Cao et al. (2026) Differences between Two Types of India–Burma Trough Events in Wintertime: Local versus Eastward-Moving

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Journal of Climate
• Year: 2026
• Date: 2026-01-06
• Authors: Xiaohang Cao, Junpeng Yuan, Xin Yan, Tong Yang, Kang Yang
• DOI: 10.1175/jcli-d-25-0412.1

Research Groups

Not specified in the abstract.

Short Summary

This study reveals that topographic forcing along the southeastern Qinghai–Tibetan Plateau bifurcates the India–Burma Trough (IBT) into two distinct archetypes, whose differing dynamic mechanisms and climatic impacts on Asia winter precipitation are primarily governed by large-scale circulation coordination rather than local forcing alone.

Objective

• To establish how topographic forcing along the southeastern Qinghai–Tibetan Plateau leads to the bifurcation of the India–Burma Trough (IBT) into distinct archetypes, and to elucidate their unique dynamic mechanisms and climatic impacts on Asia winter precipitation.

Study Configuration

• Spatial Scale: Southeastern Qinghai–Tibetan Plateau, India–Burma Trough region (west and east of 100°E longitude), extending to northern Africa, western Europe (40°–60°N latitude), and East Asia. Vertical atmospheric structure analyzed up to <500 hPa and >300 hPa.
• Temporal Scale: Winter season, with event-based analysis over multiple years to determine frequencies (17 events per year, 1.4 events per year) and mean durations (2.2 days, 5.9 days).

Methodology and Data

• Models used: Not specified in the abstract.
• Data sources: Not specified in the abstract, but implies analysis of atmospheric circulation data including Rossby wave trains, westerly anomalies, subtropical and polar jet streams, and moist layers.

Main Results

• Topographic forcing along the southeastern Qinghai–Tibetan Plateau causes the India–Burma Trough (IBT) to bifurcate into two distinct archetypes.
• Short-lived local IBTs:
  • Occur frequently (17 events per year) with a mean duration of 2.2 days.
  • Remain confined west of 100°E longitude.
  • Exhibit a shallow vertical structure (<500 hPa).
  • Driven by weak midlatitude Rossby wave trains originating from northern Africa over shallow westerly anomalies.
  • Have limited climatic impacts.
• Persistent eastward-moving IBTs:
  • Occur less frequently (1.4 events per year) with a mean duration of 5.9 days.
  • Propagate rapidly eastward at 4.98° per day, extending beyond 100°E longitude.
  • Develop deeply (>300 hPa).
  • Triggered by intense mid–high-latitude disturbances (40°–60°N latitude) over western Europe.
  • Their sustained cross-regional movement involves coordinated wave trains: energy injection from the subtropical westerly jet sustains IBT development, while a wave train along the polar jet weakens the East Asian trough, reducing cold-air resistance and facilitating eastward movement.
  • Occur within strong westerly anomalies and deep moist layers, interacting with the secondary circulation of the upper-level jet for maintenance and eastward progression.
  • Are high-impact systems, exhibiting efficient energy conversion and extensive moisture transport, driving regional precipitation extremes.
• The dichotomy between these IBT archetypes is governed by large-scale circulation coordination, not solely by local forcing.

Contributions

• Establishes that large-scale circulation coordination, rather than local forcing alone, is the primary mechanism governing the bifurcation and distinct characteristics of India–Burma Trough (IBT) archetypes.
• Identifies two fundamentally distinct IBT regimes: high-frequency/short-lived/localized events with limited impacts, and low-frequency/long-lived/high-impact systems responsible for regional precipitation extremes.
• Provides a detailed dynamic explanation for the sustained eastward movement of persistent IBTs, highlighting the coordinated roles of subtropical and polar jet wave trains and their interaction with upper-level circulation.

Funding

Not specified in the abstract.

Citation

@article{Cao2026Differences,
  author = {Cao, Xiaohang and Yuan, Junpeng and Yan, Xin and Yang, Tong and Yang, Kang},
  title = {Differences between Two Types of India–Burma Trough Events in Wintertime: Local versus Eastward-Moving},
  journal = {Journal of Climate},
  year = {2026},
  doi = {10.1175/jcli-d-25-0412.1},
  url = {https://doi.org/10.1175/jcli-d-25-0412.1}
}