Changes in aerosol properties during spring-summer period in the Arctic troposphere

Abstract

Abstract. The change in aerosol properties during the transition from the more polluted spring to the clean summer in the Arctic troposphere was studied. A six-year data set of observations from Ny-Ålesund on Svalbard, covering the months April through June, serve as the basis for the characterisation of this time period. In addition four-day-back trajectories were used to describe air mass histories. The observed transition in aerosol properties from an accumulationmode dominated distribution to an Aitken-mode dominated distribution is discussed with respect to long-range transport and influences from natural and anthropogenic sources of aerosols and pertinent trace gases. Our study shows that the air-mass transport is an important factor modulating the physical and chemical properties observed. However, the airmass transport cannot alone explain the annually repeated systematic and rather rapid change in aerosol properties, occurring within a limited time window of approximately 10 days. With a simplified phenomenological model, which delivers the nucleation potential for new-particle formation, we suggest that the rapid shift in aerosol microphysical properties between the Arctic spring and summer is mainly driven by the incoming solar radiation in concert with transport of precursor gases and changes in condensational sink.

Source identification and airborne chemical characterisation of aerosol pollution from long-range transport over Greenland during POLARCAT summer campaign 2008

“…No real boundary layer enhancement in particles over land and inland ice was found as reported previously by other authors for summertime Arctic measurements at the surface (e.g. Engvall et al, 2008), while in the marine boundary layer a maximum of 1.22 ± 0.30 µg m −3 consisting of 50 % sulphate aerosol was detected. Between 1 and 3 km a slight enhancement in aerosol volume and two distinct elevations in aerosol mass were observed which originated from low-level pollution transport out of North America (see discussion of flight from 8 July in Sect.…”

“…The green line denotes an exponential fit with a τ between 7 and 11 days. The grey lines represent fits to the data with lifetimes as found in other Arctic aerosol studies (Paris et al, 2009;Koch and Hansen, 2005;Farina et al, 2010). The red cross illustrates an outlier.…”

Arctic aerosol life cycle: linking aerosol size distributions observed between 2000 and 2010 with air mass transport and precipitation at Zeppelin station, Ny-Ålesund, Svalbard

“…Typical phases of the observed aerosol number size distribution can be characterized by three significantly different regimes: (1) the summer period, with its dominance of sub-60 nm particles, (2) the dark winter period with comparably few particles and dominance by accumulation mode size particles (> 60 nm) slowly increasing in number, and (3) the Arctic haze period with highly elevated concentrations of accumulation mode aerosol and just a few nucleation and Aitken mode particles. The timing of the transition between different characteristic aerosol regimes is, based on this and previous studies (Engvall et al, 2008b;Bodhaine, 1989;Quinn et al, 2002), consistent and very well pronounced. …”

“…The springtime domination of accumulation mode particles is diminished in favor of smaller particles over the time period of a couple of days. This phenomenon has been studied in detail by Engvall et al (2008b) using six years of aerosol size distribution observations from Mt. Zeppelin.…”

“…Lower aerosol loading, increased photochemistry and biological activity results in a peak in new particle formation during the Arctic summer (Strom et al, 2009;Engvall et al, 2008b). Where and how the new particle formation predominantly occurs is still under debate.…”