Hygroscopicity and chemical composition of Antarctic sub-micrometre aerosol particles and observations of new particle formation

Abstract

Abstract. The Antarctic near-coastal sub-micrometre aerosol particle features in summer were characterised based on measured data on aerosol hygroscopicity, size distributions, volatility and chemical ion and organic carbon mass concentrations. Hysplit model was used to calculate the history of the air masses to predict the particle origin. Additional measurements of meteorological parameters were utilised. The hygroscopic properties of particles mostly resembled those of marine aerosols. The measurements took place at 130 km from the Southern Ocean, which was the most significant factor affecting the particle properties. This is explained by the lack of additional sources on the continent of Antarctica. The Southern Ocean was thus a likely source of the particles and nucleating and condensing vapours. The particles were very hygroscopic (HGF 1.75 at 90 nm) and very volatile. Most of the sub-100 nm particle volume volatilised below 100 °C. Based on chemical data, particle hygroscopic and volatile properties were explained by a large fraction of non-neutralised sulphuric acid together with organic material. The hygroscopic growth factors assessed from chemical data were similar to measured. Hygroscopicity was higher in dry continental air masses compared with the moist marine air masses. This was explained by the aging of the marine organic species and lower methanesulphonic acid volume fraction together with the changes in the inorganic aerosol chemistry as the aerosol had travelled long time over the continental Antarctica. Special focus was directed in detailed examination of the observed new particle formation events. Indications of the preference of negative over positive ions in nucleation could be detected. However, in a detailed case study, the neutral particles dominated the particle formation process. Freshly nucleated particles had the smallest hygroscopic growth factors, which increased subsequent to particle aging.

Aerosol Properties Observed in the Subtropical North Pacific Boundary Layer

“…One objective for this study is to classify size‐selected particle composition in the MBL based on observed particle hygroscopicity. Traditional HTDMA measurements, particularly within the MBL, define observed peaks in GF distributions as GF modes and have been referred to in the literature as being barely hygroscopic, moderately hygroscopic, and highly hygroscopic (sometimes also referred to as salt) particles (Asmi et al, ; Berg et al, ; Maβling et al, ; Swietlicki et al, ). Barely hygroscopic particles include primary and secondary carbonaceous aerosol with minimal hygroscopic salt content as well as mineral dust and iodine oxides.…”

“…In the case of sodium particles, sulfuric acid (nonneutralized SO 4 2− ) particles are the only particles with comparable hygroscopic properties (Good et al, ). However, observational data suggest that ammonium is generally ubiquitous in the marine atmosphere at molar fractions sufficient to at least partly neutralize sulfuric acid (Asmi et al, ; Heintzenberg et al, ; Ovadnevaite et al, ; Pio & Lopes, ; Quinn et al, ), and thus, suppress the hygroscopicity of sulfate‐containing particles.…”

“…A literature survey was performed to collate hygroscopicity data from measurements in marine locations (Asmi et al, ; Berg et al, ; Hersey et al, ; Kim et al, ; Maβling et al, , ; Mochida et al, ; Snider & Petters, ; Swietlicki et al, ; Tomlinson et al, ; Zhou et al, ). All values and geographical locations are summarized in Table S1 in the supporting information.…”

New Particle Formation in the Atmosphere: From Molecular Clusters to Global Climate

“…Particle size distributions have been measured at several locations in Antarctica, but only few extended to the sizes below 10 nm. NPF has been observed at the Aboa station, ~130 km from the coastline, with ~20% NPF frequency during the austral summer (Asmi et al, ; Jokinen et al, ; Koponen et al, ; Kyrö et al, ; Virkkula et al, ). NPF has been observed also at continental Antarctica at Concordia station at Dome C on 5–25% of days depending on the season, with the highest occurrence frequency during the summer (Järvinen et al, ).…”

Hygroscopicity of aerosol particles and CCN activity of nearly hydrophobic particles in the urban atmosphere over Japan during summer

“…Chemical composition is the factor that governs the hygroscopicity of particles. In addition to bulk or size‐resolved studies on the association between the hygroscopicity and chemical composition [e.g., Hersey et al , ; Asmi et al , ; Bezantakos et al , ; Hersey et al , ; Kamilli et al , ; Liu et al , ], the analysis of the chemical composition of particles segregated by the hygroscopicity has been performed. Past studies on the latter subject include those using an aerosol mass spectrometer connected in series to a HTDMA [ Buzorius et al ., ; Zelenyuk et al ., ; Herich et al , ; Wang et al , ].…”