Poster EMS 2017-103 Session OSA 1.12 Using a small network of ceilometers in Austria to investigate a Saharan dust episode in April 2016 PM concentration measurements at three mountain tops Ceilometer aerosol backscatter profiles The combination of these measurements renders an optimum basis for the interpretation of air pollution events caused by long-range (e.g. Saharan dust) transport to the Alps. Mountain top air quality stations and ceilometer sites Webcame pictures before and during the event Sonnblick 26.3.2016 15:00 Sonnblick 5.4.2016 16:00 Dobratsch 18.3.2016 13:30 Dobratsch 5.4.2016 13:00 The episode lasted from March 31 to April 8, 2016. Several sub-episodes could be observed. The event peaked on April 5. On that day, daily concentrations exceeded 50 µgm-3 PM10 at most air quality stations in the Eastern Alpine area. On April 4 and 5, the ceilometer vertical backscatter profiles are in line with the PM10 concentrations at the mountain tops. Starting with April 6, cloudiness was observed at the North- and the Central-Alpine sites, and the Saharan dust cloud was no longer visible at these sites. It could however be detected at the South-Alpine site until the end of the period. Due to vigorous turbulent mixing, aerosols were most of the time equally distributed up to about 3 km. This situation is not favourable for mixing height detection, as the methodology needs distinct aerosol layer heights. Only with the onset of cloudiness, a continuous detection of the mixing height was possible. Mean daily course of MH Base of Dobratsch Time course of PM10 concentrations at mountain tops (upper panel) and ceilometer aerosol backscatter plots at nearby stations (lower panel) indicating also the mixing height (MH, yellow line, method of ZAMG) Base of Sonnblick Reduced sunshine duration, frequent low aerosol content MH can be detected in only 50 % of the time Contact: Martin Piringer, martin.piringer@zamg.ac.at, Tel. 0043 1 360 26 / 2401, www.zamg.ac.at