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Correction of stratospheric age-of-air derived from SF 6 for the effect of chemical sinks

Garny, Hella ; Eichinger, Roland; Laube, Johannes C.; Ray, Eric A.; Stiller, Gabriele P. ORCID iD icon 1; Bönisch, Harald; Saunders, Laura
1 Institut für Meteorologie und Klimaforschung – Atmosphärische Spurenstoffe und Fernerkundung (IMK-ASF), Karlsruher Institut für Technologie (KIT)


Observational monitoring of the stratospheric transport circulation, the Brewer-Dobson-Circulation (BDC), is crucial to estimate any decadal to long-term changes therein, a prerequisite to interpret trends in stratospheric composition and to constrain the consequential impacts on climate. The transport time along the BDC (i.e., the mean age of stratospheric air, AoA) can best be deduced from trace gas measurements of tracers which increase linearly in time and are chemically passive. The gas SF6 is often used to deduce AoA, because it has been increasing monotonically since the ~1950s, and previously its chemical sinks in the mesosphere have been assumed to be negligible for AoA estimates. However, recent studies have shown that the chemical sinks of SF6 are stronger than assumed, and become increasingly relevant with rising SF6 concentrations.

To adjust biases in AoA that result from the chemical SF6 sinks, we here propose a simple correction scheme for SF6-based AoA estimates accounting for the time-dependent effects of chemical sinks. The correction scheme is based on theoretical considerations with idealized assumptions, resulting in a relation between ideal AoA and apparent AoA which is a function of the tropospheric reference time-series of SF6 and of the AoA-dependent effective lifetime of SF6. ... mehr

Volltext §
DOI: 10.5445/IR/1000162264
Veröffentlicht am 15.09.2023
DOI: 10.5194/egusphere-2023-1862
Zitationen: 1
Cover der Publikation
Zugehörige Institution(en) am KIT Institut für Meteorologie und Klimaforschung – Atmosphärische Spurenstoffe und Fernerkundung (IMK-ASF)
Publikationstyp Forschungsbericht/Preprint
Publikationsjahr 2023
Sprache Englisch
Identifikator KITopen-ID: 1000162264
HGF-Programm 12.11.25 (POF IV, LK 01) Atmospheric composition and circulation changes
Verlag Copernicus
Vorab online veröffentlicht am 05.09.2023
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