Guo et al. (2025) Enhanced MODIS-derived ice physical properties within the Common Land Model (CoLM) revealing bare-ice–snow albedo feedback over Greenland

Identification

• Journal: ˜The œcryosphere
• Year: 2025
• Date: 2025-09-08
• Authors: Shuyang Guo, Yongjiu Dai, Hua Yuan, H. Liang
• DOI: 10.5194/tc-19-3553-2025

Research Groups

• Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), School of Atmospheric Science, Sun Yat-sen University, Zhuhai, China

Short Summary

This study integrates an enhanced radiative transfer model (SNICAR-ADv4) and MODIS-derived bare-ice properties into the Common Land Model (CoLM) to investigate the impact of bare-ice metamorphism on the Greenland Ice Sheet's ablation zone. The research reveals a significant bare-ice–snow albedo feedback, where bare-ice darkening due to metamorphism reduces albedo, increases surface temperature, and accelerates snowmelt, further exposing bare ice and intensifying melt.

Objective

• To develop a more reliable dataset of Greenland’s bare-ice physical properties by incorporating MODIS albedo product quality information.
• To explore the bare-ice albedo feedback associated with the metamorphism of bare ice after implementing SNICAR-ADv4 into CoLM.

Study Configuration

• Spatial Scale: Greenland Ice Sheet (GrIS) bare-ice region. MODIS data at 0.05° resolution, upscaled to 0.5° for model input. CoLM simulations at 0.25° × 0.25° resolution.
• Temporal Scale: Summer melt seasons (June, July, August) from 2000 to 2020. Model simulations were run for 1980–2020, with analysis focused on 2000–2020.

Methodology and Data

• Models used:
  • Common Land Model version 2024 (CoLM2024)
  • SNICAR-ADv4 (Snow, Ice, and Aerosol Radiative Model Adding–Doubling version 4)
  • SNICAR-AD (baseline version)
• Data sources:
  • MODIS MCD12C1 (land cover type)
  • MOD09CMG (band 2 reflectance for bare-ice–snow discrimination)
  • MOD10C1 (snow cover for cloud/snow masking)
  • MODIS MCD43C3 (spectral and broadband black-sky albedo, white-sky albedo, solar zenith angles, albedo quality index)
  • ERA5 (hourly single-level surface atmospheric forcing)
  • CESM2-WACCM (CMIP6 experiments for monthly aerosol concentrations)

Main Results

• The application of SNICAR-ADv4 in CoLM, with MODIS-derived bare-ice properties, reduced the overestimation of shortwave broadband albedo by 38%, with a bias of 0.053.
• Specific bias reductions were 50% for visible albedo and 28% for near-infrared albedo.
• Bare-ice metamorphism led to a reduction in summer bare-ice broadband albedo by 0.032.
• This albedo reduction resulted in a 2 meter air temperature forcing of 0.071 °C, a snow cover change of -0.011, and a snow water equivalent forcing of -1.345 mm over the 21-year period.
• A strong positive bare-ice–snow albedo feedback mechanism was identified, where bare-ice darkening (linked to decreased specific surface area, suggesting increased ice density and larger air bubbles) leads to increased bare-ice exposure, further reducing albedo and enhancing solar radiation absorption.
• The difference in broadband albedo showed a strong positive correlation (0.88) with the specific surface area.

Contributions

• First study to incorporate the physically based SNICAR-ADv4 radiative transfer model into the Common Land Model (CoLM).
• Developed an enhanced, quality-controlled MODIS-informed dataset of Greenland's bare-ice physical properties (ice density, air bubble effective radius, equivalent black carbon).
• Quantified the impact of bare-ice metamorphism on regional climate responses and revealed a significant bare-ice–snow albedo feedback mechanism over the Greenland Ice Sheet.
• Demonstrated substantial improvements in CoLM's albedo simulations by moving from constant ice albedo values to physically based, variable ice properties.

Funding

• Guangdong Major Project of Basic and Applied Basic Research (grant no. 2021B0301030007)
• National Natural Science Foundation of China (grant nos. U2342227, 42075160, and 42088101)
• Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai) (grant no. SML2023SP216)
• Specific research fund of the Innovation Platform for Academicians of Hainan Province (grant no. YSPTZX202143)

Citation

@article{Guo2025Enhanced,
  author = {Guo, Shuyang and Dai, Yongjiu and Yuan, Hua and Liang, H.},
  title = {Enhanced MODIS-derived ice physical properties within the Common Land Model (CoLM) revealing bare-ice–snow albedo feedback over Greenland},
  journal = {˜The œcryosphere},
  year = {2025},
  doi = {10.5194/tc-19-3553-2025},
  url = {https://doi.org/10.5194/tc-19-3553-2025}
}