Ehhalt, D. H., Rohrer, F., Blake, D. R., Kinnison, D. E., & Konopka, P. (2007). On the use of nonmethane hydrocarbons for the determination of age spectra in the lower stratosphere. *Journal of Geophysical Research*, 112(D12), D12208. https://doi.org/10.1029/2006JD007686

Eichinger, R., Dietmüller, S., Garny, H., Šácha, P., Birner, T., Bönisch, H., et al. (2019). The influence of mixing on the stratospheric age of air changes in the 21st century. *Atmospheric Chemistry and Physics*, 19(2), 921–940. https://doi.org/10.5194/acp-19-921-2019

Engel, A. (2006). Physics observation of mesospheric air inside the arctic stratospheric polar vortex in early 2003 (pp. 267–282).

Engel, A., Bönisch, H., Brunner, D., Fischer, H., Franke, H., Günther, G., et al. (2006). Highly resolved observations of trace gases in the lowermost stratosphere and upper troposphere from the spurt project: An overview. *Atmospheric Chemistry and Physics*, 6(2), 283–301. https://doi.org/10.5194/acp-6-283-2006

Engel, A., Bönisch, H., Ostermöller, J., Chipperfield, M. P., Dhomse, S., & Jöckel, P. (2018). A refined method for calculating equivalent effective stratospheric chlorine. *Atmospheric Chemistry and Physics*, 18(2), 601–619. https://doi.org/10.5194/acp-18-601-2018

Engel, A., Bönisch, H., Ullrich, M., Sitals, R., Membrive, O., Danis, F., & Crevoisier, C. (2017). Mean age of stratospheric air derived from aircore observations. *Atmospheric Chemistry and Physics*, 17(11), 6825–6838. https://doi.org/10.5194/acp-17-6825-2017

Engel, A., Mobius, T., Boenisch, H., Schmidt, U., Heinz, R., Levin, I., et al. (2009). Age of stratospheric air unchanged within uncertainties over the past 30 years. *Nature Geoscience*, 2(1), 28–31. https://doi.org/10.1038/ngeo388

Engel, A., Strunk, M., Müller, M., Haase, H.-P., Poss, C., Levin, I., & Schmidt, U. (2002). The temporal development of total chlorine in the high latitude stratosphere based on reference distributions of mean age derived from CO₂ and SF₆. *Journal of Geophysical Research*, 107(D12), 4136. https://doi.org/10.1029/2001JD000584

Fischer, H., Birk, M., Blom, C., Carli, B., Carlotti, M., von Clarmann, T., et al. (2008). MIPAS: An instrument for atmospheric and climate research. *Atmospheric Chemistry and Physics*, 8(8), 2151–2188. https://doi.org/10.5194/acp-8-2151-2008

Flury, T., Wu, D. L., & Read, W. G. (2013). Variability in the speed of the Brewer–Dobson circulation as observed by Aura/MLS. *Atmospheric Chemistry and Physics*, 13(9), 4563–4575. https://doi.org/10.5194/acp-13-4563-2013

Forster, P., & Shine, K. (1997). Radiative forcing and temperature trends from stratospheric ozone change. *Journal of Geophysical Research*, 102, 10841–10856. https://doi.org/10.1029/96JD03510

Friedl-Vallon, F., Gulde, T., Hase, F., Kleinert, A., Kulessa, T., Maucher, G., et al. (2014). Instrument concept of the imaging Fourier transform spectrometer gloria. *Atmospheric Measurement Techniques*, 7(10), 3565–3577. https://doi.org/10.5194/amt-7-3565-2014

Fritsch, F., Garny, H., Engel, A., Bönisch, H., & Eichinger, R. (2020). Sensitivity of age of air trends to the derivation method for non-linear increasing inert SF₆. *Atmospheric Chemistry and Physics*, 20(14), 8709–8725. https://doi.org/10.5194/acp-20-8709-2020

Fueglistaler, S., Legras, B., Beljaars, A., Morcrette, J.-J., Simmons, A., Tompkins, A. M., & Uppala, S. (2009). The diabatic heat budget of the upper troposphere and lower/mid stratosphere in ECMWF reanalyses. *Quarterly Journal of the Royal Meteorological Society*, 135(638), 21–37. https://doi.org/10.1002/qj.361

Fujiwara, M., Manney, G. L., Gray, L. J., & Wright, J. S. (2021). SPARC reanalysis intercomparison project (S-RIP) final report. In *WCRP/6-2021, SPARC report*. https://doi.org/10.17874/800dee57d13

Funke, B., López-Puertas, M., García-Comas, M., Stiller, G. P., von Clarmann, T., Höpfner, M., et al. (2009). Carbon monoxide distributions from the upper troposphere to the mesosphere inferred from 4.7 µm non-local thermal equilibrium emissions measured by MIPAS on Envisat. *Atmospheric Chemistry and Physics*, 9(7), 2387–2411. https://doi.org/10.5194/acp-9-2387-2009

Garcia, R. R., & Randel, W. J. (2008). Acceleration of the Brewer–Dobson circulation due to increases in greenhouse gases. *Journal of the Atmospheric Sciences*, 65(8), 2731–2739. https://doi.org/10.1175/2008JAS2712.1

Garcia, R. R., Randel, W. J., & Kinnison, D. E. (2011). On the determination of age of air trends from atmospheric trace species. *Journal of the Atmospheric Sciences*, 68(1), 139–154. https://doi.org/10.1175/2010JAS3527.1

Garny, H., Birner, T., Boenisch, H., & Bunzel, F. (2014). The effects of mixing on age of air. *Journal of Geophysical Research*, 119, 7015–7034. https://doi.org/10.1002/2013JD02147

Garny, H., Eichinger, R., Laube, J. C., Ray, E. A., Stiller, G. P., Bönisch, H., et al. (2024). Correction of stratospheric age of air (AoA) derived from sulfur hexafluoride (SF₆) for the effect of chemical sinks. *Atmospheric Chemistry and Physics*, 24, 4193–4215. https://doi.org/10.5194/acp-24-4193-2024

Garny, H., Hendon, H., Abalos, M., Chiodo, G., Purich, A., Randel, W. J., et al. (2022). Stratospheric ozone changes and climate. In WMO (Ed.), *Scientific assessment of ozone depletion: 2022, GAW report no. 278 (chapter 5), Geneva, Switzerland* (p. 509)

Garny, H., & Randel, W. J. (2013). Dynamic variability of the Asian monsoon anticyclone observed in potential vorticity and correlations with tracer distributions. *Journal of Geophysical Research*, 118(24), 13421–13433. https://doi.org/10.1002/2013JD020908

Garny, H., Saunders, L. N., Voet, F., Ray, E., von Clarmann, T., Bönisch, H., et al. (2024). Age of stratospheric air: Observational data sets [Dataset]. Zenodo. https://doi.org/10.5281/zenodo.11267157

Gille, J. C., Bailey, P. L., Russell, J. M., Russell, J. M., Massey, H. S. W., Beynon, W. J. G., et al. (1980). Temperature and composition measurements from the I.r.i.r. and l.i.m.s. experiments on nimbus 6 and 7. *Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences*, 296(1418), 205–218. https://doi.org/10.1098/rsta.1980.0165

Glanville, A. A., & Birner, T. (2017). Role of vertical and horizontal mixing in the tape recorder signal near the tropical tropopause. *Atmospheric Chemistry and Physics*, 17(6), 4337–4353. https://doi.org/10.5194/acp-17-4337-2017

