The paper presents different models of the organizational functioning of the coast guards of European countries with access to semi-enclosed seas. It analyses the Coast Guards of the Republic of Italy, the Republic of Greece, and the Kingdom of Norway with respect to different functional organizational models. Special attention is paid to the organizational structure and operations of the Coast Guard of the Republic of Croatia. The paper also explores and analyses the management model of the Coast Guard of the Republic of Croatia in the context of operational efficiency in protecting rights and interests in the maritime areas of the research geographical region, the semi-enclosed Adriatic Sea - eastern part. A comparative analysis of the considered coast guards is presented.

This study examines the impact of geomagnetic disturbances quantified by the Kp and Dst indices on the accuracy of single-frequency GPS positioning across mid-latitudes and the equatorial zone, with a focus on temporal and spatial positioning errors variability. GNSS data from a globally distributed network of 14 IGS stations were analyzed for September 2017, featuring significant geomagnetic activity. The selection of stations encompassed equatorial and mid-latitude regions (approximately ±45°), strategically aligned with the distribution of the Dst index during geomagnetic storms. Satellite navigation data were processed using RTKLIB software in standalone mode with standardized atmospheric and orbital corrections. The GPS was chosen over GLONASS following preliminary testing, which revealed a higher sensitivity of GPS positional accuracy to variations in geomagnetic indices such as Kp and Dst, despite generally lower total error magnitudes. The ECEF coordinate system calculates the total GPS error as the vector sum of deviations in the X, Y, and Z axes. Statistical evaluation was performed using One-Way Repeated Measures ANOVA to determine whether positional error variances across geomagnetic activity phases were significant. The results of the variance analysis confirm that the variation in the total GPS positioning error is non-random and can be attributed to the influence of geomagnetic storms. However, regression analysis reveals that the impact of geomagnetic storms (quantified by Kp and Dst) displays spatiotemporal variability, with no consistent correlation to GPS positioning error dynamics. The findings, as well as the developed methodology, have qualitative implications for GNSS-dependent operations in sensitive sectors such as navigation, timing services, and geospatial monitoring.

For high-quality scientific communication in the field of technical and natural sciences, it is of utmost importance to ensure clarity of the text, logical mathematical argumentation, and the possibility of verifying the obtained theoretical results using appropriate experiments [...]

Positioning error components related to tropospheric and ionospheric delays are caused by the atmosphere in positioning determined by global navigation satellite systems (GNSS). Depending on the user's requirements, the position error caused by tropospheric influences, which is commonly referred to as zenith tropospheric delay (ZTD), must be estimated during position determination or determined later by external tropospheric corrections. In this study, a new approach was adopted based on the reduction of residual tropospheric error (RTE), i.e., the unmodeled part of the tropospheric error that remains included in the total geodetic position error, along with other unmodeled systematic and random errors. The study was performed based on Global Navigation Satellite System (GLONASS) positioning solutions and accompanying meteorological parameters in a defined and harmonized temporal-spatial frame of three locations in the Republic of Croatia. A multidisciplinary approach-based analysis from a navigational science aspect was applied. The residual amount of satellite positioning signal tropospheric delay was quantitatively reduced by employing statistical analysis methods. The result of statistical regression is a model which correlates surface meteorological parameters with RTE. Considering the input data, the model has a regional character, and it is based on the Saastamoinen model of zenith tropospheric delay. The verification results show that the model reduces the RTE and thus increases the geodetic accuracy of the observed GNSS stations (with horizontal components of position accuracy of up to 3.8% and vertical components of position of up to 4.37%, respectively). To obtain these results, the Root Mean Square Error (RMSE) was used as the fundamental parameter for position accuracy evaluation. Although developed based on GLONASS data, the proposed model also shows a considerable degree of success in the verification of geodetic positions based on Global Positioning System (GPS). The purpose of the research, and one of its scientific contributions, is that the proposed method can be used to quantitatively monitor the dynamics of changes in deviations of X, Y, and Z coordinate values along coordinate axes. The results show that there is a distinct interdependence of the dynamics of Y and Z coordinate changes (with almost mirror symmetry), which has not been investigated and published so far. The resultant position of the coordinates is created by deviations of the coordinates along the Y and Z axes-in the vertical plane of space, the deviations of the coordinate X (horizontal plane) are mostly uniform and independent of deviations along the Y and Z axes. The proposed model shows the realized state of the statistical position equilibrium of the selected GNSS stations which were observed using RTE values. Although of regional character, the model is suitable for application in larger areas with similar climatological profiles and for users who do not require a maximum level of geodetic accuracy achieved by using Satellite-Based Augmentation Systems (SBAS) or other more advanced, time-consuming, and equipment-consuming positioning techniques.

