Menachem et al. (2026) Multi-decadal drought variability in the Eastern Mediterranean and its connection to large-scale climate indices

Identification

• Journal: Journal of Hydrology Regional Studies
• Year: 2026
• Date: 2026-02-12
• Authors: Yotam Menachem, Ehud Strobach
• DOI: 10.1016/j.ejrh.2026.103249

Research Groups

• Department of Earth and Planetary Sciences, Weizmann Institute of Science, Rehovot, Israel
• Institute of Soil, Water & Environmental Sciences, Volcani Institute, Agriculture Research Organization, Rishon LeZion, Israel

Short Summary

This study investigates multi-decadal agricultural drought variability in the Eastern Mediterranean using soil-moisture-based indicators from ERA5-Land, revealing a shift to consistent drying since the 1990s and strong correlations with the Atlantic Multidecadal Oscillation (AMO) and North Sea–Caspian Pattern (NCP).

Objective

• To examine the spatiotemporal evolution of agricultural drought in Israel using soil-moisture-based indicators and to analyze its connection to large-scale climate teleconnection patterns.

Study Configuration

• Spatial Scale: Israel, with analysis extending to the Eastern Mediterranean, Europe, and Western Asia.
• Temporal Scale: Two distinct periods (1952–1982 and 1992–2022) for trend analysis, and 1952–2022 for correlation analysis, focusing on the December–February (DJF) season.

Methodology and Data

• Models used: Noah, Community Land Model (CLM), and Simplified Simple Biosphere (SSiB) land surface schemes, implemented within the Noah-MP framework, to calculate the soil moisture factor (β factor). Precipitation minus evaporation (P-E) and volumetric soil water content (SWC) were also analyzed.
• Data sources:
  • ERA5-Land reanalysis data for total evaporation, total precipitation, and volumetric soil water content (SWC) across four depth layers (0–7 cm, 7–28 cm, 28–100 cm, and 100–289 cm).
  • In-situ daily precipitation data from the Israel Meteorological Service (IMS).
  • Teleconnection indices: Atlantic Multidecadal Oscillation (AMO), North Atlantic Oscillation (NAO), Pacific Decadal Oscillation (PDO), El Niño 3.4 (NINO3.4) from NOAA Physical Sciences Laboratory; Mediterranean Oscillation Index 2 (MOI2) from Climatic Research, University of East Anglia; North Sea–Caspian Pattern (NCP) from Gisela Müller-Plath.

Main Results

• A significant shift from mixed drought trends in 1952–1982 to consistent drying in 1992–2022 was observed, particularly in deeper soil layers and Israel's semi-arid region, suggesting a northward shift of the aridity line.
• Soil moisture-based indicators (SWC and β factors) showed higher statistical significance and more robust signals for drought trends compared to precipitation or P-E.
• Strong negative correlations (exceeding 0.5 in some areas) were found between drought indicators (β factors) and the Atlantic Multidecadal Oscillation (AMO), indicating that warmer Atlantic sea surface temperatures are associated with drier conditions. This relationship extends across Europe and Western Asia.
• Strong positive correlations (exceeding 0.5) were identified between drought indicators (β factors) and the North Sea–Caspian Pattern (NCP) across most of the study area, where a positive NCP phase is linked to less drought.
• Correlations with AMO and NCP were more pronounced and significant in deeper soil layers, highlighting the role of slow soil moisture processes in integrating long-term climatic variability.
• Other teleconnection indices (NAO, MOI2, NINO3.4, PDO) did not show remarkable correlations with the drought indicators.

Contributions

• Demonstrates the superior capability of soil moisture-based drought indicators (β factors) over traditional precipitation/P-E metrics in detecting significant multi-decadal drought trends and their spatial patterns, especially in deeper soil layers.
• Identifies strong, scale-dependent correlations between soil-moisture-based drought indicators and specific large-scale teleconnection patterns (AMO and NCP) in the Eastern Mediterranean and broader regions.
• Provides new hydrological insights into the northward shift of the aridity line in Israel's semi-arid region.
• Suggests potential for enhanced drought monitoring and improved decadal drought predictability in the Eastern Mediterranean and beyond, leveraging the predictability of teleconnection patterns.

Funding

• European Union’s Horizon Europe research and innovation programme under grant agreement No. 101081276 (Project PREVENT).

Citation

@article{Menachem2026Multidecadal,
  author = {Menachem, Yotam and Strobach, Ehud},
  title = {Multi-decadal drought variability in the Eastern Mediterranean and its connection to large-scale climate indices},
  journal = {Journal of Hydrology Regional Studies},
  year = {2026},
  doi = {10.1016/j.ejrh.2026.103249},
  url = {https://doi.org/10.1016/j.ejrh.2026.103249}
}