Gu et al. (2025) Energy and mass balance of glaciers in the Ulugh Muztagh driven by climate warming over 44 years

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2025
• Date: 2025-09-17
• Authors: Lailei Gu, Ninglian Wang, An’an Chen, Xuewen Yang, Mingjun Zhang, Yanjun Che, Sugang Zhou
• DOI: 10.1016/j.ejrh.2025.102771

Research Groups

• Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, College of Urban and Environmental Sciences, Northwest University, Xi’an, China
• Institute of Earth Surface System and Hazards, College of Urban and Environmental Sciences, Northwest University, Xi’an, China
• College of Geography and Environmental Science, Northwest Normal University, Lanzhou, Gansu, China
• Department of Geographical Science, Yichun University, Yichun, China
• State Key Laboratory of Cryospheric Science/National Field Science Observation and Research Station of Yulong Snow Mountain Cryosphere and Sustainable Development (or Yulong Snow Mountain Station), Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou, China

Short Summary

This study systematically investigated the mass balance and energy exchange characteristics of glaciers in the Ulugh Muztagh region from 1980 to 2023 using calibrated reanalysis data and the COSIPY model. It found a mean glacier mass balance of −0.06 ± 0.05 m water equivalent per year, with accelerated mass loss after 2000, primarily driven by net radiation and air temperature increases.

Objective

• To reconstruct the characteristics of glacier changes from 1980 to 2023 and explore long-term glacier variability.
• To quantify changes in mass balance and energy balance within the glacier extent.
• To analyze the climatic controls on the glacier mass balance.

Study Configuration

• Spatial Scale: Glaciers of the Ulugh Muztagh region (approximately 668 km²), with simulations at a 300 m grid resolution.
• Temporal Scale: 44 years, from 1980 to 2023.

Methodology and Data

• Models used: Coupled Snowpack and Ice Surface Energy and Mass Balance Model in Python (COSIPY).
• Data sources:
  • Calibrated and downscaled ERA5-Land reanalysis data (2 m air temperature, air pressure, relative humidity, 2 m wind speed, incoming shortwave radiation, precipitation, incoming longwave radiation).
  • High Asia Refined Analysis (HAR) for cloud cover fields.
  • Automatic Weather Station (AWS) data near Shenshechuan Glacier (hourly air temperature and precipitation from June 2022 to April 2023) for calibration.
  • Real-Time Kinematic Global Positioning System (RTK-GPS) measurements of glacier surface elevation changes on Shenshechuan Glacier (May to August 2023) for validation.
  • Global geodetic mass balance data (Hugonnet et al., 2021) for comparison (2000-2019).
  • Shuttle Radar Topography Mission (SRTMGL1) Digital Elevation Model (DEM) for glacier elevation, slope, and aspect.
  • Randolph Glacier Inventory (RGI) version 7.0 for glacier boundary data.

Main Results

• The mean glacier mass balance for the Ulugh Muztagh was −0.06 ± 0.05 m water equivalent per year over the 44-year period (1980-2023), with a total mass balance of −2.48 ± 2.19 m water equivalent.
• Glacier mass loss accelerated after 2000, showing a decreasing trend of −0.01 m water equivalent per year.
• Net radiation accounted for 66% (14 W/m²) of the glacier's total energy budget, making it the primary driver of glacier melt. Latent heat flux accounted for 14% (−3 W/m²), sensible heat flux for 10% (−2 W/m²), and conductive heat flux for 10% (−2 W/m²).
• Ablation primarily occurred in July and August, while accumulation mainly took place from September to March.
• Snowfall was the major mass input (89% of income), followed by refreezing (11%). Melt was the primary mass output (91% of expenditure), but sublimation dominated mass loss during the accumulation season (99% from November to February).
• Glacier mass balance showed a significant negative correlation with air temperature (p < 0.0001), with ablation increasing by approximately 1.60 mm water equivalent for every 1 °C increase in temperature.
• Albedo exhibited a strong positive correlation with mass balance (R²=0.52), being the most stable and explanatory variable.
• Spatially, mass accumulation was observed on south and southeast aspects, while ablation was predominant on north and northwest aspects. The boundary between accumulation and ablation zones was approximately 5700 m.

Contributions

• Provided the first systematic and long-term (44 years) investigation of the energy and mass balance characteristics of glaciers in the remote Ulugh Muztagh region using a physically-based model (COSIPY).
• Quantified the specific contributions of various energy and mass fluxes to glacier change, clarifying the dominant mechanisms driving glacier evolution in this high-altitude area.
• Identified the primary climatic controls on glacier mass balance, highlighting the significant roles of air temperature and albedo.
• Validated the applicability of the COSIPY model for glacier simulations in High Mountain Asia, providing a robust framework for future studies.
• Offered critical evidence for assessing the hydrological response of the Ulugh Muztagh region to climate change, which is valuable for regional water resource prediction and climate impact assessment.

Funding

• National Natural Science Foundation of China (42130516)
• National Natural Science Foundation of China (41988101)
• National Natural Science Foundation of China (42401155)

Citation

@article{Gu2025Energy,
  author = {Gu, Lailei and Wang, Ninglian and Chen, An’an and Yang, Xuewen and Zhang, Mingjun and Che, Yanjun and Zhou, Sugang},
  title = {Energy and mass balance of glaciers in the Ulugh Muztagh driven by climate warming over 44 years},
  journal = {Journal of Hydrology Regional Studies},
  year = {2025},
  doi = {10.1016/j.ejrh.2025.102771},
  url = {https://doi.org/10.1016/j.ejrh.2025.102771}
}