Glatthor, N., von Clarmann, T., Funke, B., García-Comas, M., Grabowski, U., Höpfner, M., et al. (2023). IMK/IAA MIPAS retrievals version 8: CH₄ and N₂O. In *Atmospheric measurement techniques discussions* (pp. 1–35). https://doi.org/10.5194/egusphere-2023-919

Gunson, M. R., Abbas, M. M., Abrams, M. C., Allen, M., Brown, L. R., Brown, T. L., et al. (1996). The atmospheric trace molecule spectroscopy (ATMOS) experiment: Deployment on the ATLAS space shuttle missions. *Geophysical Research Letters*, 23(17), 2333–2336. https://doi.org/10.1029/96GL01569

Gupta, A., Gerber, E. P., & Lauritzen, P. H. (2020). Numerical impacts on tracer transport: A proposed intercomparison test of atmospheric general circulation models. *Quarterly Journal of the Royal Meteorological Society*, 146(733), 3937–3964. https://doi.org/10.1002/qj.3881

Gupta, A., Gerber, E. P., Plumb, R. A., & Lauritzen, P. H. (2021). Numerical impacts on tracer transport: Diagnosing the influence of dynamical core formulation and resolution on stratospheric transport. *Journal of the Atmospheric Sciences*, 78, 3575–3592. https://doi.org/10.1175/JAS-D-21-0085.1

Gupta, A., Linz, M., Curbelo, J., Pauluis, O., Gerber, E. P., & Kinnison, D. E. (2023). Estimating the meridional extent of adiabatic mixing in the stratosphere using age-of-air. *Journal of Geophysical Research: Atmospheres*, 128(4), e2022JD037712. https://doi.org/10.1029/2022JD037712

Haenel, F. J., Stüller, G. P., von Clarmann, T., Funke, B., Eckert, E., Glatthor, N., et al. (2015). Reassessment of MIPAS age of air trends and variability. *Atmospheric Chemistry and Physics*, 15(22), 13161–13176. https://doi.org/10.5194/acp-15-13161-2015

Haine, T. W. N., & Hall, T. M. (2002). A generalized transport theory: Water-mass composition and age. *Journal of Physical Oceanography*, 32(6), 1932–1946. https://doi.org/10.1175/1520-0485(2002)032<1932:agttwm>2.0.co;2
Hall, T. M. (2000). Path histories and timescales in stratospheric transport: Analysis of an idealized model. *Journal of Geophysical Research*, 105(D18), 22811–22823. https://doi.org/10.1029/2000JD900329

Hall, T. M., & Plumb, R. A. (1994). Age as a diagnostic of stratospheric transport. *Journal of Geophysical Research*, 99(D1), 1059–1070. https://doi.org/10.1029/93JD03192

Hall, T. M., & Prather, M. J. (1993). Simulations of the trend and annual cycle in stratospheric CO₂. *Journal of Geophysical Research*, 98(D6), 10573–10581. https://doi.org/10.1029/93jd00325

Han, Y., Tian, W., Chipperfield, M. P., Zhang, J., Wang, F., Sang, W., et al. (2019). Attribution of the hemispheric asymmetries in trends of stratospheric trace gases inferred from Microwave Limb Sounder (MLS) measurements. *Journal of Geophysical Research*, 124(12), 6283–6293. https://doi.org/10.1029/2018JD029723

Hassler, B., Young, P., Ball, W. T., Damadeo, R., Keeble, J., Barras, E. M., et al. (2022). Update on global ozone: Past, present and future. In *WMO (Ed.), Scientific assessment of ozone depletion: 2022, GAW report no. 278 (chapter 3). Geneva, Switzerland* (p. 509)

Hauck, M., Bönisch, H., Hoor, P., Keber, T., Ploeger, F., Schuck, T. J., & Engel, A. (2020). A convolution of observational and model data to estimate age of air spectra in the northern hemispheric lower stratosphere. *Atmospheric Chemistry and Physics*, 20(14), 8763–8785. https://doi.org/10.5194/acp-20-8763-2020

Hauck, M., Fritsch, F., Garny, H., & Engel, A. (2019). Deriving stratospheric age of air spectra using an idealized set of chemically active trace gases. *Atmospheric Chemistry and Physics*, 19(7), 5269–5291. https://doi.org/10.5194/acp-19-5269-2019

Haynes, P. H., McIntyre, M. E., Shepherd, T. G., Marks, C. J., & Shine, K. P. (1991). On the “downward control” of extratropical diabatic circulations by eddy-induced mean zonal forces. *Journal of the Atmospheric Sciences*, 48(4), 651–678. https://doi.org/10.1175/1520-0469(1991)048(0651:OTCOED)2.0.CO;2

Haywood, J., Tilmes, S., Keutsch, F., Niemeier, U., Schmidt, A., Visioni, D., et al. (2022). Stratospheric aerosol injection and its potential effect on the stratospheric ozone layer. In *WMO (Ed.), Scientific assessment of ozone depletion: 2022, GAW report no. 278 (chapter 6), Geneva, Switzerland* (p. 509)

Hegglin, M. I., Plummer, D. A., Shepherd, T. G., Scinocca, J. F., Anderson, J., Froidevaux, L., et al. (2014). Vertical structure of stratospheric water vapour trends derived from merged satellite data. *Nature Geoscience*, 7(10), 768–776. https://doi.org/10.1038/NGE02236

Hegglin, M. I., & Shepherd, T. G. (2009). Large climate-induced changes in ultraviolet index and stratosphere-to-troposphere ozone flux. *Nature Geoscience*, 2(10), 687–691. https://doi.org/10.1038/ngeo0604

Hegglin, M. I., & Tegtmeier, S. (2017). The sparc data initiative: Assessment of stratospheric trace gas and aerosol climatologies from satellite limb sounders. In *SPARC report no. 8, WCRP-05/2017*. Retrieved from www.sparc-climate.org/publications/sparc-reports/10.3929/ethz-a-010863911

Hegglin, M. I., Tegtmeier, S., Anderson, J., Bourassa, A. E., Brohede, S., Degenstein, D., et al. (2021). Overview and update of the sparc data initiative: Comparison of stratospheric composition measurements from satellite limb sounders. *Earth System Science Data*, 13(5), 1855–1903. https://doi.org/10.5194/essd-13-1855-2021

Hegglin, M. I., Tegtmeier, S., Anderson, J., Bourassa, A. E., Brohede, S., Degenstein, D., et al. (2020). SPARC Data Initiative monthly zonal mean composition measurements from stratospheric limb sounders (1978–2018). *Zenodo*. https://doi.org/10.5281/zenodo.4265393

Holton, J. R., Haynes, P., McIntyre, M. E., Douglass, A. R., Rood, R. B., & Pfister, L. (1995). Stratosphere-troposphere exchange. *Reviews of Geophysics*, 33(4), 403–439. https://doi.org/10.1029/95rg02097

Holzer, M., & Hall, T. M. (2000). Transit-time and tracer-age distributions in geophysical flows. *Journal of the Atmospheric Sciences*, 57(21), 3539–3558. https://doi.org/10.1175/1520-0469(2000)057<3539:ttatad>2.0.co;2

Holzer, M., & Hall, T. M. (2008). Tropospheric transport climate partitioned by surface origin and transit time. *Journal of Geophysical Research*, 113(D8), D08104. https://doi.org/10.1029/2007JD009115

