Chemical composition and source attribution of submicron aerosol particles in the summertime Arctic lower troposphere

Abstract

Abstract. We use airborne measurements of aerosol particle composition to demonstrate the strong contrast between particle sources and composition within and above the summertime Arctic boundary layer. In-situ measurements from two complementary aerosol mass spectrometers, the ALABAMA and the HR-ToF-AMS, with black carbon measurements from an SP2 are presented. Particle composition analysis was complemented by trace gas measurements, satellite data, and air mass history modeling to attribute particle properties to particle origin and air mass source regions. Particle composition above the summertime Arctic boundary layer was dominated by chemically aged particles, containing elemental carbon, nitrate, ammonium, sulfate, and organic matter. From our analysis, we conclude that the presence of these particles was driven by transport of aerosol and precursor gases from mid-latitudes to Arctic regions. Particularly, elevated concentrations of nitrate, ammonium, and organic matter coincided with time spent over vegetation fires in northern Canada. In parallel, those particles were largely present in high CO environments (> 90 ppbv). Additionally, we observed that the organic-to-sulfate ratio was enhanced with increasing influence from these fires. Besides vegetation fires, particle sources in mid-latitudes further include anthropogenic emissions in Europe, North America, and East Asia. The presence of particles in the Arctic lower free troposphere correlated with time spent over populated and industrial areas in these regions. Further, the size distribution of free tropospheric particles containing elemental carbon and nitrate was shifter to larger diameters compared to particles present within the boundary layer. Moreover, our analysis suggests that organic matter when present in the Arctic free troposphere can partly be identified as low-molecular weight dicarboxylic acids (oxalic, malonic, and succinic acid). Particles containing dicarboxylic acids were largely present when the residence time of air masses outside Arctic regions was high. In contrast, particle composition within the marine boundary layer was largely driven by Arctic regional processes. Air mass history modeling demonstrated that alongside primary sea spray particles, marine-biogenic sources contributed to secondary aerosol formation by trimethylamine, methanesulfonic acid, sulfate, and other organic species.

Chemical analysis of the Asian Tropopause Aerosol Layer (ATAL) with emphasis on secondary aerosol particles using aircraft based in situ aerosol mass spectrometry

“…We used the software package CRISP (Concise Retrieval of Information from Single Particles; Klimach, 2012) to perform m/z (ion mass to charge ratio) calibration, peak area integration, and particle classification. Particles were classified by a combination of fuzzy-c means clustering (Hinz et al, 1999;Roth et al, 2016;Schneider et al, 2021) and the marker ion method (Köllner et al, 2017(Köllner et al, , 2021. For this study, we classified particles in two main categories: particles containing solely components typical for secondary formation like nitrate, sulphate, and organics (secondary type) and particles containing a mixture of secondary as well as primary components like soot, metals, salt, and organics from biomass-burning (primary or mixed type).…”

Design, characterization, and first field deployment of a novel aircraft-based aerosol mass spectrometer combining the laser ablation and flash vaporization techniques

“…Although several aerosol instruments can be operated simultaneously at one location during ground-based measurements or in 25 a laboratory environment, e.g., Möhler et al (2008), Dall'Osto et al (2012), and Roth et al (2016), up to now rarely two different aerosol mass spectrometers were available on the same aircraft, e.g., Murphy et al (2006a), Hodzic et al (2020), Schneider et al (2019), Guo et al (2021), and Köllner et al (2021). Since the two techniques deliver complementary information on the aerosol composition and also cover slightly different size ranges, a single instrument implementing both methodologies in one apparatus has obvious advantages, provided that it is sufficiently small and light.…”