New particle formation in the Arctic atmosphere is an important source of aerosol particles. Understanding the processes of Arctic secondary aerosol formation is crucial due to their significant impact on cloud properties and therefore Arctic amplification. We observed the molecular formation of new particles from low‐volatility vapors at two Arctic sites with differing surroundings. In Svalbard, sulfuric acid (SA) and methane sulfonic acid (MSA) contribute to the formation of secondary aerosol and to some extent to cloud condensation nuclei (CCN). This occurs via ion‐induced nucleation of SA and NH3 and subsequent growth by mainly SA and MSA condensation during springtime and highly oxygenated organic molecules during summertime. By contrast, in an ice‐covered region around Villum, we observed new particle formation driven by iodic acid but its concentration was insufficient to grow nucleated particles to CCN sizes. Our results provide new insight about sources and precursors of Arctic secondary aerosol particles.
Measurements of the mean and turbulent structure of the planetary boundary layer using a sodar and a sonic anemometer, and radiative measurements using a radiometer, were carried out in the summer of 1999-2000 at the Antarctic plateau station of Dome C during a two-month period. At Dome C strong ground-based inversions dominate for most of the year. However, in spite of the low surface temperatures (between )50 and )20°C), and the surface always covered by snow and ice, a regular daytime boundary-layer evolution, similar to that observed at mid-latitudes, was observed during summertime. The mixed-layer height generally reaches 200-300 m at 1300-1400 LST in high summer (late December, early January); late in the summer (end of January to February), as the solar elevation decreases, it reduces to 100-200 m. A comparison between the mixed-layer height estimated from sodar measurements and that calculated using a mixed-layer growth model shows a rather satisfactory agreement if we assign a value of 0.01-0.02 m s )1 to the subsidence velocity at the top of the mixed layer, and a value of 0.003-0.004 K m )1 to the potential temperature gradient above the mixed layer.
Daily PM10 aerosol samples were collected at the Gruvebadet observatory, Ny-Å lesund (Svalbard Islands), during the spring-summer 2014 Italian Arctic Campaign. A total of 136 samples were analysed for ion (inorganic anions and cations, selected organic anions) composition aiming to evaluate the seasonal pattern of sulfate, as a key component of the Arctic haze. Ionic balances indicated a strong sulfate seasonality with mean spring concentration about 1.5 times higher than that measured in summer. The spring and summer aerosol was almost neutral, indicating that ammonia was the major neutralizing agent for atmospheric acidic species. The linear regression between sulfate from potential acidic sources (non-sea salt sulfate and non-crustal sulfate) and ammonium indicated that the mean sulfate/ammonium ratio was intermediate between semi-(NH 4 HSO 4 ) and complete ((NH 4 ) 2 SO 4 ) neutralization. Using sea-salt sodium as sea-spray marker, non-sea-salt calcium as crustal marker and methanesulfonic acid as biogenic marker, a detailed source apportionment for sulfate was carried out. The anthropogenic input (calculated as the differences between total sulfate and the sum of sea-salt, crustal and biogenic contributes) was found to be the most relevant -016-0517-7 contribution to the sulfate budget in the Ny-Å lesund aerosol in summer and, especially, in spring. In this last season, crustal, sea-salt, biogenic and anthropogenic sources accounted for 3.3, 12.0, 11.5 and 74.8 %, respectively.
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