The Italian Fixed-Point Observatory Network (IFON) integrates well-established coastal and ocean infrastructures (buoys, platforms, moorings, mast platforms, etc.), most of them providing real-time multidisciplinary monitoring for a number of marine and atmospheric variables. Here, we describe the network characteristics and then discuss an example of its operation during the cold spell of winter 2012. One of the goals of the Italian Flagship Project Ricerca Italiana per il mare (RITMARE) is to create a common, validated IFON database able to fulfil both public and private demands, including validation of remotely sensed data and numerical models, environmental planning and management, and time-series analysis of climate and oceanographic data.

A research program MAT, supported by the Italian Ministry of the Environment and Protection of the Territory, has been devoted to monitor for four years the environmental conditions of the northern Adriatic Sea, with the main aim to study the mucilage phenomenon. These phenomena dramatically increased since the late eighties. Meteorological conditions, circulation patterns and water column stratification can affect the development and spreading of mucilage. Starting from June 1999, a monthly monitoring along three transects located in the northern Adriatic was carried out for three years. CTD casts were performed from the Italian to the Croatian coast, with water column sampling for a subset of stations. Some unusual oceanographic situations, heating of the sea surface in May-June and domination of eastwards transport of freshened waters formed in the Po Delta area, were observed during the investigated period in the years with more intense mucilage events (2000 and 2002).

A physical and chemical dataset collected in the Jabuka (Pomo) depression area (middle Adriatic Sea) was analysed for seasonal and interannual changes in temperature, salinity, density, dissolved oxygen and nitrates. A historical dataset collected from 1980 to 1997 was extended with data from 15 oceanographic cruises conducted between 1998 and 2002 in the framework of the SINAPSI research program. The bottom water masses of the Jabuka pits are periodically renewed by Northern Adriatic Deep Water (NAdDW) at 1 to 3 yr intervals. During late winter-early spring, the new water eventually flows into the western pit and then into the central and eastern ones. During 1 yr of residence in the pits, bottom water nitrates increase 3-fold and dissolved oxygen decreases by 28% due to mineralisation processes. Some aspects of recently observed decadal climatic anomalies in the Northern Adriatic Sea, in particular the average winter sea surface warming, are revealed by the analysed dataset. Relationships were observed between these anomalies and the Eastern Mediterranean Transient (EMT), and from this (and other indirect indications) we infer that since 1999 the Adriatic Sea has re-emerged as a major source of Eastern Mediterranean Deep Water (EMDW). These findings confirm the worth of the mesoadriatic depressions as an easily accessible recording site of interannual oceanographic variations in the Adriatic basin.

A winter oceanographic field experiment provided an opportunity to examine the atmospheric marine conditions over the northern Adriatic. Mean February winds are from a northeasterly direction over most of the Adriatic and a more northerly direction along the western coast. Wind speeds are fastest in jets over the NE coast during bora events and weakest in the mid‐northwestern Adriatic. Diurnal air temperature cycles are smallest on the NE coast and largest in the midwestern Adriatic. The maximum sea‐air difference is +10°C on the eastern coast and near zero on the midwestern Adriatic. Boras are northeasterly (from) wind events that sweep off Croatia and Slovenia, bringing slightly colder and drier air over the northern Adriatic. The main bora season is December to March. Winter 2002–2003 was normal for bora events. Synoptic‐scale temporal variations are correlated over the northern Adriatic. Fastest Bora winds and highest wind stress over the northern Adriatic is concentrated in four topographically controlled jets. The strongest is the Senj Jet, while the Trieste Jet extends across the entire northern Adriatic. Between each two jets is a weak wind zone. The greatest mean net heat loss is in bora jets in the NE Adriatic, where it was −438 W m−2 and is weakest in the midwestern northern Adriatic, where it was near zero. Wind stress is concentrated over the NE half of Adriatic in four bora jets, while wind stress is weak in the NW Adriatic. There is significant variation in wind stress mean and standard deviation structure over the northern Adriatic with each bora event.

