|CIESM International Conference on East - West Cooperation in Marine Science
(Sochi, 1-3 December 2014)
Abstracts of Panel communications
Panel [A] - Physical processes in coastal waters
Panel [B] - Geo-hazards
Panel [C] - Invasive species
Panel [D] - Contaminants & marine litter
Panel [E] - Marine biotechnology & society
Panel [F] - Data harmonization
Panel [A] - Physical processes in coastal waters
co-moderators : Drs Miroslav Gacic and Andrey G. Zatsepin
Title : From open ocean to coastal seas: numerical modeling across scales.
by Andrea Cucco
IAMC-CNR, Torregrande – Oristano, Italy
Operational forecasting systems, capable of predicting ocean and weather conditions provide a rapid and efficient tool allowing decision makers to promptly respond to environmental emergencies on the basis of a technical assessment and risk analysis procedures. A wide variety of numerical systems, based on hydrodynamic and meteorological models, was developed in order to analyse and predict the main physical and biogeochemical properties of European sea waters.
The temporal and spatial variability of the main hydrodynamics is commonly reproduced by structured grid ocean models based on the finite difference method. These systems are generally adequate in open sea or shelf waters, where the geometry is regular or smooth. However, for irregular and complex geometries, such as in coastal areas, these operational tools are not suitable to provide information over the fundamental physical variables controlling the fluid motion, as well as the wind wave propagation and the surface transport processes (Chen et al., 2007).
As a partial solution, nesting procedures are widely used to improve the accuracy of numerical model predictions along coastal areas. Such techniques, if applied between structured mesh ocean models, are generally efficient to downscale the hydrodynamic model solutions only within a restricted downscaling ratio, ranging between 2 and 5 (Denis et al., 2002).
An alternative approach is provided by the use of numerical models based on an unstructured grid, which allows to reproduce the fluid motion, the wind wave propagation and the surface transport processes over different spatial scales (Cucco and Umgiesser, 2006). However, many forecasting systems for predicting operationally the water currents and waves in open ocean are often still using structured grid numerical models (Tonani et al., 2009). They are well tested against measurements and their accuracy is generally high especially when reproducing water surface temperature fields. Therefore, an optimal approach for investigating the main physical properties of coastal and shelf sea waters would be represented by the adoption of nesting procedures combining high resolution numerical models in coastal areas, based on unstructured grid, and coarse resolution numerical model in open ocean and shelf areas, based on structured grid.
Such novel approach to both hydrodynamic, wind wave and pollutant transport modelling was applied to the several areas and test cases along the Mediterranean coastal areas. A set different examples and applications will be described, ranging from the development of oil spill operational systems to the investigation of the main hydrodynamics and transport time scales of semi-enclosed basins up to the support to the design of maritime structures such as harbours and coastal defences.
Denis, B., Laprise, R., Caya, D., Cote, J., 2002. Downscaling ability of one-way nested regional climate models: the Big-Brother Experiment. Climate Dynamics. 18, 627–646
Chen, H., Li, D., Li, X., 2007. Mathematical modeling of oil-spill on the sea and application of the modeling in Daya Bay. Journal of Hydrodynamics, 19, 3, 282–291
Cucco, A., Umgiesser, G., 2006. Modeling the Venice Lagoon residence times. Ecological Modeling, 193, 34–51
Tonani, M., Pinardi, N., Fratianni, C., Pistoia, J., Dobricic, S., Pensieri, S., de Alfonso, M., Nittis, K., 2009. Mediterranean Forecasting System: forecast and analysis assessment through skill scores. Ocean Science, 5, 649–660
Title : The Lagoon of Venice - an example of coastal circulation studies
by Miroslav Gacic
OGS, Trieste, Italy
Lagoons are very sensitive water bodies from the biogeochemical point of view. They are under the important anthropogenic influence which on one hand may change the ecological status and on the other their morphology. The former one depends on the human activities and the water discharge into lagoons and the latter is a function of the equilibrium between the sediment input from land and its exchange with the open sea. In the Adriatic Sea two important lagoons are present: Lagoon of Venice and the Lagoon of Marano-Grado, both situated in the north-western part of the sea. Especially endangered is the Lagoon of Venice due to frequent flooding, strong industrial activities and heavy maritime traffic. Since the times of the Venetian Republic number of measures have been undertaken to reduce the sediment input from a number of rivers. This has resulted in the continuous net sediment losses. Another important phenomena which cause rather important damages to the city of Venice on a long term time scale, is meteorologically induced high sea-level episodes and the city floods. In order to prevent mitigate their negative effects, system of mobile damns has been under construction and will probably be put into function in 2017.
