Articles | Volume 22, issue 7
Atmos. Chem. Phys., 22, 4779–4799, 2022
Atmos. Chem. Phys., 22, 4779–4799, 2022
Research article
12 Apr 2022
Research article | 12 Apr 2022

Upper stratospheric ClO and HOCl trends (2005–2020): Aura Microwave Limb Sounder and model results

Lucien Froidevaux et al.

Data sets

EOS MLS Version 5.0 x Level 2 and 3 data quality and description document N. J. Livesey, W. G. Read, P. A. Wagner, L. Froidevaux, M. L. Santee, M. J. Schwartz, A. Lambert, G. L. Manney, L. F. M. Valle, H. C. Pumphrey, R. A. Fuller, R. F. Jarnot, B. W. Knosp, and R. R. Lay

Atmospheric Chemistry Experiment SciSat Level 2 Processed Data Peter F. Bernath, Johnathan Steffen, Jeffrey Crouse, and Chris D. Boone

Data Quality Flags for ACE-FTS Level 2 Version 4.1/4.2 Patrick Sheese and Kaley Walker

The 10.7 cm solar radio flux (F10.7) ( K. F. Tapping

The Whole Atmosphere Community Climate Model version 6 (WACCM6) ( A. Gettelman, M. J. Mills, D. E. Kinnison, R. R. Garcia, A. K. Smith, D.R. Marsh, S. Tilmes, F. Vitt, C. G. Bardeen, J. McInerny, H.-L. Liu, S. C. Solomon, L. M. Polvani, L. K. Emmons, J.-F. Lamarque, J. H. Richter, A. S. Glanville, J. T Bacmeister, A. S. Phillips, R. B. Neale, I. R. Simpson, A. K. DuVivier, A. Hodzic, and W. J. Randel

The Modern-Era Retrospective Analysis for Research and Applications, Version 2 (MERRA2) ( Ronald Gelaro, Will McCarty, Max J. Suárez, Ricardo Todling, Andrea Molod, Lawrence Takacs, Cynthia A. Randles, Anton Darmenov, Michael G. Bosilovich, Rolf Reichle1, Krzysztof Wargan, Lawrence Coy, Richard Cullathe, Clara Draper, Santha Akella, Virginie Buchard, Austin Conaty, Arlindo M. da Silva, Wei Gu, Gi-Kong Kim, Randal Koster, Robert Lucchesi, Dagmar Merkova, Jon Eric Nielsen, Gary Partyka, Steven Pawson, William Putman, Michele Rienecker, Siegfried D. Schubert, Meta Sienkiewicz, and Bin Zhao

Short summary
We analyze satellite-derived distributions of chlorine monoxide (ClO) and hypochlorous acid (HOCl) in the upper atmosphere. For 2005–2020, from 50°S to 50°N and over ~30 to 45 km, ClO and HOCl decreased by −0.7 % and −0.4 % per year, respectively. A detailed model of chemistry and dynamics agrees with the results. These decreases confirm the effectiveness of the 1987 Montreal Protocol, which limited emissions of chlorine- and bromine-containing source gases, in order to protect the ozone layer.
Final-revised paper