Cluster analysis as a statistical method for identification of the water bodies present in the Gulf of Trieste (Northern Adriatic Sea)

In the framework of Project \"Alpe Adria\", between 1991 and 1993, vertical CTD profiles were taken in the Gulf of Trieste. Temperature, salinity and density are averaged over metre intervals and analyzed with a cosine least squares fit procedure using two waves of annual and semiannual period. Data are organized into monthly matrices, on which cluster analysis, with a complete linkage method, based on the similarity ratio matrix is done. Four different water bodies are identified in the Gulf during the year using this method. However, only three water bodies are noted in November, mainly due to the break in thermal stratification and to mixing. The vertical distribution of the density excess varies seasonally, and shows the dominance of dense and homogeneous water during the winter, and strong stratification during the summer. Furthermore, an estimation of the volume of the water masses present and their temporal evolution is computed.