Moisture Mode Oscillations in Steady‐State Weak Temperature Gradient Simulations

Abstract Weak Temperature Gradient modeling using a small cloud‐resolving model admits multiple equilibria depending upon the initial model conditions. There were thought to be two equilibrium states, a moist precipitating state and a dry non‐precipitating state. In this paper, we describe a periodi...

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Bibliographic Details
Main Authors: Miguel Bernardez, Larissa Back
Format: Article
Language:English
Published: American Geophysical Union (AGU) 2025-06-01
Series:Journal of Advances in Modeling Earth Systems
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Online Access:https://doi.org/10.1029/2024MS004391
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Summary:Abstract Weak Temperature Gradient modeling using a small cloud‐resolving model admits multiple equilibria depending upon the initial model conditions. There were thought to be two equilibrium states, a moist precipitating state and a dry non‐precipitating state. In this paper, we describe a periodic equilibrium which has oscillatory behavior from static boundary conditions. We show that the periodic oscillation has the characteristics of a moisture mode in the vertical dimension, instead of in the horizontal dimension. Further, we show that the oscillation occurs due to a balance between vertical advection and radiation, which can be described using a simple two vertical mode model. The first mode is related to the column relative humidity anomaly and a first baroclinic mode, while the second mode is related to a moisture dipole centered around 600 hPa and a second baroclinic mode. The first mode is associated with the generation of a moisture dipole, while the second mode is associated with the generation of a column moisture anomaly.
ISSN:1942-2466