Vishnu (2026) Contribution of Low Pressure Systems Rainfall to Interannual Variability of the Indian Summer Monsoon

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

Identification

• Journal: Journal of Climate
• Year: 2026
• Date: 2026-03-27
• Authors: S. Vishnu
• DOI: 10.1175/jcli-d-25-0381.1

Research Groups

Not explicitly mentioned in the abstract.

Short Summary

This study re-examines the relationship between Monsoon Low-Pressure Systems (LPS) and Indian Summer Monsoon Rainfall (ISMR) variations, finding a strong correlation where increased LPS-generated rainfall, driven by higher rainfall rates from elevated humidity and stronger vertical motions, contributes substantially to excess ISMR, and reveals a coupling between LPS dynamical intensity and rainfall rates.

Objective

• To revisit the relationship between Monsoon Low-Pressure Systems (LPS) and Indian Summer Monsoon Rainfall (ISMR) variations, including extreme rainfall events, with an emphasis on the role of LPS-generated rainfall.

Study Configuration

• Spatial Scale: Indian Summer Monsoon region.
• Temporal Scale: Interannual variation of the Indian Summer Monsoon Rainfall.

Methodology and Data

• Models used: Not explicitly mentioned in the abstract.
• Data sources: Not explicitly mentioned in the abstract; analysis of "traditional LPS intensity indices" and "our analysis" implies use of meteorological data.

Main Results

• A strong correlation exists between LPS-generated rainfall and ISMR variations.
• Years with excess ISMR correspond to increased LPS-induced rainfall, while years with decreased ISMR show a reduction in LPS rainfall.
• The increase in LPS rainfall during excess years is primarily linked to higher rainfall rates.
• Higher rainfall rates are attributed to elevated background humidity and stronger vertical motions associated with LPS.
• Traditional LPS intensity indices indicate only minor variation in dynamical intensity despite higher rainfall rates, suggesting an apparent decoupling between precipitation rate and dynamical strength.
• Increased rain rates coincide with strengthened horizontal pressure gradients and higher wind speeds in the vicinity of the LPS vortex center.
• LPS are more intense and spatially more confined during excess monsoon years compared to drought years, indicating a degree of coupling between the dynamical intensity of monsoon LPS and their rainfall rates.

Contributions

• Clarifies the significant contribution of LPS-generated rainfall to interannual variations in ISMR.
• Identifies the meteorological mechanisms (elevated humidity, stronger vertical motions) responsible for increased LPS rainfall rates during excess monsoon years.
• Challenges the notion of decoupling between LPS dynamical intensity and precipitation rate by demonstrating that increased rain rates are associated with stronger pressure gradients, higher wind speeds, and more confined LPS during excess monsoon years.

Funding

Not explicitly mentioned in the abstract.

Citation

@article{Vishnu2026Contribution,
  author = {Vishnu, S.},
  title = {Contribution of Low Pressure Systems Rainfall to Interannual Variability of the Indian Summer Monsoon},
  journal = {Journal of Climate},
  year = {2026},
  doi = {10.1175/jcli-d-25-0381.1},
  url = {https://doi.org/10.1175/jcli-d-25-0381.1}
}