Copula-based Assessment of Synoptic Weather Patterns Driving Mediterranean Droughts

The Mediterranean Basin, a climate change hotspot, experiences escalating drought risks shaped by large-scale atmospheric and oceanic systems. This study employs k-medoids clustering and copula functions to map spatial drought patterns across multiple timescales (SPI-1 to SPI-120), interpreted through a physical climatological lens. Composite maps reveal the Azores High driving persistent multi-year droughts in the Iberian Peninsula (Cluster 1), with pronounced drying during warm Atlantic Multidecadal Oscillation (AMO) phases, while Siberian High intrusions trigger intense short-term droughts in the Eastern Mediterranean (Cluster 7). Central Mediterranean droughts (Cluster 2) show synchronized risks, linked to blocking patterns, affecting shared water resources. Short-term droughts (SPI-1 to SPI-6) reflect synoptic variability, such as medicane activity in the Adriatic, while longer-term trends (SPI-60 to SPI-120) align with oceanic influences. Using 35 years of NCEP/NCAR Reanalysis data (1990–2024), this framework delineates seven hydroclimatic regimes, offering a physical narrative of drought dynamics beyond traditional SPI’s pointwise focus. These insights, grounded in synoptic evidence, highlight the need for coordinated water management and provide a scalable approach to understanding drought in an aridifying Mediterranean.