Holzer, M., & Waugh, D. W. (2015). Interhemispheric transit time distributions and path-dependent lifetimes constrained by measurements of SF₆, CFCS, and CFC replacements. *Geophysical Research Letters*, 42(1), 1–9. https://doi.org/10.1002/2015GL064172

Hooghiem, J. J. D., Popa, M. E., Röckmann, T., Grooß, J.-U., Tritscher, I., Müller, R., et al. (2020). Wildfire smoke in the lower stratosphere identified by in situ co observations. *Atmospheric Chemistry and Physics*, 20(22), 13985–14003. https://doi.org/10.5194/acp-20-13985-2020

Iglesias-Suarez, F., Wild, O., Kinnison, D. E., Garcia, R. R., Marsh, D. R., Lamarque, J.-F., et al. (2021). Tropical stratospheric circulation and ozone coupled to Pacific multi-decadal variability. *Geophysical Research Letters*, 48(11), e2020GL092162. https://doi.org/10.1029/2020GL092162

Johnson, D. G., Jucks, W., Traub, W. A., Chance, K. V., Toon, G. C., Iii, J. M. R., & McCormick, M. P. (1999). Stratospheric age spectra derived from observations of water vapor and methane. *Journal of Geophysical Research*, 104(D17), 21595–21602. https://doi.org/10.1029/1999jd900363

Karion, A., Sweeney, C., Tans, P., & Newberger, T. (2010). AirCore: An innovative atmospheric sampling system. *Journal of Atmospheric and Oceanic Technology*, 27(11), 1839–1853. https://doi.org/10.1175/2010JTECHA1448.1

Karpechko, A. Y., Afargan-Gerstman, H., Butler, A. H., Domeisen, D. I. V., Kretschmer, M., Lawrence, Z., et al. (2022). Northern hemisphere stratosphere-troposphere circulation change in CMIP6 models: 1. Inter-model spread and scenario sensitivity. *Journal of Geophysical Research: Atmospheres*, 127(18), e2022JD036992. https://doi.org/10.1029/2022JD036992

Kida, H. (1983). General circulation of air parcels and transport characteristics derived from a hemispheric GCM. 2. Very long-term motions of air parcels in the troposphere and stratosphere. *Journal of the Meteorological Society of Japan*, 61(4), 510–523. https://doi.org/10.2151/jmsj1965.61.4_510

Konopka, P., Grooß, J.-U., Günther, G., Ploeger, F., Pommrich, R., Müller, R., & Livesey, N. (2010). Annual cycle of ozone at and above the tropical tropopause: Observations versus simulations with the chemical Lagrangian model of the stratosphere (CLaMS). *Atmospheric Chemistry and Physics*, 10(1), 121–132. https://doi.org/10.5194/acp-10-121-2010

Konopka, P., Ploeger, F., Tao, M., & Riese, M. (2016). Zonally resolved impact of ENSO on the stratospheric circulation and water vapor entry values. *Journal of Geophysical Research*, 121(19), 11486–11501. https://doi.org/10.1002/2015JD024698

Kovács, T., Feng, W., Totterdill, A., Plane, J. M. C., Dhomse, S., Gómez-Martín, J. C., et al. (2017). Determination of the atmospheric lifetime and global warming potential of sulfur hexafluoride using a three-dimensional model. *Atmospheric Chemistry and Physics*, 17(2), 883–898. https://doi.org/10.5194/acp-17-883-2017

Krause, J., Hoor, P., Engel, A., Plöger, F., Grooß, J.-U., Bönisch, H., et al. (2018). Mixing and ageing in the polar lower stratosphere in winter 2015–2016. *Atmospheric Chemistry and Physics*, 18(8), 6057–6073. https://doi.org/10.5194/acp-18-6057-2018

Laube, J. C., Elvidge, E. C. L., Adcock, K. E., Baier, B., Brenninkmeijer, C. A. M., Chen, H., et al. (2020). Investigating stratospheric changes between 2009 and 2018 with halogenated trace gas data from aircraft, aircores, and a global model focusing on CFC-11. *Atmospheric Chemistry and Physics*, 20(16), 9771–9782. https://doi.org/10.5194/acp-20-9771-2020
Laube, J. C., Engel, A., Bönisch, H., Möbius, T., Sturges, W. T., Braß, M., & Röckmann, T. (2010). Fractional release factors of long-lived halogenated organic compounds in the tropical stratosphere. *Atmospheric Chemistry and Physics*, 10(3), 1093–1103. https://doi.org/10.5194/acp-10-1093-2010

Leedham Elvidge, E., Bönisch, H., Brenninkmeijer, C. A. M., Engel, A., Fraser, P. J., Gallacher, E., et al. (2018). Evaluation of stratospheric age of air from $CF_4$, $C_2F_6$, $C_4F_8$, CHF$_3$, HFC-125, HFC-227EA and SF$_6$: implications for the calculations of halocarbon lifetimes, fractional release factors and ozone depletion potentials. *Atmospheric Chemistry and Physics*, 18(5), 3369–3385. https://doi.org/10.5194/acp-18-3369-2018

Li, F., Newman, P., Pawson, S., & Perlwitz, J. (2018). Effects of greenhouse gas increase and stratospheric ozone depletion on stratospheric mean age of air in 1960–2010. *Journal of Geophysical Research: Atmospheres*, 123(4), 2098–2110. https://doi.org/10.1002/2017JD027562

Li, F., Waugh, D. W., Douglass, A. R., Newman, P. A., Strahan, S. E., Ma, J., et al. (2012). Long-term changes in stratospheric age spectra in the 21st century in the Goddard Earth observing system chemistry-climate model (GEOSCCM). *Journal of Geophysical Research*, 117(D20), D20119. https://doi.org/10.1029/2012JD017905

Li, J., Baier, B. C., Moore, F., Newberger, T., Wolter, S., Higgs, J., et al. (2023). A novel, cost-effective analytical method for measuring high-resolution vertical profiles of stratospheric trace gases using a gas chromatograph coupled with an electron capture detector. *Atmospheric Measurement Techniques*, 16(11), 2851–2863. https://doi.org/10.5194/amt-16-2851-2023

Lin, P., & Fu, Q. (2013). Changes in various branches of the Brewer-Dobson circulation from an ensemble of chemistry climate models. *Journal of Geophysical Research: Atmospheres*, 118(1), 73–84. https://doi.org/10.1029/2012JD018813

Linz, M., Abalos, M., Glanville, A. S., Kinnison, D. E., Ming, A., & Neu, J. L. (2019). The global diabatic circulation of the stratosphere as a metric for the Brewer-Dobson circulation. *Atmospheric Chemistry and Physics*, 19(7), 5069–5090. https://doi.org/10.5194/acp-19-5069-2019

Linz, M., Plumb, R. A., Gerber, E. P., Haenel, F. J., Stiller, G., Kinnison, D. E., et al. (2017). The strength of the meridional overturning circulation of the stratosphere. *Nature Geoscience*, 10(663), 663–667. https://doi.org/10.1038/ngeo03013

Linz, M., Plumb, R. A., Gerber, E. P., & Sheshadri, A. (2016). The relationship between age of air and the diabatic circulation of the stratosphere. *Journal of the Atmospheric Sciences*, 73(11), 4507–4518. https://doi.org/10.1175/JAS-D-16-0125.1

Linz, M., Plumb, R. A., Gupta, A., & Gerber, E. P. (2021). Stratospheric adiabatic mixing rates derived from the vertical gradient of age of air. *Journal of Geophysical Research*, 126(21), e2021JD035199. https://doi.org/10.1029/2021JD035199

