Dynamics of turbulent western-boundary currents at low latitude in a shallow-water model

Akuetevi, Cataria Quam Cyrille; Wirth, Achim

doi:10.5194/os-11-471-2015

Cited by 14 publications

(21 citation statements)

References 40 publications

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“…They are due to the tearing off from the boundary current of intense patches of positive vorticity called bursts that later get organized in coherent cyclones (see Akuetevi and Wirth, 2015). The cyclones often pair with the large anticyclones.…”

Section: Discussionmentioning

confidence: 99%

“…ORCA025 is extensively described in Barnier et al (2006) and has been widely used to address scientific questions in physical oceanography, biogeochemistry, and marine biology (see refereed publications at www.drakkar-ocean.eu). Although ORCA025 is only eddy-permitting, even at these low latitudes, it is widely used to perform ocean reanalyses (Balmaseda et al, 2015) and is the ocean component of several Earth System Models in Europe (Megann et al, 2014;Williams et al, 2015). Therefore, we find it useful to report any assessment of its solution.…”

Section: Numerical Model Simulationsmentioning

confidence: 99%

“…These events were previously identified and called bursts in analogy with the bursts or ejections of vorticity patterns in the classical western boundary-layer dynamics (see Robinson, 1991;Akuetevi and Wirth, 2015). Akuetevi and Wirth (2015) explain that the thin layer of large positive values (cyclonic) of relative vorticity that exists along the coast in a low-latitude western boundary current is the siege of intermittent detachments of such cyclonic vorticity bursts. Note that if the occurrence of the bursts compares well between all simulations, the ejection of the bursts off the boundary and their offshore motion are much better resolved at 1/12…”

Section: Burstsmentioning

confidence: 99%

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Interactions between the Somali Current eddies during the summer monsoon: insights from a numerical study

et al. 2016

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Abstract. Three hindcast simulations of the global ocean circulation differing by resolution (1/4 or 1/12• ) or parametrization or atmospheric forcing are used to describe the interactions between the large anticyclonic eddies generated by the Somali Current system during the Southwest Monsoon. The present investigation of the Somalian coherent eddy structures allows us to identify the origin and the subsequent development of the cyclones flanked upon the Great Whirl (GW) previously identified by Beal and Donohue (2013) in satellite observations and to establish that similar cyclones are also flanked upon the Southern Gyre (SG). These cyclones are identified as potential actors in mixing water masses within the large eddies and offshore the coast of Somalia.All three simulations bring to light that during the period when the Southwest Monsoon is well established, the SG moves northward along the Somali coast and encounters the GW. The interaction between the SG and the GW is a collision without merging, in a way that has not been described in observations up to now. During the collision the GW is pushed to the east of Socotra Island, sheds several smaller patches of anticyclonic vorticity, and often reforms into the Socotra Eddy, thus proposing a formation mechanism for that eddy. During this process the GW gives up its place to the SG. This process is robust throughout the three simulations.

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Section: Discussionmentioning

confidence: 99%

Section: Numerical Model Simulationsmentioning

confidence: 99%

Section: Burstsmentioning

confidence: 99%

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Interactions between the Somali Current eddies during the summer monsoon: insights from a numerical study

et al. 2016

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“…Three global ocean hindcast simulations, one at 1/4 • resolution and two at 1/12 • resolution, made available by the DRAKKAR consortium (DRAKKAR-Group et al, 2007, 2014 are used here to study the Somali eddies during the Southwest Monsoon.…”

Section: Numerical Model Simulationsmentioning

confidence: 99%

“…Schott et al, 2009;. A more thorough validation of the 1/12 • model simulations can be found in Akuetevi (2014). The model surface circulation during the summer monsoon is compared with an observational reference in Fig.…”

Section: Arabian Sea Upper-ocean Circulation During the Summer Monsoonmentioning

confidence: 99%

Interactions between the Somali Current eddies during the summer monsoon: insights from a numerical study

Barnier¹,

Akuetevi²,

Verron³

et al. 2015

Preprint

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Three hindcast simulations of the global ocean circulation differing by resolution (1/4 or 1/12 • ) or parametrization or atmospheric forcing are used to describe the interactions between the large anticyclonic eddies generated by the Somali Current system during the Southwest Monsoon. The present investigation of the Somalian coherent eddy structures allows us to identify the origin and the subsequent development of the cyclones flanked upon the Great Whirl (GW) previously identified by Beal and Donohue (2013) in satellite observations and to establish that similar cyclones are also flanked upon the Southern Gyre (SG). These cyclones are identified as potential actors in mixing water masses within the large eddies and offshore the coast of Somalia.All three simulations bring to light that during the period when the Southwest Monsoon is well established, the SG moves northward along the Somali coast and encounters the GW. The interaction between the SG and the GW is a collision without merging, in a way that has not been described in observations up to now. During the collision the GW is pushed to the east of Socotra Island, sheds several smaller patches of anticyclonic vorticity, and often reforms into the Socotra Eddy, thus proposing a formation mechanism for that eddy. During this process the GW gives up its place to the SG. This process is robust throughout the three simulations.Published by Copernicus Publications on behalf of the European Geosciences Union.

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Eddy‐topography interactions and the fate of the Persian Gulf Outflow

et al. 2015

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The Persian Gulf feeds a warm and salty outflow in the Gulf of Oman (northern Arabian Sea). The salt climatological distribution is relatively smooth in the Gulf of Oman, and the signature of a slope current carrying salty waters is difficult to distinguish hundreds of kilometers past the Strait of Hormuz, in contrast to other outflows of the world ocean. This study focuses on the mechanisms involved in the spreading of Persian Gulf Water (PGW) in the Gulf of Oman, using a regional primitive equation numerical simulation. The authors show that the dispersion of PGW occurs through a regime that is distinct from, for example, the one responsible for the Mediterranean outflow dispersion. The background mesoscale eddy field is energetic and participates actively to the spreading of PGW. Remotely formed eddies propagate into the Gulf of Oman and interact with the topography, leading to submesoscales formation and PGW shedding. Eddy‐topography interactions are isolated in idealized simulations and reveal the formation of intense frictional boundary layers, generating submesoscale coherent vortices (SCVs). Interactions take place at depths encompassing the PGW depth, thus SCVs trap PGW and contribute to its redistribution from the boundaries to the interior of the Gulf of Oman. The overall efficiency of these processes is confirmed by a strong contribution of eddy salt fluxes in the interior of the basin, and is quantified using particle statistics. It is found to be a highly dispersive regime, with an approximated eddy diffusivity of ∼1700 normalm2 normals−1.

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Dynamics of turbulent western-boundary currents at low latitude in a shallow-water model

Cited by 14 publications

References 40 publications

Interactions between the Somali Current eddies during the summer monsoon: insights from a numerical study

Interactions between the Somali Current eddies during the summer monsoon: insights from a numerical study

Interactions between the Somali Current eddies during the summer monsoon: insights from a numerical study

Eddy‐topography interactions and the fate of the Persian Gulf Outflow

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