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Sikora M.,University of Split | Mihanovic H.,Hydrographic Institute of the Republic of Croatia | Vilibic I.,Croatian Institute Of Oceanography And Fisheries
Acta Adriatica | Year: 2014

The paper documents the use of a Digital Elevation Model (DEM) method to reconstruct paleo-channels and the paleo-coastline during the Last Glacial Maximum (LGM) in the Central Eastern Adriatic area. We focused on the paleo-coastline and paleo-channels of the Neretva and the Cetina rivers, which were estimated from the 15’’ bathymetry available for the Adriatic Sea. While being aware of the limitations of the method and the resolution of the bathymetry grid, we successfully reproduced the paleo-channels of both rivers. Results for the Cetina River indicate the presence of depressions that were filled with water along its flow. The configurations of existing seabeds in the vicinity of the Cetina and Neretva River mouths indicate morphologies, similar to river mouths. The vertical profiles suggest that during the LGM the sea level was about 115 m lower than today. The total length of the Neretva riverbed was longer for about 136 km than today, and the Cetina River was approximately 154 km longer. © 2014, Institute of Oceanography and Fisheries. All rights reserved.

Mihanovic H.,Hydrographic Institute of the Republic of Croatia | Mihanovic H.,Croatian Institute Of Oceanography And Fisheries | Beg Paklar G.,Croatian Institute Of Oceanography And Fisheries | Orlic M.,University of Zagreb
Continental Shelf Research | Year: 2014

Analysis of oceanographic data collected during 2006 in the eastern Adriatic Sea indicated the presence of large internal waves (with a maximum range of about 30. m) at the diurnal frequency around the island of Lastovo. The amplitude ratio and phase difference between diurnal surface tides and diurnal isotherm fluctuations changed considerably between pronounced internal wave episodes, depending on stratification properties, thus suggesting possible resonant excitation of internal oscillations. On the contrary, no significant diurnal thermocline fluctuations were observed at two other islands (Biševo and Sušac). Theoretical analysis presented here focused on the trapping of long-period internal waves around a circular island corresponding to Lastovo and confirmed that stratification properties during the summer of 2006 around the island were close to resonant ones. The analysis also showed that Biševo and Sušac are too small to support diurnal near-resonant excitation. Application of a numerical model for the current flow around equivalent circular and elliptical islands in the stratified sea provided more details on resonant excitation. Theoretical and numerical modeling results particularly emphasized the importance of island dimensions, stratification properties (pyconocline depth and density defect) and the periodicity of the forcing. Furthermore, idealized numerical simulations demonstrated that the waves trapped at Lastovo behave as the gravest azimuthal mode of internal Kelvin-like waves, revolving in a clockwise direction around the island, and that the eccentricity of the island has almost no effect on the resonant period. © 2014 Elsevier Ltd.

Lovrincevic D.,Hydrographic Institute of the Republic of Croatia
Cartographic Journal | Year: 2016

A good seabed representation is one of the important characteristics of any navigational chart. Along with depth contours and coloured depth areas, soundings are used for this task. All the soundings on a navigational chart are selected for a reason. Soundings contribute to the navigational chart safety aspect by alerting to all the threats and dangers. They also show all the attributes of a seabed relief without overcrowding it, thus maintaining the overall chart quality. Soundings are selected from a hydrographic survey and since it consists of a vast number of data, the process of sounding selection is a challenging and demanding task. It requires experience and knowledge from the nautical cartographer and is mostly done manually. Some types of software nowadays provide an automatic selection feature. This paper analyses a process of automatic sounding selection in the dKart Editor software. On the Croatian side of the Adriatic Sea, Šibenski Kanal (Šibenik channel) and Kanal Sv. Ante (St. Ante’s channel) are used as the study area. A hydrographic survey of the area represents the input data. The official navigational chart of the surveyed area is used as the basis for determining three different sets of parameters for the selection process. After the selection, obtained results are assessed based on geometrical accuracy and on the conservation level of navigational safety. For geometrical accuracy, the best results were produced by the third set that was divided in two subsets for each channel. It was determined that the nature of the seabed relief had an impact on the selection process. The same set had the best result for navigational safety assessment but it was concluded that all the sets undermined the aspect. Because of these crucial shortcomings noticed in all the tested sets of parameters, the feature is considered inadequate for serious usage as a completely automatic tool for the process of sounding selection on navigational charts. © The British Cartographic Society 2016

Vilibic I.,Croatian Institute Of Oceanography And Fisheries | Mihanovic H.,Hydrographic Institute of the Republic of Croatia | Charrayre F.,Institute of Engineering science of Toulon and Var
Natural Hazards | Year: 2013

High-resolution air pressure series collected from a triangle of middle Adriatic microbarograph stations between April 2009 and March 2011 have been analysed to extract the rapid pressure changes normally found during meteotsunamis. Five-minute air pressure tendencies were used to detect an event. Wavelet and cross-wavelet analysis showed that the energies of high-frequency pressure changes that occurred during the warm part of the year were an order of magnitude higher than those that occurred during the cold part of the year. Coherence between stations was normally found at periods longer than 1 h, while air pressure disturbances were dispersive and not coherent at shorter periods. This implies that the disturbances had little to no potential to generate meteotsunamis in the middle Adriatic area, as the eigenoscillations in bays and harbours of the region are over timescales of minutes up to a few tens of minutes. © 2013, Springer Science+Business Media Dordrecht.

Loncar G.,University of Zagreb | Leder N.,Hydrographic Institute of the Republic of Croatia | Paladin M.,University of Zagreb
Oceanologia | Year: 2012

Hypothetical cases of oil spills, caused by ship failure in the northern Adriatic, are analysed with the aim of producing three-dimensional models of sea circulation and oil contaminant transport. Sea surface elevations, sea temperature and salinity fields are applied as a forcing argument on the model's open boundaries. The Aladin-HR model with a spatial resolution of 8 km and a time interval of 3 hours is used for atmospheric forcing. River discharges along the coastline in question are introduced as point source terms and are assumed to have zero salinity at their respective locations. The results of the numerical modelling of physical oceanography parameters are validated by measurements carried out in the 'Adriatic Sea monitoring programme' in a series of current meter and CTD stations in the period from 1 January 2008 to 15 November 2008. The oil spill model uses the current field obtained from a circulation model. Besides the convective dispersive transport of oil pollution (Lagrangian model of discrete particles), the model takes into account a number of reactive processes such as emulsification, dissolution, evaporation and heat balance between the oil, sea and atmosphere. An actual event took place on 6 February 2008, when the ship 'Und Adriyatik' caught fire in the vicinity of the town of Rovinj (Croatia) en route from Istanbul (Turkey) to Trieste (Italy). At the time the fire broke out, the ship was carrying around 800 tons of oil. Thanks to the rapid intervention of the fire department, the fire was extinguished during the following 12 hours, preventing possible catastrophic environmental consequences. Based on this occurrence, five hypothetical scenarios of ship failure with a consequent spill of 800 tons of oil over 12 hours were analysed. The main distinction between the simulated scenarios is the time of the start of the oil spill, corresponding to the times when stronger winds were blowing (>7 m s-1) with a minimum duration of 24 h within the timeframe. Each scenario includes a simulation of oil transport for a period of two months after the beginning of the oil spill. The results show that the coastal belt between the towns of Poreč and Rovinj is seriously exposed to an oil pollution load, especially a few days after a strong and persistent bora (NE wind). © Polish Academy of Sciences, Institute of Oceanology, 2012.

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