Das Projekt "In situ IN (Ice Nuclei) Messungen" wird vom Umweltbundesamt gefördert und von Johannes Gutenberg-Universität Mainz, Institut für Physik der Atmosphäre durchgeführt. Ziel des Teilprojekts ist die Entwicklung und Auswahl eines Gerätes zu kontinuierlichen, zeitlich hochaufgelösten Messung der Konzentration von Eiskeimen im luftgetragenen Zustand. Dabei sollen die unterschiedlichen experimentellen Ansätze der beiden beteiligten Institute zunächst getrennt verfolgt werden. Nach Ablauf der ersten Bewilligungsperiode ist zu entscheiden, welches Verfahren weiterentwickelt und genutzt werden soll.
Das Projekt "Field and laboratory studies of the chemical composition and mixing state of black carbon particles and their ability to act as cloud condensation and ice nuclei" wird vom Umweltbundesamt gefördert und von Eidgenössische Technische Hochschule Zürich, Institut für Atmosphäre und Klima durchgeführt. Summary and background: Black carbon (BC) aerosols influence the Earth's radiative budget directly by absorbing incoming solar radiation and indirectly by acting as cloud condensation nuclei (CCN) and ice nuclei (IN), and thereby changing microphysical and radiative properties of the clouds. The influence of BC on warm, mixed-phase and cold cloud indirect effects is highly uncertain due to an insufficient characterization of BC-sources, insufficient information on the physico-chemical properties of ambient BC particles, and an inadequate understanding and hence description of the aerosol-cloud interactions and microphysical processes applied in climate models. We propose to perform field and laboratory studies of the chemical composition and mixing state of BC particles and their ability to act as cloud condensation and ice nuclei. The results will help to understand the dependence of water and ice nucleating behavior of BC particles on their chemical composition and mixing state, and to identify distinct BC sources. Aims and relevance: The understanding and investigation of climate change and related atmospheric processes is a highly topical research field and subject of academic and public interest. The recent 2007 report of the IPCC (Intergovernmental Panel of Climate Change) stressed the need to improve our understanding of the aerosol radiative forcing component for constraining it's climate impact more accurately. The lack of understanding of the aerosol effects on climate is mainly due to the lack of knowledge of aerosol-cloud interactions. Herein, the proposed laboratory and field experiments will provide new data to improve aerosol-cloud interactions in climate and process-related models and to reduce the uncertainties of the anthropogenic influence on climate via the direct and indirect effect aerosol effects. Moreover, the new measurement approach we propose herein for source apportionment of BC particles, i.e. identify and quantify distinct BC sources, is of interest for local climate change estimates and questions related to air pollution and public health. This is due to the fact that our field measurements focus on particles emitted locally (in Switzerland) and transported on a regional scale. However, the role of BC emissions from residential heating is far more important in other region of the world.
Das Projekt "Interaction of Aerosols with Clouds and Radiation" wird vom Umweltbundesamt gefördert und von Paul Scherrer Institut, Labor für Atmosphärenchemie durchgeführt. High uncertainties in future climate predictions arise from insufficient knowledge of the interaction of clouds with visible (solar) and infrared (terrestrial) radiation. The optical properties and lifetime of clouds are strongly influenced by the ability of atmospheric aerosol particles to act as cloud condensation nuclei (CCN) or ice nuclei (IN). This so-called indirect aerosol effect has been recognized as one of the greatest source of uncertainty in assessing human impact on climate. Up to now, the climate relevant properties of clouds and their formation processes are still poorly understood, particularly those of mixed-phase clouds where supercooled cloud droplets and ice crystals coexist. Previous research has found that the cloud radiative properties strongly depend on the cloud ice mass fraction, which is influenced by the abundance of IN. Increased IN concentrations are also thought to enhance precipitation, thus causing a decrease in cloud lifetime and cloud cover, resulting in a warming of the atmosphere. Burning questions that we will address are: Which aerosol particles act as IN in our atmosphere ? By which detailed mechanisms do atmospheric aerosols contribute to the formation of ice ? To answer these questions, one major goal of this project is to develop a new inlet for the measurement of cloud droplets and ice crystals. This inlet will also allow the extraction of small ice particles in mixed-phase clouds for the physico-chemical characterization of tropospheric IN. The inlet will represent a novel tool for the in-situ investigation of clouds and will deliver information that is not available by means of any other existing inlet. Measurements will be performed at the Jungfraujoch, one of the world's most prominent high Alpine research stations located at 3580 m altitude in the middle of Switzerland. This unique location offers the possibility to perform these studies in mixed-phase clouds that are representative for the current European background. The proposed research will be performed in a collaborative effort of the Laboratory of Atmospheric Chemistry of the Paul Scherrer Institut (aerosol/cloud research) and the Institute for Meteorology and Climate Research at the Karlsruhe Institute of Technology (cloud microphysics and optics).