Small Mesoscale Features at a Meandering Upper-Ocean Front in the Western Ionian Sea (Mediterranean Sea): Vertical Motion and Potential Vorticity Analysis

Abstract. Meddies, intra-thermocline eddies of Mediterranean water, can often be detected at the sea surface as positive sea-level anomalies. Here we study the surface signature of several meddies tracked with RAFOS floats and AVISO altimetry. While pushing its way through the water column, a meddy raises isopycnals above. As a consequence of potential vorticity conservation, negative relative vorticity is generated in the upper layer. During the initial period of meddy acceleration after meddy formation or after a stagnation stage, a cyclonic signal is also generated at the sea-surface, but mostly the anticyclonic surface signal follows the meddy. Based on geostrophy and potential vorticity balance, we present theoretical estimates of the intensity of the surface signature. It appears to be proportional to the meddy core radius and to the Coriolis parameter, and inversely proportional to the core depth and buoyancy frequency. This indicates that surface signature of a meddy may be strongly reduced by the upper ocean stratification. Using climatic distribution of the stratification intensity, we claim that the southernmost limit for detection in altimetry of small meddies (with radii on the order of 10–15 km) should lie in the subtropics (35–45° N), while large meddies (with radii of 25–30 km) could be detected as far south as the northern tropics (25–35° N). Those results agree with observations.

Download Full-text

Downward fluxes of elemental carbon, metals and polycyclic aromatic hydrocarbons in settling particles from the deep Ionian Sea (NESTOR site), Eastern Mediterranean

Biogeosciences Discussions ◽

10.5194/bgd-9-19165-2012 ◽

2012 ◽

Vol 9 (12) ◽

pp. 19165-19197 ◽

Cited By ~ 1

Author(s):

C. Theodosi ◽

C. Parinos ◽

A. Gogou ◽

A. Kokotos ◽

S. Stavrakakis ◽

...

Keyword(s):

Polycyclic Aromatic Hydrocarbons ◽

Mediterranean Sea ◽

Aromatic Hydrocarbons ◽

Elemental Carbon ◽

Eastern Mediterranean ◽

Vertical Transport ◽

Sea Surface ◽

Ionian Sea ◽

Eastern Mediterranean Sea ◽

Polycyclic Aromatic

Abstract. To assess sources and major processes controlling vertical transport of both anthropogenic and natural chemical species in deep basins of the Eastern Mediterranean Sea (SE Ionian Sea, Nestor site), we performed chemical characterization (elemental carbon, major and trace metals and polycyclic aromatic hydrocarbons) of marine sinking particles. Sediment traps were deployed at five successive depths, 700 m, 1200 m, 2000 m, 3200 m and 4300 m from the sea surface, during the period of May 2007 to October 2008. Fluxes of all measured species exhibited minimum values from January to March 2008 and maximum from April to September 2008, with an evident covariance revealing a common and rapid vertical transport mechanism from 700 m down to 4300 m depth. Crustal matter flux from atmospheric deposition plays an important role in the temporal variability of particulate matter with significant contribution from biogenic constituents namely the seasonal succession in the export of planktonic biomass, expressed by particulate organic carbon (POC), carbonates and biogenic Si fluxes (Stavrakakis et al., 2012). Tracers (elemental carbon, retene) of the devastating forest fires occurred in August 2007 in southern Greece, were detected at sediment trap material in all depths with a delay of 15 days at 4300 m, indicating a rapid and well-coupled transport of sinking particulate material between the sea-surface and deep layers of the Eastern Mediterranean Sea. Lateral inputs of pollutants at the deepest trap (4300 m) are probably of importance, due to the influence of deep Adriatic water at the study site.

Download Full-text

First record of the Combtooth Blenny, Microlipophrys adriaticus (Steindachner & Kolombatovic, 1883) (Pisces, Blenniidae), for the Italian Ionian Sea

Check List ◽

10.15560/11.3.1646 ◽

2015 ◽

Vol 11 (3) ◽

pp. 1646 ◽

Cited By ~ 1

Author(s):

F. Tiralongo ◽

R. Baldacconi

Keyword(s):

Mediterranean Sea ◽

Black Sea ◽

Adriatic Sea ◽

First Record ◽

The Black Sea ◽

Ionian Sea ◽

Sea Of Marmara ◽

Limited Distribution ◽

The North ◽

The Mediterranean

Microlipophrys adriaticus (Steindachner & Kolombatovic, 1883) is an endemic blenny of the Mediterranean Sea. It is also known from the Sea of Marmara and the Black Sea. However, unlike other species of combtooth blennies, M. adriaticus is a fish with a limited distribution in Adriatic Sea, especially in the north, where it can be common. We report here the first record of this species from the waters of the Ionian Sea.

Download Full-text

Dynamical Diagnosis: A Comparison of Quasigeostrophy and Ertel Potential Vorticity

Meteorological Monographs ◽

10.1175/0065-9401-33.55.183 ◽

2008 ◽

Vol 55 ◽

pp. 183-202 ◽

Cited By ~ 2

Author(s):

John W. Nielsen-Gammon ◽

David A. Gold

Keyword(s):

Potential Vorticity ◽

Vertical Motion ◽

Geostrophic Wind ◽

Diagnostic Techniques ◽

Ensemble Forecasting ◽

Model Resolution ◽

The West ◽

Definition Of ◽

Improved Model ◽

The Right

Abstract Advances in computer power, new forecasting challenges, and new diagnostic techniques have brought about changes in the way atmospheric development and vertical motion are diagnosed in an operational setting. Many of these changes, such as improved model skill, model resolution, and ensemble forecasting, have arguably been detrimental to the ability of forecasters to understand and respond to the evolving atmosphere. The use of nondivergent wind in place of geostrophic wind would be a step in the right direction, but the advantages of potential vorticity suggest that its widespread adoption as a diagnostic tool on the west side of the Atlantic is overdue. Ertel potential vorticity (PV), when scaled to be compatible with pseudopotential vorticity, is generally similar to pseudopotential vorticity, so forecasters accustomed to quasigeostrophic reasoning through the height tendency equation can transfer some of their intuition into the Ertel-PV framework. Indeed, many of the differences between pseudopotential vorticity and Ertel potential vorticity are consequences of the choice of definition of quasigeostrophic PV and are not fundamental to the quasigeostrophic system. Thus, at its core, PV thinking is consistent with commonly used quasigeostrophic diagnostic techniques.

