Long term lidar measurements of aerosol properties over thessaloniki Nikolaos Siomos, Kalliopi A. Voudouri, Eleni Giannakaki, Vasilis Amiridis, Maria Filioglou, Alexandros Papayannis and Dimitris S. Balis EPJ Web Conf., 176 (2018) 05033 Published online: 13 April 2018 DOI: 10.1051/epjconf/201817605033