Huang et al. (2026) Classification and mechanisms of summer drought types in Eastern Northwest China

Identification

• Journal: Atmospheric Research
• Year: 2026
• Date: 2026-05-19
• Authors: Bicheng Huang, Yue Zhang, Hongyan Shen, Rong Zhi, Tao Su, Zhonghua Qian, 吴永萍
• DOI: 10.1016/j.atmosres.2026.109095

Research Groups

• College of Physical Science and Technology, Yangzhou University, China
• Meteorological Institute of Shaanxi Province, China
• Laboratory for Climate Studies, National Climate Center, China Meteorological Administration, China

Short Summary

This study classifies summer droughts in Eastern Northwest China (ENC) into persistent and episodic types based on SPEI-3 evolution, revealing that they are driven by distinct atmospheric circulations and oceanic precursors.

Objective

• To classify summer drought (SD) types in Eastern Northwest China (ENC) and investigate their spatiotemporal characteristics, atmospheric drivers, and sea surface temperature (SST) precursors.

Study Configuration

• Spatial Scale: Eastern Northwest China (ENC).
• Temporal Scale: Boreal summer (June–August).

Methodology and Data

• Models used: 3-month Standardized Precipitation Evapotranspiration Index (SPEI-3).
• Data sources: Precipitation and evapotranspiration data (for SPEI-3 calculation), sea surface temperature (SST) data, and atmospheric circulation indices.

Main Results

• Persistent Drought (PD): Characterized by spatially coherent, season-long negative SPEI-3 anomalies. It is maintained by a stable Eurasian wave train and persistent moisture divergence, with the South Indian Ocean Dipole (SIOD) acting as a key SST precursor.
• Episodic Drought (ED): Characterized by a transition from near-normal or wet conditions in June to drought in July–August. It is driven by an intraseasonal circulation shift involving the weakening and eastward retreat of the Western Pacific Subtropical High (WPSH), shifting moisture from convergence to divergence. The tropical North Pacific meridional mode (TNP) serves as the primary SST precursor.
• Key Insight: Regional SST persistence and evolution are more critical for distinguishing drought types in ENC than general ENSO background conditions.

Contributions

• Refines the understanding of summer drought in ENC by introducing a classification based on temporal evolution (persistent vs. episodic) rather than spatial patterns alone.
• Identifies specific oceanic precursors (SIOD for PD and TNP for ED), providing a basis for extending the lead time of subseasonal-to-seasonal drought predictions in the region.

Funding

• Not specified in the provided text.

Citation

@article{Huang2026Classification,
  author = {Huang, Bicheng and Zhang, Yue and Shen, Hongyan and Zhi, Rong and Su, Tao and Qian, Zhonghua and 吴永萍},
  title = {Classification and mechanisms of summer drought types in Eastern Northwest China},
  journal = {Atmospheric Research},
  year = {2026},
  doi = {10.1016/j.atmosres.2026.109095},
  url = {https://doi.org/10.1016/j.atmosres.2026.109095}
}