LOAC: a small aerosol optical counter/sizer for ground-based and balloon measurements of the size distribution and nature of atmospheric particles – Part 2: First results from balloon and unmanned aerial vehicle flights

Abstract

Abstract. In the companion (Part I) paper, we have described and evaluated a new versatile optical particle counter/sizer named LOAC (Light Optical Aerosol Counter), based on scattering measurements at angles of 12 and 60 • . That allows for some typology identification of particles (droplets, carbonaceous, salts, and mineral dust) in addition to sizesegregated counting in a large diameter range from 0.2 µm up to possibly more than 100 µm depending on sampling conditions . Its capabilities overpass those of preceding optical particle counters (OPCs) allowing the characterization of all kind of aerosols from submicronicsized absorbing carbonaceous particles in polluted air to very coarse particles (> 10-20 µm in diameter) in desert dust plumes or fog and clouds. LOAC's light and compact design allows measurements under all kinds of balloons, on-board unmanned aerial vehicles (UAVs) and atPublished by Copernicus Publications on behalf of the European Geosciences Union. 3674J.-B. Renard et al.: LOAC: a counter/sizer for ground-based and balloon measurements -Part 2 ground level. We illustrate here the first LOAC airborne results obtained from a UAV and a variety of scientific balloons. The UAV was deployed in a peri-urban environment near Bordeaux in France. Balloon operations include (i) tethered balloons deployed in urban environments in Vienna (Austria) and Paris (France), (ii) pressurized balloons drifting in the lower troposphere over the western Mediterranean (during the Chemistry-Aerosol Mediterranean Experiment -ChArMEx campaigns), (iii) meteorological sounding balloons launched in the western Mediterranean region (ChArMEx) and from Aire-sur-l'Adour in south-western France (VOLTAIRE-LOAC campaign). More focus is put on measurements performed in the Mediterranean during (ChArMEx) and especially during African dust transport events to illustrate the original capability of balloon-borne LOAC to monitor in situ coarse mineral dust particles. In particular, LOAC has detected unexpected large particles in desert sand plumes.

Vertical profiles of aerosol mass concentration derived by unmanned airborne in situ and remote sensing instruments during dust events

“…This method assumes a linear relationship between the aerosol extinction and backscatter (i.e. the fixed lidar ratio S) throughout the entire atmospheric column, a critical assumption that can induce uncertainties up to 20-30 % of the retrieved property from statistical and systematic errors (Bösenberg and Brassington, 1997;Comerón et al, 2004;Rocadenbosch et al, 2010).…”

“…What is more, manned aircraft cannot cover the lowermost part of the atmosphere due to safety restrictions, posing another major limitation. Recent efforts in aerosol instrumentation have provided lightweight and miniaturized instruments that can measure the size and concentration of aerosol particles on board UAVs (Altstädter et al, 2015;Bezantakos et al, 2015Bezantakos et al, , 2017Barmpounis et al, 2016;Brady et al, 2016;Renard et al, 2016;Surawski et al, 2017) in a much simpler and cost-effective manner. As a result, vertical profiling of key aerosol parameters can now be performed over long periods of time on a routine basis, and at much lower altitudes compared to measurements with manned research aircraft.…”

Adapted ECC ozonesonde for long-duration flights aboard boundary-layer pressurised balloons

“…During the 2012 and 2013 campaigns, this payload was either the ozone sensor under consideration in this article or the LOAC 4 sensor for measurement of aerosol properties (not in the scope of the present article, see Legain et al, 2013;Renard et al, 2016b, a).…”

In situ measurements of desert dust particles above the western Mediterranean Sea with the balloon-borne Light Optical Aerosol Counter/sizer (LOAC) during the ChArMEx campaign of summer 2013

“…Briefly, the instrument provides aerosol particle concentration measurements within 19 size classes in the 0.2-100 µm diameter size range, and an estimate of the typology of aerosols based on dual-angle measurements. LOAC can be carried by all kinds of balloons (Renard et al, 2016b). The gondola weight, including the instrument, batteries (alkaline or lithium), and telemetry system, is about 1.0 kg, for an electric consumption of 3 W. Aerosols are sucked in by a small pump in order to pass through a red laser diode beam.…”