Horizontal Ocean Circulation Forced by Deep-Water Formation. Part I: An Analytical Study

Crépon, Michel; Boukthir, Moncef; Barnier, Bernard; Aikman, Frank

doi:10.1175/1520-0485(1989)019<1781:hocfbd>2.0.co;2

Cited by 39 publications

(25 citation statements)

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“…Where there is no continental shelf, and just because of geostrophic adjustment, dense water tending to sink sucks AW that tends to flow cyclonically around the zone where this dense water is sinking, hence in particular between that zone and the coast/ slope. Because such a geostrophic adjustment, and hence the dense water sinking, have a time scale larger than one year (Crépon et al 1989), the largest surface densities at the beginning of a given winter are found offshore, which will be where convection will most likely occur. When the densification of AW is moderate, convection creates an intermediate water that then spreads over the denser waters as over a virtual shelf.…”

Section: Introductionmentioning

confidence: 93%

Levantine Intermediate Water characteristics: an astounding general misunderstanding!

Millot¹

2013

Sci. Mar.

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SUMMARY: Levantine Intermediate Water (LIW) is a warm salty water formed in one out of four main zones of dense water formation in the Mediterranean Sea. LIW spreads as a density current and first appears on a q-S diagram as a sharp peak that then smoothens out, often leading to the so-called "scorpion-tail" image with a q (S) maximum above (below) the expected core. Both maxima have always been considered, somewhat fuzzily (even by us), as LIW characteristics without having ever been analysed theoretically. We question neither the "scorpion-tail" image nor the "core-method" nor qualitative analyses of either LIW or other waters characterized by similar extrema. But data from the Strait of Gibraltar demonstrate that characterizing and/or delimiting LIW by these maxima gives LIW a much greater importance than it actually merits so all quantitative analyses of LIW musts be reconsidered. Calculations made as simple as possible to simulate a warm salty layer of intermediate water (IW) mixing with waters lying above and below suggest that these maxima i) can be understood only when all three waters are considered together, ii) can evolve in different ways, iii) generally tend to move from the core of the IW layer outwards, and hence iv) can neither characterize nor delimit the IW in any way. Actual simulations with more sophisticated parameterizations are obviously needed. In addition, we suggest that what has to date been called LIW in the western basin in fact represents all intermediate waters formed in all zones of dense water formation in the eastern basin, i.e. not only Levantine waters but also, in particular, Aegean/Cretan waters. To provide a logical counterpart to WIW (Western Intermediate Water), we therefore suggest that, from the Channel of Sicily downstream, LIW should be renamed Eastern Intermediate Water (EIW).Keywords: Mediterranean Sea, water mass, temperature, salinity, maximum, extremum. RESUMEN: Las características de LiW: un maLentendido asombroso. -El Agua Levantina Intermedia (LIW) es una masa de agua caliente y salada que se forma en el Mediterráneo Oriental. Se esparce como una corriente de densidad y aparece en un diagrama q-S como un pico pronunciado que se va suavizando, produciendo a menudo una imagen de "cola de escorpión" con un máximo de q (S) por encima (por debajo) del nivel esperado de su núcleo. Ambos máximos se han considerado siempre, de forma algo difusa, como características definidoras de LIW sin haber sido analizados nunca teóricamente. No cuestionamos aquí ni la imagen de "cola de escorpión" ni el "método del núcleo" ni los análisis cualitativos de LIW ni de otras masas de agua caracterizadas por extremos similares. Pero datos obtenidos en el Estrecho de Gibraltar demuestran que caracterizar y/o limitar LIW por estos máximos otorga a esta masa de agua una importancia mucho mayor que la que tiene en realidad, con lo cual todos los análisis cuantitativos de LIW hechos hasta ahora deben ser reconsiderados. Cálculos hechos de la forma más simple posible para simular una capa de...

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Section: Introductionmentioning

confidence: 93%

Levantine Intermediate Water characteristics: an astounding general misunderstanding!

Millot¹

2013

Sci. Mar.

