Mesoscale current variability in the Otranto Straits, Adriatic Sea

Kastanos, Nikos; Ferentinos, G.

doi:10.1029/89jc03262

Cited by 3 publications

(2 citation statements)

References 19 publications

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“…The vertical current pattern varies on a variety of timescales from interannual to tidal ones. Previous observational studies in the Strait of Otranto [ Ferentinos and Kastanos , 1988; Kastanos and Ferentinos , 1991] have presented evidence of unstable flow in the shear zone between the northward and southward currents. This variability has been explained in terms of the near‐inertial waves and mesoscale eddies.…”

Section: Introductionmentioning

confidence: 99%

Footprints of mesoscale eddy passages in the Strait of Otranto (Adriatic Sea)

2011

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The footprints of mesoscale eddies propagating through the Strait of Otranto are documented from current meter records, and their formation mechanism is hypothesized. Bottom‐mounted Acoustic Doppler Current Profilers data, collected during 5 months (November 2006 through April 2007) at a transect in the core of the outflowing Adriatic Dense Water, reveal energetic events that manifest as vertically uniform current vector rotations on a time scale of about 10 days. At the two moorings close to the center of the strait, coherent current vector rotations were in opposite senses. Simulation of the passage of an idealized cyclonic or anticyclonic rigid circular eddy confirms that these opposed rotations could be associated with passages of eddies in the southward direction. Characteristic parameters of the eddies were estimated: the duration was several days, the peak azimuthal velocity was around 10–20 cm/s, and advection velocity below 15 cm/s was predominantly in the southwestward direction. Cyclones were bigger (diameter 30–36 km) than anticyclones (14–24 km), and they traveled at greater depths. The eddy passage left a prominent signal in the thermohaline and turbidity properties. This latter is probably due to sediment resuspension by strong currents and to the advection of the suspended particles through an upstream located canyon. The eddy formation is explained in terms of stretching of the high potential vorticity water column outflowing the Strait of Otranto, a mechanism similar to that observed in the Denmark Strait overflow. Another possible explanation is the baroclinic instability of the overflow layer which results in the eddy formation.

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Section: Introductionmentioning

confidence: 99%

Footprints of mesoscale eddy passages in the Strait of Otranto (Adriatic Sea)

2011

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“…A discussion of the mesoscale activity from in‐situ measurements has only been attempted twice. Kastanos and Ferentinos [1991] analyzed currentmeter data taken from the Strait of Otranto and noted current fluctuations in the shear zone separating the inflowing and outflowing waters. They ascribed these fluctuations to mesoscale eddies and near‐inertial waves.…”

Section: Introductionmentioning

confidence: 99%

Simulation and characterization of the Adriatic Sea mesoscale variability

et al. 2007

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[1] This paper presents simulations of the Adriatic Sea using the DieCAST model applied on a 1.2-min grid (about 2-km resolution). The simulations resolve the mesoscale variability because the grid size falls below the first baroclinic deformation radius (about 5-10 km) and DieCAST has very low horizontal dissipation. The model is initialized with seasonally averaged temperature and salinity data and forced with climatological winds and surface buoyancy fluxes (both heat flux and evaporation minus precipitation). River discharges are varied daily according to a perpetual year for every river, and the open-boundary conditions at Otranto Strait are obtained by nesting in two larger-scale models. The present simulations demonstrate that the DieCAST model allows mesoscale instabilities to develop at length scales of 5-20 km and over time scales of a few days. The simulated variability exhibits pronounced similarities with the actual mesoscale variability, in terms of location, nature and temporal evolution of the features. Meanders, swirls and eddies are noted along the relatively smooth Italian coast while offshore jets and filaments better describe the mesoscale activity along the more rugged coast of Croatia. In sum, DieCAST is highly suitable for the study of mesoscale variability in the Adriatic Sea. The present simulations also show that the seasonal hydrography of the Adriatic Sea is intrinsically unstable to mesoscale perturbations, and that the mesoscale variability along the Italian coast is the result of baroclinic instability of the Western Adriatic Current. It is shown how the properties of this instability are related to the local bottom topography.

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