For many years, the navigation team at the French Space Agency (CNES) has been developing its Precise Point Positioning project. The goal was initially to promote a technique called undifferenced ambiguity resolution. One of the main characteristics of this technique is the capability for a user receiver to perform centimeter-level accuracy in real time. To do so, a demonstrator has been built. Its architecture is composed of three main elements: a correction processing software called the server part, a means to transmit the corrections using standardized messages, and a user software capable of handling the corrections to compute an accurate positioning at the user level. In this paper, we present the recent advances in the CNES precise point positioning demonstrator. They are composed of some evolution of the network of stations and server software, the implementation of the new state space representation standard, a new method for instantaneous ambiguity resolution using uncombined four-frequency signals, its implementation in real-time at the server and the user level, and the use of high-rate Doppler measurements to improve the accuracy of the solution in harsh urban environments. On top of that, the computation of high-accuracy post-processed phase biases with the majority of current GNSS signals supported, compatible with the uncombined method and a new online positioning service to demonstrate the capacity of the user software, is demonstrated.

The multimodal door-to-door transport chain connecting Central Europe with Far East origins predominantly calls the North European ports. However, already the geographic features are dictating the reasonable possibility of routes’ redirection via several alternatives through the Mediterranean Sea. This study represents the continuation of the research in terms of analysis and evaluation of the Southern European freight transport flow through the Northern Adriatic. The aim was to elaborate further on the justification of the possible redirection of cargoes via the Adriatic corridor. In these terms, the land segment of the transport chain from ports to the final destination was isolated and analysed. The authors were primarily guided by natural features, that are respective geographical locations and their mutual distances. For this purpose, container transport on two traffic flows was simulated, with emphasis on the land segment between the second (destination) port and the final destination. Considering the usual freight lines, the door-to-door container transport between origin and destination was selected. Both road and rail transportation modes were investigated. Besides general parameters, such as distances, time, and fuel consumption, the environmental impact for all scenarios was determined for both downstream and final fuel cycle processes. In these terms, basic environmental parameters for four possible scenarios were calculated: energy consumption, emissions of carbon dioxide, greenhouse gases, nitrogen oxides, sulphur dioxide, non-methane hydrocarbons, and particulate matter. Results are indicating that, together with a significant reduction of sea transportation impacts on the environment, the eventual redirection contributes to emissions’ mitigation and the sustainability of transportation. These results are accompanied by several initiatives in the area. Apart from potential benefits, the findings were discussed from the reliability point of view, i.e. the ability of Northern Adriatic ports and the land infrastructure to successfully take over this task, at least to a certain extent, and finally, in a reasonable future.

Container transport by sea has almost doubled in the last decade. Accordingly, container ships’ size has increased significantly, and the latest container ships carry up to 24000 Twenty-foot Equivalent Units (TEU). In the near future, the appearance of container ships with a capacity of 25000 TEUs can be expected on the market, because the design is already available. It is known that 10-12% of transported containers contain International Maritime Dangerous Goods (IMDG) cargo. The above stated reasons directly impact the frequency of container ship fires in cargo spaces. According to the Insurance Companies, fires occur on average every two months, and this is a growing problem of container transport by sea. In this paper, 23 fires in the cargo area, either in cargo holds or on deck, were analysed. The analysis results determined the most common causes of fires and have shown that the current fire protection systems on container ships are ineffective. It is unacceptable that firefighting systems’ inefficiency results in the loss of human lives, abandonment of vessels, environmental pollution, and extensive property losses related to cargo and ship structure. Due to all the above, it is necessary to continuously work on new regulatory and technical solutions to improve the fire safety of cargo areas on container ships.

