Tan et al. (2026) Impact of the NCEP TKE‐Based Eddy‐Diffusivity Mass‐Flux Boundary Layer Scheme on the Climatology and Warming Response of GFDL AM4.0 Model

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

Identification

• Journal: Journal of Advances in Modeling Earth Systems
• Year: 2026
• Date: 2026-01-01
• Authors: Zhihong Tan, Ming Zhao
• DOI: 10.1029/2025ms005168

Research Groups

• National Centers for Environmental Prediction (NCEP)
• Geophysical Fluid Dynamics Laboratory (GFDL)

Short Summary

This study implements and evaluates a turbulent kinetic energy (TKE)‐based eddy‐diffusivity mass‐flux (EDMF) scheme in the GFDL atmospheric model (AM4.0) to improve subgrid‐scale planetary boundary layer (PBL) turbulence parameterization. The EDMF scheme leads to a deeper, more well‐mixed PBL, improving vertical temperature and humidity profiles and reducing near‐surface wet bias, particularly over subtropical and midlatitude oceans.

Objective

• To improve the physical consistency of subgrid‐scale planetary boundary layer (PBL) turbulence parameterization in the Geophysical Fluid Dynamics Laboratory atmospheric model (AM4.0) by implementing the National Centers for Environmental Prediction turbulent kinetic energy (TKE)‐based eddy‐diffusivity mass‐flux (EDMF) scheme.

Study Configuration

• Spatial Scale: Global atmospheric model simulations, with analysis focusing on zonal-mean profiles, subtropical and midlatitude oceans, equatorial regions, extratropical regions, and coastal stratocumulus.
• Temporal Scale: Climate-scale simulations for evaluating model performance and biases.

Methodology and Data

• Models used: Geophysical Fluid Dynamics Laboratory atmospheric model (AM4.0), National Centers for Environmental Prediction turbulent kinetic energy (TKE)‐based eddy‐diffusivity mass‐flux (EDMF) scheme.
• Data sources: Not explicitly detailed in the abstract, but implied comparison with observational or reanalysis data for model evaluation of biases and performance.

Main Results

• The EDMF scheme produces a deeper and more well‐mixed planetary boundary layer (PBL) compared to the original eddy-diffusivity (ED)-only scheme.
• This leads to better zonal‐mean vertical temperature and humidity profiles and a reduced near‐surface wet bias over subtropical and midlatitude oceans.
• Other model performance changes are generally minor, including similar biases in global top of atmosphere (TOA) net radiation and shortwave cloud radiative effects.
• Small and compensating changes are observed in low cloud amount and cloud liquid water path.
• The scheme results in improved low‐level equatorial easterlies but deteriorated extratropical westerlies.
• A slight increase in global‐mean precipitation and a weaker TOA radiative response to uniform sea surface warming are also noted.
• Three key adaptations of EDMF were crucial for its performance at AM4.0's relatively coarse vertical resolution: limiting the overshoot of mass flux (MF) updraft above PBL‐top, reducing the ED‐induced mixing across PBL‐top, and disabling the MF transport of TKE.
• Low clouds and their radiative effects are sensitive to four EDMF parameters controlling ED in the lower and upper PBL, the TKE dissipation rate, and the lateral entrainment of MF updraft and downdraft.
• An automatic linear tuning of these parameters slightly improves the radiative bias, particularly for coastal stratocumulus.

Contributions

• Implementation and evaluation of a TKE-based EDMF scheme in a state-of-the-art global atmospheric model (GFDL AM4.0), addressing a known limitation of its original ED-only PBL parameterization regarding countergradient transport and coherent convective structures.
• Identification of critical adaptations required for the EDMF scheme to perform effectively at coarse vertical resolutions typical of global climate models.
• Quantification of the scheme's impact on PBL structure, atmospheric profiles, and various climate metrics, providing insights for future model development and parameterization improvements.

Funding

• Not specified in the abstract.

Citation

@article{Tan2026Impact,
  author = {Tan, Zhihong and Zhao, Ming},
  title = {Impact of the NCEP TKE‐Based Eddy‐Diffusivity Mass‐Flux Boundary Layer Scheme on the Climatology and Warming Response of GFDL AM4.0 Model},
  journal = {Journal of Advances in Modeling Earth Systems},
  year = {2026},
  doi = {10.1029/2025ms005168},
  url = {https://doi.org/10.1029/2025ms005168}
}