Dense water formation on the Icelandic shelf and its contribution to the North Icelandic Jet

<p>Convection in the North Atlantic Ocean is a key component of the global overturning circulation (MOC) as it produces dense water at high latitudes. Recent work has highlighted the dominant role of the Irminger and Iceland basins in the production of the North Atlantic deep waters. Dense water formation in these basins is mainly explained by buoyancy forcing that transforms surface waters to the deep waters of the MOC lower limb. Air-sea fluxes and the surface density field are both key determinants of the buoyancy-driven transformation. To better understand the connection between atmospheric forcing and the Atlantic overturning circulation, we analyze the contributions of the air-sea fluxes and of the density structure to the transformation of surface water over the eastern subpolar gyre. More precisely, we consider the densification of subpolar mode water (SPMW) in the Iceland Basin that &#8216;pre-conditions&#8217; the dense water formation downstream. Analyses using 40 years of observations (1980&#8211;2019) reveal that variability in transformation is only weakly sensitive to changes in the heat and freshwater fluxes. Instead, changes in SPMW transformation are largely driven by the variance in the surface density structure, as expressed by the outcropping area for those isopycnals that define SPMW.This large influence of the surface density on the SPMW transformation partly explains the unusually large SPMW transformation in winter 2014&#8211;15 over the Iceland Basin. &#160;</p>

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Dense water formation in the north-western Mediterranean area during HyMeX-SOP2 in 1/36° ocean simulations: Sensitivity to initial conditions

Journal of Geophysical Research Oceans ◽

10.1002/2015jc011542 ◽

2016 ◽

Vol 121 (8) ◽

pp. 5549-5569 ◽

Cited By ~ 11

Author(s):

Fabien Léger ◽

Cindy Lebeaupin Brossier ◽

Hervé Giordani ◽

Thomas Arsouze ◽

Jonathan Beuvier ◽

...

Keyword(s):

Initial Conditions ◽

Mediterranean Area ◽

Western Mediterranean ◽

Dense Water ◽

The North ◽

Water Formation ◽

Dense Water Formation ◽

North Western ◽

Sensitivity To Initial Conditions

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Role of air–sea fluxes and ocean surface density in the production of deep waters in the eastern subpolar gyre of the North Atlantic

Ocean Science ◽

10.5194/os-17-1353-2021 ◽

2021 ◽

Vol 17 (5) ◽

pp. 1353-1365

Author(s):

Tillys Petit ◽

M. Susan Lozier ◽

Simon A. Josey ◽

Stuart A. Cunningham

Keyword(s):

North Atlantic ◽

Surface Density ◽

Ocean Surface ◽

Density Field ◽

The North ◽

Iceland Basin ◽

Deep Waters ◽

Water Formation ◽

Dense Water Formation

Abstract. Wintertime convection in the North Atlantic Ocean is a key component of the global climate as it produces dense waters at high latitudes that flow equatorward as part of the Atlantic Meridional Overturning Circulation (AMOC). Recent work has highlighted the dominant role of the Irminger and Iceland basins in the production of North Atlantic Deep Water. Dense water formation in these basins is mainly explained by buoyancy forcing that transforms surface waters to the deep waters of the AMOC lower limb. Air–sea fluxes and the ocean surface density field are both key determinants of the buoyancy-driven transformation. We analyze these contributions to the transformation in order to better understand the connection between atmospheric forcing and the densification of surface water. More precisely, we study the impact of air–sea fluxes and the ocean surface density field on the transformation of subpolar mode water (SPMW) in the Iceland Basin, a water mass that “pre-conditions” dense water formation downstream. Analyses using 40 years of observations (1980–2019) reveal that the variance in SPMW transformation is mainly influenced by the variance in density at the ocean surface. This surface density is set by a combination of advection, wind-driven upwelling and surface fluxes. Our study shows that the latter explains ∼ 30 % of the variance in outcrop area as expressed by the surface area between the outcropped SPMW isopycnals. The key role of the surface density in SPMW transformation partly explains the unusually large SPMW transformation in winter 2014–2015 over the Iceland Basin.

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The improvements of the ships of opportunity program in MFS-TEP

Ocean Science ◽

10.5194/os-3-245-2007 ◽

2007 ◽

Vol 3 (2) ◽

pp. 245-258 ◽

Cited By ~ 16

Author(s):

G. M. R. Manzella ◽

F. Reseghetti ◽

G. Coppini ◽

M. Borghini ◽

A. Cruzado ◽

...

Keyword(s):

Mediterranean Sea ◽

Pilot Project ◽

Quality Data ◽

Dense Water ◽

Short Period ◽

Water Formation ◽

Dense Water Formation ◽

Forecasting System ◽

Opportunity Program ◽

The Mediterranean

Abstract. The Ships Of Opportunity Program in the Mediterranean Sea was established at the end of 1999, in the framework of the Mediterranean Forecasting System – Pilot Project (MFS-PP). Many improvements have been made in data collection, transmission and management. Calibration of selected XBTs and a comparison of XBTs vs. CTDs during some research cruises have assured the quality of the data. Transmission now allows receiving data in full resolution by using GSM or satellite telecommunication services; management is offering access to high quality data and view services. The effects of technological and methodological improvements in the observing system are assessed in terms of capability to represent the most important circulation features. The improved methodologies have been tested during the Mediterranean Forecasting System – Toward Environmental Prediction (MFS-TEP) – Targeted Operational Period (MFS-TOP), lasting from September 2004 to February 2005. In spite of the short period of measurements, several important aspects of the Mediterranean Sea circulation have been verified, such as eddies and gyres in the various sub-basins, and dense water formation processes in some of them (vertical homogeneous profiles of about 13°C down to ~800 m in the Provençal, and of about 14.9°C down to ~300 m in the Levantine have allowed defining an index of dense water formation).

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