Search

In March 2020, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. At the genus rank, 20 new genera were added, two were deleted, one was moved, and three were renamed. At the species rank, 160 species were added, four were deleted, ten were moved and renamed, and 30 species were renamed. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.

Employed for over a century, the traditional way of monitoring sea level variability by tide gauges – in combination with modern observational techniques like satellite altimetry – is an inevitable ingredient in sea level studies over the climate scales and in coastal seas. The development of the instrumentation, remote data acquisition, processing, and archiving in the last decades has allowed the extension of the applications to a variety of users and coastal hazard managers. The Mediterranean and Black seas are examples of such a transition – while having a long tradition of sea level observations with several records spanning over a century, the number of modern tide gauge stations is growing rapidly, with data available both in real time and as a research product at different time resolutions. As no comprehensive survey of the tide gauge networks has been carried out recently in these basins, the aim of this paper is to map the existing coastal sea level monitoring infrastructures and the respective data availability. The survey encompasses a description of major monitoring networks in the Mediterranean and Black seas and their characteristics, including the type of sea level sensors, measuring resolutions, data availability, and existence of ancillary measurements, altogether collecting information about 240 presently operational tide gauge stations. The availability of the Mediterranean and Black seas sea level data in the global and European sea level repositories has been also screened and classified following their sampling interval and level of quality check, pointing to the necessity of harmonization of the data available with different metadata and series in different repositories. Finally, an assessment of the networks' capabilities for their use in different sea level applications has been done, with recommendations that might mitigate the bottlenecks and ensure further development of the networks in a coordinated way, a critical need in the era of hu

A detailed study of phytoplankton composition and dynamics was carried out during three contrasting situations (cruises F1, F2, and F3) in the northwestern (NW) Mediterranean Sea. Haptophytes, diatoms, and green algae dominated in F1, during the spring bloom, with high nutrients and high phytoplankton biomass. In F2, the post-bloom situation with a still weak stratification and lower nutrient concentrations, we found a high spatial variability. Stations were clearly dominated by either Synechococcus, haptophytes or cryptophytes; with Synechococcus reaching the highest abundance (4 × 105 cells mL−1, 60% of the integrated chlorophyll a) reported to date for the open Mediterranean Sea. Cryptophytes accumulated close to the surface in very shallow mixed layer stations. In late summer, F3 revealed a fully developed stratification with low nutrients and a marked deep chlorophyll maximum (DCM). Prochlorococcus was present only during this cruise, mainly in deep layers together with haptophytes and pelagophytes, while haptophytes and Synechococcus dominated the upper mixed layer. Flow cytometry (FCM) and pigment-based abundance estimates for Prochlorococcus, Synechococcus and cryptophytes were well correlated, as happened also between small picoeukaryotes (FCM) and green algae (pigments), and between large picoeukaryotes (FCM) and haptophytes (pigments). Dinoflagellate abundance by microscopy and by pigments did not agree well, probably due to the presence of heterotrophic forms or because they contained pigments other than peridinin, the standard dinoflagellate marker. The decrease in size of the FCM large picoeukaryotes group with depth was presumably related to the increasing contribution of pelagophytes, with smaller cells than haptophytes, the other main component of this fraction. Cell size increase of Prochlorococcus and Synechococcus with depth suggests vertical segregation of genotypes or photoadaptation. The groups' ecological preferences are presented with respec

In March 2020, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. At the genus rank, 20 new genera were added, two were deleted, one was moved, and three were renamed. At the species rank, 160 species were added, four were deleted, ten were moved and renamed, and 30 species were renamed. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.

In March 2020, following the annual International Committee on Taxonomy of Viruses (ICTV) ratification vote on newly proposed taxa, the phylum Negarnaviricota was amended and emended. At the genus rank, 20 new genera were added, two were deleted, one was moved, and three were renamed. At the species rank, 160 species were added, four were deleted, ten were moved and renamed, and 30 species were renamed. This article presents the updated taxonomy of Negarnaviricota as now accepted by the ICTV.