In the early 2000s intensive studies were carried out in order to understand water and sediment exchange dynamics between the lagoon and the open sea. This on one hand, gave as a result the quantification of the water flow through the lagoon inlets and their response to the tidal, wind and, in general, atmospheric forcing and, on the other based on these studies, it was possible to estimate both water and the sediment long-term balance. The relationship between the sea-level variability and the water flow for different wind pattern has been established. In addition, the current field in the close vicinity of the lagoon inlets was studied using the coastal radar measurements giving the possibility to describe in details the submesoscale flow pattern in function of either the wind or the outflow/inflow states. Special attention was given to the water exchange pattern associated with the characteristic winds in the area, mainly responsible for the city of Venice floods. Also, sea level distribution within the lagoon has been studied and connected with the wind forcing; northerly winds generating strong longitudinal sea level differences reaching up to 15 cm over the 50 km distance.
Title : Numerical model of the hydrodynamics of the Black Sea and the Sea of Azov with refinement near Bay of Gelendzhik
by A. Gusev, V. Zalesny, V. Agoshkov, S. Moshonkin
Russian Academy of Sciences, Moscow, Russia
The problem of the numerical modelling of the Black Sea large-scale circulation is considered. The INMOM (Institute of Numerical Mathematics Ocean Model) is used. The model is based on primitive equations written in spherical s-coordinates with a free surface in the hydrostatic and Boussinesq approximations. The structure of numerical algorithm is described. The algorithm is based on the method of multicomponent splitting and includes splitting by physical processes and spatial coordinates. The equations of sea dynamics are written in a symmetrized form. The problem is split into several energetically balanced subsystems (splitting by physical processes). Each subsystem can be additionally split into subsystems of a simpler structure (splitting by spatial coordinates).The computational area is constructed in the spherical coordinate system with shifted point of the North Pole which is placed in the vicinity of Bay of Gelendzhik to increase the spatial resolution near Gelendzhik coast where the SIORAS hydrophysical polygon is situated. The preliminary numerical experiment is performed consisting in simulating Black Sea hydrodynamic fields. The results of the experiment are presented.
Title : Mesoscale and frontal scale processes regulating plankton production in the Black Sea food web
by Temel Oguz
Institue of Marine Sciences, METU, Erdemli, Turkey
The narrow peripheral zone around the Black Sea maintains persistently high biological production at all trophic levels with respect to the cyclonic interior cell and this phenomoenon is explained customarily by the anthropogenic-based nutrient enrichment process. Except coastal regions, the long-term and large scale impact of eutrophication is to build up nutrients in the chemocline so that they are made available into the phopic layer for new production repeatedly by an appropriate physical driving mechanism. We describe an eddy - resolving physical - biological model study to document the frontogenesis as the mechanism for supporting an enhanced biological activity within the Black Sea peripheral waters. It arises under the conditions of moderate-to-highly nonlinear and unstable rim current and thus collapse of the along-front geostrophic balance. Strong upward vertical velocities (up to 100 m day-1) of the resulting ageostrophic cross-frontal circulation augment nutrient capacity and thus phytoplankton biomass of surface waters (~ 1.0-2.0 mmol N m-3) on the less dense, coastal anticyclonic side of the front relative to the cyclonic offshore side. This process may prevail throughout the year in regions where the frontogenesis mechanism takes place, but it may also be supported by the buoyancy-induced vertical turbulent mixing during autumn-winter due to the effect of buoyancy-induced cooling. The eddy-induced horizontal and vertical nutrient transports introduce further complexity into the system by distributing nutrients and biogenic material over the basin.
Title : Moored automatic mobile profilers (MAMPs) for continental margins of the ocean
by Alexander G. Ostrovskii
Russian Academy of Sciences, Moscow, Russia
Modern MAMPs provide cost-effective profiles of density, velocity, and water quality (i.e. fluorescence, nutrients, dissolved oxygen) at high temporal and vertical resolution over extended durations in a variety of marine environments and are an important component of modern ocean observation systems. While several different types of MAMPs are in use today, they all consist of a single instrument package that is raised and lowered through a specific depth range at pre-programmed intervals, allowing observation of intermittent processes and vertical ocean structure. Oceanographic data collected during recent deployments of the moored profiler Aqualog in the northeastern Black Sea highlight its capability as a tool for multidisciplinary oceanographic observations at the continental margin.
