Lin et al. (2025) MJO Energy Budget Residuals in CMIP6: A Focus on Vertical Resolution

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

Identification

• Journal: Journal of Geophysical Research Atmospheres
• Year: 2025
• Date: 2025-10-11
• Authors: Qiao‐Jun Lin, Víctor C. Mayta
• DOI: 10.1029/2025jd044262

Research Groups

Not explicitly stated in the abstract. This study primarily uses reanalysis data and CMIP6 model output for analysis.

Short Summary

This study investigates how the vertical resolution of model output influences the Madden-Julian Oscillation (MJO)-related moist static energy (MSE) budget, finding that limited vertical levels in daily output lead to significant budget residuals due to overestimated vertical MSE advection caused by unrealistic dry static energy (DSE) gradients.

Objective

• To investigate the influence of model-output vertical resolution on the Madden-Julian Oscillation (MJO)-related moist static energy (MSE) budget.

Study Configuration

• Spatial Scale: Global, focusing on tropical atmospheric processes related to the MJO.
• Temporal Scale: Sub-seasonal (MJO timescale), with analysis of daily output.

Methodology and Data

• Models used: Not models run by the authors, but analysis of output from:
  • Reanalysis data (at varying vertical resolutions: raw levels, six standard CMIP6 layers, fine upper-tropospheric, fine lower-tropospheric).
  • CMIP6 model daily output.
• Data sources: Reanalysis data, CMIP6 model output.

Main Results

• Limiting vertical levels to six in reanalysis data leads to substantial MSE budget residuals, mirroring those found in CMIP6 daily output.
• Enhanced upper-tropospheric resolution captures moist processes more accurately compared with high resolution in the lower troposphere.
• Budget residuals amplify with rainfall anomalies and are primarily caused by overestimated vertical MSE advection.
• This overestimated advection is driven by an unrealistically strong vertical gradient in mean-state dry static energy (DSE) in the upper troposphere.
• Including an additional 150 hPa level in the six standard layers substantially reduces the background DSE bias and MSE budget residuals.
• In CMIP6 models, unrealistic mean DSE gradients appear in daily output but not in finer-resolution monthly output, contributing to overestimated vertical MSE advection.
• Limited vertical resolution in CMIP6 daily output partially contributes to the observed MSE budget residuals.

Contributions

• Demonstrates a direct link between limited vertical resolution in model output (specifically CMIP6 daily output) and significant residuals in the MJO-related moist static energy budget.
• Identifies the specific mechanism for these residuals: an unrealistic mean-state dry static energy gradient in the upper troposphere leading to overestimated vertical MSE advection.
• Provides a potential solution by showing that adding a single additional vertical level (150 hPa) can substantially mitigate the identified biases and residuals.
• Highlights a critical consideration for the interpretation and use of CMIP6 daily output for MJO studies.

Funding

Not explicitly stated in the abstract.

Citation

@article{Lin2025MJO,
  author = {Lin, Qiao‐Jun and Mayta, Víctor C.},
  title = {MJO Energy Budget Residuals in CMIP6: A Focus on Vertical Resolution},
  journal = {Journal of Geophysical Research Atmospheres},
  year = {2025},
  doi = {10.1029/2025jd044262},
  url = {https://doi.org/10.1029/2025jd044262}
}