engleski

Trajectory cluster analysis for two Croatian mountainous locations

The synoptic meteorological influence on the pollution transport is assessed for Risnjak (1528 m asl.) and Troglav (1913 m asl.) - locations situated at two adjacent mountainous regions close to the Adriatic sea. For both of these two regions is provided a proper "weather type climatology" based on a local weather type classification which is in application in Croatia last thirty five years (Poje, 1965). Simultaneously, different atmospheric transport to the Risnjak and Troglav suggest the more or less different weather types predomination at two regions. The transport differences between these two locations are more precisely analysed applying the statistical technique of cluster analysis to isentropic trajectories arriving at each location. For Risnjak and Troglav are calculated 366 three-dimensional 72-h backward trajectories for the period January-December 1996. The HYSPLIT4 (Hybrid Syngle-Particle Lagrangian Integrated Trajectory) model has been used (Draxler and Hess, 1999). The calculation started from 100 m agl. once a day beginning at 0600 UTC. The cluster program developed by Stunder (1996), which is used for the purpose of this paper, uses Ward's method (Ward, 1963). Clusterin is applied in classification of all 366 trajectories for the whole one-year period as well as in classifcation of the seasonal trajectories. For each season and a year in all and for each location separately, the appropriate number of cluster is identified as well as the cluster-mean trajectories. Namely, the cluster model used offers few numbers of clusters for each period considered. At first, this paper shows the results of the analysed significance for pollution transport of all the clusters groups of trajectories suggested by the model. Discovered are mainly the different numbers of corressponding clusters representative for the same period for Risnjak and Troglav. Finally, the comparisons of the mentioned finally accepted numbers of clusters are shown together with the appropriate cluster-mean trajectories for Risnjak and Troglav.

trajectory; cluster analysis; Croatia

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