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The Mediterranean Sea is a prominent climate-change hot spot, with many socioeconomically vital coastal areas being the most vulnerable targets for maritime safety, diverse met-ocean hazards and marine pollution. Providing an unprecedented spatial and temporal resolution at wide coastal areas, high-frequency radars (HFRs) have been steadily gaining recognition as an effective land-based remote sensing technology for continuous monitoring of the surface circulation, increasingly waves and occasionally winds. HFR measurements have boosted the thorough scientific knowledge of coastal processes, also fostering a broad range of applications, which has promoted their integration in coastal ocean observing systems worldwide, with more than half of the European sites located in the Mediterranean coastal areas. In this work, we present a review of existing HFR data multidisciplinary science-based applications in the Mediterranean Sea, primarily focused on meeting end-user and science-driven requirements, addressing regional challenges in three main topics: (i) maritime safety, (ii) extreme hazards and (iii) environmental transport process. Additionally, the HFR observing and monitoring regional capabilities in the Mediterranean coastal areas required to underpin the underlying science and the further development of applications are also analyzed. The outcome of this assessment has allowed us to provide a set of recommendations for future improvement prospects to maximize the contribution to extending science-based HFR products into societally relevant downstream services to support blue growth in the Mediterranean coastal areas, helping to meet the UN's Decade of Ocean Science for Sustainable Development and the EU's Green Deal goals., peer-reviewed

Due to the semi-enclosed nature of the Mediterranean Sea, natural disasters and anthropogenic activities impose stronger pressures on its coastal ecosystems than in any other sea of the world. With the aim of responding adequately to science priorities and societal challenges, littoral waters must be effectively monitored with high-frequency radar (HFR) systems. This land-based remote sensing technology can provide, in near-real time, fine-resolution maps of the surface circulation over broad coastal areas, along with reliable directional wave and wind information. The main goal of this work is to showcase the current status of the Mediterranean HFR network and the future roadmap for orchestrated actions. Ongoing collaborative efforts and recent progress of this regional alliance are not only described but also connected with other European initiatives and global frameworks, highlighting the advantages of this cost-effective instrument for the multi-parameter monitoring of the sea state. Coordinated endeavors between HFR operators from different multi-disciplinary institutions are mandatory to reach a mature stage at both national and regional levels, striving to do the following: (i) harmonize deployment and maintenance practices; (ii) standardize data, metadata, and quality control procedures; (iii) centralize data management, visualization, and access platforms; and (iv) develop practical applications of societal benefit that can be used for strategic planning and informed decision-making in the Mediterranean marine environment. Such fit-for-purpose applications can serve for search and rescue operations, safe vessel navigation, tracking of marine pollutants, the monitoring of extreme events, the investigation of transport processes, and the connectivity between offshore waters and coastal ecosystems. Finally, future prospects within the Mediterranean framework are discussed along with a wealth of socioeconomic, technical, and scientific challenges to be faced during the implementation of this integrated HFR regional network., This study has been partially developed in the framework of the Interreg MED Strategic Project SHAREMED, co-financed by the European Regional Development Fund under the funding program Interreg MED 2014–2020. Website: https://sharemed.interreg-med.eu/ (last access: 31 March 2022). We are also grateful for the partial support of the (i) the project PO FEAMP 2014/2020 (Misura 2.51) funded by Regione Campania (Italy), (ii) the 2017 PRIN project EMME (Exploring the fate of Mediterranean microplastic: from distribution pathways to biological effects) funded by the Italian Ministry for Research (grant agreement no. 2017WERYZP), and (iii) the CMEMS-INSTAC phase II, which provides the context of the activities for HFR data harmonization, standardization, and distribution. Collaborative discussion on data management harmonization at the European level has also been carried out thanks to the contribution of the projects INCREASE (CMEMS Service Evolution Call for Tenders 21-SE-CALL1) and SeaDataCloud (EU-H2020 GA no. 730960).