This research represents a contribution to the theory on the coupling of the volcanic activity and the ionospheric dynamics, represented by total electron content (TEC) patterns and their behaviour. The ionospheric response to the activity of the Etna volcano has been analysed using global navigation satellite system (GNSS)-derived TEC values, employing data from International GNSS Service (IGS) reference station near the volcano and on two distant IGS locations. Volcanic activity has been modelled using volcanic radiative power (VRP) data obtained by the Middle InfraRed Observation of Volcanic Activity (MIROVA) system. The estimated minimal night TEC values have been averaged over defined index days of the VRP increase. During the analysed period of 19 years, the volcano activity was categorised according to pre-defined criteria. The influence of current space weather and short-term solar activity on TEC near the volcano was systematically minimised. The results showed mean/median TEC increases of approximately +3 standard deviations from the overall mean values, with peak values placed approximately 5 days before the VRP increase and followed by general TEC depletion around the time of the actual volcanic activity increase. Additionally, TEC oscillation pattern was found over the volcano site with a half-period of 6.25 days. The main interpretation of results indicates that the volcanic activity has modified the ionospheric dynamics within the nearby ionospheric region before the actual VRP increase, and that the residual impact in the volcano’s surrounding area refers to terrestrial endogenous processes and air–earth currents. Those changes can be detected during criteria predefined in the research: during quiet space weather conditions, observing night-time TEC values and within the limits of low short-term solar influence.

Global and regional positional accuracy assessment is of the highest importance for any satellite navigation system, including the Global Positioning System (GPS). Although positioning error can be expressed as a vector quantity with direction and magnitude, most of the research focuses on error magnitude only. The positional accuracy can be evaluated in terms of navigational quadrants as further refinement of error distribution, as it was shown here. This research was conducted in the wider area of the Northern Adriatic Region, employing the International Global Navigation Satellite Systems (GNSS) Service (IGS) data and products. Similarities of positional accuracy and deviations distributions for Single Point Positioning (SPP) were addressed in terms of magnitudes. Data were analyzed during the 11-day period. Linear and circular statistical methods were used to quantify regional positional accuracy and error behavior. This was conducted in terms of both scalar and vector values, with assessment of the underlying probability distributions. Navigational quadrantal positioning error subset analysis was carried out. Similarity in the positional accuracy and positioning deviations behavior, with uneven positional distribution between quadrants, indicated the directionality of the total positioning error. The underlying distributions for latitude and longitude deviations followed approximately normal distributions, while the radius was approximated by the Rayleigh distribution. The Weibull and gamma distributions were considered, as well. Possible causes of the analyzed positioning deviations were not investigated, but the ultimate positioning products were obtained as in standard, single-frequency positioning scenarios.

Solar-induced earthquakes are a relatively new field of research of possible connection between events originating from Sun, and the Earth's lithosphere dynamics. This is a theory that tries to explain the temporal correlation between the solar activity increase, particularly measured using proton density values, and occurrence of the strongest earthquakes on Earth. In this paper, the case study of Croatian major earthquake in December 2020 was investigated. The increase in proton density as measured by STEREO satellite, by +4.2 standard deviations from the monthly mean value, preceded the main shock of M=6.4 by 16 hours. Such proton density increases, within one day before major earthquake, agrees with previous research where strong temporal correlation of those two events was found.

