Temporal consistency of lidar observations during aerosol transport events in the framework of the ChArMEx/ADRIMED campaign at Minorca in June 2013

Abstract

Abstract. We performed synergetic daytime and nighttime active and passive remote-sensing observations at Minorca (Balearic Islands, Spain), over more than 3 weeks during the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Effect in the Mediterranean (ChArMEx/ADRIMED) special observation period (SOP 1a, June-July 2013). We characterized the aerosol optical properties and type in the low and middle troposphere using an automated procedure combining Rayleigh-Mie-Raman lidar (355, 387 and 407 nm) with depolarization (355 nm) and AERONET Cimel ® sun-photometer data. Results show a high variability due to varying dynamical forcing. The mean column-averaged lidar backscatter-to-extinction ratio (BER) was close to 0.024 sr −1 (lidar ratio of ∼ 41.7 sr), with a large dispersion of ±33 % over the whole observation period due to changing atmospheric transport regimes and aerosol sources. The ground-based remote-sensing measurements, coupled with satellite observations, allowed the documentation of (i) dust particles up to 5 km (above sea level) in altitude originating from Morocco and Algeria from 15 to 18 June with a peak in aerosol optical thickness (AOT) of 0.25 ± 0.05 at 355 nm, (ii) a long-range transport of biomass burning aerosol (AOT = 0.18 ± 0.16) related to North American forest fires detected from 26 to 28 June 2013 by the lidar between 2 and 7 km and (iii) mixture of local sources including marine aerosol particles and pollution from Spain. During the biomass burning event, the high value of the particle depolarization ratio (8-14 %) may imply the presence of dust-like particles mixed with the biomass burning aerosols in the mid-troposphere. For the field campaign period, we also show linearity with SEVIRI retrievals of the aerosol optical thickness despite 35 % relative bias, which is discussed as a function of aerosol type.

Long-range transport and mixing of aerosol sources during the 2013 North American biomass burning episode: analysis of multiple lidar observations in the western Mediterranean basin

“…The characteristics of the aerosol layers are summarized in Table 3. The Minorca lidar data are discussed in a companion paper by Chazette et al (2016). An aerosol layer between 3 and 5 km seen in Minorca is quite similar to the CALIOP observations on 28 June.…”

“…The large concentration of absorbing material (BC particles) within smoke plumes leads to significant absorption of solar radiations within the atmospheric layer where smoke resides, which could perturb the relative humidity and temperature vertical profiles. In the framework of the Chemistry-Aerosol Mediterranean Experiment/Aerosol Direct Radiative Impact in the Mediterranean (ChArMEx/ADRIMED) experimental campaign, many aerosol lidar and aircraft measurements were made in June-July 2013 in the Mediterranean region during a case of intense biomass burning transport from North America to Europe Chazette et al, 2016;Pelon et al, 2015). Only a few studies report such long-range transport observations from North America to Europe (Forster et al, 2001;Petzold et al, 2007) or even the eastern Mediterranean (Formenti et al, 2002).…”

Advanced characterisation of aerosol size properties from measurements of spectral optical depth using the GRASP algorithm

“…14 correspond to PLASMA measurements at different heights during one of the aforementioned dust plumes, specifically in the take-off from Minorca airport on the 17 June 2013 between 11:45 and 12:00 UTC (flight 32; Denjean et al, 2016). The average values of the three τ a data measured during this period by the ground-based AERONET sun photometer at Minorca (AERONET site Cap d'en Font; see Chazette et al, 2016) are also plotted as reference. Note that the groundbased sun photometer is standard (see description in Table A1) and does not have the 1640 nm channel.…”

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

“…Satellite-derived AOD shows that starting on 29 June, a new dust plume from north-western Africa with high AOD emerged from the Atlantic and Mediterranean coasts of Morocco. The plume extended a bit to the north and further east over the sea during the following days but remained confined to the southernmost part of the basin, with moderate AODs and some dust over Minorca on 2 July (AOD at 550 nm up to 0.22; Chazette et al, 2016). A BLPB flight was conducted on 2 July; the mean MODIS AOD was of 0.15 during this period.…”