Mucilage events (formation of very large organic aggregates and gelatinous surface layers) have been documented several times during the past two centuries in the northern Adriatic Sea (NA), while their frequency has significantly increased since 1988. In this work, meteorological and oceanographic conditions in the NA during the period June 1999–July 2002 are described and their relation to the outbreak and fate of the mucilage phenomenon was investigated. Salinity and temperature data were collected during approximately monthly cruises along three transects in the NA. Relevant meteorological situations (air temperature, rainfall, wind) were selected from large-scale ECMWF analyses and from the Local Analysis and Prediction System (LAPS; Emilia Romagna Meteorological Service), while sea conditions (waves) were analysed by means of the Wave Adriatic Model (WAM). Data for air temperature, rainfall, and wind from several meteorological stations in the region were used. Average seasonal cycles of sea temperature and salinity simulated with statistical models, based on historical data collected in the NA since 1972, were used to determine thermal and haline anomalies. The monthly anomaly variability of maximum and minimum air temperatures, rainfall amount and number of rainy days did not appear to be relevant for the mucilage phenomenon outbreak. In contrast, both vertical and horizontal thermohaline gradients in the region were more developed during late spring and summer of 2000 and particularly of 2002, when the mucilage events were of greatest extent in space and time, compared to 2001 (short-lived event) and 1999 (no event). These more pronounced gradients were due to a combination of several unusual conditions: sharp heating of the sea surface in May–June, domination of eastwards transport of freshened waters formed in the Po Delta area, and intrusion of very high salinity intermediate waters originating in the eastern Mediterranean. Moreover, in winter of both 2000 and 2002 very dense and cold water formed and remained in the bottom layer until spring, contributing to increase the stratification degree of the water column. The duration of the mucilage events and their spatial distribution in the region depend strongly on meteorological changes. Recurrent anticyclonic conditions, characterized by low wind and calm sea, favour extended events in time (up 2 months in 2002). In contrast, highly perturbed weather, particularly due to strong “bora” wind, can be determined in sharp decay of the event (e.g. in July 2000).

The dramatic increase in the occurrence of massive mucilage events in the northern Adriatic (NA) since their recent conspicuous reappearance in the late 1980s prompted a study of circulation and horizontal fluxes. Three transects with equidistant stations (10 km) were thus monitored monthly between June 1999 and July 2002. The geostrophic method was used to compute currents across the three transects from the CTD data, and dynamic heights provided a picture of the horizontal surface circulation. Currentmeter data records were used to adjust the reference surface and to validate the results for the southernmost and deeper (up to 70 m) transect (Senigallia–Susak Island). Geostrophic currents allowed estimation of monthly water fluxes across the transect. Different circulation regimes in the NA were observed, which may have affected mucilage events. When mucilage was absent (1999) or reduced (2001) in the western sector, the Western Adriatic Current (WAC, carrying water out of the NA) was found to be active, whilst the WAC was very weak or reversed when massive mucilage events occurred (2000 and 2002). Opposite behaviour has been observed for the Istrian Coastal Counter-Current (ICCC, retaining freshwater water in the NA) which was more intense during or after massive mucilage events and did not appear when mucilage was absent. Both WAC weakening and ICCC strengthening indicate a longer residence time of riverine waters in the NA, which favours mucilage development. Conclusively, WAC and ICCC result as key elements in controlling massive mucilage phenomena in the NA.