The Mediterranean Sea is a prominent climate change hot spot, being their socio-economically vital coastal areas the most vulnerable targets for maritime safety, diverse met-ocean hazards and marine pollution. Providing an unprecedented spatial and temporal resolution at wide coastal areas, High-frequency radars (HFRs) have been steadily gaining recognition as an effective land-based remote sensing technology for a continuous monitoring of the surface circulation, increasingly waves and occasionally winds. HFR measurements have boosted the thorough scientific knowledge of coastal processes, also fostering a broad range of applications, which has promoted their integration in the Coastal Ocean Observing Systems worldwide, with more than half of the European sites located in the Mediterranean coastal areas. In this work, we present a review of existing HFR data multidisciplinary science-based applications in the Mediterranean Sea, primarily focused on meeting end-users and science-driven requirements, addressing regional challenges in three main topics: i) maritime safety; ii) extreme hazards; iii) environmental transport process. Additionally, the HFR observing and monitoring regional capabilities in the Mediterranean region required to underpin the underlying science and the further development of applications are also analyzed. The outcome of this assessment has allowed us to finally provide a set of recommendations for the future improvement prospects to maximize the contribution in extending the science-based HFR products into societal relevant downstream services to support the blue growth in the Mediterranean coastal areas, helping to meet the UN’s Decade of Ocean Science for Sustainable Development and the EU’s Green Deal goals.

Blooms of invasive ctenophore Mnemiopsis leidyi can have massive consequences on fish stocks and marine food webs. The distribution, abundance and diet of this ctenophore were investigated in the northeastern (NE) Adriatic between 2016 and 2019. The abundance of M. leidyi was determined daily along the coast of Rovinj (Croatia), and its spatial distribution monitored by visual census from research vessels and by pelagic trawl during acoustic surveys in September of each year. Mesozooplankton samples were collected along the western coast of Istria by vertical tows from the bottom to the surface. Spatial distribution and abundance of anchovy ( Engraulis encrasicolus ) assemblages were determined by geo-referenced hydro-acoustic sampling using a scientific echosounder. Large swarms of M. leidyi covering several km 2 were regularly reported between July and November extending up to 25 NM from the western coast of the Istrian peninsula and reaching maximum offshore densities of 270 individuals per m 2 . The abundance of anchovy in the areas where M. leidyi was present evidently decreased. The content of M. leidyi ’s digestive tract and plankton samples consisted both mainly of cladocerans, copepods, pteropods, echinodermata and bivalvia larvae. Results indicate that M. leidyi may accumulate and increase its abundance in the stagnant and trophically rich areas of the northern Adriatic gyres, spreading to the surrounding larger areas with currents. We assume that M. leidyi presence correlates with a decrease in anchovy population due to competition for food (zooplankton). Our findings support the importance of implementing an international monitoring program throughout the Adriatic Sea and demonstrate the ability of current MEDIAS surveys to detect changes in the pelagic ecosystem throughout surveyed areas.

The paper investigates wintertime dynamics of the coastal northeastern Adriatic Sea, and is based on numerical modelling and in situ data collected through field campaigns executed during the winter and spring of 2015. The data have been collected by a variety of instruments and platforms (ADCPs, CTDs, glider, profiling float), and have been accompanied with a one-way coupled ALADIN/ROMS modelling effort. Research focus has been put on dense water formation (DWF), thermal changes and circulation, and water exchange between the coastal and open Adriatic. According to both observations and modelling results, dense waters are formed in the northeastern coastal Adriatic during cold bora outbreaks, even during milder-than-average winters (as was the winter of 2015). However, dense water formed in this coastal region has, due to lower salinities, lower densities than dense water formed at the open Adriatic. Since the sea is deeper in the coastal area than at the open Adriatic, dense waters from the open Adriatic occasionally enter the coastal area near the bottom of the connecting passages, while the surface flow is mostly outward from the coastal area. Median residence time of the coastal area is estimated to about 1–2 months, indicating that the coastal area may be relatively quickly renewed by the open Adriatic waters. The model significantly underestimates currents and transports in connecting channels, which may be a result of a too coarse resolution of atmospheric forcing, misrepresentation of bathymetry or absence of the air-sea feedback in the model. Obtained data represents a comprehensive marine dataset, pointing to a number of interesting phenomena to be investigated in the future.

