PNRA18_00069_STEAR - Studio degli scambi stratosfera-troposfera nella regione Antartica

Stratosphere-to-troposphere exchange (STE) is one of the natural processes with substantial impacts on meteorology and atmospheric chemistry, and it is an important aspect of climate change. Several past studies have highlighted the relevance of such process on both the physics and the oxidative capacity of the Antarctic atmosphere. However, the frequency and seasonality of STE events, and the relative influence of specific transport mechanisms as well as on snow chemistry, are still under debate. In particular, the frequency of STE events from previous research remains still a largely uncertain parameter, with huge differences between the Antarctic plateau and the coast. The STEAR project will focus on providing an assessment of STE events in Antarctica, by using both observations and modeling outputs. Our reference site will be the WMO/GAW station Concordia (Dome C, DMC, 3280 m a.s.l.) located in the eastern Antarctic plateau. Here, we will install a new high volume aerosol sampler for the determination of Beryllium-7 (7Be), a key tracer of STE events, with the aim of providing, for the first time at this location, systematic measurements throughout the whole project duration. Furthermore, we will investigate the impact of STE on key variables (i.e., near-surface ozone, total ozone, aerosol chemistry, and nitrate in surface snow). In addition to the DMC measurements, we will also analyze simultaneous atmospheric composition datasets from Antarctic coastal observatories (i.e., the Mario Zucchelli (MZS) and the Jang Bogo (JBS) stations). To integrate and finalize the information from in situ measurements, modeling analyses will be performed, on different time scales (i.e., periods in common with measurements, climatology, and specific case studies). We will use Lagrangian (i.e., FLEXPART, HYSPLIT and STEFLUX) models, with the aim of better representing and describing the complex flow of stratospheric air masses deep into the Antarctic troposphere.