A study on the connection between the state of the atmosphere, as represented by cluster-mean trajectories, and the chemical composition of precipitation at the Croatian GAW regional station of Zavižan is presented. The trajectory cluster analysis has been done on the basis of daily backward trajectories calculated for 1996, using the HYSPLIT_4 trajectory model. The seasonal cluster analysis indicates four major flow directions in the region:
1) fast W-NW flow, 2) strong SW flow, 3) N-NE flow, 4) very short trajectories of different directions. The major transport route that brings higher levels of acidifying compounds to the region, is from the NW wind sector. The most polluted precipitation has been observed in spring with precipitation connected with three cluster means: NNW, SE and E