Loeffel, S., Eichinger, R., Garny, H., Reddmann, T., Fritsch, F., Versick, S., et al. (2022). The impact of sulfur hexafluoride (SF$_6$) sinks on age of air climatologies and trends. *Atmospheric Chemistry and Physics*, 22(2), 1175–1193. https://doi.org/10.5194/acp-22-1175-2022

Luo, Z. J., Pan, L. L., Atlas, E. L., Chelpon, S. M., Honomichl, S. B., Apel, E. C., et al. (2018). Use of airborne in situ VOC measurements to estimate transit time spectrum: An observation-based diagnostic of convective transport. *Geophysical Research Letters*, 45(1), 13150–13157. https://doi.org/10.1029/2018GL080424

McIntyre, M. E., & Palmer, T. N. (1984). The 'surf zone' in the stratosphere. *Journal of Atmospheric and Terrestrial Physics*, 46(9), 825–849. https://doi.org/10.1016/0021-9169(84)90063-1

McLandress, C., Shepherd, T. G., Scinocca, J. F., Plummer, D. A., Sigmond, M., Jonsson, A. I., & Reader, M. C. (2011). Separating the dynamical effects of climate change and ozone depletion. Part II: Southern hemisphere troposphere. *Journal of Climate*, 24(6), 1850–1868. https://doi.org/10.1175/2010JCLI3958.1

Membrive, O., Crevoisier, C., Sweeney, C., Danis, F., Hertzog, A., Engel, A., et al. (2017). Aircore-hr: A high-resolution column sampling to enhance the vertical description of $CH_4$ and $CO_2$. *Atmospheric Measurement Techniques*, 10(6), 2163–2181. https://doi.org/10.5194/amt-10-2163-2017

Michelsen, H. A., Manney, G. L., Gunson, M. R., & Zander, R. (1998). Correlations of stratospheric abundances of NOY, $O_3$, $N_2O$ and $CH_4$ derived from atmos measurements. *Journal of Geophysical Research*, 103(D21), 28347–28359. https://doi.org/10.1029/98jd02850

Milz, M., Clarmann, T. V., Bernath, P., Boone, C., Buehler, S. A., Chauhan, S., et al. (2009). Validation of water vapour profiles (version 13) retrieved by the IMK/IAA scientific retrieval processor based on full resolution spectra measured by MIPAS on board Envisat. *Atmospheric Measurement Techniques*, 2(2), 379–399. https://doi.org/10.5194/acp-2-379-2009

Mote, P. W., Rosenlof, K. H., McIntyre, M. E., Carr, E. S., Gille, J. C., Holton, J. R., et al. (1996). An atmospheric tape recorder: The imprint of tropical tropopause temperatures on stratospheric water vapor. *Journal of Geophysical Research*, 101(D2), 3989–4006. https://doi.org/10.1029/95JD03422

Murcray, D. G., Bonomo, F. S., Brooks, J. N., Goldman, A., Murcray, F. H., & Williams, W. J. (1975). Detection of fluorocarbons in the stratosphere. *Geophysical Research Letters*, 2(3), 109–112. https://doi.org/10.1029/GL002i003p00109

Muthers, S., Kuchar, A., Stenke, A., Schmitt, J., Anet, J. G., Raible, C. C., & Stocker, T. F. (1986). Stratospheric age of air variations between 1600 and 2100. *Geophysical Research Letters*, 43(10), 5409–5418. https://doi.org/10.1002/2016GL068734

Nakajima, H., Sugita, T., Yokota, T., Ishigaki, T., Mogi, Y., Araki, N., et al. (2006). Characteristics and performance of the improved limb atmospheric spectrometer-II (ILAS-II) on board the ADEOS-II satellite. *Journal of Geophysical Research*, 111(D11), 8213. https://doi.org/10.1029/2005JD006334

Neu, J. L., Glanville, A. S., & Kinnison, D. E. (2018). Decadal-scale variations in stratospheric circulation driven by seasonal timing of the Quasi-Biennial Oscillation. In *AGU Fall Meeting Abstracts*, A31A-07.

Neu, J. L., & Plumb, R. A. (1999). Age of air in a “leaky pipe” model of stratospheric transport. *Journal of Geophysical Research*, 104(D16), 19243–19255. https://doi.org/10.1029/1999JD0900251

Newman, P. A., Daniel, J. S., Waugh, D. W., & Nash, E. R. (2007). A new formulation of equivalent effective stratospheric chlorine (EESC). *Atmospheric Chemistry and Physics*, 7(17), 4537–4552. https://doi.org/10.5194/acp-7-4537-2007

Newman, P. A., Nash, E. R., Kawa, S. R., Montzka, S. A., & Schaufller, S. M. (2006). When will the Antarctic ozone hole recover? *Geophysical Research Letters*, 33(12), L12814. https://doi.org/10.1029/2005GL025232

Niwano, M., Yamazki, K., & Shiotani, M. (2003). Seasonal and QBO variations of ascent rate in the tropical lower stratosphere as inferred from UARS haloe trace gas data. *Journal of Geophysical Research*, 108(D24), D18304. https://doi.org/10.1029/2003JD003871

Oberländer, S., Langematz, U., & Meul, S. (2013). Unraveling impact factors for future changes in the Brewer-Dobson circulation. *Journal of Geophysical Research: Atmospheres*, 118(18), 10296–10312. https://doi.org/10.1002/jgrd.50775

Oman, L., Waugh, D. W., Pawson, S., Stolarski, R. S., & Newman, P. A. (2009). On the influence of anthropogenic forcings on changes in the stratospheric mean age. *Journal of Geophysical Research*, 114(D3), D03105. https://doi.org/10.1029/2008JD010378

Orbe, C., Holzer, M., Polvani, L. M., & Waugh, D. (2013). Air-mass origin as a diagnostic of tropospheric transport. *Journal of Geophysical Research: Atmospheres*, 118(3), 1459–1470. https://doi.org/10.1002/jgrd.50133

Orbe, C., Rind, D., Jonas, J., Nazarenko, L., Faluvegi, G., Murray, L. T., et al. (2020). Giss model e2.2: A climate model optimized for the middle atmosphere—2. Validation of large-scale transport and evaluation of climate response. *Journal of Geophysical Research: Atmospheres*, 125(24), e2020JD033151. https://doi.org/10.1029/2020JD033151
Ostermöller, J., Bönisch, H., Jöckel, P., & Engel, A. (2017). A new time-independent formulation of fractional release. *Atmospheric Chemistry and Physics*, 17(6), 3785–3797. https://doi.org/10.5194/acp-17-3785-2017

Palmeiro, F. M., Calvo, N., & Garcia, R. R. (2014). Future changes in the Brewer–Dobson circulation under different greenhouse gas concentrations in WACCM4. *Journal of the Atmospheric Sciences*, 71(8), 2962–2975. https://doi.org/10.1175/JAS-D-13-0289.1

Park, S., Jim, R., Daube, B. C., Pfister, L., Conway, T. J., Gottlieb, E. W., et al. (2007). The CO₂ tracer clock for the tropical tropopause layer. *Atmospheric Chemistry and Physics*, 3, 3989–4000.

