Age of air from ACE-FTS measurements of sulfur hexafluoride

Details

• Journal Title:
  Atmospheric Chemistry and Physics
• Personal Author:
  Saunders, Laura N. ; Walker, Kaley A. ; Stiller, Gabriele P. ; von Clarmann, Thomas ; Haenel, Florian ; Garny, Hella ; Bönisch, Harald ; Boone, Chris D. ; Castillo, Ariana E. ; Engel, Andreas ; Laube, Johannes C. ; Linz, Marianna ; Ploeger, Felix ; Plummer, David A. ; Ray, Eric A. ; Sheese, Patrick E.
• NOAA Program & Office:
  OAR (Oceanic and Atmospheric Research) ; CSL (Chemical Sciences Laboratory)
• Description:
  Climate models predict that the Brewer–Dobson circulation (BDC) will accelerate due to tropospheric warming, leading to a redistribution of trace gases and, consequently, to a change of the radiative properties of the atmosphere. Changes in the BDC are diagnosed by the so-called “age of air”, that is, the time since air in the stratosphere exited the troposphere. These changes can be derived from a long-term observation-based record of long-lived trace gases with increasing concentration in the troposphere, such as sulfur hexafluoride (SF6). The Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) provides the longest available continuous time series of vertically resolved SF6 measurements, spanning 2004 to the present. In this study, a new age-of-air product is derived from the ACE-FTS SF6 dataset. The ACE-FTS product is in good agreement with other observation-based age-of-air datasets and shows the expected global distribution of age-of-air values. Age of air from a chemistry–climate model is evaluated, and the linear trend of the observation-based age of air is calculated in 12 regions within the lower stratospheric midlatitudes (14–20 km, 40–70°) in each hemisphere. In 8 of 12 regions, there was not a statistically significant trend. The trends in the other regions, specifically 50–60 and 60–70° S at 17–20 km and 40–50° N at 14–17 and 17–20 km, are negative and significant to 2 standard deviations. This is therefore the first observation-based age-of-air trend study to suggest an acceleration of the shallow branch of the BDC, which transports air poleward in the lower stratosphere, in regions within both hemispheres.
• Source:
  Atmospheric Chemistry and Physics, 25(7), 4185-4209
• DOI:
  https://doi.org/10.5194/acp-25-4185-2025
• ISSN:
  1680-7324
• Format:
  pdf
• Publisher:
  Copernicus GmbH
• Document Type:
  Journal Article
• License:
  https://creativecommons.org/licenses/by/4.0/
• Rights Information:
  CC BY
• Compliance:
  Submitted
• Main Document Checksum:
  urn:sha-512:a55376fd816011c54e9164881b599343b9bdbfd1863b93202932223fab43fa57253b17af2ca5a950633432965f78f17e6467d7ef9c506671696dfd38917ddd1f
• Download URL:
  https://repository.library.noaa.gov/view/noaa/71523/noaa_71523_DS1.pdf
• File Type:
  [PDF - 6.89 MB ]