The spatial and temporal distributions of different types of visible mucilaginous aggregates were investigated monthly by underwater video cameras in the northern Adriatic (NA) from June 1999 to July 2002.Small aggregates (floes, macroflocs and stringers) were observed in all seasons with higher values in autumn and winter. Larger aggregates (ribbons, cobwebs, clouds, and false bottoms) formed only during late-spring and summer, particularly in 2000 and 2002, when the seasonal thermohaline stratification was marked. In fact, the process of mucilage formation took place mainly in the upper water column, above the main pycnocline.The spatial distribution shows that higher concentrations of small aggregates occur in the more productive coastal waters. The larger aggregates form or accumulate mainly in coastal waters in the southern part of the NA and in the central part of the Po River delta-Rovinj transect, where a gyre greatly influences the aggregates distribution. The fronts between low salinity coastal waters and high salinity waters of southern origin play an important role for accumulation and aggregation of the mucilage during spring and summer. Most of the aggregates accumulate in correspondence with strong pycnoclines with differences in density anomaly of 2 kg m(-3) or higher. False bottoms formed in correspondence with strong haloclines (Delta S congruent to 2), while cobwebs and ribbons also occurred when the halocline was less marked (Delta S < 0.5). Meteorological conditions greatly influenced the aggregate formation. Calm weather and weak winds favour aggregation processes, while strong north-easterly winds, causing intense mixing, result in the dispersion of the mucilaginous aggregates, as occurred during the Bora event in July 2000. (c) 2005 Elsevier B.V. All rights reserved.

In the framework of the PRISMA 2 programme, an HF Coastal Dynamics Applications Radar (CoDAR) has been utilized starting in July 1997, in order to identify surface frontal structures characterizing the Italian coast of the Adriatic Sea and to study the surface circulation, which plays a fundamental role in heat and momentum transfer processes between coastal and offshore areas.Near-surface currents in the coastal area between Ancona and Senigallia derived from the shore-based HF radar have been mapped at weekly intervals at a resolution of 1.5 km over an a rea of approximately 30 x 30 km.Preliminary results show a southeastward (i.e. alongshore) coastal jet that extends its influence as far as 10 km from the coast; farther offshore a cyclonic eddy, with a diameter of 10-20 km typically occurs. This circulation can occasionally be reversed showing an anticyclonic eddy that forces a northward coastal current with a far less energetic signature.

Recent quasi-synoptic seasonal observations (May 1995-February 1996) carried out within the framework of the national programme PRISMA (Programma di Ricerca e Sperimentazione del Mare Adriatico) have significantly contributed to a better understanding of longitudinal water exchanges across four sections of the Adriatic Sea. The observations show the complex variability due to forcing mechanisms (i.e. the atmospheric forcing, the fresh-water buoyancy input and the inflow of warm and highly saline water originating in the Eastern Mediterranean Sea) and the natural seasonal variability, as an inherent component of the system. During winter, a homogeneous cold and dense water mass is formed in the northern shelf area (sigma (theta) congruent to 29.40 kg .m(-3)), while open-ocean deep convective movements lead to dense-water formation in the southern cyclonic gyre (sigma (theta) congruent to 29.18 kg .m(-3)). The Northern Adriatic dense water (NADW) flows southward along the western continental shelf. A part of NADW flows over the Pelagosa sill with a potential density of about 29.14 kg/m(3) however, without filling the deepest part of the Southern Adriatic basin. The latter fraction reaches the Otranto Strait at the shelf break and intrudes into the Northern Ionian Sea. The Adriatic deep water (ADW), formed through open-ocean convection in the Southern Adriatic Sea, flows over the sill of Otranto to form the main component of the Eastern Mediterranean deep water. The Adriatic Sea is defined on the yearly scale as a dilution basin; thus, an inflow of water from the Ionian Sea, saltier and warmer than the Adriatic waters, i.e. the Levantine intermediate water (LIW), occurs. The LIW enters the Otranto Strait and penetrates, diluted, towards the eastern portion of the Southern Adriatic Sea where it is entrained cyclonically in the gyre. A branch of modified LIW extends over the Pelagosa sill and intrudes into the northern shelf regions. The maximum northward flow of the LIW was observed during the autumn, probably compensating the fresh water buoyancy input in the north that had occurred mainly in spring and early autumn.