Plieninger, J., Laeng, A., Lossow, S., von Clarmann, T., Stiller, G. P., Kellmann, S., et al. (2016). Validation of revised methane and nitrous oxide profiles from MIPAS-ENVISAT. *Atmospheric Measurement Techniques*, 9(2), 765–779. https://doi.org/10.5194/amt-9-765-2016

Plieninger, J., von Clarmann, T., Stiller, G. P., Grabowski, U., Glatthor, N., Kellmann, S., et al. (2015). Methane and nitrous oxide retrievals from MIPAS-ENVISAT. *Atmospheric Measurement Techniques*, 8(11), 4657–4670. https://doi.org/10.5194/amt-8-4657-2015

Ploeger, F., Abalos, M., Birner, T., Konopka, P., Legras, B., Müller, R., & Riese, M. (2015). Quantifying the effects of mixing and residual circulation on trends of stratospheric mean age of air. *Geophysical Research Letters*, 42(6), 2047–2054. https://doi.org/10.1002/2014GL062927.1

Ploeger, F., & Birner, T. (2016). Seasonal and inter-annual variability of lower stratospheric age of air spectra. *Atmospheric Chemistry and Physics*, 2016(15), 10195–10213. https://doi.org/10.5194/acp-16-10195-2016

Ploeger, F., Diallo, M., Charlesworth, E., Konopka, P., Legras, B., Laube, J. C., et al. (2021). The stratospheric Brewer–Dobson circulation inferred from age of air in the ERA5 reanalysis. *Atmospheric Chemistry and Physics*, 21(11), 8393–8412. https://doi.org/10.5194/acp-21-8393-2021

Ploeger, F., & Garny, H. (2022). Hemispheric asymmetries in recent changes in the stratospheric circulation. *Atmospheric Chemistry and Physics*, 22(8), 5559–5576. https://doi.org/10.5194/acp-22-5559-2022

Ploeger, F., Legras, B., Charlesworth, E., Yan, X., Diallo, M., Konopka, P., et al. (2019). How robust are stratospheric age of air trends from different reanalyses? *Atmospheric Chemistry and Physics*, 19(9), 6085–6105. https://doi.org/10.5194/gmd-12-2441-2019

Plumb, R. A. (1996). A “tropical pipe” model of stratospheric transport. *Journal of Geophysical Research*, 101(D2), 3957–3972. https://doi.org/10.1029/95JD03002

Plumb, R. A. (2002). Stratospheric transport. *Journal of the Meteorological Society of Japan*, 80(4), 793–809. https://doi.org/10.2151/jmsj.80.793

Plumb, R. A. (2007). Tracer interrelationships in the stratosphere. *Reviews of Geophysics*, 45(4), 1–33. https://doi.org/10.1029/2005RG000179

Plumb, R. A., & Ko, M. K. W. (1992). Interrelationships between mixing ratios of long-lived stratospheric constituents. *Journal of Geophysical Research*, 97(D9), 10145–10156. https://doi.org/10.1029/92JD00450

Podglajen, A., & Ploeger, F. (2019). Retrieving the age of air spectrum from tracers: Principle and method. *Atmospheric Chemistry and Physics*, 19(1), 1767–1783. https://doi.org/10.5194/acp-19-1767-2019

Polvani, L. M., Abalos, M., Garcia, R., Kinnison, D., & Randel, W. J. (2018). Significant weakening of Brewer-Dobson circulation trends over the 21st century as a consequence of the Montreal protocol. *Geophysical Research Letters*, 45(1), 401–409. https://doi.org/10.1002/2017gl075345

Polvani, L. M., Wang, L., Abalos, M., Butchart, N., Chipperfield, M. P., Dameris, M., et al. (2019). Large impacts, past and future, of ozone-depleting substances on Brewer-Dobson circulation trends: A multimodel assessment. *Journal of Geophysical Research: Atmospheres*, 124(13), 6669–6680. https://doi.org/10.1029/2018JD029516

Poshyvailo-Strube, L., Müller, R., Fueglistaler, S., Hegglin, M. I., Laube, J. C., Volk, C. M., & Ploeger, F. (2022). How can Brewer-Dobson circulation trends be estimated from changes in stratospheric water vapour and methane? *Atmospheric Chemistry and Physics*, 22(15), 9895–9914. https://doi.org/10.5194/acp-22-9895-2022

Prather, M. J. (1996). Time scales in atmospheric chemistry: Theory, GWPs for CH₄ and CO, and runaway growth. *Geophysical Research Letters*, 23(19), 2597–2600. https://doi.org/10.1029/96GL02371

Prather, M. J., Froidevaux, L., & Livesey, N. J. (2023). Observed changes in stratospheric circulation: Decreasing lifetime of N₂O, 2005–2021. *Atmospheric Chemistry and Physics*, 23(2), 843–849. https://doi.org/10.5194/acp-23-843-2023

Raspollini, P., Arnone, E., Barbara, F., Bianchini, M., Carli, B., Ceccherini, S., et al. (2022). Level 2 processor and auxiliary data for ESA version 8 final full mission analysis of MIPAS measurements on ENVISAT. *Atmospheric Measurement Techniques*, 15(6), 1871–1901. https://doi.org/10.5194/amt-15-1871-2022

Ray, E. A., Atlas, E. L., Schauffler, S., Chelpon, S. M., Pan, L. L., Boenisch, H., & Rosenlof, K. R. (2022). Age spectra and other transport diagnostics in the North American monsoon UTLS from SEAC4ES in situ trace gas measurements. *Atmospheric Chemistry and Physics*, 22(1), 6539–6558. https://doi.org/10.5194/acp-22-6539-2022

Ray, E. A., Moore, F. L., Elkins, J. W., Dutton, G. S., Fahey, D. W., Vomel, H., et al. (1999). Transport into the northern hemisphere lowermost stratosphere revealed by in situ tracer measurements. *Journal of Geophysical Research*, 104(D21), 26565–26580. https://doi.org/10.1029/1999jd0900323

Ray, E. A., Moore, F. L., Elkins, J. W., Rosenlof, K. H., Laube, J. C., Röckmann, T., et al. (2017). Quantification of the SF₆ lifetime based on mesospheric loss measured in the stratospheric polar vortex. *Journal of Geophysical Research: Atmospheres*, 122(8), 4626–4638. https://doi.org/10.1002/2016JD026198

Ray, E. A., Moore, F. L., Rosenlof, K. H., Davis, S. M., Sweeney, C., Tans, P., et al. (2014). Improving stratospheric transport trend analysis based on SF₆ and CO₂ measurements. *Journal of Geophysical Research: Atmospheres*, 119(24), 14110–14128. https://doi.org/10.1002/2014JD021802

Ray, E. A., Moore, F. L., Rosenlof, K. H., Plummer, D. A., Kolonjari, F., & Walker, K. A. (2016). An idealized stratospheric model useful for understanding differences between long-lived trace gas measurements and global chemistry-climate model output. *Journal of Geophysical Research: Atmospheres*, 121(10), 5356–5367. https://doi.org/10.1002/2015JD024447

Reddmann, T., Ruhnke, R., & Kouker, W. (2001). Three-dimensional model simulations of SF₆ with mesospheric chemistry. *Journal of Geophysical Research*, 106(D13), 14525–14537. https://doi.org/10.1029/2000JD0900700

Reithmeier, C., Sausen, R., & Grewe, V. (2008). Investigating lower stratospheric model transport: Lagrangian calculations of mean age and age spectra in the GCM ECHAM4. *Climate Dynamics*, 30(2–3), 225–238. https://doi.org/10.1007/s00382-007-0294-1

