Case Study on Combined Lidar-Photometer Retrieval of Volcanic ASH Properties Josef Gasteiger, Matthias Wiegner, Carlos Toledano, Silke Groß and Volker Freudenthaler EPJ Web of Conferences, 119 (2016) 07004 Published online: 07 June 2016 DOI: 10.1051/epjconf/201611907004