Xiao et al. (2026) Mechanism of the quasi-biweekly precipitation variability over the Mongolian Plateau and its simulations in CMIP6 models

Identification

• Journal: Atmospheric Research
• Year: 2026
• Date: 2026-01-10
• Authors: Yepeng Xiao, Yingxia Gao, Rong Li, Yitian Qian, Xiaodong Liu
• DOI: 10.1016/j.atmosres.2026.108767

Research Groups

• Ministry of Education Key Laboratory of Ecology and Resource Use of the Mongolian Plateau, School of Ecology and Environment, Inner Mongolia University, Hohhot, China
• Key Laboratory of Meteorological Disaster, Ministry of Education (KLME), Joint International Research Laboratory of Climate and Environmental Change (ILCEC), Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters (CIC-FEMD), Nanjing University of Information Science and Technology, Nanjing, China
• Inner Mongolia Climate Center, Hohhot, China

Short Summary

This study investigates the characteristics of quasi-biweekly precipitation variability over the Mongolian Plateau and evaluates its representation in 20 CMIP6 climate models, finding that models significantly underestimate precipitation intensity due to deficiencies in simulating dynamic conditions and mid-latitude wave-train systems.

Objective

• To investigate the characteristics of quasi-biweekly precipitation variability over the Mongolian Plateau and evaluate its representation in CMIP6 climate models.

Study Configuration

• Spatial Scale: Mongolian Plateau (MP), encompassing Mongolia and the Inner Mongolia Autonomous Region of China.
• Temporal Scale: Summer season, focusing on 10–30-day (quasi-biweekly) precipitation variability.

Methodology and Data

• Models used: 20 CMIP6 climate models.
• Data sources: Observations (implied by comparison with models), reanalysis data (implied by "diagnosis of the scale-decomposed moisture budget equation" and "vertical motion diagnosis").

Main Results

• Quasi-biweekly precipitation accounts for approximately 40% of the total precipitation variability over the Mongolian Plateau during summer.
• All 20 CMIP6 models underestimate the intensity of quasi-biweekly precipitation, simulating only 35–80% of the observed intensity.
• This underestimation primarily stems from insufficient dynamic conditions associated with ascending motion, rather than thermodynamic conditions related to moisture.
• Anomalous water vapor in the MP is mainly attributed to horizontal moisture advection, with positive contributions from anomalous southeasterlies transporting background moisture and background westerlies transporting moisture perturbations.
• CMIP6 models reasonably capture these moisture processes but poorly simulate the critical mid-latitude wave-train system responsible for generating ascending motion.
• The pronounced positive vorticity advection observed on the lee-side of the Altai Mountains is not captured in CMIP6 simulations.
• Consequently, simulated upward motion is confined to the eastern plateau, unlike the observed ascending motion across the entire MP, leading to negative biases in circulation anomalies that suppress rainfall intensity.

Contributions

• This study provides a comprehensive diagnosis of the mechanisms driving quasi-biweekly precipitation variability over the Mongolian Plateau.
• It offers a detailed evaluation of CMIP6 models' ability to simulate this variability, identifying specific dynamical deficiencies (e.g., mid-latitude wave-trains, vorticity advection) as the primary cause of underestimation, rather than thermodynamic processes.
• The findings highlight areas for improvement in climate models for better representation of precipitation variability in arid and semi-arid regions.

Funding

• Not explicitly mentioned in the provided text.

Citation

@article{Xiao2026Mechanism,
  author = {Xiao, Yepeng and Gao, Yingxia and Li, Rong and Qian, Yitian and Liu, Xiaodong},
  title = {Mechanism of the quasi-biweekly precipitation variability over the Mongolian Plateau and its simulations in CMIP6 models},
  journal = {Atmospheric Research},
  year = {2026},
  doi = {10.1016/j.atmosres.2026.108767},
  url = {https://doi.org/10.1016/j.atmosres.2026.108767}
}