---
OA_place: publisher
OA_type: hybrid
_id: '21217'
abstract:
- lang: eng
text: This study investigates the mechanisms driving clustered convection and the
breakdown of the Intertropical Convergence Zone (ITCZ) over the Western Pacific
Warm Pool using high‐resolution cloud‐resolving simulations and machine‐learning
sensitivity experiments. Results show that ITCZ breakdown episodes, marked by
spatially homogeneous convection and weakened meridional moisture gradients, are
triggered primarily by anomalous moisture advection linked to the equatorial Rossby‐wave
activity. While large‐scale moisture advection regulates the background convective
state strongly, it is the surface and low‐level meridional winds that dominate
transitions between clustered and random convection. Simulations demonstrate that
moisture alone can sustain convective clustering, but breakdown episodes are more
persistent and widespread when coupled with southerly meridional advection. These
findings confirm that wave‐driven advection acts as a regulatory mechanism, periodically
disrupting convective clustering and reshaping the meridional moisture gradient.
This modulation of organization by wave‐induced breakdown events is critical for
understanding tropical convection variability and its implications for the climate
system.
acknowledgement: This article is based on chapter 5 of the PhD thesis of A. Casallas.
The authors thank Graziano Giuliani for discussions on the boundary-condition experiments.
A. Casallas was supported by a PhD fellowship awarded by the Abdus Salam International
Centre for Theoretical Physics. A. Casallas also acknowledges support by the European
Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie
grant agreement No 101034413. C. Muller acknowledges funding from the European Research
Council (ERC) under the European Union's Horizon 2020 research and innovation program
(Project CLUSTER, Grant Agreement No. 805041). The authors gratefully acknowledge
Daniel Hernández-Deckers, Lokahith Agasthya, Chris Holloway, and Paolina Cerlini
for their valuable feedback and insightful discussions. They are especially thankful
to Bety Pechacova for suggesting the use of SHAP to complement their analysis. They
also thank the two anonymous reviewers for their constructive comments, which improved
the quality and clarity of the article significantly. Open Access funding provided
by Institute of Science and Technology Austria/KEMÖ.
article_number: e70131
article_processing_charge: Yes (via OA deal)
article_type: original
author:
- first_name: Alejandro
full_name: Casallas Garcia, Alejandro
id: 92081129-2d75-11ef-a48d-b04dd7a2385a
last_name: Casallas Garcia
orcid: 0000-0002-1988-5035
- first_name: Adrian
full_name: Mark Tompkins, Adrian
last_name: Mark Tompkins
- first_name: Caroline J
full_name: Muller, Caroline J
id: f978ccb0-3f7f-11eb-b193-b0e2bd13182b
last_name: Muller
orcid: 0000-0001-5836-5350
citation:
ama: Casallas Garcia A, Mark Tompkins A, Muller CJ. Moisture and wind effects of
Rossby waves on Western Pacific Intertropical Convergence Zone breakdown events.
Quarterly Journal of the Royal Meteorological Society. 2026. doi:10.1002/qj.70131
apa: Casallas Garcia, A., Mark Tompkins, A., & Muller, C. J. (2026). Moisture
and wind effects of Rossby waves on Western Pacific Intertropical Convergence
Zone breakdown events. Quarterly Journal of the Royal Meteorological Society.
Wiley. https://doi.org/10.1002/qj.70131
chicago: Casallas Garcia, Alejandro, Adrian Mark Tompkins, and Caroline J Muller.
“Moisture and Wind Effects of Rossby Waves on Western Pacific Intertropical Convergence
Zone Breakdown Events.” Quarterly Journal of the Royal Meteorological Society.
Wiley, 2026. https://doi.org/10.1002/qj.70131.
ieee: A. Casallas Garcia, A. Mark Tompkins, and C. J. Muller, “Moisture and wind
effects of Rossby waves on Western Pacific Intertropical Convergence Zone breakdown
events,” Quarterly Journal of the Royal Meteorological Society. Wiley,
2026.
ista: Casallas Garcia A, Mark Tompkins A, Muller CJ. 2026. Moisture and wind effects
of Rossby waves on Western Pacific Intertropical Convergence Zone breakdown events.
Quarterly Journal of the Royal Meteorological Society., e70131.
mla: Casallas Garcia, Alejandro, et al. “Moisture and Wind Effects of Rossby Waves
on Western Pacific Intertropical Convergence Zone Breakdown Events.” Quarterly
Journal of the Royal Meteorological Society, e70131, Wiley, 2026, doi:10.1002/qj.70131.
short: A. Casallas Garcia, A. Mark Tompkins, C.J. Muller, Quarterly Journal of the
Royal Meteorological Society (2026).
corr_author: '1'
date_created: 2026-02-12T10:13:02Z
date_published: 2026-02-12T00:00:00Z
date_updated: 2026-02-16T10:19:52Z
day: '12'
ddc:
- '550'
department:
- _id: CaMu
doi: 10.1002/qj.70131
ec_funded: 1
has_accepted_license: '1'
language:
- iso: eng
license: https://creativecommons.org/licenses/by-nc/4.0/
main_file_link:
- open_access: '1'
url: https://doi.org/10.1002/qj.70131
month: '02'
oa: 1
oa_version: Published Version
project:
- _id: fc2ed2f7-9c52-11eb-aca3-c01059dda49c
call_identifier: H2020
grant_number: '101034413'
name: 'IST-BRIDGE: International postdoctoral program'
- _id: 629205d8-2b32-11ec-9570-e1356ff73576
call_identifier: H2020
grant_number: '805041'
name: Organization of CLoUdS, and implications of Tropical cyclones and for the
Energetics of the tropics, in current and waRming climate
publication: Quarterly Journal of the Royal Meteorological Society
publication_identifier:
eissn:
- 1477-870X
issn:
- 0035-9009
publication_status: epub_ahead
publisher: Wiley
quality_controlled: '1'
scopus_import: '1'
status: public
title: Moisture and wind effects of Rossby waves on Western Pacific Intertropical
Convergence Zone breakdown events
tmp:
image: /images/cc_by_nc.png
legal_code_url: https://creativecommons.org/licenses/by-nc/4.0/legalcode
name: Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)
short: CC BY-NC (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2026'
...