The RADMED project is devoted to the implementation and maintenance of a multidisciplinary monitoring system around the Spanish Mediterranean waters. This observing system is based on periodic multidisciplinary cruises covering the coastal waters, continental shelf and slope waters and some deep stations (>2000 m) from the Westernmost Alboran Sea to Barcelona in the Catalan Sea, including the Balearic Islands. This project was launched in 2007 unifying and extending some previous monitoring projects which had a more reduced geographical coverage. Some of the time series currently available extend from 1992, while the more recent ones were initiated in 2007. The present work updates the available time series up to 2015 (included) and shows the capability of these time series for two main purposes: the calculation of mean values for the properties of main water masses around the Spanish Mediterranean, and the study of the interannual and decadal variability of such properties. The data set provided by the RADMED project has been merged with historical data from the MEDAR/MEDATLAS data base for the calculation of temperature and salinity trends from 1900 to 2015. The analysis of these time series shows that the intermediate and deep layers of the Western Mediterranean have increased their temperature and salinity with an acceleration of the warming and salting trends from 1943. Trends for the heat absorbed by the water column for the 1943–2015 period, range between 0.2 and 0.6 W/m2 depending on the used methodology. The temperature and salinity trends for the same period and for the intermediate layer are 0.002 °C/yr and 0.001 yr−1 respectively. Deep layers warmed and increased their salinity at a rate of 0.004 °C/yr and 0.001 yr−1.

The RADMED project is devoted to the implementation and maintenance of a multidisciplinary monitoring system around the Spanish Mediterranean waters. This observing system is based on periodic multidisciplinary cruises covering the coastal waters, continental shelf and slope waters and some deep stations (>2000 m) from the Westernmost Alboran Sea to Barcelona in the Catalan Sea, including the Balearic Islands. This project was launched in 2007 unifying and extending some previous monitoring projects which had a more reduced geographical coverage. Some of the time series currently available extend from 1992, while the more recent ones were initiated in 2007. The present work updates the available time series up to 2015 (included) and shows the capability of these time series for two main purposes: the calculation of mean values for the properties of main water masses around the Spanish Mediterranean, and the study of the interannual and decadal variability of such properties. The data set provided by the RADMED project has been merged with historical data from the MEDAR/MEDATLAS data base for the calculation of temperature and salinity trends from 1900 to 2015. The analysis of these time series shows that the intermediate and deep layers of the Western Mediterranean have increased their temperature and salinity with an acceleration of the warming and salting trends from 1943. Trends for the heat absorbed by the water column for the 1943–2015 period, range between 0.2 and 0.6 W/m2 depending on the used methodology. The temperature and salinity trends for the same period and for the intermediate layer are 0.002 °C/yr and 0.001 yr−1 respectively. Deep layers warmed and increased their salinity at a rate of 0.004 °C/yr and 0.001 yr−1.

This paper presents a review of the state-of-the-art in understanding and quantification of the Mediterranean heat and mass (i.e. salt and water) budgets. The budgets are decomposed into a basin averaged surface component, lateral boundary components (through the Gibraltar and the Dardanelles Straits), a river input component and a content change component. An assessment of the different methods and observational products that have been used to quantify each of these components is presented. The values for the long term average of each component are also updated based on existing literature and a first estimate of heat fluxes associated with the riverine input has been produced. Special emphasis is put on the characterization of associated uncertainties and proposals for advancing current knowledge are presented for each budget component. With the present knowledge of the different components, the Mediterranean budgets can be closed within the range of uncertainty. However, the uncertainty range remains relatively high for several terms, particularly the basin averaged surface heat fluxes. Consequently, the basin averaged heat budget remains more strongly constrained by the Strait of Gibraltar heat transport than by the surface heat flux. It is worth remarking that if a short (∼few years) averaging period is used, then the heat content change must also be considered to constrain the heat budget. Concerning the water and salt fluxes, the highest uncertainties are found in the direct estimates of the Strait of Gibraltar water and salt transport. Therefore, the indirect estimate of those transports using the budget closure leads to smaller uncertainties than the estimates based on direct observations. Finally, estimates of Mediterranean heat and salt content trends are also reviewed. However, these cannot be improved through the indirect estimates due to the large temporal uncertainties associated to the surface fluxes and the fluxes through Gibraltar. The consequences

