Composition and Chemistry
A 15-year climatology of stratosphere–troposphere exchange with a Lagrangian particle dispersion model 2. Mean climate and seasonal variability
Article first published online: 8 MAR 2003
Copyright 2003 by the American Geophysical Union.
Journal of Geophysical Research: Atmospheres (1984–2012)
Volume 108, Issue D12, 27 June 2003
How to Cite
2003), A 15-year climatology of stratosphere–troposphere exchange with a Lagrangian particle dispersion model 2. Mean climate and seasonal variability, J. Geophys. Res., 108, 8522, doi:10.1029/2002JD002639, D12., , , , , and (
- Issue published online: 8 MAR 2003
- Article first published online: 8 MAR 2003
- Manuscript Accepted: 13 SEP 2002
- Manuscript Revised: 12 SEP 2002
- Manuscript Received: 10 JUN 2002
 A comprehensive climatology of stratosphere–troposphere exchange (STE), based on 15 years of ECMWF global atmospheric reanalysis data for the period 1979–1993, has been carried out with a specially tuned version of the Lagrangian particle dispersion model, FLEXPART. The typical amplitudes, timescales, seasonality, and spatial variability of STE revealed in the climatology are described. Mean distributions of STE air masses of various ages relate to aspects of the global circulation, while anomaly patterns, such as the North Atlantic Oscillation (NAO) and El Niño, influence STE variability. Characteristic differences are seen between shallow STE flows remaining within the tropopause region (TPR) and deep STE transports, which include cases of stratospheric air reaching the lower troposphere. Unlike for shallow STE events, such deep intrusions show a distinct winter maximum. This subsequently impacts on the seasonal cycle of stratospheric ozone in the troposphere, which thus depends on altitude but also on the decay timescale of ozone. A much broader view of STE than has previously been possible is enabled. The inherent scope of STE is far wider than a discussion of cross-tropopause fluxes alone. Indeed, more than 90% of all cross-tropopause flows return within 6 hours. It is thus crucial to distinguish between short-term STE, during which air parcels rapidly recross the tropopause, and deep and/or long-term STE, in which air parcels have subsequently long residence times away from their source.