The lack of information on the vertical distribution of dust, in turn, results in large uncertainties when attempting to evaluate the impacts of dust on climate processes. We analyzed over two years of LIDAR measurements from NASA’s CALIPSO and CloudSat satellites to document the vertical pathways of transatlantic transport of Saharan dust. Our analysis overcomes the limitations of quantitative dust detections with passive satellite measurements over land and low clouds and provides the fine vertical resolved structures. The results show the strong seasonal shift in dust source regions and transportation pathways due to the meteorological and thermodynamical conditions, which also control the dust vertical distribution as well as the depth of the dust layer. The dust layer top descending rates of 35？m/degree in summer, 25？m/degree in autumn and spring, and 10？m/degree in winter are found, respectively, while the dust is being transported across the Atlantic. Comparison with the model simulation highlights the potentials of dust observations using CALIPSO LIDAR. The observed seasonal dependence of these pathways gives new insights into the transport of the Saharan dust and provides important guidance for simulations of the production and transport of the global dust aerosol. 1. Introduction Mineral dust is mainly generated from the continents and can be transported both horizontally and vertically into the atmosphere and affect vast area on the earth. Mineral dust plays an important role in climate processes by affecting radiation [1, 2], modifying cloud and precipitation processes by acting as cloud condensation nuclei (CCN), giant CCN (GCCN), and effective ice nuclei (IN) [3–8]. Also mineral is an important source of nutrition which modulates a variety of marine biogeochemical processes [9]. However, among different types of aerosols, there are large uncertainties in dust sources, sinks, and their long-range transports [10, 11]. The Sahara is a primary source of dust, the majority of which is transported westward across the Atlantic to the Southeastern United States, the Caribbean Sea, and South America [12–14]. African dust and its transport have been documented by several passive remote sensors, for example, the Advanced Vary High Resolution Radiometer (AVHRR), Meteosat, Total Ozone Mapping Spectrometer (TOMS), and Moderate Resolution Imaging Spectroradiometer (MODIS) [15–18]. Modeling and observation results also suggest that Saharan dust and dust containing Sahara Air Layer (SAL) could impact the hurricane formation and evolution in the region of
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