The RADMED project is devoted to the implementation and maintenance of a multidisciplinary monitoring system around the Spanish Mediterranean waters. This observing system is based on periodic multidisciplinary cruises covering the coastal waters, continental shelf and slope waters and some deep stations (>2000 m) from the Westernmost Alboran Sea to Barcelona in the Catalan Sea, including the Balearic Islands. This project was launched in 2007 unifying and extending some previous monitoring projects which had a more reduced geographical coverage. Some of the time series currently available extend from 1992, while the more recent ones were initiated in 2007. The present work updates the available time series up to 2015 (included) and shows the capability of these time series for two main purposes: the calculation of mean values for the properties of main water masses around the Spanish Mediterranean, and the study of the interannual and decadal variability of such properties. The data set provided by the RADMED project has been merged with historical data from the MEDAR/MEDATLAS data base for the calculation of temperature and salinity trends from 1900 to 2015. The analysis of these time series shows that the intermediate and deep layers of the Western Mediterranean have increased their temperature and salinity with an acceleration of the warming and salting trends from 1943. Trends for the heat absorbed by the water column for the 1943–2015 period, range between 0.2 and 0.6 W/m2 depending on the used methodology. The temperature and salinity trends for the same period and for the intermediate layer are 0.002 °C/yr and 0.001 yr−1 respectively. Deep layers warmed and increased their salinity at a rate of 0.004 °C/yr and 0.001 yr−1.

The RADMED project is devoted to the implementation and maintenance of a multidisciplinary monitoring system around the Spanish Mediterranean waters. This observing system is based on periodic multidisciplinary cruises covering the coastal waters, continental shelf and slope waters and some deep stations (>2000 m) from the Westernmost Alboran Sea to Barcelona in the Catalan Sea, including the Balearic Islands. This project was launched in 2007 unifying and extending some previous monitoring projects which had a more reduced geographical coverage. Some of the time series currently available extend from 1992, while the more recent ones were initiated in 2007. The present work updates the available time series up to 2015 (included) and shows the capability of these time series for two main purposes: the calculation of mean values for the properties of main water masses around the Spanish Mediterranean, and the study of the interannual and decadal variability of such properties. The data set provided by the RADMED project has been merged with historical data from the MEDAR/MEDATLAS data base for the calculation of temperature and salinity trends from 1900 to 2015. The analysis of these time series shows that the intermediate and deep layers of the Western Mediterranean have increased their temperature and salinity with an acceleration of the warming and salting trends from 1943. Trends for the heat absorbed by the water column for the 1943–2015 period, range between 0.2 and 0.6 W/m2 depending on the used methodology. The temperature and salinity trends for the same period and for the intermediate layer are 0.002 °C/yr and 0.001 yr−1 respectively. Deep layers warmed and increased their salinity at a rate of 0.004 °C/yr and 0.001 yr−1.

Marine biogeochemistry dynamics in coastal marine areas is strongly influenced by episodic events such as rain, intense winds, river discharges and anthropogenic activities. We evaluated in this study the importance of these forcing events on modulating seasonal changes in the marine biogeochemistry of the northwestern coast of the Mediterranean Sea, based on data gathered from a fixed coastal sampling station in the area. A 4-year (2011–2014) monthly sampling at four depths (0.5 m, 20 m, 50 m and 80 m) was performed to examine the time variability of several oceanographic variables: seawater temperature, salinity, inorganic nutrient concentrations (NO3−, PO43 − and SiO2), chlorophyll a (Chl a), dissolved organic carbon (DOC) and fluorescent dissolved organic matter (FDOM). FDOM dynamics was predominantly influenced by upwelling events and mixing processes, driven by strong and characteristic wind episodes. SW wind episodes favored the upwelling of deeper and denser waters into the shallower shelf, providing a surplus of autochthonous humic-like material and inorganic nutrients, whereas northerlies favored the homogenization of the whole shelf water column by cooling and evaporation. These different wind-induced processes (deep water intrusion or mixing), reported along the four sampled years, determined a high interannual environmental variability in comparison with other Mediterranean sampling sites.

