Abstract View
Annual Variability of Particle Size, Cloud Condensation Nuclei and Particle Hygroscopicity in the Central Arctic
XIANDA GONG, Jiaoshi Zhang, Heike Wex, Chongai Kuang, Janek Uin, Matthew Shupe, Jian Wang, Washington University in St. Louis
Abstract Number: 168
Working Group: Aerosols, Clouds and Climate
Abstract
Temperatures in the Arctic are rising at more than twice the global average rate. The climate-relevant properties of Arctic aerosols and the processes that drive these properties remain poorly understood, especially in the central Arctic where observations are scarce. Here we present the seasonal variations of central Arctic aerosol properties, including particle number size distribution (PNSD), CCN number concentration (NCCN), and particle hygroscopicity based on the measurements onboard the R/V Polarstern during the recent Multidisciplinary Drifting Observatory for the Study of Arctic Climate (MOSAiC) campaign, which took place from October 2019 to September 2020.
The seasonal variation of PNSD in the central Arctic is similar to those observed at other Arctic sites, including Mt. Zeppelin and Svalbard. The PNSD exhibited a high accumulation mode number concentration during springtime due to Arctic haze and high Aitken mode number concentration during summertime as a result of more frequent new particle formation events. NCCN during the springtime was often the highest (~110 cm-3 at a supersaturation of 0.30%), whereas, during summertime, NCCN is usually low (~ 20 cm-3) except when newly formed particles grow and reach a sufficiently large size to act as CCN. Particle hygroscopicity (expressed as a single parameter, κ) was low (~0.2 to 0.3) during summertime due to strong contributions of organics to particle composition. During springtime, κ ranged from ~0.5 to 0.8, consistent with mixtures of long-range transported continental aerosols and sea-salt particles. During the polar night, high NCCN (~200 cm-3) and elevated κ (~1.0) were observed under strong winds, suggesting a substantial contribution from blowing snow or highly hygroscopic particles transported from lower latitudes during storms. The processes that drive the seasonal variations of the aerosol properties in the central Arctic will be discussed.