ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-6-283-2006 Highly resolved observations of trace gases in the lowermost stratosphere and upper troposphere from the Spurt project: an overview Engel A. 1 Bönisch H. 1 Brunner D. 5 Fischer H. 3 Franke H. 6 Günther G. 2 Gurk C. 3 Hegglin M. 5 Hoor P. 3 Königstedt R. 3 Krebsbach M. 2 Maser R. 6 Parchatka U. 3 Peter T. 5 Schell D. 6 Schiller C. 2 Schmidt U. 1 Spelten N. 2 Szabo T. 4 Weers U. 3 Wernli H. 4 Wetter T. 1 Wirth V. 4 Institut für Atmosphäre und Umwelt, J. W. Goethe Universität Frankfurt, Germany Institut für Chemie und Dynamik der Geosphäre, ICG-I, Forschungszentrum Jülich, Germany Max-Planck-Institut für Chemie, Mainz, Germany Institut für Physik der Atmosphäre, Universität Mainz, Germany Institute for Atmospheric and Climate Science, ETH Zürich, Switzerland Enviscope GmbH, Frankfurt, Germany 02 02 2006 6 2 283 301 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/6/283/2006/acp-6-283-2006.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/6/283/2006/acp-6-283-2006.pdf

During SPURT (Spurenstofftransport in der Tropopausenregion, trace gas transport in the tropopause region) we performed measurements of a wide range of trace gases with different lifetimes and sink/source characteristics in the northern hemispheric upper troposphere (UT) and lowermost stratosphere (LMS). A large number of in-situ instruments were deployed on board a Learjet 35A, flying at altitudes up to 13.7 km, at times reaching to nearly 380 K potential temperature. Eight measurement campaigns (consisting of a total of 36 flights), distributed over all seasons and typically covering latitudes between 35&deg; N and 75&deg; N in the European longitude sector (10&deg; W&ndash;20&deg; E), were performed. Here we present an overview of the project, describing the instrumentation, the encountered meteorological situations during the campaigns and the data set available from SPURT. Measurements were obtained for N<sub>2</sub>O, CH<sub>4</sub>, CO, CO<sub>2</sub>, CFC12, H<sub>2</sub>, SF<sub>6</sub>, NO, NO<sub>y</sub>, O<sub>3</sub> and H<sub>2</sub>O. We illustrate the strength of this new data set by showing mean distributions of the mixing ratios of selected trace gases, using a potential temperature-equivalent latitude coordinate system. The observations reveal that the LMS is most stratospheric in character during spring, with the highest mixing ratios of O<sub>3</sub> and NO<sub>y</sub> and the lowest mixing ratios of N<sub>2</sub>O and SF<sub>6</sub>. The lowest mixing ratios of NO<sub>y</sub> and O<sub>3</sub> are observed during autumn, together with the highest mixing ratios of N<sub>2</sub>O and SF<sub>6</sub> indicating a strong tropospheric influence. For H<sub>2</sub>O, however, the maximum concentrations in the LMS are found during summer, suggesting unique (temperature- and convection-controlled) conditions for this molecule during transport across the tropopause. The SPURT data set is presently the most accurate and complete data set for many trace species in the LMS, and its main value is the simultaneous measurement of a suite of trace gases having different lifetimes and physical-chemical histories. It is thus very well suited for studies of atmospheric transport, for model validation, and for investigations of seasonal changes in the UT/LMS, as demonstrated in accompanying and elsewhere published studies.