Title : Dense shelf water cascading in the north-western Mediterranean: An overview.
by Pere Puig
Institut de Ciències del Mar, ICM-CSIC, Barcelona, Spain
Cascading of dense shelf waters is a global oceanographic phenomenon whose effects on sedimentation processes on continental margins have been poorly studied and largely underestimated. The north-western Mediterranean is one of the regions of the world where massive dense water formation occurs because of cooling and evaporation of surface waters during winter-time. Concurrent with the well known open-sea convection process on the MEDOC region, coastal surface waters over the wide shelf of the Gulf of Lion also become denser than the underlying waters and cascade downslope during sustained periods of time until reaching their equilibrium depth. Through this climate-driven phenomenon, dense shelf waters carrying large quantities of particles and associated elements in suspension and as bed load are rapidly advected hundreds of meters deep, mainly through submarine canyons, acting as an efficient cross-margin transport mechanism. Numerous mooring observations collected recently in the north-western Mediterranean in the context of successive research efforts have allowed characterizing the sediment fluxes associated to this phenomenon and identify several morphological evidences of sediment erosion and deposition attributed to dense shelf water cascading. Additionally, deep-sea hydrographic observations after major cascading events indicate a direct effect on the Western Mediterranean Deep Water (WMDW) thermohaline properties and a subsequent formation of a thick and persistent bottom nepheloid layer that can spread throughout the western Mediterranean basin.
While this process starts to be relatively well understood in terms of water and sediment transport, many scientific questions arise on how the large fluxes associated with this phenomenon may determine the functioning of deep-sea ecosystems in the north-western Mediterranean. Recent findings suggest that dense shelf water cascades from the Gulf of Lion have a direct effect on the long-term fluctuations of deep-sea fisheries and on the distribution of cold-water coral communities. Because of the flushing and recurrent behavior of major deep-reaching dense shelf water cascading events (i.e., approximately once every 6-7 years), a continuous monitoring of this phenomenon should be necessary to assess in detail its effects and implications in the deep-sea ecosystem and living resources. Since cascading of dense shelf water from continental shelves is a global phenomenon whose effects may have been largely underestimated, it can be anticipated that, under present conditions, cascading sites identified worldwide could constitute preferential regions for active contemporary sediment transport, from the coastal ocean to the deep basins, along with the associated consequences. Overall, their influence on deep-sea ecosystems worldwide could be larger than previously thought, and in that sense such oceanographic phenomenon should be properly studied using a trans-disciplinary approach.
Title : Usage of remote sensing data for marine ecosystem study.
by S.V. Stanichny, Burduyugov V.M., Davydova E.P., Kalinin E.I., Kubryakov A.A., Soloviev D.M., Stanichnaya R.R.
Marine Hydrophysical Institute, Sevastopol, Russia
Satellite data from AVHRR, MODIS, SeaWiFS, ETM+, OLI, TIRS and other sensors presented for description of the processes and phenomena in the Black Sea and particularly in its coastal zone.
Next topics are discussed:
- Anomalous blooms and role of the wind impact on different temporal scales,
- Mesoscale and submesoscale processes,
- Existence and manifestation of the phenomena in different spectral ranges, advantages of the multi-spectral, multi-platform approach,
- Pollutions and system for control on the base of satellite data.
Title : Coastal zone permanent ecological monitoring at the selected polygons: example from the Black Sea.
by A.G. Zatsepin
P.P. Shirshov Institute of Oceanology, Moscow, Russia
A polygon for permanent ecological monitoring of the Black Sea coastal zone based on combined utility of anchored autonomous measuring platforms and regular multidisciplinary R/V surveys is developed by SIO RAS in the north-eastern Black Sea. The polygon occupies an area of 15*10 km2 near Gelendzhik, where the Southern Branch of SIO RAS is situated and used as a monitoring center. Three types of autonomous platforms are exploited: 1) acoustic Doppler velocity profiler (ADCP) at the bottom station, 2) thermo-chain at the mooring line, 3) robotic profiler "Akvalog" at the moored buoy station. By these platforms the long rows of hydrophysical and bio-optical data (vertical profiles of temperature, salinity, density, current velocity, acoustic backscatter, water transparency, chlorophyll_”a” fluorescence, etc.) of high spatial and temporal resolution are obtained. In the report selected results of the observations fulfilled at the SIO RAS Black Sea ecological polygon are described and analyzed.