Das Projekt "Feldmessungen zu den Leitprojekten 1.2 und 2.2 sowie Modellieraktivitaeten zu den Leitprojekten 2.3 und 2.4 des Ozonforschungsprogramms (Teil II) des BMBF" wird vom Umweltbundesamt gefördert und von Leibniz-Institut für Atmosphärenphysik e.V. an der Universität Rostock durchgeführt.
Das Projekt "EASOE Forschung mit Hilfe von Ballons" wird vom Umweltbundesamt gefördert und von Forschungszentrum Jülich GmbH, Institut für Chemie und Dynamik der Geosphäre durchgeführt.
Das Projekt "Aerosole, Wolken in der polaren Stratosphaere und die Messung ihrer chemischen Zusammensetzung in der Arktis und Westskandinavien" wird vom Umweltbundesamt gefördert und von Universität Bonn, Physikalisches Institut durchgeführt. The main objective of this project is to perform field measurements of chemical species and aerosols at high latitudes yielding data which help to test the present understanding on how polar stratospheric clouds and (volcanic) aerosols affect the nitrogen and chlorine partitioning. Particulate measurements will be performed by lidar, one ground-based at Andoya (69.3 degree N, 16.0 degree E) and one airborne with the aircraft stationed at Kiruna (67.9 degree N, 21.1 degree E) during SESAME. The lidar measurements will show the presence of aerosols and the vertical distribution. In the case of LEANDRE lidar the horizontal scales can be determined, while the Andoya lidar measures the temporal evolution at a fixed location. Polarization and two colour measurements will delineate the particulate shape, i.e. its physical phase, and distribution changes, which can be used to identify spherical PSCs among sulfur acid droplets. Composition measurements will be performed by two ground-based spectrometers at Kiruna. One of the instruments is a differential absorption spectrometer (DOAS) using zenith scattering, off-axis solar scattering or direct moonlight observation geometries. The other instrument is a Fourier transform spectrometer (FTIR) operated in solar occultation geometry. The primary quantities derived will be zenith column amounts of various trace gases, among them NO2, NO3, CIONO2 and HNO3, which are involved in the nitrogen partitioning scheme. In addition other gases of relevance to the ozone depletion problem are measured. They include O3, HCl, BrO, OCIO, CFC12, CH4, H2O and HDO. For some of these gases, the tropospheric and stratospheric contributions can be separated or even an altitude profile derived. The techniques used are based on measurements at several zenith angles (DOAS) or exploit the high spectral resolution (FTIR). Also, it is possible for the DOAS to detect changes in the sky colour during twilight which may be attributed to polar stratospheric clouds above the station. Prime Contractor: Rheinische Friedrich-Wilhelms-Universität Bonn, Physikalisches Institut; Bonn; Germany.
Das Projekt "Veraenderung der Leewellen von Wolken der polaren Stratosphaere ueber der skandinavischen Gebirgskette" wird vom Umweltbundesamt gefördert und von Universität Bonn, Physikalisches Institut durchgeführt. Heterogeneous reactions on polar stratospheric clouds (PSCs) initiate a long chain of chemical reactions which lead to the formation of the polar ozone holes. Necessary for the formation of PSCs are sufficiently low temperatures in the polar stratosphere. Meteorological statistics show the Arctic stratosphere to be on average too warm for PSC formation to occur on a large scale. lt is known that in the lee waves forming downwind of large mountain ranges, such as the Scandinavian mountains, temperatures may fall below PSC formation thresholds and PSCs will occur quite regularly even if the PSC formation temperature condjtion is not met in the overall stratosphere. Questions that arise concern the frequency of formation for PSCs in lee-wave fields and what are the meteorological conditions. How intense are such PSCs, what is their surface density? Are they of small spatial extent or will the lee wave field be the source region for stratiform PSCs covering wide areas? More generally, how will lee waves modify PSC fields that may be carried by the general circulation across a mountain ridge? Answers to these and other questions should be beneficial to computer models that predict the evolution of the ozone layer since reactions on PSCs are the first step towards ozone destruction. Initiating such models with erroneous amounts of PSCs (too much, too little, wrong time, altitude, surface area, or persistence) should lead to an equally erroneous prediction. The main objective is to perform field measurements down- and upstream of the Scandinavian mountain to search for generation, destruction, or modification of PSCs as the air parcels cross the mountain ridge. To achieve the objective we employ active remote sensing techniques deployed in two almost identical sets of instruments on each side of the Scandinavian mountains. Backscatter lidars will detect and characterize the stratospheric particulate load and identify PSCs. The ozone lidars will identify air masses from similarities in the ozone profiles. Temperature profiles will be measured by lidars using the rotational and vibrational Raman techniques. Lee waves will be identified from the ozone and temperature profiles. MST radars will perform wind measurements in the upper troposphere (which relates to lee wave generation) and a camera array will image the sky and connect lidar detection of PSCs and visual detection over a wider area. All instruments are located in a region where mountain lee waves tend to generate polar stratospheric clouds during the winter months. The detection of a chemically induced, large scale ozone hole in the spring of 1995 in the Arctic vortex was preceded by observations of intense and persistent polar stratospheric clouds in January 1995. The objective of this proposal contributes to a better understanding of the initial process that leads to modification of the stratospheric ozone layer, in particular the ozone hole in the northern hemisphere.
Das Projekt "Koordinierte Feldmessungen zum Einfluss von Leewellen auf Wolkenfelder in der polaren Stratosphaere" wird vom Umweltbundesamt gefördert und von Universität Bonn, Physikalisches Institut durchgeführt. Wolken in der polaren Winterstratosphaere (PSCs) setzen eine lange Kette chemischer Reaktionen in Gang, an deren Ende der katalytische Abbau von Ozon in der chlorangereicherten Stratosphaere steht. In der Arktis entstehen PSCs vorwiegend in den Leewellegebieten grosser Gebirgszuege. Mit einem Verbund von sieben aktiven Fernerkundungsexperimenten (Lidars, Radars und Kameras), die beiderseits des skandinavischen Bergrueckens aufgestellt werden, soll die Bildung solcher Leewellen-PSCs in den Wintern 1996/1997 und 1997/1998 untersucht werden. Solche Informationen werden fuer Modelle zur Vorhersage der Ozonentwicklung benoetigt. Mit diesem Antrag wird um Unterstuetzung des Einsatzes des Rueckstreulidars der Universitaet Bonn gebeten, das im Rahmen dieses Verbundes in Kiruna PSCs nachweisen soll und deren Oberflaechendichte sowie Temperaturprofile messen soll.