This paper presents a review of the state-of-the-art in understanding and quantification of the Mediterranean heat and mass (i.e. salt and water) budgets. The budgets are decomposed into a basin averaged surface component, lateral boundary components (through the Gibraltar and the Dardanelles Straits), a river input component and a content change component. An assessment of the different methods and observational products that have been used to quantify each of these components is presented. The values for the long term average of each component are also updated based on existing literature and a first estimate of heat fluxes associated with the riverine input has been produced. Special emphasis is put on the characterization of associated uncertainties and proposals for advancing current knowledge are presented for each budget component. With the present knowledge of the different components, the Mediterranean budgets can be closed within the range of uncertainty. However, the uncertainty range remains relatively high for several terms, particularly the basin averaged surface heat fluxes. Consequently, the basin averaged heat budget remains more strongly constrained by the Strait of Gibraltar heat transport than by the surface heat flux. It is worth remarking that if a short (∼few years) averaging period is used, then the heat content change must also be considered to constrain the heat budget. Concerning the water and salt fluxes, the highest uncertainties are found in the direct estimates of the Strait of Gibraltar water and salt transport. Therefore, the indirect estimate of those transports using the budget closure leads to smaller uncertainties than the estimates based on direct observations. Finally, estimates of Mediterranean heat and salt content trends are also reviewed. However, these cannot be improved through the indirect estimates due to the large temporal uncertainties associated to the surface fluxes and the fluxes through Gibraltar. The consequences

Surface waters are an attractive foraging ground for small fish in the open ocean. This study aims to determine the importance of vertically migrating species in the neuston of oceanic waters across the Atlantic, Indian and Pacific Oceans and to ascertain the influence of environmental variables on their distribution patterns. Neustonic fish assemblages were primarily controlled by light. They were dominated by late-larvae and juveniles of Exocoetidae, Hemiramphidae and Scomberesocidae during the day. At night, the vertical migration of mesopelagic species changed the dominance pattern in favour of Myctophidae and Scomberesocidae. The neustonic families’ distribution was primarily related to sea surface temperatures, whereas environmental variables at deeper layers were related to mesopelagic migrating families. Canonical correspondence analysis showed a low but statistically significant contribution of several environmental variables to myctophid species composition (10%), with minimum oxygen concentrations ranking first in variance explanation followed by maximum fluorescence, sea surface temperature and 400-m temperature. Spatial autocorrelation also explained 17% of the variance, indicating the influence of other factors such as historical, demographic and dispersal constraints. The low number of myctophid species in the North Pacific Equatorial Countercurrent appears to be related to the low oxygen concentrations observed in this province.

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. But 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.

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. But 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.

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. But 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.

The paper is based on larval distribution data from five lanternfish species outside the spawning grounds of the adult populations. Using hydrographic information collected with the larvae, the effect of surface currents on the observed patterns of distribution is discussed. In the South-East Atlantic, adjacent to the Benguela upwelling system, larvae of the pseudoceanic Lampanyctodes hectoris were found farther offshore (250 – 450 km) than usual. The general flow of the current is parallel to the coast, but upwelling filaments extend offshore. The size distributions of the L. hectoris larvae found, together with the rather low temperature at two of the oceanic stations sampled, indicate that they had been displaced by a filament. In the South-West Indian Ocean, the distribution of larvae of highly oceanic species of lanternfish over the shelf is related to onshore intrusions of the Agulhas Current. The size distributions of Hygophum hygomii and Scopelopsis multipunctatus indicate southward transport of larvae. The presence of larvae of Myctophum selenops and Benthosema pterotum, which have not been documented as adults in the region, indicates not only transport to the area, but also that spawning could be taking place closer to the area than previously reported.

The paper is based on larval distribution data from five lanternfish species outside the spawning grounds of the adult populations. Using hydrographic information collected with the larvae, the effect of surface currents on the observed patterns of distribution is discussed. In the South-East Atlantic, adjacent to the Benguela upwelling system, larvae of the pseudoceanic Lampanyctodes hectoris were found farther offshore (250 – 450 km) than usual. The general flow of the current is parallel to the coast, but upwelling filaments extend offshore. The size distributions of the L. hectoris larvae found, together with the rather low temperature at two of the oceanic stations sampled, indicate that they had been displaced by a filament. In the South-West Indian Ocean, the distribution of larvae of highly oceanic species of lanternfish over the shelf is related to onshore intrusions of the Agulhas Current. The size distributions of Hygophum hygomii and Scopelopsis multipunctatus indicate southward transport of larvae. The presence of larvae of Myctophum selenops and Benthosema pterotum, which have not been documented as adults in the region, indicates not only transport to the area, but also that spawning could be taking place closer to the area than previously reported.