Riese, M., Oelhaf, H., Preusse, P., Blank, J., Ern, M., Friedl-Vallon, F., et al. (2014). Gimballed limb observer for radiance imaging of the atmosphere (GLORIA) scientific objectives. *Atmospheric Measurement Techniques*, 7, 1915–1928. https://doi.org/10.5194/amt-7-1915-2014

Riese, M., Ploeger, F., Rap, A., Vogel, B., Konopka, P., Dameris, M., & Forster, P. (2012). Impact of uncertainties in atmospheric mixing on simulated UTLS composition and related radiative effects. *Journal of Geophysical Research*, 117(D16), D16305. https://doi.org/10.1029/2012JD017751

Rind, D., Suozzo, R., Balachandran, N. K., & Prather, M. J. (1990). Climate change and the middle atmosphere. Part I: The doubled CO₂ climate. *Journal of the Atmospheric Sciences*, 47(4), 475–494. https://doi.org/10.1175/1520-0469(1990)047<0475:ccatma>2.0.co;2
Rinsland, C. P., Brown, L. R., & Farmer, C. B. (1990). Infrared spectroscopic detection of sulfur hexafluoride ($SF_6$) in the lower stratosphere and upper troposphere. *Journal of Geophysical Research*, **95**(D5), 5577–5585. https://doi.org/10.1029/89JD03413

Rinsland, C. P., Mahieu, E., Zander, R., Gunson, M. R., Salawitch, R. J., Chang, A. Y., et al. (1996). Trends of OCS, HCN, $SF_6$, CHCIF2 (HCFC-22) in the lower stratosphere from 1985 and 1994 Atmospheric Trace Molecule Spectroscopy experiment measurements near 30°N latitude. *Geophysical Research Letters*, **23**(17), 2349–2352. https://doi.org/10.1029/96g101234

Rivoire, L., Linz, M., & Li, J. (2024). Observational limitations to the emergence of climate signals. *Geophysical Research Letters*, **51**, e2024GL109638. https://doi.org/10.1029/2024GL109638

Rosenlof, K. H. (1995). Seasonal cycle of the residual mean meridional circulation in the stratosphere. *Journal of Geophysical Research*, **100**(D3), 5173–5191. https://doi.org/10.1029/94jd03122

Saunders, L. N., Walker, K. A., Stiller, G. P., von Clarmann, T., Haenel, F., Garny, H., et al. (2024). Age of air from ACE-FTS measurements of sulfur hexafluoride [preprint]. *EGUSphere*. https://doi.org/10.5194/egusphere-2024-2117

Scheele, M. P., Siegmund, P. C., & Velthoven, P. F. J. V. (2005). Stratospheric age of air computed with trajectories based on various 3D-Var and 4D-Var data sets. *Atmospheric Chemistry and Physics*, **5**, 1–7. https://doi.org/10.5194/acp-5-1-2005

Schmidt, U., Bauer, R., Khedim, A., Klein, E., Kulessa, G., & Schiller, C. (1991). Profile observations of long-lived trace gases in the Arctic vortex. *Geophysical Research Letters*, **4**, 767–770. https://doi.org/10.1029/91GL00552

Schoeberl, M. R., Douglass, A. R., Polansky, B., Boone, C., Walker, K. A., & Bernath, P. (2005). Estimation of stratospheric age spectrum from chemical tracers. *Journal of Geophysical Research*, **110**(D21), D21303. https://doi.org/10.1029/2005JD006125

Schoeberl, M. R., Douglass, A. R., Stolarski, R. S., Pawson, S., Strahan, S. E., & Read, W. (2008). Comparison of lower stratospheric tropical mean vertical velocities. *Journal of Geophysical Research*, **113**(D24), D24109. https://doi.org/10.1029/2008JD010221

Schoeberl, M. R., Sparling, L. C., Jackman, C. H., & Fleming, E. L. (2000). A Lagrangian view of stratospheric trace gas distributions. *Journal of Geophysical Research*, **105**(D1), 1537–1552. https://doi.org/10.1029/1999JD900787

Sheese, P. E., Walker, K. A., Boone, C. D., Bernath, P. F., Froidevaux, L., Funke, B., et al. (2017). ACE-FTS ozone, water vapour, nitrous oxide, nitric acid, and carbon monoxide profile comparisons with MIPAS and MLS. *Journal of Quantitative Spectroscopy and Radiative Transfer*, **186**, 63–80. https://doi.org/10.1016/j.jqsrt.2016.06.026

Shepherd, T. G., & McLandress, C. (2011). A robust mechanism for strengthening of the Brewer–Dobson circulation in response to climate change: Critical-layer control of subtropical wave breaking. *Journal of the Atmospheric Sciences*, **68**(4), 784–797. https://doi.org/10.1175/2010jas3608.1

Shindell, D. T., Fuglestvedt, J. S., & Collins, W. J. (2017). The social cost of methane: Theory and applications. *Faraday Discussions*, **200**, 429–451. https://doi.org/10.1039/c7fd00009j

Shuckburgh, E., d'Ovidio, F., & Legras, B. (2009). Local mixing events in the upper troposphere and lower stratosphere. Part II: Seasonal and interannual variability. *Journal of the Atmospheric Sciences*, **66**(12), 3695–3706. https://doi.org/10.1175/2009JAS2983.1

Solomon, S., Daniel, J. S., Neely, R. R., Vernier, J.-P., Dutton, E. G., & Thomason, L. W. (2011). The persistently variable “background” stratospheric aerosol layer and global climate change. *Science*, **333**(6044), 866–870. https://doi.org/10.1126/science.1206027

Solomon, S., Rosenlof, K. H., Portmann, R. W., Daniel, J. S., Davis, S. M., Sanford, T. J., & Plattner, G.-K. (2010). Contributions of stratospheric water vapor to decadal changes in the rate of global warming. *Science*, **327**(5970), 1219–1223. https://doi.org/10.1126/science.1182488

Stiller, G. P., Fierli, F., Ploeger, F., Cagnazzo, C., Funke, B., Haenel, F. J., et al. (2017). Shift of subtropical transport barriers explains observed hemispheric asymmetry of decadal trends of age of air. *Atmospheric Chemistry and Physics*, **17**(18), 11177–11192. https://doi.org/10.5194/acp-17-11177-2017

Stiller, G. P., von Clarmann, T., Glatthor, N., Grabowski, U., Kellmann, S., Kiefer, M., et al. (2023). Version 8 IMK/IAA MIPAS measurements of CFC-11, CFC-12, and HCFC-22. *Atmospheric Measurement Techniques Discussions*, **2023**, 1–48. https://doi.org/10.5194/amt-2023-172

Stiller, G. P., von Clarmann, T., Haenel, F., Funke, B., Glatthor, N., Grabowski, U., et al. (2012). Observed temporal evolution of global mean age of stratospheric air for the 2002 to 2010 period. *Atmospheric Chemistry and Physics*, **12**(7), 3311–3331. https://doi.org/10.5194/acp-12-3311-2012

Stiller, G. P., von Clarmann, T., Höpfner, M., Glatthor, N., Grabowski, U., Kellmann, S., et al. (2008). Global distribution of mean age of stratospheric air from MIPAS $SF_6$ measurements. *Atmospheric Chemistry and Physics*, **8**(3), 677–695. https://doi.org/10.5194/acp-8-677-2008

