Shi et al. (2025) The Characteristics and Mechanism of the Inter-Centennial Variations in Indian Summer Monsoon Precipitation

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Identification

• Journal: Water
• Year: 2025
• Date: 2025-12-20
• Authors: Guangxun Shi, Shushuang Liu, Mingli ZHANG
• DOI: 10.3390/w18010017

Research Groups

Not explicitly stated in the provided text.

Short Summary

This paper investigates centennial-scale Indian Summer Monsoon (ISM) precipitation variability over the past two millennia, identifying volcanic, solar, and internal climate variability as key drivers of observed 105, 150, and 200-year cycles.

Objective

• To identify and attribute the centennial-scale periodicities in Indian Summer Monsoon (ISM) precipitation variability over the past two millennia.

Study Configuration

• Spatial Scale: Indian Summer Monsoon (ISM) region, Northern Hemisphere, global, North Pacific, Indian Ocean.
• Temporal Scale: Past two millennia (2000 years).

Methodology and Data

• Models used: CESM (Community Earth System Model) - specifically NNU-2K dataset, all-forcing (AF), volcanic single-forcing (Vol), total solar irradiance (TSI) single-forcing, and control (Ctrl) experiments.
• Data sources: CESM-simulated NNU-2K dataset, proxy reconstructions of ISM precipitation.

Main Results

• Indian Summer Monsoon (ISM) precipitation exhibits significant centennial-scale periodicities of 105, 150, and 200 years over the past two millennia.
• Volcanic activity is a major driver of the 105- and 200-year cycles. Volcanic forcing induces global cooling, which reduces land-sea thermal contrast, weakens the interhemispheric temperature gradient, and suppresses cross-equatorial low-level flow, thereby reducing ISM precipitation.
• Solar variability drives the 105- and 150-year cycles. Increased solar irradiance enhances Northern Hemisphere warming, strengthening thermal contrasts and interhemispheric/cross-equatorial pressure gradients, which intensifies ISM and increases precipitation.
• Internal climate variability, including a quasi-decadal Pacific Decadal Oscillation (PDO)-like sea surface temperature anomaly, contributes to the 150-year cycle. A negative PDO-like phase is linked to reduced sea-level pressure over the ISM region, enhanced low-level convergence, and increased precipitation, also strengthening the Mascarene High and Somali Jet.

Contributions

• Provides a comprehensive attribution of centennial-scale ISM precipitation variability to external forcings (volcanic, solar) and internal climate variability.
• Elucidates the specific mechanisms through which volcanic and solar forcings influence ISM dynamics, including changes in thermal contrasts, interhemispheric temperature gradients, and cross-equatorial flow.
• Identifies the role of internal variability, specifically a PDO-like mechanism, in shaping ISM centennial cycles.

Funding

Not explicitly stated in the provided text.

Citation

@article{Shi2025Characteristics,
  author = {Shi, Guangxun and Liu, Shushuang and ZHANG, Mingli},
  title = {The Characteristics and Mechanism of the Inter-Centennial Variations in Indian Summer Monsoon Precipitation},
  journal = {Water},
  year = {2025},
  doi = {10.3390/w18010017},
  url = {https://doi.org/10.3390/w18010017}
}