Download Full-text

Marginal Sea Overflows and the Upper Ocean Interaction

Journal of Physical Oceanography ◽

10.1175/2008jpo3934.1 ◽

2009 ◽

Vol 39 (2) ◽

pp. 387-403 ◽

Cited By ~ 13

Author(s):

Shinichiro Kida ◽

Jiayan Yang ◽

James F. Price

Keyword(s):

Ocean Circulation ◽

Potential Vorticity ◽

Baroclinic Instability ◽

Upper Ocean ◽

Marginal Sea ◽

The Mediterranean ◽

The Difference ◽

Set Up ◽

Numerical Model Experiments ◽

Gyre Circulation

Abstract Marginal sea overflows and the overlying upper ocean are coupled in the vertical by two distinct mechanisms—by an interfacial mass flux from the upper ocean to the overflow layer that accompanies entrainment and by a divergent eddy flux associated with baroclinic instability. Because both mechanisms tend to be localized in space, the resulting upper ocean circulation can be characterized as a β plume for which the relevant background potential vorticity is set by the slope of the topography, that is, a topographic β plume. The entrainment-driven topographic β plume consists of a single gyre that is aligned along isobaths. The circulation is cyclonic within the upper ocean (water columns are stretched). The transport within one branch of the topographic β plume may exceed the entrainment flux by a factor of 2 or more. Overflows are likely to be baroclinically unstable, especially near the strait. This creates eddy variability in both the upper ocean and overflow layers and a flux of momentum and energy in the vertical. In the time mean, the eddies accompanying baroclinic instability set up a double-gyre circulation in the upper ocean, an eddy-driven topographic β plume. In regions where baroclinic instability is growing, the momentum flux from the overflow into the upper ocean acts as a drag on the overflow and causes the overflow to descend the slope at a steeper angle than what would arise from bottom friction alone. Numerical model experiments suggest that the Faroe Bank Channel overflow should be the most prominent example of an eddy-driven topographic β plume and that the resulting upper-layer transport should be comparable to that of the overflow. The overflow-layer eddies that accompany baroclinic instability are analogous to those observed in moored array data. In contrast, the upper layer of the Mediterranean overflow is likely to be dominated more by an entrainment-driven topographic β plume. The difference arises because entrainment occurs at a much shallower location for the Mediterranean case and the background potential vorticity gradient of the upper ocean is much larger.

Download Full-text

Reliability of Unmanned Aerial Vehicles for the groups size estimation of Grampus griseus (Cuvier, 1812) in the Gulf of Taranto (Northern Ionian Sea, Central-eastern Mediterranean Sea)

10.1109/metrosea52177.2021.9611613 ◽

2021 ◽

Author(s):

Roberto Crugliano ◽

Rosalia Maglietta ◽

Stefano Bellomo ◽

Roberto Carlucci ◽

Giulia Cipriano ◽

...

Keyword(s):

Unmanned Aerial Vehicles ◽

Mediterranean Sea ◽

Eastern Mediterranean ◽

Ionian Sea ◽

Size Estimation ◽

Eastern Mediterranean Sea ◽

Grampus Griseus ◽

Aerial Vehicles ◽

Central Eastern

Download Full-text

Assessment of cetacean–fishery interactions in the marine food web of the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea)

Reviews in Fish Biology and Fisheries ◽

10.1007/s11160-020-09623-x ◽

2020 ◽

Author(s):

Roberto Carlucci ◽

Francesca Capezzuto ◽

Giulia Cipriano ◽

Gianfranco D’Onghia ◽

Carmelo Fanizza ◽

...

Keyword(s):

Food Web ◽

Mediterranean Sea ◽

Positive Impact ◽

Ionian Sea ◽

Central Mediterranean ◽

Marine Food Web ◽

Selective Targeting ◽

Fishing Gears ◽

Central Mediterranean Sea ◽

By Catch

AbstractThe exploitation of fishery resources acts as a driving force on cetaceans both directly, by determining their fishing mortality or injury as by-catch species, and indirectly, through the lowering the availability of their prey. This competitive overlap between fishing and cetaceans often results in inadequate solutions so that in some cases there have been cases of intentional cetacean culling to maximize fishing production. A modelling approach applied to investigate the ecological roles of cetaceans in the food web could prove more effective to integrate ecological and fishing aspects and to provide suggestions for management. The comparative analysis carried out in the Gulf of Taranto (Northern Ionian Sea, Central Mediterranean Sea) showed that fishing exploitation provides impacts on the investigated food web greater than those due to cetacean predation. Trawling was estimated to be the most negatively impacting fishing gear considering the mortality rates and consumption flows. On the other hand, the striped dolphin was the main impact on the food web due to its highest consumption flows. Analysis showed a negative and non-selective impact on the exploited species due to the fishing gears, while the odontocetes proved to select their prey species and provide a positive impact in the assemblage. In particular, while the fishing gears are primarily size selective, targeting mostly large and economically valuable fish, the odontocetes seem to follow a co-evolution process with their prey, developing a specialization in their resources, providing control of the meso-consumers and ensuring a trophic stability in the ecosystem.

Download Full-text