Zhang et al. (2025) Impact of Spring Soil Moisture Over the Eastern Iranian Plateau on Interannual Variability of Persistent Spring‐Summer Dryness/Wetness in Yunnan, China

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Identification

• Journal: Journal of Geophysical Research Atmospheres
• Year: 2025
• Date: 2025-11-17
• Authors: Hao Zhang, Ke Fan, Juan Wang
• DOI: 10.1029/2025jd044384

Research Groups

Not available from the provided text.

Short Summary

This study investigates the first leading mode of spring-summer dryness/wetness in Yunnan, China, revealing an in-phase variation driven by spring soil moisture anomalies over the Eastern Iranian Plateau through a series of atmospheric teleconnections that lead to consistent dry conditions in Yunnan.

Objective

• To investigate the characteristics and associated mechanisms of the first leading mode of spring-summer dryness/wetness variation in Yunnan, China.

Study Configuration

• Spatial Scale: Yunnan (China), Eastern Iranian Plateau (EIP), Indochina Peninsula (ICP), Bay of Bengal, East Asia.
• Temporal Scale: Spring and summer seasons; persistent conditions from spring to summer.

Methodology and Data

• Models used: Extended empirical orthogonal function (EOF) analysis, Linear Baroclinic Model.
• Data sources: Seasonal Standardized Precipitation Evapotevaporation Index (SPEI).

Main Results

• The first leading mode of spring-summer dryness/wetness in Yunnan exhibits an in-phase variation, where a positive (negative) phase indicates consistent wetness (dryness) across both seasons.
• Spring soil moisture over the Eastern Iranian Plateau (EIP) plays a crucial role in shaping this consistent mode.
• Enhanced spring EIP soil moisture boosts local convective precipitation through positive soil moisture-precipitation feedback.
• Anomalous diabatic heating from increased EIP precipitation intensifies with altitude, triggering a mid-upper tropospheric cyclone anomaly over the EIP.
• This leads to a strengthened and southward-shifted East Asian subtropical westerly jet during spring.
• Concurrently, an anomalous anticyclone dominates the lower troposphere over the Bay of Bengal, weakening the Southern Branch Trough and suppressing water vapor transport and precipitation over Yunnan and the Indochina Peninsula (ICP), contributing to spring dry conditions and reduced soil moisture.
• Persistently low soil moisture from spring to summer over Yunnan and the ICP favors an equivalent barotropic high-pressure anomaly, reinforcing the westward extension of the western Pacific subtropical high and eastward displacement of the South Asian high, thereby maintaining dry conditions during summer in Yunnan.
• The Linear Baroclinic Model further supports this physical mechanism.

Contributions

• Identifies and characterizes the first leading mode of spring-summer dryness/wetness variation in Yunnan, demonstrating its consistent in-phase nature across seasons.
• Uncovers the critical role of spring soil moisture over the Eastern Iranian Plateau as a remote driver for Yunnan's spring-summer dryness/wetness.
• Elucidates the detailed atmospheric teleconnection mechanisms, including soil moisture-precipitation feedback, diabatic heating, jet stream changes, and subtropical high anomalies, linking EIP soil moisture to Yunnan's climate.

Funding

Not available from the provided text.

Citation

@article{Zhang2025Impact,
  author = {Zhang, Hao and Fan, Ke and Wang, Juan},
  title = {Impact of Spring Soil Moisture Over the Eastern Iranian Plateau on Interannual Variability of Persistent Spring‐Summer Dryness/Wetness in Yunnan, China},
  journal = {Journal of Geophysical Research Atmospheres},
  year = {2025},
  doi = {10.1029/2025jd044384},
  url = {https://doi.org/10.1029/2025jd044384}
}