Prediction of satellite positioning errors represents a substantial step towards the Global Navigation Satellite System (GNSS) performance assessment. Satellite positioning accuracy in the particular area can be expected to be similar due to prevailing environmental conditions. This similarity opens the opportunity to estimate and predict the positioning errors of close locations. The paper aims to develop a regional model of positioning errors estimation for Global Positioning System (GPS) single-frequency receivers based on ground truth data from reference stations, in this phase considering different levels of space weather activity as one f the criteria defining environmental conditions. The model should provide a simple positioning error prediction in cases where reference stations and respective data do not exist. The space weather conditions were examined to determine the influence on GPS satellite positioning performance at three selected International GNSS Service (IGS) stations in the Adriatic Region - Graz, Padua, and Matera. The mutual relations in terms of positioning error patterns were elaborated. The same 15-day period in three consecutive years was analysed. Pearson’s coefficient was utilised as a major indicator for determining the degree of correlation. The data from IGS stations Padua and Graz showed better, significant correlation results. The IGS station Matera, located farther and southward slightly differed in positioning deviations’ patterns and was not used for the model development. Satellite positioning errors of IGS Padua were used as a reference to determine the positioning errors of IGS Graz. Due to the significant correlation results, the linear regression model has been developed for the latitude, longitude, and height positioning errors. The final model coefficients were calculated as average values of the model coefficients for latitude, longitude, and height errors for elaborated periods. The cross-validation with five folds has been carried out, showing good model performance with R2 values of 0.7785 for geographic latitude, 0.8132 for the geographic longitude, and 0.7796 for height above sea level, respectively. The validation showed that the model could be applied during all levels of space weather activity on a regional basis.

The international trade, in the long run being influenced primarily by global economy, is hardly imaginable without maritime transport of goods. The investors in the shipping market, i.e. shipowners, foresee the key return of their capital investments through collection of the freight payments. Consequently, the position and ultimately survival of the owners is intensely influenced with the freight rate cycles, which in turn depend on demand and supply of ships. As historically proved, the higher the freight rates, the more orders for new ships are secured by shipyards. Most of the factors that impact shipowners’ decisions, especially those related to placing the orders, thus extend their influence towards shipyards’ operations and earnings. Competition among shipyards to ever attract more shipowners and secure more new orders or higher value orders, results in expanding their facilities, shortening delivery dates, making their ships’ design more appealing, lowering prices, etc. Observing fluctuations of the market and understanding impact factors on the freight rates’ segment and on shipbuilding segment therefore, is a crucial occupation accompanying executive decision making process for both, shipbuilders and shipowners. Recent state of the global shipbuilding industry is presented in this paper, based on the most recently available data on shipping market and on the global shipbuilding activities. Near-future outlook is given through analysis of the current market developments and industry potentials as well as with respect to the rivalry among competitors. Besides, clarification of market present state’s impact factors is herein given and significant conclusions for their current development and future perspectives are addressed, considering available information.

Research into the consequences of the accumulation of copper biocides in the marine environment has intensified since the ban on the use of organotin tributyltin (TBT) and the introduction of copper-based compounds in antifouling (AF) coatings. The specific emission of copper biocides and the surface of the wetted area of a vessel are the key parameters for the estimation of biocide emission. The estimated values of specific emissions of copper biocides should be taken with caution and their limitations and suitability for various surfaces and types of vessel should be known. Baseline limitations are also present in determining vessels’ wetted area. The available models do not provide realistic values, allowing multiple deviations. The proposed method of determining the wetted area considering container vessels and the specifics of their forms results in a set of hydrostatic diagrams that enable much more accurate estimation. The use of Automatic Identification System (AIS) is also proposed in terms of independent collection of required calculation parameters, enabling a full assessment of the total emission of copper biocides from container ships in the observed area.

