AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
Abstract View
State-of-the-art New Particle Formation Research at the High-Altitude Site Jungfraujoch
ERIK HERRMANN, Federico Bianchi, Jasmin Tröstl, Carla Frege, Ugo Molteni, Stephan Henne, Nicolas Bukowiecki, Martin Gysel, Ernest Weingartner, Josef Dommen, Urs Baltensperger, Paul Scherrer Institute
Abstract Number: 300 Working Group: Remote and Regional Atmospheric Aerosols
Abstract Model studies suggest that up to 45% of cloud condensation nuclei (CCN) are the result of new particle formation (NPF) in the atmosphere with a significant fraction produced in the free troposphere (FT). NPF has been extensively studied and is therefore reasonably well understood in the planetary boundary layer (PBL). At high altitude, however, the level of understanding is much lower, with fewer data sets, shorter observations, and less sophisticated instrumentation. As a consequence, global models continue to consider free tropospheric nucleation merely via the sulfuric acid-water pathway.
Starting in 2013, NPF at high altitude has been the focus of a number of completed, on-going and planned campaigns at the Jungfraujoch research station (3580 m a.s.l.) in the Swiss Alps. These campaigns saw the first deployments of an API-TOF and a CI-API-TOF at high altitude to investigate the chemical composition of nucleating clusters. In addition, a nano-SMPS, a particle size magnifier, and a neutral cluster and air ion spectrometer were employed to physically characterize particle formation and early growth. Also, the contribution of NPF to CCN numbers was investigated. The FLEXPART model and trace gas observations were used to determine how PBL influences affect nucleation. Since October 2014, aerosol measurements at a nearby site (Jungfraujoch East Ridge, 3700 m a.s.l.) allows for a closer look at how nucleation varies locally.
The most recent Jungfraujoch nucleation research has so far been published in two dedicated manuscripts (Bianchi et al., Science, 2016; Tröstl et al., JGR-A, 2016) and as part of a long-term analysis (Herrmann et al., JGR-A, 2015). Findings include that nucleation is mostly driven by highly oxygenated multifunctional compounds (HOMs), but also sulfuric acid-ammonia events have been observed. We also found that NPF is limited to a narrow window of opportunity after significant PBL contact of an air mass.