The Liguro-Provencal-Catalan current, associated with a permanent shelf/slope front, terminates near the Eivissa channel, in the southern part of the Catalan Sea. Also in this region, the North Balearic front is formed, associated with lighter waters of recent Atlantic origin. In May-June 1991, the oceanographic cruise FE'91 was carried out covering the region with CTD casts. The results of water mass analysis and geostrophic circulation are presented in this paper, and the interaction between the Catalan and North Balearic currents is described and discussed.

The present paper describes the major results obtained from 1989 to 1992 by the EUROMODEL group in studying the circulation in the Western Mediterranean Sea. Particular emphasis has been given to the physical processes responsible for seasonal and mesoscale variabilities. Observations (in situ and satellite), together with theoretical, physical and numerical models, have been widely used in the course of these studies. Attention has been focused on the dynamics of the northern basin (deep water formation, dynamics of the Northern Mediterranean Current, circulation and shelf/slope interaction in the Balearic Sea) and of the southern basin (Alboran Sea circulation, instabilities of the Algerian Current). The straits dynamics have been studied with particular reference to the Corsica channel. Preliminary runs of a basin-scale circulation model of the Western Mediterranean Sea forced by the straits are also presented. They are shown to be capable of generating a cyclonic circulation in the western basin.

The Liguro-Provencal-Catalan current, associated with a permanent shelf/slope front, terminates near the Eivissa channel, in the southern part of the Catalan Sea. Also in this region, the North Balearic front is formed, associated with lighter waters of recent Atlantic origin. In May-June 1991, the oceanographic cruise FE'91 was carried out covering the region with CTD casts. The results of water mass analysis and geostrophic circulation are presented in this paper, and the interaction between the Catalan and North Balearic currents is described and discussed.

The present paper describes the major results obtained from 1989 to 1992 by the EUROMODEL group in studying the circulation in the Western Mediterranean Sea. Particular emphasis has been given to the physical processes responsible for seasonal and mesoscale variabilities. Observations (in situ and satellite), together with theoretical, physical and numerical models, have been widely used in the course of these studies. Attention has been focused on the dynamics of the northern basin (deep water formation, dynamics of the Northern Mediterranean Current, circulation and shelf/slope interaction in the Balearic Sea) and of the southern basin (Alboran Sea circulation, instabilities of the Algerian Current). The straits dynamics have been studied with particular reference to the Corsica channel. Preliminary runs of a basin-scale circulation model of the Western Mediterranean Sea forced by the straits are also presented. They are shown to be capable of generating a cyclonic circulation in the western basin.

The present paper describes the major results obtained from 1989 to 1992 by the EUROMODEL group in studying the circulation in the Western Mediterranean Sea. Particular emphasis has been given to the physical processes responsible for seasonal and mesoscale variabilities. Observations (in situ and satellite), together with theoretical, physical and numerical models, have been widely used in the course of these studies. Attention has been focused on the dynamics of the northern basin (deep water formation, dynamics of the Northern Mediterranean Current, circulation and shelf/slope interaction in the Balearic Sea) and of the southern basin (Alboran Sea circulation, instabilities of the Algerian Current). The straits dynamics have been studied with particular reference to the Corsica channel. Preliminary runs of a basin-scale circulation model of the Western Mediterranean Sea forced by the straits are also presented. They are shown to be capable of generating a cyclonic circulation in the western basin.

The Liguro-Provencal-Catalan current, associated with a permanent shelf/slope front, terminates near the Eivissa channel, in the southern part of the Catalan Sea. Also in this region, the North Balearic front is formed, associated with lighter waters of recent Atlantic origin. In May-June 1991, the oceanographic cruise FE'91 was carried out covering the region with CTD casts. The results of water mass analysis and geostrophic circulation are presented in this paper, and the interaction between the Catalan and North Balearic currents is described and discussed.

