Highly resolved observations of trace gases in the lowermost stratosphere and upper troposphere from the Spurt project: an overview

A. Engel (1) , H. Bönisch (1) , D. Brunner (2) , H. Fischer (3) , H. Franke (4) , G. Günther (5) , C. Gurk (3) , M. Hegglin (2) , P. Hoor (3) , R. Königstedt (3) , M. Krebsbach (5) , R. Maser (4) , U. Parchatka (3) , Th. Peter (2) , D. Schell (4) , C. Schiller (5) , U. Schmidt (1) , N. Spelten (5) , T. Szabo (6) , U. Weers (3) , H. Wernli (6) , Th. Wetter (1) , V. Wirth (6)

1 IAU - Institut für Atmosphäre und Umwelt [Frankfurt/Main]
2 IAC - Institute for Atmospheric and Climate Science [Zürich]
3 MPIC - Max-Planck-Institut für Chemie
4 enviscope GmbH
5 Institut für Chemie und Dynamik der Geosphäre
6 IPA - DLR Institut für Physik der Atmosphäre = DLR Institute of Atmospheric Physics

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° N and 75° N in the European longitude sector (10° W?20° 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 N₂O, CH₄, CO, CO₂, CFC12, H₂, SF₆, NO, NO_y, O₃ and H₂O. 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 O₃ and NO_y and the lowest mixing ratios of N₂O and SF₆. The lowest mixing ratios of NO_y and O₃ are observed during autumn, together with the highest mixing ratios of N₂O and SF₆ indicating a strong tropospheric influence. For H₂O, 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.

Domaines: Océan, Atmosphère

A. Engel, H. Bönisch, D. Brunner, H. Fischer, H. Franke, et al.. Highly resolved observations of trace gases in the lowermost stratosphere and upper troposphere from the Spurt project: an overview. Atmospheric Chemistry and Physics Discussions, 2005, 5 (4), pp.5081-5126. ⟨hal-00301630⟩