Strahan, S. E., Schoeberl, M. R., & Steenrod, S. D. (2009). The impact of tropical recirculation on polar composition. *Atmospheric Chemistry and Physics*, **9**(7), 2471–2480. https://doi.org/10.5194/acp-9-2471-2009

Strahan, S. E., Smale, D., Douglass, A. R., Blumenstock, T., Hannigan, J. W., Hase, F., et al. (2020). Observed hemispheric asymmetry in stratospheric transport trends from 1994 to 2018. *Geophysical Research Letters*, **47**(17), e2020GL088567. https://doi.org/10.1029/2020GL088567

Sugawara, S., Ishidoya, S., Aoki, S., Morimoto, S., Nakazawa, T., Toyoda, S., et al. (2018). Age and gravitational separation of the stratospheric air over Indonesia. *Atmospheric Chemistry and Physics*, **18**(3), 1819–1833. https://doi.org/10.5194/acp-18-1819-2018

Tegtmeier, S., Hegglin, M. I., Anderson, J., Funke, B., Gille, J., Jones, A., et al. (2016). The SPARC data initiative: Comparisons of CFC-11, CFC-12, HF and SF6 climatologies from international satellite limb sounders. *Earth System Science Data*, **8**(1), 61–78. https://doi.org/10.5194/essd-8-61-2016

Thompson, C. R., Wofsy, S. C., Prather, M. J., Newman, P. A., Hanisco, T. F., Ryerson, T. B., et al. (2022). The NASA atmospheric tomography (atom) mission: Imaging the chemistry of the global atmosphere. *Bulletin America Meteorology Social*, **103**(3), E761–E790. https://doi.org/10.1175/BAMS-D-20-0315.1

Toon, G. C. (1991). The JPL MkIV interferometer. *Optics & Photonics News*, **2**(10), 19–21. https://doi.org/10.1364/opn.2.10.000019

Umezawa, T., Matsueda, H., Sawa, Y., Niwa, Y., Machida, T., & Zhou, L. (2018). Seasonal evaluation of tropospheric $CO_2$ over the Asia-Pacific region observed by the contrail commercial airliner measurements. *Atmospheric Chemistry and Physics*, **18**(20), 14851–14866. https://doi.org/10.5194/acp-18-14851-2018

Urban, J., Lautié, N., Flochmoën, E. L., Jiménez, C., Eriksson, P., de La Noë, J., et al. (2005). Odin/SMR limb observations of stratospheric trace gases: Level 2 processing of CCIO, $N_2O$, $HNO_3$, and $O_3$. *Journal of Geophysical Research*, **110**(D14), D14307. https://doi.org/10.1029/2004JD005741

Vernier, J.-P., Thomason, L. W., Pommereau, J.-P., Bourassa, A., Pelon, J., Garnier, A., et al. (2011). Major influence of tropical volcanic eruptions on the stratospheric aerosol layer during the last decade. *Geophysical Research Letters*, **38**(12), 389. https://doi.org/10.1029/2011GL047563

Vogel, B., Volk, C. M., Wintel, J., Lauther, V., Müller, R., Patra, P. K., et al. (2023). Reconstructing high-resolution in-situ vertical carbon dioxide profiles in the sparsely monitored Asian monsoon region. *Communications Earth & Environment*, **4**(1), 72. https://doi.org/10.1038/s43247-023-00725-5
Volk, C. M., Elkins, J. W., Fahey, D. W., Dutton, G. S., Gilligan, J. M., Loewenstein, M., et al. (1997). Evaluation of source gas lifetimes from stratospheric observations. *Journal of Geophysical Research*, 102(D21), 25543–25564. https://doi.org/10.1029/97JD02215

von Clarmann, T., & Grabowski, U. (2016). Direct inversion of circulation and mixing from tracer measurements—Part 1: Method. *Atmospheric Chemistry and Physics*, 16(22), 14563–14584. https://doi.org/10.5194/acp-16-14563-2016

von Clarmann, T., & Grabowski, U. (2021). Direct inversion of circulation from tracer measurements—Part 2: Sensitivity studies and model recovery tests. *Atmospheric Chemistry and Physics*, 21(4), 2509–2526. https://doi.org/10.5194/acp-21-2509-2021

von Clarmann, T., Grabowski, U., Stiller, G. P., Monge-Sanz, B. M., Glatthor, N., & Kellmann, S. (2021). The middle atmospheric meridional circulation for 2002-2012 derived from MIPAS observations. *Atmospheric Chemistry and Physics*, 21(11), 8823–8843. https://doi.org/10.5194/acp-21-8823-2021

von Clarmann, T., Höpfner, M., Kellmann, S., Linden, A., Chauhan, S., Funke, B., et al. (2009). Retrieval of temperature, H₂O, O₃, HNO₃, CH₄, N₂O, ClONO₂, and ClO from MIPAS reduced resolution nominal mode limb emission measurements. *Atmospheric Measurement Techniques*, 2(1), 159–175.

von Clarmann, T., Oelhaf, H., & Fischer, H. (1993). Retrieval of atmospheric O₃, HNO₃, CFC-11, and CFC-12 profiles from MIPAS-B–89 limb emission spectra. *Applied Optics*, 32(33), 6808–6817. https://doi.org/10.1364/AO.32.006808

Wagenhäuser, T., Engel, A., Bönisch, H., Ray, E., Garny, H., & Voet, F. (2024). AtmosphericAngels/AoA from convolution: Software version as used in Garny et al. 2024 (v1.0.0) [Dataset]. Zenodo. https://doi.org/10.5281/zenodo.11127613

Wagenhäuser, T., Engel, A., & Sitals, R. (2021). Testing the altitude attribution and vertical resolution of aircore measurements with a new spiking method. *Atmospheric Measurement Techniques*, 14(5), 3923–3934. https://doi.org/10.5194/amt-14-3923-2021

Wagenhäuser, T., Jesswein, M., Keber, T., Schuck, T., & Engel, A. (2023). Mean age from observations in the lowermost stratosphere: An improved method and interhemispheric differences. *Atmospheric Chemistry and Physics*, 23(7), 3887–3903. https://doi.org/10.5194/acp-23-3887-2023

Waters, J., Froidevaux, L., Harwood, R., Jarnot, R., Pickett, H., Read, W., et al. (2006). The Earth observing system microwave limb sounder (EOS MLS) on the aura satellite. *IEEE Transactions on Geoscience and Remote Sensing*, 44(5), 1075–1092. https://doi.org/10.1029/2007JD008824

Waugh, D. (2009). The age of stratospheric air. *Nature Geoscience*, 2(1), 14–16. https://doi.org/10.1038/ngeo397

Waugh, D., & Hall, T. M. (2002). Age of stratospheric air: Theory, observations, and models. *Reviews of Geophysics*, 40(4), 1010. https://doi.org/10.1029/2000RG000101

Wofsy, S. C. (2011). Pole-to-pole observations (hippo): Fine-grained, global-scale measurements of climatically important atmospheric gases and aerosols. *Philosophical Transactions of the Royal Society A*, 369(1943), 2073–2086. https://doi.org/10.1098/rsta.2010.0313

## References From the Supporting Information

Etheridge, D. M., Steele, L. P., Francey, R. J., & Langenfelds, R. L. (1998). Atmospheric methane between 1000 a.d. and present: Evidence of anthropogenic emissions and climatic variability. *Journal of Geophysical Research*, 103(D13), 15979–15993. https://doi.org/10.1029/98JD00923