This paper describes the upper ocean thermal structure between New Zealand and the Ross Sea, and its evolution from the austral spring to summer 1994-95 on the basis of four high resolution XBT sections, and during the summer 1995-96 with two high resolution XBT sections. The area of investigation is almost completely (with the exception of the southernmost part) interested by the Antarctic Circumpolar Current (ACC). The main fronts (SubAntarctic Front, Polar Front and southern front) included in the ACC are individuated, and a new front, supposed to derive from a splitting of the SAF in a Northern SAF (NSAF) and a Southern SAF (SSAF), is identified. The NSAF is always located at the end of the Campbell Plateau, on the continental slope, and the SSAF is located around 58 °S, with the exception of the December 1994-January 1995 cruises. Going from spring to the end of the austral summer, the PF appears to retreat from north to south, while the southern front shows a stable position on the northern flanks of the Pacific-Antarctic and Southeast Indian Ridges. The thermal structure of the six sections reveals the presence of intense mesoscale dynamics, with cold nuclea of Antarctic Surface Water (AASW) detached from the PF and noticed up to 1000 km north of it.

A comprehensive historical hydrographic dataset for the overall Adriatic Sea basin is analyzed in order to define the open ocean seasonal climatology of the basin. The authors also define the regional climatological seasons computing the average monthly values of heat fluxes and heat storage from a variety of atmospheric datasets. The long term mean surface heat balance corresponds to a heat loss of 19-22 W m(-2). Thus, in steady state, the Adriatic should import about the same amount of heat from the northern Ionian Sea through the Otranto Channel. The freshwater balance of the Adriatic Sea is defined by computing the average monthly values of evaporation, precipitation, and river runoff, obtaining an annual average gain of 1.14 m. The distribution of heat marks the difference between eastern and western Adriatic areas, showing the winter heat losses in different parts of the basin.Climatological water masses are defined for three regions of the Adriatic: (i) the northern Adriatic where Seasonal variations in temperature penetrate to the bottom; deep water (NAdDW) with sigma(t) > 29.2 kg m(-3) is produced and salinity is greatly affected by river discharges; (ii) the middle Adriatic where a pool of modified NAdDW is stored during the summer season after being renewed in winter and modified Levantine Intermediate Water (MLIW) intrudes from the southern regions between spring and autumn; and (iii) the southern Adriatic where homogeneous water properties are found below 150 m (the local maximum depth of the seasonal thermocline) and a different deep water mass (SAdDW) is found with sigma(t) > 29.1 kg m(-3), T approximate to 13.5 degrees C, and S approximate to 38.6 psu. Due to river runoff waters, the surface layers of all three regions are freshened during the spring-summer seasons. The vertical distributions of dissolved oxygen vary quantitatively in the three regions showing a spring-summer subsurface maximum due to the balance between phytoplankton growth in the euphotic zone and low vertical mixing in the water column. This behavior can be reconciled with open ocean conditions except for the northernmost part of the Adriatic where well-mixed oxygen conditions prevail throughout the year.Large interannual anomalies of both temperature and salinity are found at the geographical center of the basin in surface and deep waters (100 m).

In the second part of the paper dedicated to the Adriatic Sea general circulation, the horizontal structure of the hydrographic parameters and dissolved oxygen fields is described on a seasonal timescale.Maps of temperature and salinity climatological fields reveal the enhanced seasonal variability of the Adriatic Sea, which at the surface is associated with the major dilution effects of river runoff.The density and derived dynamic height fields show for the first time the baroclinic geostrophic structure of the general circulation. Winter is dominated by compensation effects between temperature and salinity fronts along the western coastline. The resulting baroclinic circulation is weak and suggests the presence of barotropic current components not accessible by the dataset. Spring and summer seasons have the smallest spatial scales in the temperature and salinity fields and stronger subbasin-scale gyres and current systems, which have been classified in a schematic representation of the circulation. The Adriatic Sea general circulation comprises boundary currents and jets that strengthen and change spatial scales in different seasons. Two separate Cyclonic gyres clearly exist in the middle and southern Adriatic except during winter.The rates of formation of the northern Adriatic deep waters and southern Adriatic deep waters are estimated to be 0.07 and 0.36 Sv (Sv = 10(6) m(3) s(-1)), respectively. Likely driving mechanisms of the circulation are discussed.

