Serdjo Kos

Klobuchar-Like Local Model of Quiet Space Weather GPS Ionospheric Delay for Northern Adriatic

Ionospheric delay is the major source of satellite positioning system performance degradation. Designers of satellite positioning systems attempt to mitigate the impact of the ionospheric delay by deployment of correction models. For instance, the American GPS utilises a global standard (Klobuchar) model, based on the assumption that the daily distribution of GPS ionospheric delay values follows a biased cosine curve during day-time, while during the night-time the GPS ionospheric delay remains constant. Providing a compromise between computational complexity and accuracy, the Klobuchar model is capable of correcting up to 70% of actual ionospheric delay, mainly during quiet space weather conditions. Unfortunately, it provides a very poor performance during severe space weather, geomagnetic and ionospheric disturbances. In addition, a global approach in Klobuchar model development did not take into account particularities of the local ionospheric conditions that can significantly contribute to the general GPS ionospheric delay. Current research activities worldwide are concentrating on a better understanding of the observed GPS ionospheric delay dynamics and the relation to local ionosphere conditions. Here we present the results of a study addressing daily GPS ionospheric delay dynamics observed at a Croatian coastal area of the northern Adriatic (position Q=45xN, l=15xE) in the periods of quiet space weather in 2007. Daily sets of actual GPS ionospheric delay values were assumed to be the time series of composite signals, consisting of DC, cosine and residual components, respectively. Separate models have been developed that describe components of actual GPS ionospheric delay in the northern Adriatic for summer and winter, respectively. A special emphasis was given to the statistical description of the residual component of the daily distribution of GPS ionospheric delay, obtained by removing DC (bias) and cosine components from the composite GPS ionospheric delay. Future work will be focused on further evaluation and validation of a quiet space weather GPS ionospheric delay model for the northern Adriatic, transition to a non-Klobuchar model, and on research in local GPS ionospheric delay dynamics during disturbed and severe space weather conditions.

Ranking of sailing routes according to the potential number of groundings

AbstractThe paper presents the selection of ship sailing routes in the coastal area according to the probability of grounding. Taking into consideration the dangers in the heading direction as well as the vicinity and length of the coastline parallel to the ship course, the paper will try to propose a model for choosing the sailing route with the smallest possibility of grounding. The estimation of the dangers on the routes will be based on the potential number of groundings; human factor will not be taken into account, assuming that a human error on each route will have the same probability of occurrence.

Dst Index as a Potential Indicator of Approaching GNSS Performance Deterioration

Space weather disturbances cause considerable effects on Global Navigation Satellite Systems (GNSS) performance and operation, affecting society and the economy due to the growing reliance on GNSS, especially in densely populated mid-latitudes. Recent studies hypothesised potential utilisation of the Disturbance storm-time (Dst) index for indication of an approaching ionospheric storm and possible deterioration of the GNSS positioning performance. We challenged the hypothesis in the case of the Halloween 2003 event in an attempt to confirm the direct correlation between the Dst index dynamics and the Global Positioning System (GPS) positioning performance in the mid-latitude Mediterranean area. Our results provide no evidence of the direct Dst-GNSS performance correlation for the observed event.

Northern and Southern European Traffic Flow Land Segment Analysis as Part of the Redirection Justification

Natural geotraffic flows act as one of the most important factors directly affecting redirections of the world transportation routes. In terms of door‐to‐door multimodal transport chain, several routes from Far East toward European destinations exist, with Northern European route acting as prevailing one. The proposed paper elaborates possibilities of redirection of the traffic flow by directing cargoes to an alternative route through the Adriatic Sea. The aim is to justify realisation of mentioned possibility in terms of land transportation segment analysis, i.e. by analysing cargo transportation from ports to final destinations in Central Europe, placed in natural gravitational hinterland of ports of Northern Adriatic Port Association (NAPA). Geo‐traffic and logistics’ analyses of NAPA ports are presented in the paper. Container traffic and its trend as compared with Northern European ports are analysed. The development plans of inland connections are presented in function of justification of the traffic flow redirection. A model for the selection and evaluation of the optimal container transport route by using the multiple criteria analysis (MCA) has been introduced and developed. The model was applied for the selection of the representative service connecting Far East (origin) and the central Europe (destination) by detailed analysis of the land transportation segment. The PROMETHEE method was used for the model testing and evaluation. Summarised results are presented and discussed tending to confirmation of the traffic flow redirection justification. http://www.transnav.eu the International Journal on Marine Navigation and Safety of Sea Transportation Volume 11