Manatsa et al. (2026) Multiscale ENSO and Indian Ocean Dipole Controls on Drought Across Mainland SADC : A Meridional Teleconnection Dipole, Its Seasonal and Sectoral Structure and a Domain‐Gated Readiness Index

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Identification

• Journal: International Journal of Climatology
• Year: 2026
• Date: 2026-08-03
• Authors: Desmond Manatsa, Terence Darlington Mushore, James Ngoma
• DOI: 10.1002/joc.70542

Research Groups

Not specified in the provided text.

Short Summary

This study evaluates the influence of the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD) on drought in the SADC mainland, identifying a meridional teleconnection dipole dominated by ENSO.

Objective

• To assess how ENSO and IOD control drought across the SADC mainland using the Standardised Precipitation Evapotranspiration Index (SPEI).

Study Configuration

• Spatial Scale: Mainland SADC (including the Democratic Republic of the Congo and southern Tanzania) on a 0.25° grid.
• Temporal Scale: January 1950 to March 2026.

Methodology and Data

• Models used: Standardised Precipitation Evapotranspiration Index (SPEI), SCODP-GATE (domain-gated readiness index).
• Data sources: ERA5 (reanalysis for SPEI and soil moisture), CHIRPS (rainfall data).
• Analytical Techniques: Fixed-lead correlation, split-sample cross-validation, partial correlation, interaction regression, phase-stratified composites, and circulation composites at three atmospheric levels.

Main Results

• Meridional Teleconnection Dipole: Drought patterns are organized by a dipole where the southern interior dries during El Niño, while the northern tier exhibits the opposite sign; the inversion point is located between 12° and 15° S. This pattern is validated by CHIRPS (correlation 0.89) and soil moisture (correlation 0.90).
• Driver Dominance: ENSO is the primary driver of the linear signal, with the IOD contributing little independent variance.
• Compound Effects: The driest conditions occur during compound El Niño and positive IOD seasons, characterized by vertically coherent subsidence (upper-level convergence, mid-level descent, and low-level divergence).
• Scale and Seasonality: The coupling between these oscillations and drought deepens with increasing accumulation scales (peaking at SPEI-12) and strengthens during the rainy season.

Contributions

• Development of the SCODP-GATE readiness index, a tool providing skillful drought forecasting for the central interior, southern interior, and western drylands of the SADC region.

Funding

Not specified in the provided text.

Citation

@article{Manatsa2026Multiscale,
  author = {Manatsa, Desmond and Mushore, Terence Darlington and Ngoma, James},
  title = {Multiscale <scp>ENSO</scp> and Indian Ocean Dipole Controls on Drought Across Mainland <scp>SADC</scp> : A Meridional Teleconnection Dipole, Its Seasonal and Sectoral Structure and a Domain‐Gated Readiness Index},
  journal = {International Journal of Climatology},
  year = {2026},
  doi = {10.1002/joc.70542},
  url = {https://doi.org/10.1002/joc.70542}
}