Observation and modeling of the historic “Godzilla” African dust intrusion into the Caribbean Basin and the southern US in June 2020

Abstract. This study characterizes a massive African dust intrusion into the Caribbean Basin and southern US in June 2020, which is nicknamed “Godzilla” plume, using comprehensive set of satellite ground-based observations (including MODIS, CALIOP, SEVIRI, AERONET, EPA Air Quality network) NASA GEOS global aerosol transport model. The MODIS data record registered this event as most intense episode over past 2 decades. During event, optical depth (AOD) observed by AERONET peaked at 3.5 off coast West Africa 1.8 Basin. CALIOP show that top plume reached altitudes 6–8 km descended to about 4 altitude Gulf Mexico coast. degraded air quality Puerto Rico hazardous level, with maximum daily PM10 concentration 453 µg m?3 recorded on 23 June. raised PM2.5 27 level exceeding standard 40 % stations US. Satellite reveal emissions from convection-generated haboobs other sources were large albeit not extreme basis. However, anomalous strength northern shift North Atlantic Subtropical High (NASH) together Azores low formed closed circulation pattern allowed for accumulation near d. When NASH was weakened wandered back south, outflow region dominated strong easterly jet rapidly transported accumulated coastal toward Basin, resulting record-breaking intrusion. In comparison observations, model reproduced tracks meandering well it carried wind systems. substantially underestimated did lift up enough middle troposphere ensuing long-range transport. Consequently, largely missed satellite-observed elevated along cross-ocean track factor more than 4. Modeling improvements need focus developing realistic representations moist convection, haboobs, vertical dust.