Modelling of the ionospheric Total Electron Content (TEC) represents a challenging and demanding task in Global Navigation Satellite Systems (GNSS) positioning performance. In terms of satellite Positioning, Navigation and Timing (PNT), TEC represents a significant cause of the satellite signal ionospheric delay. There are several approaches to TEC estimation. The Standard (Klobuchar) ionospheric delay correction model is the most common model for Global Positioning System (GPS) single-frequency (L1) receivers. The development of International GNSS Service (IGS) Global Ionospheric Maps (GIM) has enabled the insight into global TEC dynamics. GIM analyses in the Northern Adriatic area have shown that, under specific conditions, local ionospheric delay patterns differ from the one defined in the Klobuchar model. This has been the motivation for the presented research, with the aim to develop a rudimentary model of the TEC estimation, with emphasis on areas where ground truth data are not available. The local pattern of the ionospheric delay has been modelled with wave functions based on the similarity of waveforms, considering diurnal differences in TEC behavior from defined TEC patterns. The model represents a spatiotemporal winter-time ionospheric delay correction with the Klobuchar model as a basis. The evaluation results have shown accurate approximation of the local pattern of the ionospheric delay. The model was verified in the same seasonal period in 2007, revealing it successfulness under pre-defined conditions. The presented approach represents a basis for the further work on the local ionospheric delay modelling, considering local ionospheric and space weather conditions, thus improving the satellite positioning performance for single-frequency GNSS receivers.

The paper deals with some specific aspects of electronic chart ussage.The advantages of electronic charts over the traditional ones have been pointed out.Basic characteristics of S-57 standard with reference to SENC have been set out.A particular attention has been paid to ECS-Ecdis relation.Sincly timely alarms and warnings are utmost importance for the enhancement of safety at sea including risk avoidance, three major kinds of messages covering obut 95% of near incident situations have been analysed.

In the proposed paper, structural analysis of relevant parameters of the maritime coastal line ZadarPreko (Croatia) was conducted. Passenger and vehicle traffic are observed during a three-year period. Based on the official data processing, parameters of the existing line capacity utilization are determined on a monthly basis. The passenger and vehicle turnover is presented as well as the utilized and nonutilized carrying capacities of the line. The highly seasonal nature of the turnover is emphasized as a result of tourist season, including the discussion on the line unprofitability for the shipping company which is directly due to the seasonality. In this connection, the need for a Government grant is further discussed with a view to maintaining sufficient carrying capacities and line frequency. For further research, a conceptual system is suggested to be based on computer simulations aimed at optimizing the operation of the terminal.

The importance of the Port of Ploče lies in serving the majority of the Bosnian market. However, the Pan-European Corridor Vc provides access to a much wider market in Central and South-Eastern Europe. The purpose of this paper is to express views on the future development of the Corridor and its consequential impact on the Port. This was conducted by means of analysis, comparison, and synthesis of cargo flow data and the dynamics data of the Corridor Vc construction. It covers the relations between Bosnia and Herzegovina (BiH) and the Republic of Croatia, and the assessment of importance of the Corridor in those countries. Statistical indicators show the importance of the Corridor completion for the successful execution of port development plans. The analysis of the Corridor status points to the current prevailing circumstances in BiH that make its realization ultimately uncertain, especially its railway component. The findings show that the most significant obstacles for a successful realization of Port of Ploče development plans are not only within the BiH internal geo-political relationships but in the disputes between BiH and the Republic of Croatia (RH) as well. Consequently, it has been shown that the Port of Ploče is not able to define and carry out the necessary measures toward BiH on its own but necessarily with the participation of the RH Government. The analysis offers observations and recommendations for improving relations with BiH, which would significantly advance the completion of the Corridor in BiH. In this way, it would allow for a full establishment of the Port of Ploče on target markets.

The paper presents the application of the pseudo-spatial model of the GLONASS system in determining the navigation parameters of the vessel's movement together with the applied ionospheric model accuracy. The atmosphere affects the signal reception causing signal delay, which leads to the error of determining the navigation parameters of the ship, with ionosphere causing the greatest impact on error values. By forming and solving the system in which the number of equations corresponds to the number of visible satellites, with the input data of pseudo-range, the constant error of distance measurement and the known satellite coordinates, the current position of the vessel is obtained. Differentiating this system of equations results in a system that gives the velocity of the vessel concerning the three spatial coordinates. By reducing velocity change with respect to the two spatial coordinates, the final speed of the vessel is obtained. Utilizing a known velocity of the vessel with respect to the x and y coordinates, the direction of navigation is also possible to be determined. Various satellite systems with different mathematical algorithms predict the state of the ionosphere and the value of the incurred error. Dual-band receivers of the GLONASS system perform simultaneously receiving, processing and comparison of signals at two frequencies to which the ionosphere has a different level of interaction.

