Multidecadal Analysis of the Saharan Oscillation Index (SaOI) and Its Correlation with Large-Scale Climate Indicators

Understanding regional climate variability over North Africa and the Mediterranean Basin is crucial given the region’s vulnerability to extreme weather events, such as heatwaves, droughts, and dust storms. Despite growing attention to tropical–extratropical teleconnections, limited research has examined how pressure patterns over the Saharan sector interact with large-scale climate modes. In this context, the Saharan Oscillation Index (SaOI) a newly defined climate index representing the pressure dipole between the Azores High and the Saharan Low offers new potential for understanding and anticipating regional climate dynamics.Using data from 1950 to 2022, this study investigates the SaOI’s multidecadal interplay with thirteen major large-scale climate indicators (LSCIs). Annual and seasonal lagged correlations were analyzed between the SaOI and indices such as the North Atlantic Oscillation Index (NAOI), Arctic Oscillation Index (AOI), Oceanic Niño Index (ONI), Tropical North and South Atlantic Indices (TNAI/TSAI), and the Mediterranean Oscillation Index (MOI), among others. Extreme phases of the SaOI were also characterized using percentile-based thresholding.The analysis reveals moderate correlations, characterized by seasonal robustness of the SaOI with the NAOI (r = 0.42), AOI (r = 0.42), and ONI (r = − 0.44) articulate the SaOI’s ability to respond to both tropical and extratropical anomalies of sea-level pressure and sea surface temperature. Other seasonal linkages emerge with the TNAI and TSAI, through which the Atlantic SSTs influence Saharan atmospheric dynamics, with prominence from winter through summer. These interactions govern the modulation of heatwaves, pressure gradients, moisture advection, notably dust activity, and air quality degradation over North Africa.Positive SaOI phases characterized by a reinforced Azores High and deep Saharan low intensify dry northeasterly flows and enhance atmospheric stability, which can suppress rainfall and exacerbate both heat extremes and dust emissions. Conversely, negative phases tend to weaken pressure gradients and increase moisture influx, especially in winter and spring. Dust transport and air pollution, assessed through selected case studies, emerge as downstream effects of the broader circulation regime shaped by SaOI variability.Overall, this work reveals the SaOI's relevance as an integrative diagnostic and predictive index for regional climate dynamics. Its statistically significant coupling with multiple LSCIs reinforces its utility for seasonal forecasting, compound risk assessments, and the development of early warning systems for climate-sensitive sectors, including public health, agriculture, and water security.