Description: Das Projekt "CLOUD" wird vom Umweltbundesamt gefördert und von Paul Scherrer Institut, Labor für Atmosphärenchemie durchgeführt. CLOUD is an acronym for Cosmics Leaving OUtdoor Droplets. CLOUD was designed to investigate the influence of galactic cosmic rays (GCRs) on ions, aerosols, cloud condensation nuclei (CCN) and clouds, with the CLOUD facility at CERN, and thereby to assess the significance of a possible ''solar indirect'' contribution to climate change. In a more general term, CLOUD aims at resolving one of the most challenging and long-standing problems in atmospheric science - to understand how new aerosol particles are formed in the atmosphere and the effect these particles have on the global atmosphere and climate. The present poor experimental understanding of aerosol nucleation and growth is preventing the inclusion of physics-based mechanisms in global models, and limiting our understanding of how a major fraction of atmospheric aerosol will influence future climate. The contribution of aerosols and clouds is recognized by the Intergovernmental Panel on Climate Change as the most important source of uncertainty in the radiative forcing of climate change, and is limiting our capability to make reliable climate projections. With the CLOUD facility at CERN we have for the first time an experimental chamber of the highest technological performance available, where the atmosphere is recreated from ultra-pure air with added water vapor, trace gases under study and, for certain experiments, aerosols. The chamber is located at the beamline (T11) at the CERN Proton Synchrotron accelerator, and is equipped with a wide range of sensitive instruments to analyze their contents via optical ports or sampling probes. The accelerator provides an adjustable and precisely measurable beam of 'cosmic rays' that closely matches natural cosmic rays in ionization density, uniformity and intensity, spanning the atmospheric range from ground level to the maximum around 15 km altitude. In contrast with experiments in the atmosphere, CLOUD will be able to compare processes when the cosmic ray beam is varied, and all experimental parameters can be precisely controlled and measured. As a result of this, CLOUD has established itself as the worlds pre-eminent experiment for these studies. Within the next 10 years, a multi-parameter experimental phase space will be mapped, involving numerous variables such as temperature, relative humidity, trace gases and their concentrations, ionization, nucleation rates, growth rates, droplet and ice particle activation, as well as liquid and ice cloud microphysics.
SupportProgram
Origin: /Bund/UBA/UFORDAT
Tags: Wolkenbildung ? Wolke ? Klimaprojektion ? Atmosphärisches Aerosol ? Wasserdampf ? Aerosol ? Partikelgrößenverteilung ? Strahlendosis ? Temperatur ? Hafen ? Ionen ? Simulation ? Studie ? Wirkungsanalyse ? Laborversuch ? Kondensationskern ? Partikel ? Strahlenwirkung ? Arbeit ? Atmosphäre ? Forschungseinrichtung ? Klimawandel ? Feuchtigkeit ? Klimawirkung ? Kosmische Strahlung ? Atmosphärischer Prozess ? Strahlungsantrieb ? Klimaszenario ? Climate forcing ? Ionendichte ? Ionisation ? Nucleation ? Cosmic rays ? Elektrisches Feld ? Grundlagenforschung ? Atmospheric physics ?
License: cc-by-nc-nd/4.0
Language: Englisch/English
Time ranges: 2013-06-01 - 2015-05-31
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