HR: 15:25h
AN: A13H-07    [Abstracts]
TI: Ozone trends (1975-2000) in the northern hemisphere UTLS using measurements from ozone sondes and regular aircraft
AU: Schnadt Poberaj, C
EM: christina.schnadt@env.ethz.ch
AF: Institute of Atmospheric and Climate Science, ETH, Universitatstr. 16, CHN, Zurich, 8092, Switzerland
AU: * Staehelin, J
EM: johannes.staehelin@env.ethz.ch
AF: Institute of Atmospheric and Climate Science, ETH, Universitatstr. 16, CHN, Zurich, 8092, Switzerland
AU: Brunner, D
EM: dominik.brunner@empa.ch
AF: Laboratory for Air Pollution / Environmental Technology, Empa, Ueberlandstr. 129, Dubendorf, 8600, Switzerland
AU: Thouret, V
EM: thov@aero.obs-mip.fr
AF: Laboratoire d'Aerologie, UMR 5560, Universite Paul Sabatier, Toulouse, 31400, France
AB: Ozone is a particularly strong greenhouse gas in the tropopause region, and therefore trends in this altitude are important for changes in radiative forcing. The knowledge of ozone trends in the UTLS is mostly based on a confined number of stations operating regular ozone measurements from balloons with the longest measurement series starting in the late 1960s. In this study we use ozone measurements from regular aircraft of the GASP project (Global Atmospheric Sampling Program) providing ozone data from four B-747 aircraft operated from USA from 1975 to 1979 in comparison with measurements of the ongoing MOZAIC project. For building climatologies of the two ozone data sets and hence their comparison, the data were binned relative to the dynamical tropopause, and coordinates in equivalent latitudes are used for analysis of stratospheric data. Additionally, in the upper troposphere, averages were computed for specific regions of the world such as, for example, North America, Europe, or Japan. The analysis shows that lower stratospheric ozone decreased significantly over northern mid- and high latitudes from the late 1970s to the second half of the 1990s in autumn and winter, and to a lesser extent also in spring. In the upper troposphere, pronounced increases are found over South Asia including India in the spring and summer seasons. On contrast, no clear changes are seen over the United States and Europe. In addition, a comparison of long-term changes deduced from the regular aircraft measurements and from ozonesondes is presented. Differences between the climatologies of the late 1970s and 1990s for the aircraft data over Europe and ozonesonde measurements at European stations show differing long-term changes, which will be discussed.
DE: 0300 ATMOSPHERIC COMPOSITION AND STRUCTURE
DE: 0365 Troposphere: composition and chemistry
SC: Atmospheric Sciences [A]
MN: 2007 Fall Meeting