Sanow et al. (2025) Let Us Change the Aerodynamic Roughness Length as a Function of Snow Depth

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Identification

• Journal: Climate
• Year: 2025
• Date: 2025-10-31
• Authors: Jessica E. Sanow, Steven R. Fassnacht
• DOI: 10.3390/cli13110226

Research Groups

Not explicitly stated in the provided text.

Short Summary

This study demonstrates that aerodynamic roughness length (z0) for shallow, seasonal snowpacks is a dynamic variable dependent on snow depth (ds), significantly impacting sublimation modeling.

Objective

• To observe and quantify the spatial and temporal variability of aerodynamic roughness length (z0) in shallow, seasonal snowpacks.
• To demonstrate that z0 is a dynamic variable, specifically a function of snow depth (ds), rather than a static parameter.
• To assess the implications of dynamic z0 for sublimation modeling.

Study Configuration

• Spatial Scale: Nine distinct study sites in northwest Colorado.
• Temporal Scale: The 2019 to 2020 winter season.

Methodology and Data

• Models used: N/A (observational study focused on data collection and analysis).
• Data sources: Terrestrial LiDAR data collected from 91 site visits.

Main Results

• Aerodynamic roughness length (z0) is a dynamic variable, not static, and is a function of snow depth (ds).
• z0 values decrease during initial snow accumulation as the snow conforms to underlying terrain features.
• Once the snowpack reaches a sufficient depth (dependent on ground surface roughness), the surface becomes more uniform.
• As melt commences, z0 increases due to the snow surface becoming more irregular.
• Human disturbance at several sites altered the z0 correlation.
• The z0 versus ds correlation remained almost constant, irrespective of initial roughness conditions, which only influenced the initial z0.
• The dynamic nature of z0 has a significant impact on sublimation modeling, particularly for shallow snowpacks.

Contributions

• Provides empirical evidence demonstrating z0 as a dynamic variable dependent on snow depth, challenging the common assumption of a static z0 in models.
• Quantifies the temporal evolution of z0 throughout the snow season (accumulation, deep snow, melt) using high-resolution LiDAR data.
• Highlights the critical importance of incorporating dynamic z0 into hydrologic and atmospheric models for improved sublimation estimates, especially for shallow snowpacks.

Funding

Not explicitly stated in the provided text.

Citation

@article{Sanow2025Let,
  author = {Sanow, Jessica E. and Fassnacht, Steven R.},
  title = {Let Us Change the Aerodynamic Roughness Length as a Function of Snow Depth},
  journal = {Climate},
  year = {2025},
  doi = {10.3390/cli13110226},
  url = {https://doi.org/10.3390/cli13110226}
}