Preprints
https://doi.org/10.5194/gmd-2024-17
https://doi.org/10.5194/gmd-2024-17
Submitted as: model experiment description paper
 | 
07 Feb 2024
Submitted as: model experiment description paper |  | 07 Feb 2024
Status: this preprint is currently under review for the journal GMD.

Impact of ITCZ width on global climate: ITCZ-MIP

Angeline G. Pendergrass, Michael P. Byrne, Oliver Watt-Meyer, Penelope Maher, and Mark J. Webb

Abstract. The width of the Inter-Tropical Convergence Zone (ITCZ) affects tropical rainfall, Earth's albedo, large-scale circulation and climate sensitivity; yet we do not understand what controls it. To better understand the ITCZ width and its effects on global climate, we present a protocol to force changes in ITCZ width in climate models. Starting from an aquaplanet configuration with a slab ocean, adding surface heat fluxes in the deep tropics forces the ITCZ to narrow, and subtracting them causes it to widen. The protocol successfully generates changes in ITCZ width in four climate models; within each model, ITCZ width responds linearly to forcing magnitude and sign. Comparing across the four climate models, a response to varying ITCZ width that is remarkably consistent among models is the ITCZ strength, which is greater the narrower the ITCZ. On the other hand, the effect of varying ITCZ width on climate sensitivity is divergent among our four models, varying even in sign. These results indicate that idealized model experiments have the potential to increase our understanding of ITCZ width.

Angeline G. Pendergrass, Michael P. Byrne, Oliver Watt-Meyer, Penelope Maher, and Mark J. Webb

Status: open (until 03 Apr 2024)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on gmd-2024-17', Anonymous Referee #1, 28 Feb 2024 reply
  • CC1: 'Comment on gmd-2024-17', Wenyu Zhou, 29 Feb 2024 reply
Angeline G. Pendergrass, Michael P. Byrne, Oliver Watt-Meyer, Penelope Maher, and Mark J. Webb

Data sets

Model output Angeline G. Pendergrass et al. https://doi.org/10.5281/zenodo.10558341

Interactive computing environment

Jupyter notebook Oliver Watt-Meyer and Angeline G. Pendergrass https://doi.org/10.5281/zenodo.10558341

Angeline G. Pendergrass, Michael P. Byrne, Oliver Watt-Meyer, Penelope Maher, and Mark J. Webb

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Short summary
The width of the tropical rain belt affects many aspects of our climate; yet we do not understand what controls it. To better understand it, we present a method to change it in numerical model experiments. We show that the method works well in four different models. The behavior of the width is unexpectedly simple in some ways, such as how strong the winds are as it changes; but in other ways, it is more complicated, especially how temperature increases with carbon dioxide.