and Charrassin, Jean-Benoît (2017) The ocean mixed-layer under Southern Ocean sea-ice: Seasonal cycle and forcing. Open Access Journal of Geophysical Research: Oceans, 122 (2). pp. 1608-1633. DOI 10.1002/2016JC011970.

[img]
Preview
Text
jgrc22039.pdf - Published Version

Download (3459Kb) | Preview

Supplementary data:

Abstract

The oceanic mixed-layer is the gateway for the exchanges between the atmosphere and the ocean; in this layer all hydrographic ocean properties are set for months to millennia. A vast area of the Southern Ocean is seasonally capped by sea-ice, which alters the characteristics of the ocean mixed-layer. The interaction between the ocean mixed-layer and sea-ice plays a key role for water-mass transformation, the carbon cycle, sea-ice dynamics, and ultimately for the climate as a whole. However, the structure and characteristics of the under-ice mixed-layer are poorly understood due to the sparseness of in-situ observations and measurements. In this study, we combine distinct sources of observations to overcome this lack in our understanding of the Polar Regions. Working with Elephant Seal-derived observations, ship-based and Argo float observations, we describe the seasonal cycle of the ocean mixed-layer characteristics and stability of the ocean mixed-layer over the Southern Ocean and specifically under sea-ice. Mixed-layer heat and freshwater budgets are used to investigate the main forcing mechanisms of the mixed-layer seasonal cycle. The seasonal variability of sea surface salinity and temperature are primarily driven by surface processes, dominated by sea-ice freshwater flux for the salt budget, and by air-sea flux for the heat budget. Ekman advection, vertical diffusivity and vertical entrainment play only secondary roles.Our results suggest that changes in regional sea-ice distribution and annual duration, as currently observed, widely affect the buoyancy budget of the underlying mixed-layer, and impact large-scale water-mass formation and transformation with far reaching consequences for ocean ventilation.

Document Type: Article
Funder compliance: info:eu-repo/grantAgreement/EC/H2020/637770
Keywords: Southern Ocean; Mixed-layer; Sea-ice; Elephant Seals; Salt budget; Heat budget
Research affiliation: OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-PO Physical Oceanography
Refereed: Yes
Open Access Journal?: No
DOI etc.: 10.1002/2016JC011970
ISSN: 2169-9275
Date Deposited: 29 Nov 2016 08:11
Last Modified: 01 Feb 2019 15:01
URI: http://oceanrep.geomar.de/id/eprint/34943

Actions (login required)

View Item View Item

Document Downloads

More statistics for this item...