Dong et al. (2025) The effect of precipitation-induced advective heat on permafrost in the Tibetan Plateau

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2025
• Date: 2025-11-27
• Authors: Qingxue Dong, Siqiong Luo, Zihang Chen, Zhaoguo Li, Lunyu Shang, Jingyuan Wang, Yao Xiao, Yongping Qiao
• DOI: 10.1016/j.ejrh.2025.102981

Research Groups

• State Key Laboratory of Cryospheric Science and Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China
• University of Chinese Academy of Sciences, Beijing 100049, China
• Cryosphere Research Station on the Qinghai-Tibet Plateau, Key Laboratory of Cryospheric Science and Frozen Soil Engineering, Northwest Institute of Eco-Environment and Resources, Chinese Academy of Sciences, Lanzhou 730000, China

Short Summary

This study quantifies the precipitation-induced advective heat flux (EPre) and infiltration dynamics in the Tibetan Plateau's permafrost using a modified CLM5.0 model and observational data, revealing a predominant net cooling effect regionally but significant warming potential during deep infiltration events.

Objective

• To quantify precipitation-induced advective heat flux (EPre), infiltration depth, and the probability of precipitation reaching frozen soil in the Tibetan Plateau permafrost.
• To understand how precipitation amount, soil texture, soil moisture, and freeze–thaw state jointly control infiltration processes and influence the soil thermal regime.

Study Configuration

• Spatial Scale: The Tibetan Plateau (TP), China, including three permafrost monitoring sites (Qumalai, Xidatan, Tanggula) and regional simulations across the entire TP.
• Temporal Scale: Site-specific observations from 2010 to 2022 (e.g., QML: 2021.1.1–2022.1.1, XDT: 2015.9.1–2016.9.1, TGL: 2010.8.9–2011.8.9); regional simulations for 1979–2018 (40-year spin-up and trend analysis) and 1999–2018 (20-year regional analysis).

Methodology and Data

• Models used: Community Land Model version 5.0 (CLM5.0), modified to explicitly include precipitation-induced advective heat flux (EPre) in the soil energy balance (modified SoilTemperatureMod.F90 module). The Dry Surface Layer (DSL) scheme was disabled.
• Data sources:
  • Observational data: Meteorological and soil data (precipitation, 2 m air temperature, relative humidity, 2 m wind speed, air pressure, downward longwave and shortwave radiation, soil temperature at 5 cm, 10 cm, 20 cm, 40 cm, 80 cm, and soil moisture) from Qumalai, Xidatan, and Tanggula permafrost sites.
  • Regional forcing data: China Meteorological Forcing Dataset (CMFD; 1979–2018), integrating ground-based observations, TRMM satellite data, and reanalysis products (TRMM3B42, GLDAS, Princeton).
  • Surface datasets: CLM5.0 mksurfdata_map module generated vegetation functional type, leaf area index, soil texture, and soil organic matter.
  • Code availability: Modified CLM5.0 SoilTemperatureMod with Precipitation-Induced Advective Heat (Figshare: https://doi.org/10.6084/m9.figshare.30664934).

Main Results

• Site-specific EPre: EPre is predominantly negative (cooling), with maximum cooling reaching −84.14 W m⁻² (QML), −73.24 W m⁻² (XDT), and −56.63 W m⁻² (TGL). However, it can become positive (warming) during prolonged summer rainfall, reaching up to 45.43 W m⁻² (QML).
• Infiltration Dynamics: Infiltration depth is complex, influenced by initial soil moisture, precipitation duration, amount, soil texture, and freeze–thaw state. Deeper infiltration, especially into the active layer, tends to induce warming. Normal intensity, continuous precipitation can also cause deep infiltration and soil heating.
• Diurnal Variation: EPre exhibits higher values during the daytime (more cooling) and lower values at night (reduced cooling or warming), reflecting diurnal soil temperature changes.
• Regional EPre (1999–2018): The regional mean EPre is −0.08 W m⁻², with cooling dominating 90.65 % of the area. Warming effects (maximum 0.64 W m⁻²) are concentrated in the southeastern and central TP, while strong cooling (minimum −0.37 W m⁻²) is observed in the arid west and high-elevation north.
• Regional Infiltration Depth (1999–2018): Mean infiltration depth is approximately 2 soil layers (~5 cm), with a southeast–northwest decreasing trend. Deepest infiltration (up to 8 layers) occurs in southeastern TP.
• Probability of reaching frozen soil (1999–2018): Approximately 99.80 % of the TP shows potential for precipitation to interact with frozen soil, with an average regional probability of 0.07. The TGL site, with a shallow active layer, showed the highest frequency (60 times per year).
• Seasonal Variability (1999–2018): Autumn exhibits the greatest infiltration depth (mean 2.4 layers). Summer shows the strongest cooling EPre (mean −0.19 W m⁻²), with warming EPre maxima reaching 1.46 W m⁻². Winter has the highest probability of precipitation contacting frozen soil (0.30).
• Long-term Trends (1979–2018): Annual precipitation increased by 31.75 mm per decade regionally. EPre declined by −0.0052 W m⁻² per decade. Infiltration depth decreased by −0.0395 layers per decade, with decreases in eastern/southeastern TP and increases in central/western regions. The probability of reaching frozen soil showed a weak declining trend (−0.0022 per decade).
• Long-term Effects on Energy Balance: The inclusion of EPre induces long-lasting fluctuations in ground heat flux (G0), sensible heat flux (H), and latent heat flux (LE), with effects persisting into the following year's thaw period due to the soil's memory effect.

Contributions

• First comprehensive quantification of precipitation-induced advective heat flux (EPre) and its hydrological impacts across the entire Tibetan Plateau permafrost region.
• Developed and implemented a modification to the Community Land Model version 5.0 (CLM5.0) to explicitly account for EPre, enhancing its capability for permafrost simulations.
• Demonstrated that not only extreme but also normal, continuous precipitation can significantly warm deep soil layers by facilitating infiltration to the active layer.
• Provided detailed spatial, seasonal, and long-term trend analyses of EPre, precipitation infiltration depth, and the probability of precipitation reaching frozen soil across the TP.
• Highlighted the complex controls of precipitation amount, soil texture, soil moisture, and freeze–thaw state on EPre and infiltration processes.
• Revealed the long-lasting "memory effect" of EPre on surface energy fluxes (ground heat flux, sensible heat flux, latent heat flux), influencing subsequent freeze-thaw cycles.

Funding

• West Light Foundation of the Chinese Academy of Sciences [xbzg-zdsys-202102]
• National Natural Science Foundation of China [U20A2081]
• Program of the State Key Laboratory of Cryospheric Science and Frozen Soil Engineering, CAS [CSFSE-ZZ-2410]

Citation

@article{Dong2025effect,
  author = {Dong, Qingxue and Luo, Siqiong and Chen, Zihang and Wu, Tonghua and Li, Zhaoguo and Shang, Lunyu and Wang, Jingyuan and Xiao, Yao and Qiao, Yongping},
  title = {The effect of precipitation-induced advective heat on permafrost in the Tibetan Plateau},
  journal = {Journal of Hydrology Regional Studies},
  year = {2025},
  doi = {10.1016/j.ejrh.2025.102981},
  url = {https://doi.org/10.1016/j.ejrh.2025.102981}
}