Girard, A., Besson, J., Brard, D., Laurent, J., Lemaître, M., Lippens, C., et al. (1988). Global results of grille spectrometer experiment on board spacelab 1. *Planetary and Space Science*, 36(3), 291–300. https://doi.org/10.1016/0032-0633(88)90136-5

Grossmann, K., Gusev, O., Kaufmann, M., Kutepov, A., & Knieling, P. (2004). A review of the scientific results from the crista missions. *Advances in Space Research*, 34(8), 1715–1721. https://doi.org/10.1016/j.asr.2003.02.041

Gunson, M. R., Farmer, C. B., Norton, R. H., Zander, R., Rinsland, C. P., Shaw, J. H., & Gao, B. C. (1990). Measurements of CH₄, N₂O, CO, H₂O, and O₃ in the middle atmosphere by the atmospheric trace molecule spectroscopy experiment on Spacelab 3. *Journal of Geophysical Research*, 95(D9), 13867–13882. https://doi.org/10.1029/jd095id09p13867

Homan, C. D., Volk, C. M., Kuhn, A. C., Werner, A., Baehr, J., Viciani, S., et al. (2010). Tracer measurements in the tropical tropopause layer during the AMMA/SCOUT-O3 aircraft campaign. *Atmospheric Chemistry and Physics*, 10(8), 3615–3627. https://doi.org/10.5194/acp-10-3615-2010

Hoor, P., Gurk, C., Brunner, D., Hegglin, M. I., Wernli, H., & Fischer, H. (2004). Seasonality and extent of extratropical TST derived from in-situ co measurements during spurt. *Atmospheric Chemistry and Physics*, 4(5), 1427–1442. https://doi.org/10.5194/acp-4-1427-2004

Keeling, C. D., Piper, S. C., Bacastow, R. B., Wahlen, M., Whorf, T. P., Heimann, M., & Meijer, H. A. (2005). Atmospheric CO₂ and ¹³CO₂ exchange with the terrestrial biosphere and oceans from 1978 to 2000: Observations and carbon cycle implications (pp. 83–113). Springer.

Khosrawi, F., Müller, R., Irie, H., Engel, A., Toon, G. C., Sen, B., et al. (2004). Validation of CFC-12 measurements from the improved limb atmospheric spectrometer (ILAS) with the version 6.0 retrieval algorithm. *Journal of Geophysical Research*, 109(D6), D06311. https://doi.org/10.1029/2003JD004325

Kikuchi, K.-I., Nishibori, T., Ochiai, S., Ozeki, H., Irimajiri, Y., Kasai, Y., et al. (2010). Overview and early results of the superconducting submillimeter-wave limb-emission sounder (smiles). *Journal of Geophysical Research*, 115(D23), D23306. https://doi.org/10.1029/2010JD014379

Kloss, C., Tan, V., Leen, J. B., Madsen, G. L., Gardner, A., Du, X., et al. (2021). Airborne mid-infrared cavity enhanced absorption spectrometer (AMICA). *Atmospheric Measurement Techniques*, 14(8), 5271–5297. https://doi.org/10.5194/amt-14-5271-2021

Meinshausen, M., Vogel, E., Nauels, A., Lorbacher, N., Meinshausen, K., Etheridge, D. M., et al. (2017). Historical greenhouse gas concentrations for climate modelling (CMIP6). *Geoscientific Model Development*, 10(5), 2057–2116. https://doi.org/10.5194/gmd-10-2057-2017

National Aeronautics and Space Administration, & Roche, A. (2006). Cryogenic limb array etalon spectrometer (class 13): Vertical temperature profiles and atmospheric particle concentration measurements, 15 September 2023. NCAS British Atmospheric Data Centre. Retrieved from http://catalogue.ceda.ac.uk/uuid/1ae11ab1741c29c15ab58baaeebc9550

Natural Environment Research Council, British National Space Centre, & National Aeronautics and Space Administration. (2013). *Hirdls: Level 2 version 7.00 atmospheric chemical and temperature measurements, 18 September 2023*. NCAS British Atmospheric Data Centre. Retrieved from https://catalogue.ceda.ac.uk/uuid/c547fe67f0e49bc3861b4369b921fb21

NASA Jet Propulsion Laboratory, National Aeronautics and Space Administration, Waters, J., Harwood, R., & Pumphrey, H. (2006). *Upper atmosphere research satellite (UARS) vertical profiles of atmospheric components from the microwave limb sounder (MLS L3) instrument and NERC microwave limb sounder (MLS) prototype water vapour data, 15 September 2023*. NCAS British Atmospheric Data Centre. Retrieved from http://catalogue.ceda.ac.uk/uuid/2e4c98d91a9237c128c0acbf3e11ce7f
NASA Langley Research Center, NASA Langley DAAC, Russell, J., & Harries, J. (2006). *Halogen occultation experiment (haloe): Global stratospheric and mesospheric profiles of pressure, temperature and chemical composition, 15 September 2023*. NCAS British Atmospheric Data Centre. Retrieved from http://catalogue.ceda.ac.uk/uuid/6297603d25100cc5e977b750c1a524f7

Offermann, D., Grossmann, K.-U., Barthol, P., Knieling, P., Riese, M., & Trant, R. (1999). Cryogenic infrared spectrometers and telescopes for the atmosphere (crista) experiment and middle atmosphere variability. *Journal of Geophysical Research*, 104(D13), 16311–16325. https://doi.org/10.1029/1998JD100047

Papineau, N., Camy-Peyret, C., & Ackerman, M. (1989). Monitoring of the middle atmosphere: Grille spectrometer experiment results on board spacelab 1 and scientific program of atlas 1 mission. In *Advanced optical instrumentation for remote sensing of the earth's surface from space*. https://doi.org/10.1117/12.961483

Rinsland, C. P., Gunson, M. R., Abrams, M. C., Lowes, L. L., Zander, R., & Mahieu, E. (1993). ATMOS/ATLAS1 measurements of sulfur hexafluoride (SF₆) in the lower stratosphere and upper troposphere. *Journal of Geophysical Research*, 98(D11), 20491–20494. https://doi.org/10.1029/93JD02258

Schuck, T. J., Brenninkmeijer, C. A. M., Baker, A. K., Slemr, F., von Velthoven, P. F. J., & Zahn, A. (2010). Greenhouse gas relationships in the Indian summer monsoon plume measured by the caribic passenger aircraft. *Atmospheric Chemistry and Physics*, 10(8), 3965–3984. https://doi.org/10.5194/acp-10-3965-2010

Taylor, F., & Rogers, C. (2006). *Improved stratospheric and mesospheric sounder (ISAMS) vertical profiles of temperature and atmospheric constituents*. NCAS British Atmospheric Data Centre. Retrieved from http://catalogue.ceda.ac.uk/uuid/fb0a13f4a913daee7a93c393e6a67e79

Taylor, F. W., Rodgers, C. D., Nutter, S. T., & Oslik, N. (1989). *Nimbus-7 stratospheric and mesospheric sounder (SAMS) experiment data user's guide (NASA Reference Publication No. 1221)*. Goddard Space Flight Center, National Aeronautics and Space Administration.

Yokota, T., Nakajima, H., Sugita, T., Tsubaki, H., Itou, Y., Kaji, M., et al. (2002). Improved limb atmospheric spectrometer (ILAS) data retrieval algorithm for version 5.20 gas profile products. *Journal of Geophysical Research*, 107(D24), 8216doi. https://doi.org/10.1029/2001JD000628