Airborne measurements of volcanic particles and gases with small aircrafts - Examples of measurements in the Eyjafjallajökull ash plume over Germany and Iceland

During the 2010 eruption period of the Eyjafjallajökull the University of Applied Sciences of Duesseldorf and the University of Reykjavik performed several measurement flights with small aircraft in the volcanic plume. Whereas the University of Applied Sciences mapped the distal plume over Germany, the University of Iceland explored the airspace overwestern Iceland and near the Eyjafjallajökull, partly entering the volcanic plume boundary directly. The use of the small piston-motor driven research aircraft in the special situation of volcanic plumes has several advantages over jet engine driven research aircrafts: The piston-motor driven aircraft are robust enough to operate even at elevated ash concentration levels. The small aircrafts allow a low cruising speed during the measurements and have thus the advantage of delivering results with a high spatial resolution. The low possible aircraft cruising speed during the  measurements simplifies the intake of even bigger ash particles into the measurement systems. Small aircraft allow a very cost effective operation. The aircraft were equipped with optical particle counters (OPCs) for on-line in-situ results. Moreover, the German aircraft was equipped with a DOAS system for SO2 and a
NDIR analyzer for CO2 measurements. The measurement flights revealed that the ash plume over Germany had a very inhomogeneous structure. Sub-plumes
and different vertical plume layers could be identified. Regional elevated SO2 concentrations could be detected. Peak ash particle concentrations of more than 330 μg/m3 could be found during the measurement flights over northern Germany, whereas the flights over Iceland showed low concentrations outside the plume, but values of about 2000 μg/m3 within the boundary of the plume.