Impact of Climate Variability on Atmospheric Drivers of major Dust Storms over North Africa

Abstract

Dust storms over North Africa represent a critical component of the regional and global climate system, influencing radiation balance, precipitation processes, ecosystem functioning, and human health. Despite their importance, recent studies suggest a multidecadal decline in dust activity across the region, though the driving mechanisms remain debated. This study investigates the spatiotemporal trends in North African dust storm frequency over the past four decades and explores the meteorological and climate drivers underlying these changes using a combination of observational datasets, reanalysis products, and statistical and machine learning methods. Seasonal and annual dust frequency trends derived from surface visibility records reveal a pronounced decrease in dust activity, particularly across the Sahel and central Sahara. Using Theil-Sen trend estimation and Mann-Kendall significance testing, we detect statistically significant declines in surface wind speeds and increases in vegetation cover (leaf area index) and precipitation, especially between 10°N and 15°N. Concurrently, the Saharan Heat Low (SHL) shows signs of intensification and expansion, suggesting possible suppression of dust uplift due to modifications in regional circulation and thermodynamic stability. Correlation analyses further highlight strong seasonal associations between dust storm frequency and drivers such as 10-m wind speed, precipitation, SHL strength, and climate indices (Atlantic Multidecadal Oscillation (AMO), North Atlantic Oscillation (NAO)). A Self-Organizing Map (SOM) classification of sea level pressure and 925 hPa wind patterns during dust storm days reveals dominant atmospheric configurations associated with dust generation, with a clear seasonality and regional preference in SOM node activation. Additionally, Long Short-Term Memory (LSTM) models using climatic and environmental predictors demonstrate skill in reconstructing the historical evolution of dust storms, reinforcing the predictability of dust activity based on climate variability. Overall, the results support the hypothesis that recent declines in North African dust storm activity are linked to a combination of decreased surface wind stress, increased vegetation and rainfall, and changes in the SHL and large-scale climate drivers influence. These findings provide an updated understanding of dust-climate interactions and underscore the importance of land-atmosphere coupling and climate teleconnections in shaping dust variability.