Abalos, M. and Birner, T. and Chrysanthou, A. and Davis, S. and de la Cámara, A. and Dhomse, S. and Garny, H. and Hegglin, M.I. and Hubert, D. and Ivaniha, O. and Keeble, J. and Linz, M. and Minganti, D. and Neu, J. and Plummer, D. and Saunders, L. and Shah, K. and Stiller, G. and Tourpali, K. and Waugh, D. and Abraham, N.L. and Akiyoshi, H. and Chipperfield, M.P. and Jöckel, P. and Josse, B. and Marchand, M. and Martineau, P. and Morgenstern, O. and Sukhodolov, T. and Watanabe, S. and Yamashita, Y. (2026) Evaluation of stratospheric transport in three generations of Chemistry-Climate Models. Atmospheric Chemistry and Physics, 26 (8). pp. 5249-5291. ISSN 1680-7316
Full text not available from this repository.Abstract
The representation of stratospheric transport in Chemistry-Climate Models (CCMs) is key for accurately reproducing and projecting the evolution of the ozone layer and other radiatively relevant trace gases. We evaluate stratospheric transport in CCMs that have participated in three model intercomparison initiatives (CCMVal-2, CCMI-1, and CCMI-2022) over the last ∼ 15 years using modern satellite datasets and reanalyses. Key long-standing model biases persist across generations, with some worsening in recent simulations. Transport remains overly fast in the models, with a global mean age of air young bias of ∼ 1 year for the CCMI-2022 median. It is argued that this bias could be associated with too fast tropical upwelling in the lower stratosphere and possibly to excessive vertical diffusion, with mixing biases being more uncertain. In the springtime southern polar stratosphere, the final warming is delayed (∼ 3 weeks), downwelling is underestimated (∼ 25 %), and the depth of the ozone minimum is overestimated (∼ 10 DU) on average in the most recent models. The tropopause is too high in all generations, and the tropical cold point tropopause is too warm in the latest generation (∼ 1–2 K). Long-term trends in transport over 1980–1999 are consistent across model generations and highlight the crucial role of ozone depletion in contributing to accelerate the Brewer-Dobson circulation and delaying the southern polar vortex breakdown.