Articles | Volume 17, issue 7
Research article
12 Apr 2017
Research article |  | 12 Apr 2017

Ice nucleating particles over the Eastern Mediterranean measured by unmanned aircraft systems

Jann Schrod, Daniel Weber, Jaqueline Drücke, Christos Keleshis, Michael Pikridas, Martin Ebert, Bojan Cvetković, Slobodan Nickovic, Eleni Marinou, Holger Baars, Albert Ansmann, Mihalis Vrekoussis, Nikos Mihalopoulos, Jean Sciare, Joachim Curtius, and Heinz G. Bingemer

Abstract. During an intensive field campaign on aerosol, clouds, and ice nucleation in the Eastern Mediterranean in April 2016, we measured the abundance of ice nucleating particles (INPs) in the lower troposphere from unmanned aircraft systems (UASs). Aerosol samples were collected by miniaturized electrostatic precipitators onboard the UASs at altitudes up to 2.5 km. The number of INPs in these samples, which are active in the deposition and condensation modes at temperatures from −20 to −30 °C, were analyzed immediately after collection on site using the ice nucleus counter FRIDGE (FRankfurt Ice nucleation Deposition freezinG Experiment). During the 1-month campaign, we encountered a series of Saharan dust plumes that traveled at several kilometers' altitude. Here we present INP data from 42 individual flights, together with aerosol number concentrations, observations of lidar backscattering, dust concentrations derived by the dust transport model DREAM (Dust Regional Atmospheric Model), and results from scanning electron microscopy. The effect of the dust plumes is reflected by the coincidence of INPs with the particulate matter (PM), the lidar signal, and the predicted dust mass of the model. This suggests that mineral dust or a constituent related to dust was a major contributor to the ice nucleating properties of the aerosol. Peak concentrations of above 100 INPs std L−1 were measured at −30 °C. The INP concentration in elevated plumes was on average a factor of 10 higher than at ground level. Since desert dust is transported for long distances over wide areas of the globe predominantly at several kilometers' altitude, we conclude that INP measurements at ground level may be of limited significance for the situation at the level of cloud formation.

Short summary
In this paper we present data of ice-nucleating particles (INPs) from a 1-month campaign in the Eastern Mediterranean using unmanned aircraft systems (UASs, drones) and offline sampling with subsequent laboratory analysis. To our knowledge, this is the first time INPs were measured onboard a UAS. We find that INP concentrations were 1 magnitude higher aloft than at the ground, highlighting that surface-based measurement of INP may only be of limited significance for the situation at cloud level.
Final-revised paper