N.sub.2O as a regression proxy for dynamical variability in stratospheric trace gas trends

Trends in stratospheric trace gases like HCl, N.sub.2 O, O.sub.3, and NO.sub.y show a hemispheric asymmetry over the last 2Ãádecades, with trends having opposing signs in the Northern Hemisphere and Southern Hemisphere. Here we use N.sub.2 O, a long-lived tracer with a tropospheric source, as a prox...

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Bibliographic Details
Published in:Atmospheric chemistry and physics 2023-10, Vol.23 (20), p.13283
Main Authors: DubȨ, Kimberlee, Tegtmeier, Susann, Bourassa, Adam, Zawada, Daniel, Degenstein, Douglas, Sheese, Patrick E, Walker, Kaley A, Randel, William
Format: Article
Language:English
Subjects:
Analysis
Atmospheric chemistry
Proxy
Stratospheric circulation
Tropospheric circulation
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Summary:Trends in stratospheric trace gases like HCl, N.sub.2 O, O.sub.3, and NO.sub.y show a hemispheric asymmetry over the last 2Ãádecades, with trends having opposing signs in the Northern Hemisphere and Southern Hemisphere. Here we use N.sub.2 O, a long-lived tracer with a tropospheric source, as a proxy for stratospheric circulation in the multiple linear regression model used to calculate stratospheric trace gas trends. This is done in an effort to isolate trends due to circulation changes from trends due to the chemical effects of ozone-depleting substances. Measurements from the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) and the Optical Spectrograph and InfraRed Imager System (OSIRIS) are considered, along with model results from the Whole Atmosphere Community Climate Model (WACCM). Trends in HCl, O.sub.3, and NO.sub.y for 2004-2018 are examined. Using the N.sub.2 O regression proxy, we show that observed HCl increases in the Northern Hemisphere are due to changes in the stratospheric circulation. We also show that negative O.sub.3 trends above 30ÇëhPa in the Northern Hemisphere can be explained by a change in the circulation but that negative ozone trends at lower levels cannot. Trends in stratospheric NO.sub.y are found to be largely consistent with trends in N.sub.2 O.
ISSN:1680-7316