Lin et al. (2025) A Theory for the Spurious Pressure Waves in Compressible Large Eddy Simulations of Shallow Cumulus Clouds

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Geophysical Research Letters
• Year: 2025
• Date: 2025-10-14
• Authors: Yi Lin, Bowen Zhou
• DOI: 10.1029/2025gl118786

Research Groups

Not specified in the abstract. The study refers to "three compressible community LES models," implying a general community effort rather than specific research groups for this particular paper.

Short Summary

This paper investigates the omnipresent spurious pressure waves in large-eddy simulations (LES) of shallow cumulus clouds, proposing an analytic theory that links their generation to latent heating and suggesting more frequent microphysics updates for stabilization.

Objective

• To explain the generation of spurious pressure waves around simulated shallow cumulus clouds in compressible large-eddy simulation (LES) models and propose a method for their stabilization.

Study Configuration

• Spatial Scale: Cloud scale to mesoscale (implied by Large-Eddy Simulation).
• Temporal Scale: Short-term atmospheric processes (seconds to minutes, related to model time steps and sound wave propagation).

Methodology and Data

• Models used: Large-eddy simulation (LES), specifically "compressible community LES models" utilizing "bulk microphysics schemes" with "saturation adjustment."
• Data sources: Numerical simulation data ("LES results") used to support the proposed analytic theory.

Main Results

• Omnipresent spurious pressure waves are observed around simulated shallow cumulus clouds in compressible community LES models, degrading pressure-related variables and leading to unclosed turbulence flux budgets.
• An analytic theory proposes that latent heating generates these pressure waves, specifically when the time rate of heating equals the time interval of a sound wave propagating through a cloud, creating a singularity condition.
• This singularity condition is tied to the model time step in most bulk microphysics schemes that adopt saturation adjustment.
• The theory suggests that stabilizing these waves requires more frequent microphysics updates than currently implemented, a finding supported by LES results.

Contributions

• Identifies and characterizes a widespread issue of spurious pressure waves in community LES models of shallow cumulus clouds.
• Develops a novel analytic theory explaining the physical mechanism of pressure wave generation by latent heating.
• Links the wave generation to specific model parameters, namely the microphysics update frequency and model time step.
• Proposes a concrete and validated solution (more frequent microphysics updates) to mitigate the spurious waves, improving the fidelity of LES for shallow cumulus.

Funding

Not specified in the abstract.

Citation

@article{Lin2025Theory,
  author = {Lin, Yi and Zhou, Bowen},
  title = {A Theory for the Spurious Pressure Waves in Compressible Large Eddy Simulations of Shallow Cumulus Clouds},
  journal = {Geophysical Research Letters},
  year = {2025},
  doi = {10.1029/2025gl118786},
  url = {https://doi.org/10.1029/2025gl118786}
}