Asimilacija podataka o temperaturi i salinitetu u jadranskom regionalnom modelu

Temperature and salinity data collected during the October 2002 - October 2003 period have been assimilated into a version of the Princeton Ocean Model implemented over the entire Adriatic Sea. The scheme used is SOFA (System for Ocean Forecast and Analysis, DE MEY & BENKIRAN, 2002) and this is the first coastal application of this scheme. The CTD data were collected in 4 coastal areas (Emilia-Romagna coastal strip, the Gulf of Trieste, the Rovinj and Pelješac-Vis-Drvenik coastal strips) while temperature profiles were acquired with XBT in the southern Adriatic Sea deep ocean areas. The analysis skill scores are examined in order to evaluate the assimilation performance. The results of the assimilation are first compared with independent analyses of satellite Sea Surface Temperature (SST) and it is found that assimilation of profiles improves the SST model estimate. Furthermore, the Root Mean Square (RMS) difference between model and temperature and salinity profiles before data insertion is analysed. The range of RMS temperature error is less than 1 0C for the entire area and decreases with time, indicating a positive impact of the assimilation. The RMS of salinity is less than 1 psu and it also shows a decreasing trend during the assimilation period.Podaci temperature i saliniteta, prikupljeni u razdoblju listopad 2002. - listopad 2003., su asimilirani u Princeton oceanski model koji je primijenjen na cijeli Jadran. Upotrijebljena shema je bila SOFA (Sys-tem for Ocean Forecast and Analysis, DE MEY & BENKIRAN, 2002), što je prva primjena ove sheme na obalno more. CTD podaci su prikupljeni na četiri obalna područja (obalni pojas Emilia–Romagna, Tršćanski zaljev, obalno područje kod Rovinja i obalno područje Pelješac-Vis-Drvenik) dok su podaci XBT-a prikupljeni u dubokim područjima južnog Jadrana. Ispitane su modelske analize, kako bi se procijenila uspješnost asimilacije. Rezultati asimilacije su najprije uspoređeni s nezavisnim analizama površinske tem-perature mora (SST) iz satelita te je nađeno da asimilacija profila poboljšava procjenu površinske tempera-ture iz modela. Nadalje je analiziran kvadratni korjen razlike (RMS) između modela te profila temperature i saliniteta prije uključivanja podataka. Raspon RMS pogreške temperature je ispod 1 0C na čitavom području i opada s vremenom, ukazujući na pozitivni utjecaj asimilacije. RMS razlika saliniteta je ispod 1 psu i pokazu-je trend opadanja za vrijeme razdoblja asimilacije

Linking 1D coastal ocean modelling to environmental management: an ensemble approach

The use of a one-dimensional interdisciplinary numerical model of the coastal ocean as a tool contributing to the formulation of ecosystem-based management (EBM) is explored. The focus is on the definition of an experimental design based on ensemble simulations, integrating variability linked to scenarios (characterised by changes in the system forcing) and to the concurrent variation of selected, and poorly constrained, model parameters. The modelling system used was previously specifically designed for the use in "data-rich" areas, so that horizontal dynamics can be resolved by a diagnostic approach and external inputs can be parameterised by nudging schemes properly calibrated. Ensembles determined by changes in the simulated environmental (physical and biogeochemical) dynamics, under joint forcing and parameterisation variations, highlight the uncertainties associated to the application of specific scenarios that are relevant to EBM, providing an assessment of the reliability of the predicted changes. The work has been carried out by implementing the coupled modelling system BFM-POM1D in an area of Gulf of Trieste (northern Adriatic Sea), considered homogeneous from the point of view of hydrological properties, and forcing it by changing climatic (warming) and anthropogenic (reduction of the land-based nutrient input) pressure. Model parameters affected by considerable uncertainties (due to the lack of relevant observations) were varied jointly with the scenarios of change. The resulting large set of ensemble simulations provided a general estimation of the model uncertainties related to the joint variation of pressures and model parameters. The information of the model result variability aimed at conveying efficiently and comprehensibly the information on the uncertainties/reliability of the model results to non-technical EBM planners and stakeholders, in order to have the model-based information effectively contributing to EBM