The Liguro-Provencal-Catalan current, associated with a permanent shelf/slope front, terminates near the Eivissa channel, in the southern part of the Catalan Sea. Also in this region, the North Balearic front is formed, associated with lighter waters of recent Atlantic origin. In May-June 1991, the oceanographic cruise FE'91 was carried out covering the region with CTD casts. The results of water mass analysis and geostrophic circulation are presented in this paper, and the interaction between the Catalan and North Balearic currents is described and discussed.

The present paper describes the major results obtained from 1989 to 1992 by the EUROMODEL group in studying the circulation in the Western Mediterranean Sea. Particular emphasis has been given to the physical processes responsible for seasonal and mesoscale variabilities. Observations (in situ and satellite), together with theoretical, physical and numerical models, have been widely used in the course of these studies. Attention has been focused on the dynamics of the northern basin (deep water formation, dynamics of the Northern Mediterranean Current, circulation and shelf/slope interaction in the Balearic Sea) and of the southern basin (Alboran Sea circulation, instabilities of the Algerian Current). The straits dynamics have been studied with particular reference to the Corsica channel. Preliminary runs of a basin-scale circulation model of the Western Mediterranean Sea forced by the straits are also presented. They are shown to be capable of generating a cyclonic circulation in the western basin.

Through the analysis of hydrographic data collected during 16 cruises (1975-1985), we identify and describe the seasonal characteristics and the permanent features of the circulation in the Catalan Sea (north-western Mediterranean). Two fronts follow the continental shelf break on the peninsular and Balearic sides, separating the central dense waters from the surrounding lighter waters of Atlantic and continental origins. One is mainly produced by strong salinity gradients (Catalan front) and the other by temperature gradients (Balearic front). Two currents are associated with these fronts: the southwest Catalan current and the northeast Balearic current. Strong vertical mesoscale motions have been observed on several occasions in the weakly stratified central area. An interpretation of these mesoscale phenomena is proposed in terms of cyclonic eddies generated by some kind of instability mechanism in the two frontal systems.

Through the analysis of hydrographic data collected during 16 cruises (1975-1985), we identify and describe the seasonal characteristics and the permanent features of the circulation in the Catalan Sea (north-western Mediterranean). Two fronts follow the continental shelf break on the peninsular and Balearic sides, separating the central dense waters from the surrounding lighter waters of Atlantic and continental origins. One is mainly produced by strong salinity gradients (Catalan front) and the other by temperature gradients (Balearic front). Two currents are associated with these fronts: the southwest Catalan current and the northeast Balearic current. Strong vertical mesoscale motions have been observed on several occasions in the weakly stratified central area. An interpretation of these mesoscale phenomena is proposed in terms of cyclonic eddies generated by some kind of instability mechanism in the two frontal systems.

Through the analysis of hydrographic data collected during 16 cruises (1975-1985), we identify and describe the seasonal characteristics and the permanent features of the circulation in the Catalan Sea (north-western Mediterranean). Two fronts follow the continental shelf break on the peninsular and Balearic sides, separating the central dense waters from the surrounding lighter waters of Atlantic and continental origins. One is mainly produced by strong salinity gradients (Catalan front) and the other by temperature gradients (Balearic front). Two currents are associated with these fronts: the southwest Catalan current and the northeast Balearic current. Strong vertical mesoscale motions have been observed on several occasions in the weakly stratified central area. An interpretation of these mesoscale phenomena is proposed in terms of cyclonic eddies generated by some kind of instability mechanism in the two frontal systems.

Through the analysis of hydrographic data collected during 16 cruises (1975-1985), we identify and describe the seasonal characteristics and the permanent features of the circulation in the Catalan Sea (north-western Mediterranean). Two fronts follow the continental shelf break on the peninsular and Balearic sides, separating the central dense waters from the surrounding lighter waters of Atlantic and continental origins. One is mainly produced by strong salinity gradients (Catalan front) and the other by temperature gradients (Balearic front). Two currents are associated with these fronts: the southwest Catalan current and the northeast Balearic current. Strong vertical mesoscale motions have been observed on several occasions in the weakly stratified central area. An interpretation of these mesoscale phenomena is proposed in terms of cyclonic eddies generated by some kind of instability mechanism in the two frontal systems.