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Abstract: The present study investigates and compares the ground and in-flight performance of three miniaturized aerosol absorption sensors integrated on board small-sized Unmanned Aerial Systems (UASs). These sensors were evaluated during two contrasted field campaigns performed at an urban site, impacted mainly by local traffic and domestic wood burning sources (Athens, Greece), and at a remote regional background site, impacted by long-range transported sources including dust (Cyprus Atmospheric Observatory, Agia Marina Xyliatou, Cyprus). The miniaturized sensors were first intercompared at the ground-level against two commercially available instruments used as a reference. The measured signal of the miniaturized sensors was converted into the absorption coefficient and equivalent black carbon concentration (eBC). When applicable, signal saturation corrections were applied, following the suggestions of the manufacturers. The aerosol absorption sensors exhibited similar behavior against the reference instruments during the two campaigns, despite the diversity of the aerosol origin, chemical composition, sources, and concentration levels. The deviation from the reference during both campaigns concerning (eBC) mass was less than 8 %, while for the absorption coefficient it was at least 15 %. This indicates that those sensors that report black carbon mass are tuned and corrected to measure eBC more accurately than the absorption coefficient. The overall potential use of miniature aerosol absorption sensors on board small UASs is also illustrated. UAS-based absorption measurements were used to investigate the vertical distribution of eBC over Athens up to 1 km above sea level during January 2016, exceeding the top of the planetary boundary layer (PBL). Our results reveal a heterogeneous boundary layer concentration of absorbing aerosol within the PBL intensified in the early morning hours due to the concurrent peak traffic emissions at ground-level and the fast development of the boundary layer. After the full development of the PBL, homogenous concentrations are observed from 100 m a.g.l. to the PBL top.
Keywords: Unmanned Aerial Systems, Cyprus Atmospheric Observatory, eBC, vertical profiling, microaethalometer
Published in RUNG: 13.05.2024; Views: 971; Downloads: 3
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Abstract: Abstract. The geographical origin and source apportionment of submicron carbonaceous aerosols (organic aerosols, OAs, and black carbon, BC) have been investigated here for the first time, deploying high time-resolution measurements at an urban background site of Nicosia, the capital city of Cyprus, in the eastern Mediterranean. This study covers a half-year period, encompassing both the cold and warm periods with continuous observations of the physical and chemical properties of PM1 performed with an Aerosol Chemical Speciation Monitor (ACSM), an aethalometer, accompanied by a suite of various ancillary offline and online measurements. Carbonaceous aerosols were dominant during both seasons (cold and warm periods), with a contribution of 57 % and 48 % to PM1, respectively, and exhibited recurrent intense nighttime peaks (> 20–30 µg m−3) during the cold period, associated with local domestic heating. The findings of this study show that high concentrations of sulfate (close to 3 µg m−3) were continuously recorded, standing among the highest ever reported for Europe and originating from the Middle East region. Source apportionment of the OA and BC fractions was performed using the positive matrix factorization (PMF) approach and the combination of two models (aethalometer model and multilinear regression), respectively. Our study revealed elevated hydrocarbon-like organic aerosol (HOA) concentrations in Nicosia (among the highest reported for a European urban background site), originating from a mixture of local and regional fossil fuel combustion sources. Although air masses from the Middle East had a low occurrence and were observed mostly during the cold period, they were shown to strongly affect the mean concentrations levels of BC and OA in Nicosia during both seasons. Overall, the present study brings to our attention the need to further characterize primary and secondary carbonaceous aerosols in the Middle East, an undersampled region characterized by continuously increasing fossil fuel (oil and gas) emissions and extreme environmental conditions, which can contribute to photochemical ageing.
Keywords: PM1, BC, source apportionment, Cyprus, long range transport
Published in RUNG: 10.05.2024; Views: 890; Downloads: 6
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Abstract: The present invention belongs to the field of devices and methods for measurement of particle concentration, more precisely to the field of devices and methods for quantification of particles based on their physical characteristics, especially with the use of optical means. The invention relates to a method for determination of ambient mineral dust concentration based on optical absorption of particles concentrated by a virtual impactor as well as a device performing the said method. The method comprises the following steps:- Sampling air samples with particle size smaller than 1 µm (PM1) and sampling air samples with particle size up to 10 µm;- Concentrating the samples with particle sizes up to 10 µm with a virtual impactor;- Measuring optical absorption of collected samples at least one wavelength from UV to IR spectre, preferably from 370 to 950 nm, most preferably at 370 nm;- Subtracting the absorption of the samples with particle size smaller than 1 µm from the absorption of the sample concentrated by the virtual impactor.
Keywords: dust, black carbon, aerosols
Published in RUNG: 24.04.2024; Views: 1805; Downloads: 7
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Keywords: mineral dust, optical absorption, virtual impactor
Published in RUNG: 22.11.2021; Views: 3080; Downloads: 0
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