1. Aerosols measurements by the LOAC instruments under meteorological balloons (BLD) J.-B. RENARD AND THE LOAC TEAM LPCER-CNRS, ORLÉANS

2. LOAC : light aerosol counter Concentrations in 19 size classes between 0.2 and ~100  m BLD (troposphere and stratosphere) BPCL (long duration and low altitude in the troposphere)

3. Estimation of the main nature of the aerosols using the measurements at 2 different scattering angles Comparison to abacus obtained in laboratory Saharan sand Black carbon

4. 19 flights under BLD (14 from Minorca and 5 from Ile du Levant) 12 flights under BCPL (9 from Minorca and 3 from Ile du Levant) BLD flights: Measurements during 3 sands plumes period: - 15 – 19 June 2013 (major event), flights every ~12 hours - 27 June – 2 July 2013 (minor events) - 28 July – 4 August 2013 (major event at the end of the period) Measurements in background conditions: - 22 July 2013

5. 15 -19 June 2013 sand event 15 June 2013 evening 16 June 2013 mid-time 16 June 2013 evening 17 June 2013 mid-time17 June 2013 evening18 June 2013 afternoon

6. - Time evolution - Vertical extend of several km - Presence of some large particles (> 10  m) - Unexpected “strong” electromagnetic field inside the plume => sometimes perturbations in the LOAC measurements 18 June 2013 evening19 June 2013 mid-time19 June 2013 afternoon

7. “Pure sand”, but also mixture of sand, salt and carbon (and sometimes inaccurate speciation due to the EM contaminations) 15 June 2013 evening 18 June 2013 evening

8. Comparison to volume size distribution from AERONOET photometers at Cap d’En Font (Minorca) – excellent agreement (LOAC data with radius > 10  m excluded) Sometime LOAC detects a “third mode” around radius=0.5  m

9. Other sand plume events : Also presence of large particles and the electro-magnetic perturbations 4 August 2013, afternoon Sand plume Liquid aerosols

10. Pure sand, and mixture of sand and salt, and sometimes small carbon particles, depending on the altitude 4 August 2013, afternoon 4 km 0.5 km 6 km

11. Conclusions LOAC has provided: - in-situ measurements on the vertical distribution of the aerosols - direct size distributions, with the presence of large particles - identification of the main nature of the particles - evidence of the presence of electro-magnetic fields