Liu et al. (2025) Spatiotemporal Dynamics of Surface Energy Balance over the Debris-Covered Glacier: A Case Study of Lirung Glacier in the Central Himalaya from 2017 to 2019

Identification

• Journal: Remote Sensing
• Year: 2025
• Date: 2025-11-29
• Authors: Hehe Liu, Zhen Zhang, Jing Ding, Xue Wang
• DOI: 10.3390/rs17233882

Research Groups

School of Geomatics, Anhui University of Science and Technology, Huainan, China

Short Summary

This study analyzed the spatiotemporal surface energy balance of Lirung glacier (Central Himalaya) from 2017 to 2019, demonstrating that net radiation is the primary ablation driver, significantly modulated by debris cover and ice cliffs, which in turn influences proglacial lake expansion.

Objective

• To investigate the temporal variations in energy flux components and spatial distribution patterns of surface energy balance on Lirung glacier from October 2017 to August 2019.
• To evaluate the regulatory effects of debris cover and ice cliffs on glacier energy exchange and ablation.
• To examine the influence of energy balance changes on the evolution of the proglacial lake area.

Study Configuration

• Spatial Scale: Lirung Glacier (area 4.79 km²) in the Central Himalaya. Analysis conducted glacier-wide and across different altitudinal zones. Data resolutions: Landsat (30 m multispectral, 30 m thermal), PlanetScope (3 m), MODIS (1 km fused to 30 m), SRTM (30 m).
• Temporal Scale: October 2017 to August 2019 (23 months). Daily dynamic monitoring of glacier-scale energy budget variations. Ablation season differences for 2018 and 2019 (May–June).

Methodology and Data

• Models used:
  • Energy Balance Equation Model
  • Fourier’s law of heat conduction (for debris thickness inversion)
  • Spatio-Temporal Weighted Regression (STWR) (for MODIS-Landsat LST fusion)
  • Normalized Difference Water Index (NDWI) with Otsu’s method (for proglacial lake extraction)
  • Paired Sample t-test (for debris thickness validation)
  • Mean Bias Error (MBE) (for debris thickness error analysis)
• Data sources:
  • Satellite: Landsat 8 OLI/TIRS, PlanetScope, MODIS/Aqua LST V061.
  • Observation: Micromet automatic weather station (temperature, wind speed, relative humidity at 15 min intervals), Ground-penetrating radar (GPR) field measurements (debris thickness).
  • Auxiliary: SRTM DEM, Debris-covered area data (Kraaijenbrink et al., 2017), Randolph Glacier Inventory (RGI) version 7.0, Global glacier surface elevation change dataset (Hugonnet et al., 2021), Ice cliff vector data (Kneib et al., 2023).

Main Results

• Net radiation flux is the predominant energy driver for ablation, reaching its peak during May–June and substantially outpacing both sensible and latent heat fluxes in magnitude.
• The energy balance exhibits pronounced spatial heterogeneity, with lower-altitude regions receiving enhanced energy inputs and displaying reduced albedo, thereby magnifying the local ablation flux.
• The average debris thickness is quantified at 0.55 ± 0.02 m; thicker debris layers (e.g., 0.8–1.4 m at 3950–4200 m elevation) mitigate ablation, while thinner layers (e.g., 0.24–0.62 m at 4250–4450 m elevation) exacerbate it.
• Ice cliffs are characterized by significantly elevated ablation fluxes, with certain areas recording values as high as 1.73 times the glacier-wide mean, and higher ablation efficiency per unit area in high-elevation zones despite smaller cliff areas.
• The proglacial lake expanded by 21.1 ± 11.4% (annual rate of 11.5 ± 6.2% year⁻¹) from October 2017 to August 2019, with its temporal variations closely tracking fluctuations in net radiation flux (Pearson correlation coefficient of 0.92, R² of 0.90).
• Debris thickness inversion results were validated with ground-penetrating radar (GPR) field measurements, showing strong consistency (RMSE = 0.08 m, R² = 0.97, MBE = 0.015 m).

Contributions

• Provides a comprehensive analysis of the energy balance of debris-covered glaciers, incorporating temporal and spatial dimensions, surface processes, and proglacial lake responses.
• Offers new scientific insights into the energy exchange mechanisms and climate responses of debris-covered glaciers in the Central Himalaya.
• Developed a replicable and high-precision energy balance monitoring solution for debris-covered glaciers, with broad application potential.
• Revealed the synchronous relationship between proglacial lake area changes and net radiation flux, enabling potential prediction of lake area changes for glacial lake outburst flood (GLOF) prevention.
• Systematically evaluated the impact of debris cover and ice cliffs on glacier energy balance and their interactions with the proglacial lake.

Funding

• Anhui Provincial Natural Science Foundation (Grant No. 2508085Y025)
• National Natural Science Foundation of China (Grant No. 42571157 and Grant No. 42071085)

Citation

@article{Liu2025Spatiotemporal,
  author = {Liu, Hehe and Zhang, Zhen and Ding, Jing and Wang, Xue},
  title = {Spatiotemporal Dynamics of Surface Energy Balance over the Debris-Covered Glacier: A Case Study of Lirung Glacier in the Central Himalaya from 2017 to 2019},
  journal = {Remote Sensing},
  year = {2025},
  doi = {10.3390/rs17233882},
  url = {https://doi.org/10.3390/rs17233882}
}