The Meteo-Oceanographic automatic station was set with one minute measurement interval. A special algorithm in form of a database procedure is developed. It has input of real-time measured wind and sea currents. The purpose is to sets and unsets an alarm. The alarm is supposed to temporally stops construction works. Alarms are visible on a special web page, and notified with automatic e-mail messages.

A pool of less saline surface waters was observed in late June 2006 at the northern edge of the South Adriatic Pit (SAP). Three possible sources were considered: (1) Albanian rivers, (2) local Croatian rivers, or (3) relatively fresh West Adriatic Current (WAC) waters. Available CTD and ADCP data, together with satellite images, indicate that WAC waters are the most likely source. This requires an excursion of WAC water across the width of the Adriatic and is especially surprising as low winds and stable atmospheric conditions prevailed in mid/late June. However, quite strong NNW winds occurred during the first 12 days of June, with peak winds close to the western shore. These winds were the result of the translation of the Azorean high to the British Isles, producing strong pressure gradients over the Adriatic. The winds enhanced the WAC during early June 2006, preconditioning a cross-basin eddy circulation that appeared during the wind relaxation and calm conditions. As the unusually calm conditions persisted for more than two weeks, the WAC eddies and filaments grew freely and had enough time to reach middle east-Adriatic waters. Navy Coastal Ocean Model (NCOM) simulations, using high-resolution Adriatic bathymetry and realistic atmospheric forcing, show that such excursions are plausible and can occur when eddies and instabilities push WAC waters across the hyperbolic flow point separating the WAC and Eastern Adriatic Current near the Palagruža Sill. During the latter half of June 2006, NCOM simulations show that the hyperbolic point was particularly well formed as an anticyclonic WAC, a cyclonic SAP rim flow, an anticyclonic cell southeast of Lastovo Island, and a cyclonic cell over the centre of the Palagruža Sill all bordered on each other. A simplified channel model suggests that the presence of the escarpment is a critical factor for producing cross-basin exchange of the coastal current following the relaxation of strong winds with a cyclonic wind stress curl. However, the introduction of the Gargano Peninsula in the simulations was critical to the production of mesoscale eddies in the exchange flow, and such eddies qualitatively agree with the convoluted structures observed in satellite images.

An ocean surface currents forecasting system, based on a Self-Organizing Maps (SOM) neural network algorithm, high-frequency (HF) ocean radar measurements and numerical weather prediction (NWP) products, has been developed for a coastal area of the northern Adriatic and compared with operational ROMS-derived surface currents. The two systems differ significantly in architecture and algorithms, being based on either unsupervised learning techniques or ocean physics. To compare performance of the two methods, their forecasting skills were tested on independent datasets. The SOM-based forecasting system has a slightly better forecasting skill, especially during strong wind conditions, with potential for further improvement when data sets of higher quality and longer duration are used for training.

Unusual weather conditions over the southern Europe and the Mediterranean area in 2003 significantly impacted the oceanographic properties of the Adriatic Sea. To document these changes, both in the atmosphere and the sea, anomalies from the normal climate were calculated. The winter 2003 was extremely cold, whereas the spring/summer period was extremely warm. The air temperature in June was more than 3 standard deviations above the average. On the other hand, precipitation and river runoff were extremely low between February and August. The response of the sea was remarkable, especially in surface salinity during spring and summer, with values at least one standard deviation above the average. Analysis of thermohaline properties in the middle Adriatic showed the importance of two phenomena responsible for the occurrence of exceptionally high salinity: (1) enhanced inflow of saline Levantine Intermediate Water (LIW) in the Adriatic, and (2) extremely low precipitation and river runoff, accompanied with strong evaporation. Two large-scale atmospheric indices: NAOI (North Atlantic Oscillation Index) and MOI (Mediterranean Oscillation Index), although generally correlated to the Adriatic climate, failed to describe anomalies in 2003. The air pressure gradients used for the definition of both indices significantly decreased in 2003 due to the presence of the high pressure areas over most of Europe and the northern Atlantic, and were actually responsible for the observed anomalies above and in the Adriatic.

