Journal Article

PreJuSER-13851

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Insight from ozone and water vapour on transport in the tropical tropopause layer (TTL)

Ploeger, F.FZJ* ; Fueglistaler, S. ; Grooß, J.-U.FZJ* ; Günther, G.FZJ* ; Konopka, P.FZJ* ; Liu, Y. S. ; Müller, R.FZJ* ; Ravegnani, F. ; Schiller, C.FZJ* ; Ulanovski, A. ; Riese, M.FZJ*

2011
EGU Katlenburg-Lindau

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Please use a persistent id in citations: http://hdl.handle.net/2128/10029  doi:10.5194/acp-11-407-2011

Abstract: We explore the potential of ozone observations to constrain transport processes in the tropical tropopause layer (TTL), and contrast it with insights that can be obtained from water vapour. Global fields from Halogen Occultation Experiment (HALOE) and in-situ observations are predicted using a backtrajectory approach that captures advection, instantaneous freeze-drying and photolytical ozone production. Two different representations of transport (kinematic and diabatic 3-month backtrajectories based on ERA-Interim data) are used to evaluate the sensitivity to differences in transport. Results show that mean profiles and seasonality of both tracers can be reasonably reconstructed. Water vapour predictions are similar for both transport representations, but predictions for ozone are systematically higher for kinematic transport. Compared to global HALOE observations, the diabatic model prediction underestimates the vertical ozone gradient. Comparison of the kinematic prediction with observations obtained during the tropical SCOUT-O3 campaign shows a large high bias above 390K potential temperature. We show that ozone predictions and vertical dispersion of the trajectories are highly correlated, rendering ozone an interesting tracer for aspects of transport to which water vapour is not sensitive. We show that dispersion and mean upwelling have similar effects on ozone profiles, with slower upwelling and larger dispersion both leading to higher ozone concentrations. Analyses of tropical upwelling based on mean transport characteristics, and model validation have to take into account this ambiguity between tropical ozone production and in-mixing from the stratosphere. In turn, ozone provides constraints on transport in the TTL and lower stratosphere that cannot be obtained from water vapour.

Keyword(s): J

Note: We thank T. Birner for helpful discussions, N. Thomas for programming support, M. Park for providing a SHADOZ-based ozone climatology and the ECMWF for reanalysis data support. F. Ploeger further thanks COST/WaVaCS (European Cooperation for Science and Technology/Atmospheric Water Vapour in the Climate System action) for funding a short term scientific mission at DAMTP/Cambridge, where main ideas for this work were developed.

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Contributing Institute(s):

1. Stratosphäre (IEK-7)

Research Program(s):

1. Atmosphäre und Klima (P23)

Appears in the scientific report 2011

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