Yang et al. (2025) Synergistic effects of precipitation and phase changes intensify future rain-on-snow events in the Tianshan and Pamir regions, Central Asia

Identification

• Journal: Weather and Climate Extremes
• Year: 2025
• Date: 2025-11-20
• Authors: Tao Yang, Lanhai Li, Rafiq Hamdi, Fengqi Cui, Zhaojun Zheng, Philippe De Maeyer, Xi Chen
• DOI: 10.1016/j.wace.2025.100833

Research Groups

• Key Laboratory of Mountain Hazards and Engineering Resilience, Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu, China
• College of Geoinformatics, Zhejiang University of Technology, Hangzhou, China
• Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China
• Meteorological and Climatological Research Department, Royal Meteorological Institute, Brussels, Belgium
• School of Civil Engineering, Shandong Jiaotong University, Jinan, China
• Key Laboratory of Radiometric Calibration and Validation for Environmental Satellites, China Meteorological Administration, National Satellite Meteorological Center, Beijing, China
• Department of Geography, Ghent University, Ghent, Belgium

Short Summary

This study utilized WRF dynamically downscaled simulations driven by bias-corrected CMIP6 data to investigate future rain-on-snow (ROS) events in the Tianshan and Pamir regions. It projects significant increases in ROS frequency and intensity by mid-century under warming climate scenarios, leading to intensified flood potential and altered regional hydrological regimes.

Objective

• Investigate spatiotemporal changes in rain-on-snow (ROS) frequency and intensity by comparing historical conditions with future scenarios.
• Quantify changes in snowmelt indices driven by ROS events.
• Analyze key climatic drivers influencing future ROS variability and evaluate their potential hydrological consequences.

Study Configuration

• Spatial Scale: Tianshan and Pamir regions, Central Asia (approximately 66° to 96° E and 36° to 46° N), covering over 800,000 km². WRF model domains: outer (27 km horizontal resolution), inner (9 km horizontal resolution).
• Temporal Scale: Historical baseline (September 1993 to August 2014, analyzed for 1995–2014). Mid-21st-century projection (September 2039 to August 2060, analyzed for 2041–2060).

Methodology and Data

• Models used: Weather Research and Forecasting (WRF-ARW v4.4) model coupled with the Noah-Multiparameterization (Noah-MP) land surface scheme.
• Data sources:
  • Historical simulations: ERA5 reanalysis data (3-hourly, 1.25° grids).
  • Future projections: Bias-corrected CMIP6-ERA5 datasets (6-hourly, 1.25° grids) under SSP245 and SSP585 scenarios, generated using a mean-variance-trend (MVT) bias-correction approach with a multi-model ensemble of 18 CMIP6 models.
  • Validation: 61 in-situ meteorological stations observations and remote sensing products for key meteorological and snow variables.

Main Results

• Historical (1995–2014) ROS characteristics: Average annual ROS frequency was 1.86 days, daily maximum ROS intensity was 13.52 mm, and total annual ROS intensity was 46.02 mm. The highest ROS frequency occurred at elevations between 2250 and 2500 m. ROS activity was most intense along the windward slopes of the Western Tianshan, Northern Tianshan, and Western Pamir, peaking seasonally in spring (50.64% of annual occurrences).
• Projected (2041–2060) ROS changes:
  • ROS frequency is projected to increase by 49.57% (SSP245) and 49.33% (SSP585).
  • Daily maximum ROS intensity is projected to increase by 43.39% (SSP245) and 45.44% (SSP585).
  • Total annual ROS intensity is projected to increase by 65.67% (SSP245) and 66.63% (SSP585).
  • The annual contribution of snowmelt to total water available for runoff (SRS ratio) is projected to decline by 11.97 percentage points (SSP245) and 11.39 percentage points (SSP585).
  • ROS-induced snowmelt contributions to total snowmelt (ROSSS ratio) are projected to climb by 1.42 percentage points (SSP245) and 1.46 percentage points (SSP585).
  • ROS intensity's contribution to water available for runoff (ROSRSRS ratio) is projected to increase by 1.32 percentage points (SSP245) and 1.35 percentage points (SSP585).
• Climatic drivers: These shifts are primarily driven by increased annual precipitation (295 mm under SSP245, 288 mm under SSP585), decreased snowfall/precipitation ratio (−8.53 percentage points under SSP245, −8.30 percentage points under SSP585), increased frequency of intense rainfall events (11.63 days under SSP245, 11.36 days under SSP585), and substantial warming (2.49 °C under SSP245, 2.51 °C under SSP585).
• Hydrological consequences: The hydrological system becomes more susceptible to ROS-driven extreme events, indicating an increased risk of ROS-induced flooding potential and a potential seasonal mismatch between runoff supply and water demand in arid alpine regions.

Contributions

• Provides the first comprehensive, runoff-relevant assessment of future rain-on-snow (ROS) events and their hydrological impacts in the Tianshan and Pamir regions.
• Utilizes a process-based land–atmosphere framework (WRF/Noah-MP) with dynamically downscaled, bias-corrected CMIP6 scenarios for mid-century projections.
• Enhances understanding of ROS-driven snowmelt variability in arid mountainous regions under warming climates.
• Offers essential insights to support disaster risk mitigation, infrastructure design, and water-resource planning.

Funding

• National Natural Science Foundation of China (Grant 42401165, 42361144887, and 42230708)
• Project of Xinjiang Key Laboratory of Water Cycle and Utilization in Arid Zone (Grant XJYS0907-2023-02)
• Science and Technology Projects of Xizang Autonomous Region, China (Grant XZ202501ZY0006)
• Bureau of International Cooperation, Chinese Academy of Sciences (Grant 072GJHZ2023086MI)
• Shandong Provincial Natural Science Foundation (Grant ZR2024QD117)

Citation

@article{Yang2025Synergistic,
  author = {Yang, Tao and Li, Lanhai and Hamdi, Rafiq and Cui, Fengqi and Zheng, Zhaojun and Maeyer, Philippe De and Chen, Xi},
  title = {Synergistic effects of precipitation and phase changes intensify future rain-on-snow events in the Tianshan and Pamir regions, Central Asia},
  journal = {Weather and Climate Extremes},
  year = {2025},
  doi = {10.1016/j.wace.2025.100833},
  url = {https://doi.org/10.1016/j.wace.2025.100833}
}