This paper encompasses the analyses of sea level data measured at four tide gauges situated in the city of Split, Croatia. Two old long-term stations comprise float-type instruments in stilling wells, with analog recording on a chart, while two modern stations were installed in 1999 and 2000, calculating sea level height from the measured sea and air pressure. Although analog recording devices with a drum may suffer from inaccuracy in timing and drum rotation speed, clock errors, and vertical pencil position, the largest errors in the data came from the digitizing process, which is subjected to the individual work of a technician. Although, the data collected with pressure systems are supposed to be more homogeneous and accurate, after several years of work, the sensors usually have a drift in time. This problem turned out to be accompanied with lower quality sensors being part of wider automatic measuring systems, whereas the station which has been specially designed for sea level measurements showed no drifts in four years of operating. Therefore, one should be careful in choosing measuring equipment between various manufacturers. In addition, the equipment should be regularly checked since the malfunction in global positioning system (GPS) clock resulted in time drift of sea level data of more than an hour.

The Bora wind field is characterised by strong vorticity and divergence. Several numerical experiments, in which an oceanographic model was forced with northeasterly winds having climatological alongshore variability, were performed in order to study the influence of spatial variability in the bora wind field on the surface currents in the northern Adriatic. Numerical model results showed that during bora episodes with lower speeds and fast offshore decay surface currents along transect Rovinj - Po River are predominantly in the downwind direction. On the other hand, during bora episodes with strong intensity and slow offshore decay, a cyclonic gyre due to the pronounced bora alongshore variability is formed in the northernmost part of the Adriatic Sea and the studied transect is influenced by the counter currents. Moreover, bora having a high speed and a short offshore range produces the same effect in the eastern part of the Rovinj - Po River transect as low-speed bora characterised by slow offshore decay. Eulerian current measurements performed in the northern Adriatic during bora episodes characterised by different synoptic conditions supported the numerical model findings. Surface currents during the bora episode of 8-11 February 1984 were directed downwind, whereas during the episode of 12-19 February 1984 they were directed upwind. The first episode was characterised by a deep bora layer with cyclonic activity over the western Mediterranean and Genoa Bay, whereas the second one was accompanied by temperature inversion and a southwesterly tropospheric wind above a shallow bora layer. According to the hydraulic theory developed by Smith(1985), an observed descent of isentropes during the second bora episode led to the stronger acceleration in the bora layer and its larger offshore extent. Different offshore bora decays during studied events were confirmed by a comparison of the wind data originating from the meteorological stations positioned on the opposite Adriatic coasts.

The north Adriatic circulation during two successive bora episodes was studied using single point current measurements and results of the Princeton Ocean Model (POM). Surface currents recorded at the gas field Ivana positioned in the central part of the northern Adriatic were directed downwind during the bora episode of 8-11 February 1984, whereas during the next bora period of 12-16 February 1984 they were directed upwind. The observed current reversal was reproduced in the numerical experiment controlled by air-sea fluxes and river inflows. Atmospheric forcing for the POM model was estimated from high resolution Mesoscale Model 5 (MM5) surface fields, while river discharges were introduced in the simulations as source terms of zero salinity in the continuity equation. The baseline experiment with realistic forcings, atmospheric and riverine, related the current reversal to displacements of the bora induced gyres. Sensitivity studies revealed a dominant role of the wind stress curl for the vorticity in the current field and showed the relevance of the changing wind divergence for the cross-shore circulation variability and accompanied current reversal. Additional numerical experiments emphasized even more the role of the spatial wind variability for the recorded flow and also stressed the importance of the model domain size for the numerical results., Površinsko strujanje u sjevernom Jadranu za vrijeme trajanja dvije uzastopne epizode bure analizirano je na temelju strujomjernih podatka i rezultata numeričkog modela Princeton Ocean Model (POM). Površinske struje zabilježene na plinskom polju Ivana smještenom u centralnom dijelu sjevernog Jadrana bile su u smjeru vjetra za vrijeme prve epizode bure od 8. do 11. veljače 1984., dok su za vrijeme slijedeće epizode bure od 12. do 16. veljače bile suprotnog smjera od vjetra. Zabilježeni obrat struje reproduciran je u numeričkom eksperimentu u kojem je oceanografski model kontroliran površinskom napetošću vjetra, protocima topline i riječnim dotocima. Atmosfersko prisilno djelovanje za POM model izračunato je na temelju prizemnih polja iz meteorološkog mod- ela Mesoscale Model 5 (MM5), dok je djelovanje sjevernojadranskih rijeka uvedeno u numeričke eksperimente kao izvor slatke vode u jednadžbi kontinuiteta. Rezultati osnovnog eksperimenta s realističnim prisilnim djelovanjima, atmosferskim i riječnim, povezali su obrat površinske struje naplinskom polju Ivana s pomacima burom induciranih vrtloga. Analize osjetljivosti numeričkih rezul -tata ukazale su na dominantnu ulogu rotora vjetra za vrtložnost u strujnom polju, dok je promjenjiva divergencija u polju vjetra utjecala na varijabilnost struja u smjeru okomitom na obalu te tako dovela do obrata površinske cirkulacije na poziciji plinskog polja Ivana. Dodatni numerički eksperimenti još su više naglasili važnost prostorne varijabilnosti vjetra za zabilježeni obrat struje, a također su pokazali i važnost veličine modelske domene za dobivene rezultate.