The Adriatic basin-wide circulation and its temporal variability are reviewed on the basis of results from the analysis of hydrographic data collected during four POEM cruises. Major well known features in the circulation are revealed in the data set which covers the period from October 1985 to April 1987. A prominent signal associated with the seasonal variability is identified in the water outflowing along the Italian coast. Differences between autumn and spring in the vein of cold and fresh water flowing along the Italian shelf manifest mainly in the temperature field. During the stratified season the fresh water spreads over the entire surface layer of the southern Adriatic. On the other hand, during spring, when the sea is vertically homogeneous, the fresh water remains confined to the surface longshore boundary layer over the entire length of the Italian coast. Layers below the seasonal thermocline at the eastern portion of the sea display very weak seasonal signals. A strong signal associated with the inter-annual variations also has been documented from the analysed data set; it mainly appears in the salinity field. It is shown that in spring 1986, the salinity averaged over the entire water column north of the Palagruza Sill is lower by 0.3 psu than in spring 1987. A similar, but less prominent difference is noted in the southern Adriatic. An attempt is made to associate these differences with variations in climatic conditions over the area, the river runoff and the Mediterranean water inflow.

The analysis of the first mesoscale experiment in the middle Adriatic Sea reveals the horizontal and vertical scale of the eddy field. The mesoscale variability is characterized by 10–20 km in diameter eddies. They are lower thermocline intensified, and the velocities in the upper and lower thermocline levels range from 10 to 1 cm s−1, respectively. The eddies are small because of the local Rossby radius deformation (5.4 and 2.8 km for the first and second internal baroclinic mode, respectively) and because they are second baroclinic mode intensified. The Levantine Intermediate Water is found in tongue-like features intruding between the intense eddy field.

A novel description of the phenomenology of the Eastern Mediterranean is presented based upon a comprehensive pooled hydrographic data base collected during 1985–1987 and analyzed by cooperating scientists from several institutions and nations (the POEM project). Related dynamical process and modeling studies are also overviewed. The circulation and its variabilities consist of three predominant and interacting scales: basin scale, subbasin scale, and mesoscale. Highly resolved and unbiased maps of the basin wide circulation in the thermocline layer are presented which provide a new depiction of the main thermocline general circulation, composed of subbasin scale gyres interconnected by intense jets and meandering currents. Semipermanent features exist but important subbasin scale variabilities also occur on many time scales. Mesoscale variabilities modulate the subbasin scale and small mesoscale eddies populate the open sea, especially the south-eastern Levantine basin. Clear evidence indicates Levantine Intermediate Water (LIW) to be present over most of the Levantine Basin, implying that formation of LIW is not localized but rather is ubiquitous. The Ionian and Levantine basins are confirmed to form one deep thermohaline cell with deep water of Adriatic origin and to have a turnover time of one and a quarter centuries. Prognostic, inverse, box and data assimilative modeling results are presented based on both climatological and POEM data. The subbasin scale elements of the general circulation are stable and robust to the dynamical adjustment process. These findings bear importantly on a broad range of problems in ocean science and marine technology that depend upon knowledge of the general circulation and water mass structure, including biogeochemical fluxes, regional climate, coastal interactions, pollution and environmental management. Of global ocean scientific significance are the fundamental processes of water mass formations, transformations and dispersion which occur in the basin.

The POEM group, 1992 General circulation of the Eastern Mediterranean Sea Earth-Sct Ret', 32 285 308 A novel description of the phenomenology of the Eastern Me&terranean is presented based upon a comprehensive pooled hydrographic data base collected during 1985-1987 and analyzed by cooperating scientists from several restitutions and nations (the POEM project) Related dynamical process and modehng studies are also overvlewed The circulation and ~ts vanablhtles consist of three predominant and interacting scales basra scale, subbasm scale, and mesoscale Highly resolved and unbiased maps of the basra wide circulation m the thermochne layer are presented which provide a new deplct~on of the main thermochne general circulation, composed of subbasln scale gyres interconnected by intense jets and meandering currents Semipermanent features exist but ~mportant subbasm scale var~ablhtles also occur on many t~me scales Mesoscale vanablhtles modulate the subbasm scale and small mesoscale eddies populate the open sea, especially the south-eastern Levantine basra. Clear ewdence indicates Levantine )ntermedmte Water (LIW) to be present over most of the