Aerosol hygroscopicity and its link to chemical composition in coastal atmosphere of Mace Head: marine and continental air masses

Xu, Wei; Ovadnevaitė, Jurgita; Fossum, Kirsten N.; Cui, Lin; Huang, Ru‐Jin; O’Dowd, Colin; Čeburnis, Darius

doi:10.5194/acp-2019-839

Cited by 5 publications

(4 citation statements)

References 40 publications

(48 reference statements)

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“…The Newton-Raphson method is used to find the solution to the cubic electroneutrality equation, following Luo et al (2020) and Moch et al (2020). Ca 2+ and Mg 2+ are assumed to constitute 3 % and 0.6 %, respectively, of the dust by mass (Claquin et al, 1999;Fairlie et al, 2010;Nickovic et al, 2012;Shao et al, 2019;Moch et al, 2020) (Xu et al, 2020).…”

Section: Control Simulationmentioning

confidence: 99%

Global modeling of heterogeneous hydroxymethanesulfonate chemistry

Song

Zhang

et al. 2021

Atmos. Chem. Phys.

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Abstract. Hydroxymethanesulfonate (HMS) has recently been identified as an abundant organosulfur compound in aerosols during winter haze episodes in northern China. It has also been detected in other regions although the concentrations are low. Because of the sparse field measurements, the global significance of HMS and its spatial and seasonal patterns remain unclear. Here, we modify and add to the implementation of HMS chemistry in the GEOS-Chem chemical transport model and conduct multiple global simulations. The model accounts for cloud entrainment and gas–aqueous mass transfer within the rate expressions for heterogeneous sulfur chemistry. Our simulations can generally reproduce quantitative HMS observations from Beijing and show that East Asia has the highest HMS concentration, followed by Europe and North America. The simulated HMS shows a seasonal pattern with higher values in the colder period. Photochemical oxidizing capacity affects the competition of formaldehyde with oxidants (such as ozone and hydrogen peroxide) for sulfur dioxide and is a key factor influencing the seasonality of HMS. The highest average HMS concentration (1–3 µg m−3) and HMS ∕ sulfate molar ratio (0.1–0.2) are found in northern China in winter. The simulations suggest that aqueous clouds act as the major medium for HMS chemistry while aerosol liquid water may play a role if its rate constant for HMS formation is greatly enhanced compared to cloud water.

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Section: Control Simulationmentioning

confidence: 99%

Global modeling of heterogeneous hydroxymethanesulfonate chemistry

Song

Zhang

et al. 2021

Atmos. Chem. Phys.

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“…They observed no differences in the wet scavenging efficiency between different rainfall intensities for different aerosol species but noted that higher rainfall intensities were needed for larger particles to acquire the same removal efficiency over the tropics. Xu et al (2020) included air mass origins into their study of hygroscopicity and chemical composition of aerosols in Mace Head, on the coast of Ireland, and found out that wintertime aerosols were usually externally mixed for both continental and marine air masses.…”

Section: Introductionmentioning

confidence: 99%

The effect of clouds and precipitation on the aerosol concentrations and composition in a boreal forest environment

et al. 2022

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Abstract. Atmospheric aerosol particle concentrations are strongly affected by various wet processes, including below and in-cloud wet scavenging and in-cloud aqueous-phase oxidation. We studied how wet scavenging and cloud processes affect particle concentrations and composition during transport to a rural boreal forest site in northern Europe. For this investigation, we employed air mass history analysis and observational data. Long-term particle number size distribution (∼15 years) and composition measurements (∼8 years) were combined with air mass trajectories with relevant variables from reanalysis data. Some such variables were rainfall rate, relative humidity, and mixing layer height. Additional observational datasets, such as temperature and trace gases, helped further evaluate wet processes along trajectories with mixed effects models. All chemical species investigated (sulfate, black carbon, and organics) exponentially decreased in particle mass concentration as a function of accumulated precipitation along the air mass route. In sulfate (SO4) aerosols, clear seasonal differences in wet removal emerged, whereas organics (Org) and equivalent black carbon (eBC) exhibited only minor differences. The removal efficiency varied slightly among the different reanalysis datasets (ERA-Interim and Global Data Assimilation System; GDAS) used for the trajectory calculations due to the difference in the average occurrence of precipitation events along the air mass trajectories between the reanalysis datasets. Aqueous-phase processes were investigated by using a proxy for air masses travelling inside clouds. We compared air masses with no experience of approximated in-cloud conditions or precipitation during the past 24 h to air masses recently inside non-precipitating clouds before they entered SMEAR II (Station for Measuring Ecosystem–Atmosphere Relations). Significant increases in SO4 mass concentration were observed for the latter air masses (recently experienced non-precipitating clouds). Our mixed effects model considered other contributing factors affecting particle mass concentrations in SMEAR II: examples were trace gases, local meteorology, and diurnal variation. This model also indicated in-cloud SO4 production. Despite the reanalysis dataset used in the trajectory calculations, aqueous-phase SO4 formation was observed. Particle number size distribution measurements revealed that most of the in-cloud SO4 formed can be attributed to particle sizes larger than 200 nm (electrical mobility diameter). Aqueous-phase secondary organic aerosol (aqSOA) formation was non-significant.

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“…A subset of near‐hydrophobic (NH) mode particles has been observed in clean marine environment and reported by Xu et al. (2020), but their source remained unclear. Despite being observed in clean marine air masses their source could have been either anthropogenic or biogenic.…”

Section: Resultsmentioning

confidence: 99%