Latif et al. (2026) El Niño-Southern Oscillation-driven variability in drought severity across the Upper Indus Basin, Pakistan

Identification

• Journal: Theoretical and Applied Climatology
• Year: 2026
• Date: 2026-01-20
• Authors: Yasir Latif, Muhammad Yaseen
• DOI: 10.1007/s00704-025-05866-5

Research Groups

• Department of Earth and Atmospheric Sciences, Cornell University, Ithaca, NY, USA
• Department of Complex Systems, Institute of Computer Science of the Czech Academy of Sciences, Prague, Czech Republic
• Center for Integrated Mountain Research (CIMR), University of the Punjab, Lahore, Pakistan

Short Summary

This study investigates the influence of El Niño-Southern Oscillation (ENSO) phases on drought severity, precipitation extremes, and consecutive dry days across the Upper Indus Basin (UIB) in Pakistan, revealing significant regional and temporal variability in hydroclimatic conditions driven by ENSO.

Objective

• To comprehensively analyze the El Niño-Southern Oscillation (ENSO)-driven variability in drought severity, consecutive dry days (CDD), and heavy/extreme precipitation days (R20/R50) across the Upper Indus Basin (UIB), including its sub-basins (Jhelum and Kabul River Basins), by examining the influence of El-Niño, La-Niña, and neutral ENSO phases.

Study Configuration

• Spatial Scale: Upper Indus Basin (UIB), Jhelum River Basin (JRB), and Kabul River Basin (KRB) in Pakistan, covering approximately 520,000 square kilometers.
• Temporal Scale:
  • ERA5 reanalysis data: 1991 to 2020.
  • In-situ measurements: 1991 to 2017.
  • Extended historical analysis for selected stations: 1971 to 2019.

Methodology and Data

• Models used:
  • Standardized Precipitation Index (SPI) for meteorological drought analysis.
  • Innovative Trend Significance Test (ITST) for trend analysis of SPI, R20, and R50.
  • Calculation of Consecutive Dry Days (CDD), Heavy Precipitation Days (R20), and Extreme Precipitation Days (R50).
• Data sources:
  • ERA5 reanalysis gridded precipitation products (European Centre for Medium-Range Weather Forecasts - ECMWF) with a horizontal resolution of 0.25 degrees.
  • In-situ daily precipitation measurements from 32 climatic stations provided by the Pakistan Meteorological Department (PMD).
  • Nino 3.4 index and Oceanic Niño Index (ONI) for categorizing ENSO phases (from NOAA CPC).
  • Hadley Centre sea ice and sea surface temperature data (HadISST) for tropical Pacific sea surface temperature.

Main Results

• A significant relationship was observed between ENSO phases and SPI across all studied basins (UIB, JRB, KRB).
• Maximum wetness (high SPI values) occurred in 1999, 2000, 2010, and 2011, primarily influenced by strong La-Niña events.
• El-Niño phases enhanced SPI (wet conditions) in 1991, 1997, 2002, 2004, 2009, 2015, and 2016.
• SPI and R20/R50 generally exhibited a decline across most stations in the JRB (e.g., Bagh, Mangla, Murree), KRB (e.g., Chitral, Dir), and UIB (e.g., Gilgit, Gupis), indicating increasing drying trends.
• Consecutive Dry Days (CDD) significantly increased at several monsoon-dominated stations in the JRB (e.g., Kallar, Murree, Mangla), while declining trends were noted at Bagh, Balakot, and Parachinar.
• ERA5 precipitation generally underestimated in-situ precipitation in terms of quantity and spatial extent but showed consistent spatial variability.
• The highest precipitation was generally observed under ENSO neutral conditions, followed by El-Niño and La-Niña phases.
• The ITST confirmed significant shifts from wetting to normal or moderate drought conditions in many stations over recent years.

Contributions

• Provides a detailed analysis of the specific influence of individual ENSO states (El-Niño, La-Niña, and neutral) on drought severity, rather than just overall large-scale interactions.
• Utilizes the Innovative Trend Significance Test (ITST) to robustly validate SPI values and precipitation extreme trends, effectively addressing serial correlation in time series data.
• Offers a comprehensive investigation into the cross-dependence between meteorological drought characteristics (SPI, CDD, R20/R50) and ENSO phases, an area previously less explored.
• Enhances the understanding of precipitation droughts and extremes under ENSO influence, particularly in the climate-vulnerable Upper Indus Basin.

Funding

• Eric and Wendy Schmidt AI in Science Postdoctoral Fellowship (awarded to Yasir Latif).
• Czech Academy of Sciences, Praemium Academiae (awarded to M. Paluš).
• Johannes Amos Comenius Programme (P JAC), project No. CZ.02.01.01/00/22_008/0004605, Natural and anthropogenic georisks.

Citation

@article{Latif2026El,
  author = {Latif, Yasir and Yaseen, Muhammad},
  title = {El Niño-Southern Oscillation-driven variability in drought severity across the Upper Indus Basin, Pakistan},
  journal = {Theoretical and Applied Climatology},
  year = {2026},
  doi = {10.1007/s00704-025-05866-5},
  url = {https://doi.org/10.1007/s00704-025-05866-5}
}