Titre
Quantifying Convective Aggregation Using the Tropical Moist Margin's Length
Type
article
Institution
Externe
Auteur(s)
Beucler, Tom
Auteure/Auteur
Leutwyler, David
Auteure/Auteur
Windmiller, Julia M.
Auteure/Auteur
Liens vers les personnes
ISSN
1942-2466
Statut éditorial
Publié
Date de publication
2020-10
Volume
12
Numéro
10
Peer-reviewed
Oui
Langue
anglais
Résumé
On small scales, the tropical atmosphere tends to be either moist or very dry. This defines two states that, on large scales, are separated by a sharp margin, well identified by the antimode of the bimodal tropical column water vapor distribution. Despite recent progress in understanding physical processes governing the spatiotemporal variability of tropical water vapor, the behavior of this margin remains elusive, and we lack a simple framework to understand the bimodality of tropical water vapor in observations. Motivated by the success of coarsening theory in explaining bimodal distributions, we leverage its methodology to relate the moisture field's spatial organization to its time evolution. This results in a new diagnostic framework for the bimodality of tropical water vapor, from which we argue that the length of the margin separating moist from dry regions should evolve toward a minimum in equilibrium. As the spatial organization of moisture is closely related to the organization of tropical convection, we hereby introduce a new convective organization index (BLW) measuring the ratio of the margin's length to the circumference of a well-defined equilibrium shape. Using BLW, we assess the evolution of self-aggregation in idealized cloud-resolving simulations of radiative-convective equilibrium and contrast it to the time evolution of the Atlantic Intertropical Convergence Zone (ITCZ) in the ERA5 meteorological reanalysis product. We find that BLW successfully captures aspects of convective organization ignored by more traditional metrics, while offering a new perspective on the seasonal cycle of convective organization in the Atlantic ITCZ.
PID Serval
serval:BIB_B7E5E07CCE15
URL éditeur
Open Access
Oui
Date de création
2023-02-21T13:36:32.890Z
Date de création dans IRIS
2025-05-21T00:15:47Z
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Nom
J Adv Model Earth Syst - 2020 - Beucler - Quantifying Convective Aggregation Using the Tropical Moist Margin s Length.pdf
Version du manuscrit
published
Licence
https://creativecommons.org/licenses/by-nc/4.0
Taille
3.32 MB
Format
Adobe PDF
PID Serval
serval:BIB_B7E5E07CCE15.P001
Somme de contrôle
(MD5):f74e29190b947ba5565427c84f9a0595