Gao et al. (2026) Dynamic and thermodynamic mechanisms of precipitation efficiency variations in China under global warming

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2026
• Date: 2026-01-15
• Authors: Yuxuan Gao, Wen Wang, FUTING WU, Fuxiong Guo, Yanjun Hu
• DOI: 10.1016/j.ejrh.2025.103089

Research Groups

• State Key Laboratory of Water Disaster Prevention, Hohai University, Nanjing 210098, China
• College of Hydrology and Water Resources, Hohai University, Nanjing 210098, China

Short Summary

This study investigates the spatiotemporal evolution and underlying dynamic and thermodynamic mechanisms of precipitation efficiency (PE) across China from 1979 to 2022 under global warming. It finds that while thermodynamic moistening generally enhances PE, dynamic changes, particularly vertical moisture advection, primarily determine its regional differences and overall variability, leading to distinct responses in arid, semi-arid, and wet regions.

Objective

• To investigate the spatiotemporal evolution of precipitation efficiency (PE) over China (1979–2022) and quantify the thermodynamic and dynamic controls on its variability.
• To assess how climate warming influences moisture transport and atmospheric stability, leading to distinct regional and temporal responses of PE.

Study Configuration

• Spatial Scale: China, divided into arid, semi-arid, and wet regions based on annual precipitation thresholds (less than 400 mm, 400-800 mm, and greater than 800 mm, respectively).
• Temporal Scale: 1979–2022 (44 years), with analysis at monthly, seasonal, and annual resolutions.

Methodology and Data

• Models used: Moisture budget equation framework, Moist static energy (MSE) advection diagnostic framework.
• Data sources:
  • ERA5 reanalysis (European Centre for Medium-Range Weather Forecasts - ECMWF): Column-integrated precipitable water (PW), 2-meter air temperature (T), surface pressure (Ps), pressure-level fields (zonal wind u, meridional wind v, vertical velocity ω, specific humidity q, air temperature T), surface geopotential (z). Spatial resolution: 0.25° × 0.25°, monthly resolution.
  • CHM_PRE daily observed precipitation spatial interpolation grid dataset (National Tibetan Plateau Scientific Data Center): Precipitation (P). Spatial resolution: 0.25° × 0.25°.
  • Non-parametric trend analysis: Mann-Kendall (MK) test and Sen’s Slope estimator.

Main Results

• PE exhibits pronounced regional contrasts: highest values over the Tibetan Plateau (20-40%) and lowest in humid southern China (10-20%).
• Over 1979–2022, PE generally increased across China, with the strongest rise in arid regions (0.25 % per year), followed by semi-arid (0.12 % per year), and humid regions (0.11 % per year).
• As temperature rises, the increase in precipitation lags behind the rapid growth of precipitable water, leading to a decline in monthly PE across all three regions, exhibiting a "hook-shaped" pattern in the P-T relationship.
• Vertical moisture advection (Vadv) dominates PE variability, exerting a far stronger influence than horizontal transport (Hadv), with significant positive correlation across most of China.
• Thermodynamic moistening (TDyn) tends to enhance PE nationwide, consistent with Clausius-Clapeyron scaling.
• Dynamic changes (Dyn) primarily determine regional differences in PE:
  • In humid regions, weakened upward motion (Dyn) limits PE growth, counteracting the positive effect of TDyn.
  • In arid and high-altitude regions (e.g., Tibetan Plateau), strengthened ascent and enhanced thermodynamic effects jointly increase PE.
  • In semi-arid regions, PE increases with Dyn up to a threshold (approximately 0.04 mm per day), beyond which further increases are suppressed due to entrainment of dry, stable air.
• The scaling rates of P and PW with temperature are generally sub-Clausius-Clapeyron (below 7 % per °C) in most regions, with PE showing decreasing scaling rates in wet and northern arid regions (-6 to 0 % per °C) and sub-Clausius-Clapeyron scaling (0 to 6 % per °C) in semi-arid regions. The Tibetan Plateau shows the highest scaling rates for P, PW, and PE.

Contributions

• Provides a comprehensive, process-based understanding of precipitation efficiency (PE) variations in China under global warming by explicitly incorporating vertical motion into the decomposition of thermodynamic and dynamic response mechanisms.
• Clarifies the dominant role of vertical moisture advection over horizontal transport in PE variability across China.
• Quantifies the distinct regional and temporal responses of PE to climate warming, highlighting the interplay between thermodynamic moistening and dynamic circulation changes in arid, semi-arid, and wet regions.
• Offers new insights into the physical controls of PE, particularly the counteracting and amplifying effects of dynamic factors on thermodynamic moistening, which is crucial for understanding regional hydrological responses.

Funding

• National Key Research and Development Program of China (No. 2023YFC3209201)
• National Natural Science Foundation of China (grant number 42471027 and 41605043)

Citation

@article{Gao2026Dynamic,
  author = {Gao, Yuxuan and Wang, Wen and WU, FUTING and Guo, Fuxiong and Hu, Yanjun},
  title = {Dynamic and thermodynamic mechanisms of precipitation efficiency variations in China under global warming},
  journal = {Journal of Hydrology Regional Studies},
  year = {2026},
  doi = {10.1016/j.ejrh.2025.103089},
  url = {https://doi.org/10.1016/j.ejrh.2025.103089}
}