Description of the four obtained line clusters. Top row: composition of each cluster. Each bar indicates the proportion of lines of a species in a cluster. The red crosses correspond to exactly zero line. For each cluster, the three species with most lines and the corresponding number of lines are highlighted. Bottom row: Pearson correlation of the most representative line of each cluster with the three main physical parameters. The most representative line of a cluster is defined as the line with the highest average correlation with the other lines. A round marker at a vertex indicates a negative correlation.