Vertical Profiling of Dust Layers in the Eastern Mediterranean: Sources, Dynamics, and Impacts

Dust pollution is a critical environmental challenge with far-reaching impacts on climate and health. Despite its significance, no unified methodology exists for identifying dust-contaminated days, leading to inconsistencies across disciplines. The most widely used approaches often rely on ground-based measurements to classify dust events. However, these methods may overlook lofted dust layers. We used a ground-based lidar system to detect and classify dust layers and compared the results to widely adopted methods. Surprisingly, at least 50% of dust-contaminated days identified by lidar were missed by traditional surface-based methods. This gap underscores the critical role of vertical profiling in accurately capturing dust presence, which is vital for improving health impact studies and climate models. Our results highlight the challenges of distinguishing between anthropogenic and natural dust events using only ground-based measurements, as many measurement approaches classify mixed aerosols as dust, potentially leading to biased exposure estimates. In addition, vertical profiling and layering data revealed distinct pollution configurations in the Eastern Mediterranean (EM) region, ranging from purely anthropogenic layers to complex mixtures of marine aerosols, anthropogenic pollution, and desert dust. Results reveal that dust layers in the EM often extend vertically up to 10 km, with depths reaching 6.3 km. We used air masses back trajectory analysis to identify the source of particles for each layering type, and found 2 distinct dust sources, North African mostly pure dust and Middle Eastern dust with anthropogenic component. Finally, we analysed the uncertainties of the conventional satellite-derived AOD measurements. It was found the presence of lofted dust layers or mixed aerosols challenge the retrieval accuracy, gaining crucial insights into the limitations of satellite-derived AOD in representing complex atmospheric environments, especially in dust dominated regions. The holistic approach applied in our study is essential for understanding the dynamic interplay between pollution sources and atmospheric interactions, particularly in regions like the EM, which serve as a crossroads for diverse aerosol types.