Drift simulation of MH370 debris using superensemble techniques

Abstract. On 7 March 2014 (UTC), Malaysia Airlines flight 370 vanished without a trace. The aircraft is believed to have crashed in the southern Indian Ocean, but despite extensive search operations the location of the wreckage is still unknown. The first tangible evidence of the accident was discovered almost 17 months after the disappearance. On 29 July 2015, a small piece of the right wing of the aircraft was found washed up on the island of Réunion, approximately 4000 km from the assumed crash site. Since then a number of other parts have been found in Mozambique, South Africa and on Rodrigues Island. This paper presents a numerical simulation using high-resolution oceanographic and meteorological data to predict the movement of floating debris from the accident. Multiple model realisations are used with different starting locations and wind drag parameters. The model realisations are combined into a superensemble, adjusting the model weights to best represent the discovered debris. The superensemble is then used to predict the distribution of marine debris at various moments in time. This approach can be easily generalised to other drift simulations where observations are available to constrain unknown input parameters. The distribution at the time of the accident shows that the discovered debris most likely originated from the wide search area between 28 and 35° S. This partially overlaps with the current underwater search area, but extends further towards the north. Results at later times show that the most probable locations to discover washed-up debris are along the African east coast, especially in the area around Madagascar. The debris remaining at sea in 2016 is spread out over a wide area and its distribution changes only slowly

A management oriented 1-D ecosystem model: Implementation in the Gulf of Trieste (Adriatic Sea).

In this paper a coupled physical-biogeochemical one-dimensional numerical model (BFM-POM 1D) was implemented in the Gulf of Trieste, (northern Adriatic Sea) and its structure was tested in order to evaluate its usability as a tool to support coastal management and planning. The evaluation concerned the ability of the model to reproduce the main trophic pathways, as well as their temporal variability, in terms of seasonal variations. The ecosystem structure comprised three phytoplankton groups, four zooplankton groups, one bacterial group, and a simple benthic return in order to parametrise benthic processes. The dynamics and interactions between groups were studied, as well as the model's sensitivity to different trophic web configurations. Results showed that the model was capable of replicating the behaviour of seasonal vertical profiles of the major biogeochemical elements, and the prevalence of the microbial food web shaping the trophic chain in the Gulf of Trieste. The model also responded to strong forcings at the surface and different trophic arrangements, thus providing initial evidence of its potential as a scientific tool aimed at marine coastal management

A General Methodology for Beached Oil Spill Hazard Mapping

The current lack of a standardized approach to compute the coastal oil spill hazard due to maritime traffic accidental releases has hindered an accurate estimate of its global impact, which is paramount to manage and intercompare the associated risks. We propose here a hazard estimation approach that is based on ensemble simulations and the extraction of the relevant distributions. We demonstrate that both open ocean and beached oil concentration distributions fit a Weibull curve, a two-parameter fat-tail probability distribution function. The simulation experiments are carried out in three different areas of the northern Atlantic. An indicator that quantify the coastal oil spill hazard is proposed and applied to the study areas