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“…This cyclonic gyre has been attributed to geostrophic adjustment to winter deep-water formation (Crépon et al, 1989) and the influence of cyclonic wind stress curl (Herbaut et al, 1997). The DYFAMED site is located in the central Ligurian subbasin, where the water depth is 2350 m. Thanks to monthly CTD monitoring programme at this site, a steady increase of θ and S has been detected in the deep waters during (Marty and Chiaverini, 2010.…”

Section: K Schroeder Et Al: Long-term Monitoring Programme Of Hydromentioning

confidence: 98%

Long-term monitoring programme of the hydrological variability in the Mediterranean Sea: a first overview of the HYDROCHANGES network

Schröeder

Millot²,

Bengara³

et al. 2013

Ocean Sci.

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Abstract. The long-term monitoring of basic hydrological parameters (temperature and salinity), collected as time series with adequate temporal resolution (i.e. with a sampling interval allowing the resolution of all important timescales) in key places of the Mediterranean Sea (straits and channels, zones of dense water formation, deep parts of the basins), constitute a priority in the context of global changes. This led CIESM (The Mediterranean Science Commission) to support, since 2002, the HYDROCHANGES programme (www. ciesm.org/marine/programs/hydrochanges.htm), a network of autonomous conductivity, temperature, and depth (CTD) sensors, deployed on mainly short and easily manageable subsurface moorings, within the core of a certain water mass. The HYDROCHANGES strategy is twofold and develops on different scales. To get information about long-term changes of hydrological characteristics, long time series are needed.Published by Copernicus Publications on behalf of the European Geosciences Union. K. Schroeder et al.: Long-term monitoring programme of hydrological variabilityBut before these series are long enough they allow the detection of links between them at shorter timescales that may provide extremely valuable information about the functioning of the Mediterranean Sea. The aim of this paper is to present the history of the programme and the current set-up of the network (monitored sites, involved groups) as well as to provide for the first time an overview of all the time series collected under the HYDROCHANGES umbrella, discussing the results obtained thanks to the programme.

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“…During wintertime the NC is narrower (20-30 km) and deeper (200-400 m), and its mesoscale activity increases, generating meanders mostly with a 10-20 day periodicity (e.g., Albérola et al 1995) and, generally in January, intense mesoscale activity can reach from surface to bottom. This intensification is due to dense water formation in the subbasin (Crépon et al, 1982;1989). Then, from the NCrim and into the center of the subbasins vigorous horizontal motions, with speeds up to 0.5 m…”

Section: Introductionmentioning

confidence: 59%

“…For the presumed more baroclinic NC, the present observations compare to some extent with models on dipoles, which have near-zero phase speed due to their interaction with the sheared current deep below (Griffiths and Pearce, 1985;Crépon et al, 1989). As a result, a particular area may receive persistent vertical flux of material during the lifetime of a jet or mesoscale meander or eddy (we cannot distinguish between them from an ADCP-record).…”

Section: Details Of Variations At Time-scales Of Meanders Eddies Jetsmentioning

confidence: 99%

“…The detection principle is based on the collection of Cherenkov photons induced by relativistic charged particles, produced in neutrino interactions, using a 3D-array of about 900 Photo-Multiplier Tubes (PMTs) sensitive to single photo-electrons (Amram et al, 2002). Each PMT together with electronics is One of potential processes is the Northern Current (NC; Millot, 1999), which flows counter-clockwise along the boundary slopes of the Ligurian and Provençal subbasins and which is driven by buoyancy forces affected by rotation (Crépon et al, 1982;1989). It is a few tens of km wide and it shows a marked seasonal variability.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Acoustic and optical variations during rapid downward motion episodes in the deep north-western Mediterranean Sea

Haren

Taupier‐Letage

Aguilar

et al. 2011

Deep Sea Research Part I: Oceanographic Research Papers

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Horizontal Ocean Circulation Forced by Deep-Water Formation. Part I: An Analytical Study

Cited by 39 publications

References 0 publications

Levantine Intermediate Water characteristics: an astounding general misunderstanding!

Levantine Intermediate Water characteristics: an astounding general misunderstanding!

Long-term monitoring programme of the hydrological variability in the Mediterranean Sea: a first overview of the HYDROCHANGES network

Acoustic and optical variations during rapid downward motion episodes in the deep north-western Mediterranean Sea

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