%0 Journal Article
%A Konopka, P.
%A Pan, L.L.
%T On the mixing-driven formation of the Extratropical Transition Layer (ExTL)
%J Journal of geophysical research / Atmospheres
%V 117
%@ 0022-1406
%C Washington, DC
%I Union
%M PreJuSER-111832
%P D18
%D 2012
%Z We thank William J. Randel for many discussions motivating the authors to conduct this study and to write this paper. We are also grateful to Anne Kunz, Rolf Muller and two anonymous reviewers for their very helpful comments. Important support by the preparation of the final version of the manuscript was provided by Shawn Honomichl. The European Centre for Medium-Range Weather Forecasts (ECMWF) provided meteorological analyses for this study.
%X We present a case study on the formation and structure of the Extratropical Transition Layer (ExTL) using in situ observations and a Lagrangian chemical transport model. The results show that the model with mixing parameterized from the large-scale flow deformations well reconstructs the observed asymmetric structure of the ExTL with a deeper transition layer on the cyclonic side of the jet stream. Information from the model and observations are integrated using tracer-tracer correlations between ozone (O-3) and carbon monoxide (CO). Transport of chemical tracers from the stratospheric or tropospheric background to the ExTL through mixing is identified by the change of the CO-O-3 correlation in the CO-O-3 space. The ExTL formation process simulated by the model, therefore, provides a scenario to connect the mixed air parcels to the history of mixing. An estimate of timescales of ExTL formation is made using model experiments. The results show that the fastest formation of the ExTL occurs on the isentropic levels below the subtropical jet core, e.g. around 3 weeks for 310 K, whereas at 360 K level (jet core) the formation of the ExTL needs around 3 months. Overall, this result demonstrates the important role of mixing in transport of trace gases across the tropopause.
%K J (WoSType)
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000309138200003
%R 10.1029/2012JD017876
%U https://juser.fz-juelich.de/record/111832