Drivers of mesoscale convective aggregation and spatial humidity variability in the tropical western Pacific

Tompkins AM, Casallas Garcia A, De Vera MV. 2025. Drivers of mesoscale convective aggregation and spatial humidity variability in the tropical western Pacific. npj Climate and Atmospheric Science. 8, 69.

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Author
Tompkins, Adrian Mike; Casallas Garcia, AlejandroISTA ; De Vera, Michie Vianca

Corresponding author has ISTA affiliation

Department
Abstract
We examine mesoscale convective organisation in the tropical western Pacific using a multivariate analysis of column humidity, precipitation and sea surface temperature (SST) observations. We demonstrate that in boreal summer and autumn, convection remains spatially random despite radiative-feedbacks acting to aggregate convection, which we attribute to the high density of convective moisture sources and the role of wind shear. Instead, in winter and spring, a weak meridional SST gradient exists and convection is usually clustered over the regions of warmer SSTs, with significant meridional humidity gradients. However, this is sporadically interrupted by episodes of convection migration to the coldest SSTs and limited spatial humidity variance. These episodes are the result of westward propagating equatorial waves, which remove meridional humidity gradients. It appears that the drivers of mesoscale convective clustering and humidity variability in the Pacific warm pool are the SST gradients, shear, and equatorial wave dynamics.
Publishing Year
Date Published
2025-02-24
Journal Title
npj Climate and Atmospheric Science
Publisher
Springer Nature
Acknowledgement
This paper is based on A.C. Ph.D. thesis, chapter 4. A.C. was supported by an ICTP Ph.D scholarship and subsequently by funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 101034413. MVDV was supported by an ICTP diploma programme scholarship while carrying out analysis for this publication. The funders played no role in study design, data collection, analysis and interpretation of data, or the writing of this manuscript. We would like to thank Maria Gehne of NOAA for providing the code for the wave activity calculation and advice on its use, and Fred Kucharski, Erika Coppola, Hernández-Deckers, Caroline Muller and Paolina Cerlini for their insightful comments and advice
Volume
8
Article Number
69
eISSN
IST-REx-ID

Cite this

Tompkins AM, Casallas Garcia A, De Vera MV. Drivers of mesoscale convective aggregation and spatial humidity variability in the tropical western Pacific. npj Climate and Atmospheric Science. 2025;8. doi:10.1038/s41612-024-00848-2
Tompkins, A. M., Casallas Garcia, A., & De Vera, M. V. (2025). Drivers of mesoscale convective aggregation and spatial humidity variability in the tropical western Pacific. Npj Climate and Atmospheric Science. Springer Nature. https://doi.org/10.1038/s41612-024-00848-2
Tompkins, Adrian Mike, Alejandro Casallas Garcia, and Michie Vianca De Vera. “Drivers of Mesoscale Convective Aggregation and Spatial Humidity Variability in the Tropical Western Pacific.” Npj Climate and Atmospheric Science. Springer Nature, 2025. https://doi.org/10.1038/s41612-024-00848-2.
A. M. Tompkins, A. Casallas Garcia, and M. V. De Vera, “Drivers of mesoscale convective aggregation and spatial humidity variability in the tropical western Pacific,” npj Climate and Atmospheric Science, vol. 8. Springer Nature, 2025.
Tompkins AM, Casallas Garcia A, De Vera MV. 2025. Drivers of mesoscale convective aggregation and spatial humidity variability in the tropical western Pacific. npj Climate and Atmospheric Science. 8, 69.
Tompkins, Adrian Mike, et al. “Drivers of Mesoscale Convective Aggregation and Spatial Humidity Variability in the Tropical Western Pacific.” Npj Climate and Atmospheric Science, vol. 8, 69, Springer Nature, 2025, doi:10.1038/s41612-024-00848-2.
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