Seasonality of aerosol optical properties in the Arctic

• Published in: Atmospheric Chemistry and Physics
• Main Authors: L. Schmeisser, J. Backman, J. A. Ogren, E. Andrews, E. Asmi, S. Starkweather, T. Uttal, M. Fiebig, S. Sharma, K. Eleftheriadis, S. Vratolis, M. Bergin, P. Tunved, A. Jefferson
• Format: Article in Journal/Newspaper
• Language: English
• Published: Copernicus Publications 2018
• Subjects: Physics; QC1-999; Chemistry; QD1-999; Arctic; Svalbard; Ny-Ålesund; Canada; Greenland; Norway; Tiksi; albedo; Ny Ålesund
• Online Access: https://doi.org/10.5194/acp-18-11599-2018; https://doaj.org/article/0ae7ffa661544a5283979320aadf6e9a

Given the sensitivity of the Arctic climate to short-lived climate forcers, long-term in situ surface measurements of aerosol parameters are useful in gaining insight into the magnitude and variability of these climate forcings. Seasonality of aerosol optical properties – including the aerosol light-scattering coefficient, absorption coefficient, single-scattering albedo, scattering Ångström exponent, and asymmetry parameter – are presented for six monitoring sites throughout the Arctic: Alert, Canada; Barrow, USA; Pallas, Finland; Summit, Greenland; Tiksi, Russia; and Zeppelin Mountain, Ny-Ålesund, Svalbard, Norway. Results show annual variability in all parameters, though the seasonality of each aerosol optical property varies from site to site. There is a large diversity in magnitude and variability of scattering coefficient at all sites, reflecting differences in aerosol source, transport, and removal at different locations throughout the Arctic. Of the Arctic sites, the highest annual mean scattering coefficient is measured at Tiksi (12.47 Mm −1 ), and the lowest annual mean scattering coefficient is measured at Summit (1.74 Mm −1 ). At most sites, aerosol absorption peaks in the winter and spring, and has a minimum throughout the Arctic in the summer, indicative of the Arctic haze phenomenon; however, nuanced variations in seasonalities suggest that this phenomenon is not identically observed in all regions of the Arctic. The highest annual mean absorption coefficient is measured at Pallas (0.48 Mm −1 ), and Summit has the lowest annual mean absorption coefficient (0.12 Mm −1 ). At the Arctic monitoring stations analyzed here, mean annual single-scattering albedo ranges from 0.909 (at Pallas) to 0.960 (at Barrow), the mean annual scattering Ångström exponent ranges from 1.04 (at Barrow) to 1.80 (at Summit), and the mean asymmetry parameter ranges from 0.57 (at Alert) to 0.75 (at Summit). Systematic variability of aerosol optical properties in the Arctic supports the notion that the sites presented here ...