Overview of aerosol properties associated with air masses sampled by the ATR-42 during the EUCAARI campaign (2008)

Abstract

Within the frame of the European Aerosol Cloud Climate and Air Quality Interactions (EUCAARI) project, the Météo-France aircraft ATR-42 performed 22 research flights over central Europe and the North Sea during the intensive observation period in May 2008. For the campaign, the ATR-42 was equipped to study the aerosol physical, chemical, hygroscopic and optical properties, as well as cloud microphysics. For the 22 research flights, retroplume analyses along the flight tracks were performed with FLEXPART in order to classify air masses into five sectors of origin, allowing for a qualitative evaluation of emission influence on the respective air parcel. <br></br> This study shows that the extensive aerosol parameters (aerosol mass and number concentrations) show vertical decreasing gradients and in some air masses maximum mass concentrations (mainly organics) in an intermediate layer (1–3 km). The observed mass concentrations (in the boundary layer (BL): between 10 and 30 μg m⁻³; lower free troposphere (LFT): 0.8 and 14 μg m⁻³) are high especially in comparison with the 2015 European norms for PM_2.5 (25 μg m⁻³) and with previous airborne studies performed over England (Morgan et al., 2009; McMeeking et al., 2012). <br></br> Particle number size distributions show a larger fraction of particles in the accumulation size range in the LFT compared to BL. The chemical composition of submicron aerosol particles is dominated by organics in the BL, while ammonium sulphate dominates the submicron aerosols in the LFT, especially in the aerosol particles originated from north-eastern Europe (~ 80%), also experiencing nucleation events along the transport. As a consequence, first the particle CCN acting ability, shown by the CCN/CN ratio, and second the average values of the scattering cross sections of optically active particles (i.e. scattering coefficient divided by the optical active particle concentration) are increased in the LFT compared to BL

Aerosol processing and CCN formation of an intense Saharan dust plume during the EUCAARI 2008 campaign

“…The AMS provided information on the mass concentration of particulate organic matter (POM), nitrate, ammonium and sulfate. It should also be noted that the upper 50 % cut-off-diameter of the onboard AMS is about 500 nm (Crumeyrolle et al, 2013). As reported by Ansmann et al (2011) airborne multiwavelength backscatter lidar has proved to be a powerful technique for detecting dust plumes and their properties.…”

“…The calibration of the devices onboard the ATR-42 aircraft during the EUCAARI-IMPACT campaign and the evaluation of their performance are discussed in detail by Crumeyrolle et al (2013) and are only briefly described here. The aerosol instrumentation sampled the particles via the ATR-42 community aerosol inlet (CAI) (Crumeyrolle et al, 2013). The CAI was designed for the ATR to allow isokinetic and isoaxial sampling relative to the incoming air stream.…”

“…The cloud condensation nuclei counter (CCNC, DMT model no. CCN-100) onboard the ATR-42 aircraft was a continuousflow streamwise thermal gradient CCN counter (Crumeyrolle et al, 2013). The design and operating principles of the instrument are based on the work of Roberts and Nenes (2005).…”

“…The CAI was designed for the ATR to allow isokinetic and isoaxial sampling relative to the incoming air stream. This inlet has a 50 % sampling efficiency for particles with diameters around 5 µm (Crumeyrolle et al, , 2013McNaughton et al, 2007). The total ambient aerosol concentrations were measured by a condensation particle counter (CPC, TSI model 3010) aboard the ATR-42 aircraft every 1 s. The 50 % detection efficiency of the TSI 3010 CPC applies to particles of diameter larger than 10 nm and its relative uncertainty is about 5 % (Mertes et al, 1995).…”

Experimental Evidence of the Feeding of the Free Troposphere with Aerosol Particles from the Mixing Layer

“…Several airborne studies have highlighted the strong contribution from organic and sulphate aerosol particles in the FT (Heald et al, 2006;Murphy et al, 2006;Crumeyrolle et al, 2013). Sulphate particles in the FT can be formed from the OH oxidation of gas-phase SO 2 .…”