The Sun acts as the main driver of processes affecting the Earth's ionosphere, directly and indirectly influencing the Global Navigation Satellite System (GNSS) signals' timing measurements. Solar impacts can be categorized according to different timescales that are short-lasting (regarding minutes during solar events), diurnal, seasonal (yearly) and perennial, covering the duration of the solar cycle. The proposed paper deals with seasonal and solar cycle and its impact on Global Positioning System (GPS) single-frequency (L1) positioning accuracy. Solar activity was analyzed during 17 years of available observation data. For this purpose, Sunspot Number (SSN) and Daily Solar Flux 10.7 cm (SFD) were analyzed. Indices were compared with GPS three-dimensional positioning deviations calculated on three locations in the broader region of the Adriatic Sea. Positioning data were calculated as single frequency solutions, obtained from the International GNSS Service (IGS) Receiver INdependent EXchange (RINEX) data. A significant correlation has been found between positioning accuracy and elaborated indices, both with and without the employment of standard ionospheric correction model, as presented. The emphasis was given on unmodelled positioning solution or errors, respectively, to employ a GPS receiver as a partial solar activity indicator. Besides solar cycle related period, seasonal positioning deviations were analyzed in the frame of the Local Equatorial Coordinate System (LECS) with declination and hour angle as main coordinates. Detectable positioning error increase has been observed during periods of positive Sun declination (in Northern hemisphere), based on the scenario of 4 consecutive years within the elaborated period. Obtained results rendered the possibility of predictive modelling of the GPS L1 positioning error. For this purpose, the elastic net regression method was used, employing SSN and SFD indices as predictors. Results are presented and discussed, with observations and findings summarized in the concluding chapter, together with the desirable continuation of the research.

Satellite navigation represents official positioning mean in maritime navigation. Importance of Global Navigation Satellite System (GNSS) increases with the emerging number of the world fleet, standard and critical services as well as the development of autonomous vessels. Quality of the GNSS positioning performance can be assessed by positioning accuracy, availability and Dilution of Precision (DOP), latter representing the influence of satellite geometry. DOP values depend on the relative position of the receiver and visible satellites. The GNSS positioning error is approximately equal to the product of the respective DOP value and the ranging accuracy. In maritime navigation where vertical positioning component can be omitted, DOP is reduced to the horizontal determination (HDOP). Limit values are defined in respective Performance Standards provided by the International Maritime Organization (IMO). The aim is to state the improvement of GNSS performance regarding employment and combination of different GNSSs as related to GPS, being the most commonly used system in maritime navigation. GPS, GLONASS, Galileo and BeiDou observations from four stations located in Italy, Peru, China and the United States were used. These stations were chosen due to their locations and the availability of positioning from all operational GNSSs. For each location, all possible combinations between satellite constellations were made. The HDOP values, single frequency positioning solutions in a horizontal plane and positioning availability were analysed for December 2017. Analyses of HDOP values confirm improvements in satellite positioning compared to GPS. An insufficient number of BeiDou satellites over the United States resulted in large HDOP values at the MDO1 IGS station (Fort Davis, USA). For the same reason, the best average HDOP values were observed at the JFNG station (Jiufeng, China). Although not fully operational. the BeiDou system improved positioning performance when it was combined with a GPS system, as proved at the AREG IGS station, located in Arequipa, Peru. Moreover, the GPS/BeiDou combination had better performance at JFNG and PADO (Padua, Italy) stations when compared with GPS/GLONASS combination.