Strujanje uzrokovano vjetrom u stratificiranom fluidu: numeričko istraživanje i primjena na Tršćanski zaljev u uvjetima jake bure

This study investigates the circulation driven by a severe bora wind event in the Gulf of Trieste during the stratification season. A preliminary numerical analysis of the wind driven transport in the surface boundary layer is carried out for an idealized, laterally unbounded, shallow domain. Then, the simulations are focused on the Gulf of Trieste, using a realistic bathymetry and assuming stably stratified initial conditions. First, the model is driven by constant wind forcing, then qualitative and quantitative estimations of the dynamics of the basin are made reproducing the strong Bora event of the 25 June 2002. Numerical results show good agreement with in situ measurements and remotely sensed images. The relevance of coastal upwelling and its persistence are also assessed. The results prove that mixing and coastal upwelling (both wind-driven) govern the circulation of the basin. When bora starts blowing, buoyant surface water is moved by EKMAN transport offshore inducing a bottom onshore current. Simultaneously, wind driven stirring breaks the initial stable stratification. The surface offshore current generates a sea surface level setup on the northern boundary. When bora decreases, this surface tilt is no longer sustained, and a reversal of the circulation is observed in the upper layer. The sensitivity to the wind forcing is also discussed. All of these issues are crucial to environmental problems such as pollutant dispersion or anoxia phenomena in the bottom layers of the Gulf.U ovom se radu analizira strujanje u Tršćanskom zaljevu uzrokovano jakom burom u vertikalno stratificiranom slučaju. Preliminarna numerička analiza strujnog polja uzrokovanog vjetrom urađena je za idealizirani slučaj horizontalno neograničene domene. Zatim su numeričke simulacije primijenjene na Tršćanski zaljev upotrebivši realnu batimetriju i uz pretpostavku vertikalno stabilne stratifikacije. 25. lipnja 2002. godine najprije je primjenijen stacionaran vjetar, a zatim realistična situacija jake bure. Rezultati numeričke integracije pokazuju dobro slaganje s in situ i daljinskim mjerenjima. Posebna je pažnja poklonjena intenzitetu obalnog “upwellinga” i njegovoj postojanosti. Rezultati ukazuju da su vertikalno miješanje i “upwelling” odgovorni za strujanje u bazenu. Bura uzrokuje EKMANOV transport i odnosi slatku vodu prema sredini zaljeva, te uzrokuje formiranje pridnene struje ka obali. Istovremeno vertikalno miješanje slabi vertikalnu stabilnost vodenog stupca. Površinska struja od obale prema sredini zaljeva uzrokuje nagib razine mora od sjeverne obale ka jugu. Kada prestane bura nagib razine mora se više ne može održati i javlja se površinska struja suprotnog smjera. U ovom je radu također istraživana osjetljivost numeričkih rješenja na utjecaj vjetra. Ovi su procesi važni za širenje otpadnih tvari kao i za eventualnu pojavu anoksije u pridnenom sloju zaljeva

Climate Change in Mediterranean and Caribbean Seas: Research Experiences and New Scientific Challenges

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On the design of a sustainable ocean drifter for developing countries

More than fifty low and medium income countries rely on the sea for their economies. Despite its importance, there is a lack of oceanographic scientific data from these countries due to the high cost of equipment and to the running costs of measurement campaigns. In this paper we present a low-cost drifter based on a LoRa communication platform and tested in a coastal area (Gulf of Trieste). The system, built using low-cost off-the-shelf components, has at least the same performances of drifters that costs about three times as much and its operation does not require any recurring costs. The use of a LoRa allows several drifters to operate simultaneously in the same area, providing a rich and homogeneous database for the statistical post processing. The high transmission rate allows an almost instantaneous position determination, facilitating the drifter recovery for successive reuse, which essential in developing countries

A Conceptual Framework for Developing the Next Generation of Marine OBservatories (MOBs) for Science and Society

In the field of ocean observing, the term of “observatory” is often used without a unique meaning. A clear and unified definition of observatory is needed in order to facilitate the communication in a multidisciplinary community, to capitalize on future technological innovations and to support the observatory design based on societal needs. In this paper, we present a general framework to define the next generation Marine OBservatory (MOB), its capabilities and functionalities in an operational context. The MOB consists of four interconnected components or “gears” (observation infrastructure, cyberinfrastructure, support capacity, and knowledge generation engine) that are constantly and adaptively interacting with each other. Therefore, a MOB is a complex infrastructure focused on a specific geographic area with the primary scope to generate knowledge via data synthesis and thereby addressing scientific, societal, or economic challenges. Long-term sustainability is a key MOB feature that should be guaranteed through an appropriate governance. MOBs should be open to innovations and good practices to reduce operational costs and to allow their development in quality and quantity. A deeper biological understanding of the marine ecosystem should be reached with the proliferation of MOBs, thus contributing to effective conservation of ecosystems and management of human activities in the oceans. We provide an actionable model for the upgrade and development of sustained marine observatories producing knowledge to support science-based economic and societal decisions