The paper presents a range of research carried out for the marine sciences using the GIS applications, which are documented scientific achievements of twenty years of Croatian-Polish cooperation in the field of geographic information systems. The resultant body of work includes, inter alia, scientific publications that are the effect of twenty international conferences organized in the framework of said cooperation efforts. The study included articles published in 1994 to 2013. An analysis of selected articles was done in accordance with the accepted range of topics in order to categorize and define the research extent. Among the distinguished six subject categories most of the articles were concerned with: marine policy strategy, marine engineering, marine biology, marine physics and some of them in marine fisheries and marine chemistry., Rad daje pregled obavljenih istraživanja u području znanosti o moru upotrebom GIS alata, nastalih tijekom 20-godišnje Hrvatsko-Poljske suradnje u području primjene zemljopisnih informacijskih sustava. Rezultirajući opus uključuje, između ostalog, znanstvene radove koji su izloženi na dvadeset međunarodnih skupova organiziranih u okviru gore spomenute suradnje. Ovdje je datpregled radova objavljenih u razdoblju od 1994. do 2013. godine. Odabrani radovi su klasificirani po prihvaćenim tematskim područjima, u sklopu kojih su kategorizirani i analizirani po temama. Većina se radova u sklopu šest prihvaćenih tematskih područja bavila: strategijom zaštite mora, pomorstvom, biologijom, fizikom i kemijom mora te ribarstvenom problematikom.

[1] A network of high-frequency (HF) radars was installed in the northern Adriatic in the second half of 2007, aimed to measure surface currents in the framework of the North Adriatic Surface Current Mapping (NASCUM) project. This study includes a detailed analysis of current measurements from February to August 2008, a period in which three radars were simultaneously operational. Current patterns and temporal evolutions of different physical processes were extracted by using self-organizing map (SOM) analysis. The analysis focused on subtidal frequency band and extracted 12 different circulation patterns on a 4 × 3 rectangular SOM grid. The SOM was also applied on a joint data set that included contemporaneous surface wind data obtained from the operational hydrostatic mesoscale meteorological model ALADIN/HR. The strongest currents were recorded during energetic bora episodes, being recognized by several current patterns and having the characteristic downwind flow with magnitudes exceeding 35 cm/s at some grid points. Another characteristic wind, the sirocco, was represented by three current patterns, while the remaining current structures were attributed to weak winds and the residual thermohaline circulation. A strong resemblance has been found between SOM patterns extracted from HF radar data only and from combined HF radar and wind data sets, revealing the predominant wind influence to the surface circulation structures and their temporal changes in the northern Adriatic. These results show the SOM analysis being a valuable tool for extracting characteristic surface current patterns and forcing functions.

[1] Diurnal coastal upwelling was previously observed when sea breezes were exceptionally strong, or when the process occurred close to critical latitudes (30°N, 30°S) where local inertial oscillations may be resonantly excited. Our data collected in the Adriatic show that the pronounced diurnal upwelling is also possible under milder wind-forcing and outside critical latitudes. It is found that the thermocline recorded in the summer of 2006 at the south coast of the island of Lastovo was subject to diurnal variability with a maximum range of about 30 m, and that the corresponding currents measured off the west coast of the island pointed to internal waves propagating around the island in a clockwise direction. We suggest that the summertime stratification occasionally promotes coastal waves that revolve daily around the island, creating the conditions needed for resonant excitation by sea breezes. Numerical modeling reveals that the 24-h waves are trapped around the island due to the influence of both the Coriolis force and bottom slope, and that the 12-h waves radiate away from the island. The biogeochemical data show that the diurnal upwelling may stimulate primary production in the area but may also adversely affect benthic organisms.

