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.

This paper examines the correlation between strong wind and the frequency of small leisure craft grounding by analysing the available data on maritime accidents in the Adriatic. The primary goal of this study was to verify the hypothesis from prior research that strong wind is the prime cause of groundings in certain areas of the Adriatic. Contrary to the conclusions of the prior research, the new analysis indicates a far more uniform spatial distribution of wind-caused grounding accidents across all the examined areas of Croatian Adriatic waters. Furthermore, the analysis indicates that most grounding accidents occur in light wind conditions, suggesting that groundings can predominantly be attributed to factors other than strong wind. Several important drawbacks of the analysis stemming from the lack of accurate data on accidents in Croatian waters are discussed and suggestions given for the improved collection thereof that would greatly contribute to the future research on this topic. The inability to determine the exact causes of particular accidents from available data makes it impossible to accurately establish the number of grounding accidents caused by strong wind. In the future, more detailed statistical data could improve our understanding of the correlation between adverse weather conditions and recreational vessel accidents in the Adriatic.

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.

In this study, the results of an evaluation of current navigational simulator Transas NTPRO 5000 ability of realistic training in search operations by radar has been presented. By testing the performance of detecting different targets at various distances from the vessel model and comparing the results to the theoretical models of radar limitations from the literature, we found that the equipment can be used in search and rescue training, but with several important limitations. Some aspects of radar simulation in the current simulator version is considered as acceptably realistic, but we identified several points where the results showed significant deviations from the theoretical models. Those points limit the equipment's ability to perform some aspects of search-by-radar training, and the instructors are advised to carefully set up exercises in a way that those shortcomings are avoided during student training.