VISIR-I: Small vessels - Least-time nautical routes using wave forecasts

A new numerical model for the on-demand computation of optimal ship routes based on sea-state forecasts has been developed. The model, named VISIR (discoVerIng Safe and effIcient Routes) is designed to support decision-makers when planning a marine voyage. The first version of the system, VISIR-I, considers medium and small motor vessels with lengths of up to a few tens of metres and a displacement hull. The model is comprised of three components: a route optimization algorithm, a mechanical model of the ship, and a processor of the environmental fields. The optimization algorithm is based on a graph-search method with time-dependent edge weights. The algorithm is also able to compute a voluntary ship speed reduction. The ship model accounts for calm water and added wave resistance by making use of just the principal particulars of the vessel as input parameters. It also checks the optimal route for parametric roll, pure loss of stability, and surfriding/broaching-to hazard conditions. The processor of the environmental fields employs significant wave height, wave spectrum peak period, and wave direction forecast fields as input. The topological issues of coastal navigation (islands, peninsulas, narrow passages) are addressed. Examples of VISIR-I routes in the Mediterranean Sea are provided. The optimal route may be longer in terms of miles sailed and yet it is faster and safer than the geodetic route between the same departure and arrival locations. Time savings up to 2.7% and route lengthening up to 3.2% are found for the case studies analysed. However, there is no upper bound for the magnitude of the changes of such route metrics, which especially in case of extreme sea states can be much greater. Route diversions result from the safety constraints and the fact that the algorithm takes into account the full temporal evolution and spatial variability of the environmental fields

Oil spill Hazard maps

This report contains the description of the methodology to produce coastal oil spill hazard mapping for the Atlantic Ocean coastlines and the description of the Web Portal used to disseminate the informatio

ADRICOSM pilot projekt: Sustav predviđanja u obalnim područjima i riječnim bazenima Jadranskog mora

The ADRICOSM project was launched in October 2001, and ended in March 2005, with the main objective of demonstrating the feasibility of a near real time operational marine monitoring and forecasting system at the shelf and coastal scales, with connections to river basin runoff and coastal town sewer systems. The basic system consisted of an efficient network for the collection of marine data such as in situ temperature and salinity profiles and satellite sea surface temperature, a regional (AREG) and shelf scale modeling system, a data assimilation system and finally a coastal scale modeling system. Every week AREG releases 7 day marine forecasts at 5 km horizontal scales, which are used to nest other hydrodynamic models toward the coastal scale. Two shelf models (ASHELF-1 and ASHELF-2) at a 1.5 km horizontal scale were nested in AREG in order to simulate (and in the future to forecast) shelf scale oceanographic features. Another important aspect of ADRICOSM was the integration of the Cetina river (Croatia) and urban sewage monitoring/ modeling (Split, Croatia) systems with the shelf marine model. This integrated model system was used to simulate the dispersion of sewer discharges from the urban area in the coastal waters for water management performance studies. ADRICOSM is one of the first integrated land and marine waters operational oceanographic systems able to meet the urgent needs for reliable integrated coastal forecasts for the effective management of marine areas.Projekt ADRICOSM započeo je u listopadu 2001. i završio u ožujku 2005. godine. Glavni je cilj projekta bio pokazati mogućnosti operacionalizacije monitoringa i prognoze u skoro realnom vremenu na šelfu te u obalnim područjima koja su povezana s riječnim bazenima i gradskim otpadnim vodama. Sustav je bio opremljen efikasnom mrežom sakupljanja podataka izmjerenih u moru kao što su profili temperature i saliniteta te satelitske površinske temperature mora, regionalnim jadranskim modelom (AREG) i modelom na skali šelfa, sustavom asimilacije podataka te konačno, obalnim modelom. Svaki tjedan AREG je izrađivao 7-dnevnu oceanografsku prognozu na horizontalnoj skali od 5 km koja je upotrebljavana za gniježđenje drugih hidrodinamičkih modela duž obale. Dva modela na šelfu (ASHELF-1 i ASHELF-2) horizontalne rezolucije od 1.5 km ugniježđeni su u jadranski AREG model s ciljem simuliranja (te u budućnosti i prognoziranja) oceanografskih osobina šelfa. Drugi važan aspekt ADRICOSM projekta bio je integracija monitoringa i modeliranja dotoka rijekom Cetinom i sustavom otpadnih voda s oceanografskim modelom šelfa. Ovaj je integracijski sustav upotrebljen za simuliranje disperzije urbanih otpadnih voda u obalnom području. Projekt ADRICOSM je jedan od prvih integracijskih sustava kojim se za potrebe operativne oceanografije i prognoze ujedinjuju obalne vode s dotocima s kopna s ciljem efikasnog upravljanja obalnim područjima