This paper documents the occurrence of strong fortnightly oscillations in the Adriatic Sea frequently observed in the current measurements. For that purpose, we analyzed half-decadal sea level series and long-term currents collected within different parts and layers of the Adriatic Sea. Harmonic analysis and band-pass filter with cutoff periods at 10 and 20 days have been applied to the series. The sea level Mf tide is found to be the only significant tidal constituent over periods between the diurnal and semi-annual ones, having no significant phase variations in the Adriatic Sea. Moreover, the currents on periods between 10 and 20 days could only partially be explained by atmospheric forcing. The fact that they are in-phase with the Mf tide gives a hint on a possible mechanism responsible for the generation of these oscillations. Additionally, these currents are usually strongly amplified during a weakly stratified season, indicating a baroclinic mechanism responsible for the multiplication of the fortnightly currents.

The paper overviews the performances of the HF radar network installed in the northern Adriatic Sea. The system architecture is designed to work in real-time and delayed modes, but the accent is given on the real-time data acquisition, processing, archiving and presenting on the web. Several minor and the major dropout of the system were reported in 2008, and the surface currents were available for 87% of the year. The measured data needs just several minutes after the measurements to appear on the web, which makes the system plausible for the rapid environmental assessment issues, such as oil spills, rescue missions and other.

[1] During the summertime bora episode of 22–25 June 1995, characterized by hazardous weather conditions with strong winds of over 20 m s−1, two satellite-tracked drifters were present in the Adriatic shelf area. One was on the open sea south of the Istrian Peninsula, while the other, which measured the surface current of 70 cm s−1, was tracked along the western coastal strip. An oceanographic model, forced by the outputs of mesoscale meteorological models and by river discharges, was applied to simulate drifter trajectories during the event. Process-oriented studies performed to determine governing forcings for the drifter movements in different areas of the Adriatic revealed that strong current along the western Adriatic coast resulted from a combined influence of the wind stress and the river discharges. The wind was responsible for the strong drifter movements, while the baroclinic current due to the coastal buoyancy fluxes prevented the drifter from moving close to the shore and from colliding with the coast. At the same time, drifter movements in the open sea resulted from the wind action solely. Differences in the alongshore and offshore vertical density profiles, primarily due to the river inflows, caused 3 times stronger currents in the coastal area as compared to the currents in the open sea. The proper formulation of the drag coefficient was crucial for the successful simulations of the drifter trajectories, as simulations with increased values of the drag coefficient reproduced well the effects of the sea surface roughness and atmospheric instability above the sea.

[1] Measurements performed in winter 2002/2003 and spring 2003 off the east Adriatic coast showed that the East Adriatic Current (EAC) peaked in January/February (as expected from previous findings) and again in May (not expected). The first maximum corresponded with the considerable cross-shore variability of seawater properties, the colder, fresher water prevailing close to the coast, the warmer, saltier water dominating the open sea. The second maximum coincided with the massive intrusion of warm, saline water from the south Adriatic. Meteorological and hydrologic forcing was anomalous over the measurement interval: during winter 2002/2003 the cooling and river outflows were strong, during spring 2003 the pronounced warming coincided with exceptional dryness. In order to interpret the two EAC maxima a simple numerical model reproducing response of the Adriatic-Mediterranean system to the wintertime forcing was developed. It was found that the first maximum could be related to the coastal freshwater input and offshore evaporation in the Adriatic area, and that the second maximum was probably due to the wintertime surface cooling of the Adriatic while warmer conditions prevailed above the Mediterranean. The resulting horizontal density gradients supported two different circulation systems, one within the Adriatic, the other between the Adriatic and east Mediterranean, and they differed not only in spatial but also in temporal scales, therefore supporting the occurrence of two distinctive EAC maxima.

