Over the last decades, the impact of mineral dust from African deserts on human health and climate has been of great interest to the scientific community. In this paper, the climatological analysis of dusty events of the past 20 years in the Caribbean area has been performed using a particulate approach. The focus is made on June 2020 extreme event dubbed “Godzilla”. To carry out this study, different types of data were used (ground-based, satellites, model, and soundings) on several sites in the Caribbean islands. First, the magnitude of June 2020 event was clearly highlighted using satellite imagery. During the peak of this event, the value of particulate matter with an aerodynamic diameter of less than 10 μμm (PM10) reached a value 9 times greater than the threshold recommended by the World Health Organization in one day. Thereafter, the PM10, the aerosol optical depth, and the volume particle size distribution analyses exhibited their maximum values for June 2020. We also highlighted the exceptional characteristics of the Saharan air layer in terms of thickness and wind speed for this period. Finally, our results showed that the more the proportion of particulate matter with an aerodynamic diameter of less than 2.5 μμm (PM2.5) in PM10 increases, the more the influence of sea salt aerosols is significant.

Desert dust coming from North African sources is a major phenomenon of the atmosphere related to its impact on the earth climate and human health. A great part of this particle product is transferred in a westward flux, over the Atlantic Ocean in form of outbreaks. Depending on the season, transport conditions and meteorological configuration along the pathway, high dust concentrations can reach either the northeast coast of South America or the islands of the Caribbean region. Their arrival corresponds with bad local air quality and numerous admittances into hospital emergency rooms. The control of health risk requires a dust-level forecast using satellite, model and ground measurements data. In this study, we investigate a correlation between PM10 measurements performed in 2015 by air quality networks at two sites, one in Dakar located on the West African coast and the other in Guadeloupe, a French Caribbean Island. The PM10 dust concentrations for both sites have been obtained using the same certified instruments (TEOM). Only Guadeloupe dust events presenting a daily mean PM10 of up to 35 µg/m 3 with back trajectories crossing in the vicinity of Dakar and verifying trajectories coming from Dakar, crossing close to Guadeloupe, have been taken into account. An air masses transport delay deduced by the HYSPLIT trajectory model was applied and a non-correlation between the two sites PM10 (correlation coefficient R = 0.3) was observed. Using the same trajectories and back trajectories, proximity conditions and HYSPLIT delay, the two sites' Aeronet photometric measurements (AOT1020) have been compared. A good correlation confirmed by a correlation coefficient, R = 0.88, was obtained between the Dakar AOT 1020 and the Guadeloupe AOT 1020. On the twelve dusty days of 2015 within eligible conditions of the pathway, an 80% decrease of AOT1020 during the transfer over the Atlantic Ocean was found.

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