Progetto

progetto: 2015/AC3.04

   
acronimo LTCPAA
responsabile ROBERTO UDISTI
ente di appartenenza UNIV. FIRENZE
descrizione
This project aims performing 4-yr continuous measurements of chemical and physical properties of aerosol, superficial snow and selected gas-phase substances at Station Concordia (Dome C, East Antarctica), in order to increase our knowledge on the climate-environment interactions at present and in the past. Direct measurements and sampling activities include: aerosol size distribution; PM10 and multi-stage samplings for the determination of ions, metals, selected organic compounds, halogens, elemental and organic carbon fractions; black carbon, ozone and NOx continuous measurements; neutron and muon counting (Cosmic Rays markers). Besides, the uppermost snow layers will be collected at daily/2-day resolution, in order to study the relationships of selected chemical species at the snow/air interface. Long-term measurements are necessary to improve climatic models and identify reliable seasonal and inter-annual trends of physical properties and chemical components useful as markers of changes in: aerosol-climate forcing and feedback processes; South-Hemisphere atmospheric circulation modes; marine biogenic activity; sea ice extent and persistence; atmosphere oxidising capacity; hydrological conditions in the dust source areas; on-site New Particle Formation. Besides, a better knowledge of present aerosol processes will address toward a more reliable interpretation of paleoclimatic and paleoenvironmental changes, as reconstructed by ice-core stratigraphies of chemical markers. In particular, the parallel analysis of aerosol and surface snow will allow studying the effect of the dry deposition on snow composition and the depositional and post depositional processes of selected components. These aspects are crucial for a reliable interpretation of firn and ice core records. This knowledge can be applied both to already achieved records (e.g., EPICA Dome C ice core) and to ice-core stratigraphies from future Antarctic deep drillings (including the “Oldest Ice” Project). The goals of a long-term aerosol study include: •understanding the climate-aerosol feedback processes in regions very sensitive to environmental and climatic changes; •establishing the background values of the atmospheric load, size distribution and chemical composition of aerosol; •improving the reliability of climatic models by making available a long-term data set for a more effective evaluation of the forcings exerted by global aerosol (ERFari and ERFaci); •studying, with sufficient statistics, the seasonal and inter-annual trend of the concentrations of key-components of aerosol (S-, N- and C-cycle compounds; biogenic emissions; dust; sea spray); •evaluating the present source strength and long-range atmospheric transport efficiency of aerosol formed in the marine and continental areas at lower latitudes; •estimating the contribution of local to regional Antarctic aerosol sources; •studying the effects of photochemistry and radical sources (ozone) on chemical reactions of gaseous aerosol precursors and new-particles formation at very peculiar (temperature, continuous summer irradiance) atmospheric conditions; •improving the reliability of paleo-climatic and paleo-environmental reconstructions by ice core stratigraphies, also by a better knowledge of the aerosol- snow surface interchange; •evaluating the possible role of cosmic rays in New Particle Formation (NPF) in an area where nucleation is unlikely due to low atmospheric concentrations of aerosol precursors. Moreover, this project fits some objectives established within the EAIIST project (French-Italian-American East Antarctic Intern. Ice Sheet Traverse). This project aims improving our knowledge on the physical features and chemical composition of superficial snow and firn along a DC-South-Pole traverse, as well as to compare aerosol chemical composition in the two sites, differing in the oceanic areas of influence and structure and dynamics of the atmosphere.