Thermohaline properties in the east Adriatic coastal area were measured bi-weekly during the cold season of 2002/2003 and weekly in the warm season of 2003 at 14 stations. The collected data set has space and time coverage suitable for comparison with general thermohaline climatology of the region. Temporal salinity changes registered during the experiment show strong departures from the typical annual cycle in which salinity follows average surface water flux variability. Throughout the experiment, high salinity values were measured as a consequence of prolonged bora events in the cold period, and unusual spring-summer atmospheric conditions. Due to the anomalously long and strong heating season, corresponding surface temperatures were also higher than the long-term averages. Surface heat and water fluxes were calculated for the research period, and were compared with climatological values originating from meteorological stations in the ADRICOSM polygon., Tijekom razdoblja listopad 2002. – rujan 2003. u području istočne obale Jadranskog mora, unutar poligona Pelješac-Vis-Drvenik, kao dio projekta ADRICOSM (Integrirano upravljajnje obalnom zonom Jadranskoga mora), obavljena su vrlo intenzivna mjerenja termohalinih osobina vodenog stupca na 14 postaja. Tijekom zimskog razdoblja mjerilo se jednom u dva tjedna, a kasnije jednom tjedno. Dobra prostorno-vremenska pokrivenost podacima omogućila je usporedbu s klimatološkim vrijednostima. Pokazano je kako su promjene saliniteta u ovom razdoblju znatno odstupale od prosjeka. Tijekom istraživanja uočen je iznadprosječno visoki salinitet koji je bio posljedica jakih i dugotrajnih epizoda bure u hladnom dijelu godine te neuobičajenih atmosferskih uvjeta tijekom razdoblja proljeće-ljeto 2003. Kao posljedica neuobičajeno duge i intenzivne sezone grijanja temperatura mora također je bila iznadprosječna. Procesi na granici atmosfera-more također su pokazali znatna odstupanja od klimatoloških vrijednosti.

The VOS2 XBT track was established through the cooperation of ENEA and IOF during the ADRICOSM1 period on the Dubrovnik–Bari route, monthly in the cold season and biweekly in the warm season, and the acquired data were send to the ENEA2 database in near real time. The results presented in this work comprise a compilation of data collected from different sources in the framework of the ADRICOSM project in the South Adriatic region. XBT profiles were compared to oceanographic ship-based measurements from CTDs from the recent cruise. In addition, the recently observed phenomenon of increased productivity of South Adriatic open waters is described and related to deep convection in the region., U suradnji s ENEA-om, Institut za oceanografiju i ribarstvo je uspostavio mjerenja na transektu u južnom Jadranu koristeći prugu između Dubrovnika i Barija (tzv. VOS2 XBT profil) za vrijeme projekta ADRICOSM, i to mjesečno u hladnom periodu godine a dvomjesečno u toplom razdoblju. Prikupljeni podaci vertikalnih profila temperature mora su u realnom vremenu slani u bazu podataka u ENEA-i. U ovom radu se opisuju rezultati XBT mjerenja s mjerenjima iz ostalih izvora u okviru projekta ADRICOSM za područje južnog Jadrana. Nadalje, vertikalni XBT profili temperature su uspoređeni s nekim ranijim i recentnim podacima mjerenim CTD sondama ili prekretnim termometrima. Opisan je i fenomen povećane produktivnosti otvorenog južnog Jadrana, koji je primijećen u novije vrijeme, a povezan je s podizanjem južno-jadranske vode.

