Principal component analysis (PCA) was carried out on annual snow cover series from 15 mountain climate stations in Bulgaria to characterize the spatial and temporal variability in snow cover over the 1931-2000 period. The PC analysis revealed three distinct snow cover response regions in Bulgarian mountains: (1) high elevation sites above 1500 mASL; (2) the eastern Rodope Mountains and (3) a mid-mountain zone covering 1000-1500 mASL. Over the 1931-2000 period snow cover exhibited evidence of decadal-scale variability but no evidence of any long-term trends linked to
climate warming. Over the more recent 1971-2000 period stations in the 1000-1500 elevation band have exhibited more coherent temporal variability in maximum snow accumulation and a trend toward a later start to the snow cover season. No clear links were found between snow cover variability and NAO, and only spring snow cover at the higher elevation sites was found to be significantly correlated with regional air temperatures. The results reflect the complex climate of Bulgaria