The Copernicus Marine Service ocean forecasting system for the Mediterranean Sea

The Mediterranean Monitoring and Forecasting Center (MED-MFC) is part of the Copernicus Marine Environment and Monitoring Service (CMEMS) and provides regular and systematic information on the time-evolving Mediterranean Sea physical (including waves) and biogeochemical state. The systems consist of 3 components: 1) Med-Physics, a numerical ocean prediction systems, based on NEMO model, that operationally produces analyses, reanalysis and short term forecasts of the main physical parameters; 2) Med-Biogeochemistry, a biogeochemical analysis, reanalysis and forecasting system based on the Biogeochemical Flux Model (BFM) which provides information on chlorophyll, phosphate, nitrate, primary productivity, oxygen, phytoplankton biomass, pH and pCO2; 3) Med-Waves based on WAM model and providing analysis, forecast and reanalysis products for waves. The systems have been recently upgraded at a resolution of 1/24 degree in the horizontal and 141 vertical levels. The Med-Physics analysis and forecasting system is composed by the hydrodynamic model NEMO 2-way coupled with the third-generation wave model WaveWatchIII and forced by ECMWF atmospheric fields. The model solutions are corrected by the 3DVAR data assimilation system (3D variational scheme adapted to the oceanic assimilation problem) with a daily assimilation cycle of sea level anomaly and vertical profiles of temperature and salinity. The model has a non-linear explicit free surface and it is forced by surface pressure, interactive heat, momentum and water fluxes at the air-sea interface. The biogeochemical analysis and forecasts are produced by means of the MedBFM v2.1 modeling system (i.e. the physical-biogeochemical OGSTM-BFM model coupled with the 3DVARBIO assimilation scheme) forced by the outputs of the Med-Physics product. Seven days of analysis/hindcast and ten days of forecast are bi-weekly produced on Wednesday and on Saturday, with the assimilation of surface chlorophyll concentration from satellite observations. In-situ data are mainly used to estimate model uncertainty at different spatial scales. The Med-Waves modelling system is based on the WAM Cycle 4.5.4 wave model code. It consists of a wave model grid covering the Mediterranean Sea at a 1/24° horizontal resolution, nested to a North Atlantic grid at a 1/6° resolution. The system is forced by ECMWF winds at 1/8°. Refraction due to surface currents is accounted by the system which assimilates altimeter along-track significant wave height observations. On a daily basis, it provides 1-day analysis and 5-day forecast hourly wave parameters. Currently, wave buoy observations of significant wave height and mean wave period along with satellite observations are used to calibrate and validate the Med-waves modelling system.PublishedHalifax, Nova Scotia, Canada4A. Oceanografia e clim

Developing European operational oceanography for Blue Growth, climate change adaptation and mitigation, and ecosystem-based management

Operational approaches have been more and more widely developed and used for providing marine data and information services for different socio-economic sectors of the Blue Growth and to advance knowledge about the marine environment. The objective of operational oceanographic research is to develop and improve the efficiency, timeliness, robustness and product quality of this approach. This white paper aims to address key scientific challenges and research priorities for the development of operational oceanography in Europe for the next 5–10 years. Knowledge gaps and deficiencies are identified in relation to common scientific challenges in four EuroGOOS knowledge areas: European Ocean Observations, Modelling and Forecasting Technology, Coastal Operational Oceanography and Operational Ecology. The areas “European Ocean Observations” and “Modelling and Forecasting Technology” focus on the further advancement of the basic instruments and capacities for European operational oceanography, while “Coastal Operational Oceanography” and “Operational Ecology” aim at developing new operational approaches for the corresponding knowledge areas

A MSFD complementary approach for the assessment of pressures, knowledge and data gaps in Southern European Seas : the PERSEUS experience

PERSEUS project aims to identify the most relevant pressures exerted on the ecosystems of the Southern European Seas (SES), highlighting knowledge and data gaps that endanger the achievement of SES Good Environmental Status (GES) as mandated by the Marine Strategy Framework Directive (MSFD). A complementary approach has been adopted, by a meta-analysis of existing literature on pressure/impact/knowledge gaps summarized in tables related to the MSFD descriptors, discriminating open waters from coastal areas. A comparative assessment of the Initial Assessments (IAs) for five SES countries has been also independently performed. The comparison between meta-analysis results and IAs shows similarities for coastal areas only. Major knowledge gaps have been detected for the biodiversity, marine food web, marine litter and underwater noise descriptors. The meta-analysis also allowed the identification of additional research themes targeting research topics that are requested to the achievement of GES. 2015 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY license.peer-reviewe

Ocean of things per la conoscenza degli oceani

Lo sviluppo di tecniche di comunicazione pervasive che connettono "cose" intelligenti (sensori, attuatori, telefoni cellulari ecc.) sono oggi disponibili a basso costo e vanno sotto il nome di Internet of Things (IoT). L'ambito d'azione di IoT si sta spostando ora anche verso il mare, dove prende il nome di Ocean of Things (OoT). Per essere efficace, la rivoluzione tecnologica generata da OoT necessita sia di scienziati che di volontari preparati rispetto alle tematiche legate al tema del mare. OoT può trovare inoltre un impiego ideale nelle aree costiere dei paesi in via di sviluppo. Incontro a cura di ICTP e OGS. Intervengono: Alessandro Crise, ricercatore OGS, Marco Zennaro, ricercatore Unità T/lct4D, ICTP. Modera Donato Ramani, giornalist