In the framework of the Croatian national oceanographic monitoring program an automatic meteo-ocean measuring system has been under development. It is expected to be an important improvement for monitoring and analyses of various physical processes in the Adriatic Sea. As a first phase in the development of the system, an automatic station (AMOS) was placed at Marjan Cape, Split. It enables acquisition, validation and archiving of data for eleven meteorological and oceanographic parameters in real time, as well as calculation of some derived parameters and their dissemination in graphic format over the Internet (http://www.izor.hr/eng/online). Most of the measured data have been compared with data obtained from the permanent meteorological station located at the top of Marjan hill, which is three kilometres away. Also, data from the AMOS station have been used by two high-resolution numerical models with the aim of achieving time-dependent spatial fields of oceanographic parameters in Kaštela Bay. The AMOS station was a part of the Integrated coastal zone management system in the Adriatic Sea (ADRICOSM) project, where its data were very useful for various analyses in the Pelješac-Vis-Drvenik area. Data analyses and numerical models results will be used for further improvements in the automatic monitoring system., U okviru hrvatskog nacionalnog programa neprekidnog praćenja stanja morskog okoliša razvija se automatski oceanografski mjerni sustav. Očekuje se da će mjerni sustav znatno doprinijeti poboljšanju praćenja i analize različitih fizikalnih procesa u Jadranskom moru jer će omogućavati mjerenja u svim vremenskim uvjetima. U sklopu prve faze razvijena je automatska mjerna postaja (AMOS) koja je postavljena na rtu poluotoka Marjan u Splitu. Ova postaja zajedno s ocenografskom bazom podataka Instituta (MEDAS) omogućava automatsko mjerenje, provjeru kvalitete i pohranu podataka jedanaest meteoroloških i oceanografskih parametara, izračun nekoliko izvedenih parametara, te njihov tablični i grafički prikaz u stvarnom vremenu preko Interneta (www.izor.hr/eng/online). Većina mjerenih podataka s postaje uspoređena je s podatcima stalne meteorološke postaje smještene na vrhu Marjana tri kilometra od postaje AMOS. Također, dva numerička hidrodinamička modela visoke rezlučivosti koriste podatke s AMOS postaje za izračun vremenski promjenjivih prostornih oceanografskih polja u Kaštelanskom zaljevu. Zbog kvalitete podataka AMOS postaja je uključena u projekt Integrirano upravljajnje obalnom zonom Jadranskoga mora (ADRICOSM) u sklopu kojega se mjerni podatci koriste za različite i vrlo korisne analize u području istraživanja Pelješac-Vis-Drvenik. Rezultati analiza podataka s AMOS postaje i rezultati numeričkih modela također će se koristiti u svrhu poboljšanja automatskog sustava praćenja stanja okoliša Jadranskoga mora.

The paper documents the occurrence of long-period internal Kelvin waves in Split Channel in spring 2002. The analyses were performed on thermohaline and current data measured at three moorings and one hydrographic section. The internal oscillation had a period of 5-6 days, being larger just after the generation which was probably excited by the alongshore Sirocco wind. The recorded current amplitude was up to 0.3 ms-1 in the surface layer, while the observed pycnocline displacement was 10-15 m. The oscillation was reproduced by one-dimensional two-layered model of a channel, imposing nodal lines at its entrances. Cross-shore properties of the oscillation, such as observed offshore decrease in pycnocline amplitude, are explained by the dynamics of an internal Kelvin wave propagating along channel boundaries, because the internal Rossby radius is smaller than the width of the channel. Conclusively, the observed oscillation probably represents the fundamental mode of internal waves trapped in the channel complex off Split.

Water exchange between a semiclosed bay and the adjacent sea, and its relation to atmospheric forcing is examined from a field experiment undertaken in the Bay of Kastela (Adriatic Sea, Yugoslavia). Four ‘Aanderaa’ RCM4 current meters were attached on a single mooring in a 45 m deep inlet of the Bay for about two months. Water samples were taken for phytoplankton and bacteria determination at several additional stations. Salinity, temperature measurements, and determinations of the Secchi-disc depth were also made. Samples were taken approximately each week during the current measurement period so as to resolve the synoptic time scale. In the first part of the current measurement period the water was stratified, while in the second part the entire water column became vertically mixed after a strong wind event. During stratified conditions kinetic energy was at a maximum in the intermediate layer, while during homogeneous conditions the kinetic energy was trapped mainly in the bottom layer. Vertical modal structure of the current field showed that during homogeneous conditions wind induced surface flow was 180° out of phase with respect to the bottom flow. The current reversal appeared at the depth between 8 and 20 m. Under stratified conditions the surface flow was in phase with the bottom flow and water entered the Bay on one side of the inlet in the whole water column and left on the other side. These water exchange structures were reflected in the horizontal distribution of density, bacteria, Secchi-disc data and phytoplankton composition.