A novel framework for future drought characterization under ranked-based subset selection and weighted aggregative...

Area of Science:

• Climate Science
• Environmental Science
• Hydrology

Background:

• Future drought characterization relies on Multi-Modal Ensembles (MMEs) of Global Climate Models (GCMs), particularly from the Coupled Model Intercomparison Project Phase 6 (CMIP6).
• Existing methods for ranking GCMs and regional aggregation in MMEs have limitations, hindering projection reliability.
• Outlier handling in regional aggregation and insufficient GCM ranking methodologies compromise drought projection accuracy.

Purpose of the Study:

• To present a novel framework for enhancing the reliability and standardization of drought projections.
• To introduce innovative methods for GCM ranking, regional aggregation, and MME construction.
• To develop an adaptable framework applicable to diverse climatic and geographic contexts for improved drought management.

Main Methods:

• Utilized Mutual Information (MI) for evaluating GCM historical precipitation simulation performance.
• Employed comprehensive rating metrics (CRM) for effective GCM ranking and advanced geometric/regression methods for MME construction.
• Introduced a novel regional aggregation technique to mitigate outlier influence and a Gaussian-Norm Weighted Drought Index (GNWDI) for enhanced standardization within the Standardized Precipitation Index (SPI) framework.

Main Results:

• Identified high-performing GCMs (MIROC-ES2L, CMCC-CM2-SR5, IPSL-CM6A-LR) for Punjab, Pakistan, using the developed framework.
• Projected an increase in extreme droughts and wet conditions under high emission scenarios (SSP5-8.5) for 2015-2100.
• Observed a notable rise in severe wet conditions under SSP5-8.5, indicating more frequent extreme hydrological swings.

Conclusions:

• The study significantly advances drought projection techniques by addressing critical gaps in model ranking, aggregation, and standardization.
• The proposed framework offers a reliable, regionally adaptable tool for policymakers and researchers.
• The findings enable proactive drought management and improved climate resilience under varying emission scenarios.