Climate models underestimate dynamic cloud feedbacks in the tropics

Hill, P. G. ORCID: https://orcid.org/0000-0002-9745-2120, Holloway, C. E. ORCID: https://orcid.org/0000-0001-9903-8989, Byrne, M. P., Lambert, F. H. and Webb, M. J. (2023) Climate models underestimate dynamic cloud feedbacks in the tropics. Geophysical Research Letters, 50 (15). ISSN 0094-8276 doi: 10.1029/2023gl104573

Abstract/Summary

Cloud feedbacks are the leading cause of uncertainty in climate sensitivity. The complex coupling between clouds and the large-scale circulation in the tropics contributes to this uncertainty. To address this problem, the coupling between clouds and circulation in the latest generation of climate models is compared to observations. Significant biases are identified in the models. The implications of these biases are assessed by combining observations of the present day with future changes predicted by models to calculate observationally constrained feedbacks. For the dynamic cloud feedback (i.e. due to changes in circulation), the observationally constrained values are consistently larger than the model-only values. This is due to models failing to capture a nonlinear minimum in cloud brightness for weakly descending regimes. Consequently, while the models consistently predict that these regimes increase in frequency in association with a weakening tropical circulation, they underestimate the positive cloud feedback associated with this increase.

Item Type	Article
URI	https://reading-pure-test.eprints-hosting.org/id/eprint/112684
Identification Number/DOI	10.1029/2023gl104573
Refereed	Yes
Divisions	Science > School of Mathematical, Physical and Computational Sciences > Department of Meteorology Central Services
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