Abstract: | Dust particles play a dual role in influencing cloud systems as cloud condensation nuclei (CCN) and ice-nucleating particles (INPs). These roles significantly affect cloud lifespan, albedo, and precipitation patterns, with implications for regional and global climate systems. Although dust alone is a poor CCN, its hygroscopicity improves when mixed with other aerosols like sulfate, enhancing its effectiveness as a CCN. This study investigates the impact of dust on cloud systems and precipitation in the United Arab Emirates during August 2019, utilizing data from the National Centre of Meteorology’s flight campaigns.
Dusty and less dusty periods were identified using SEVIRI RGB dust products and MERRA-2 reanalysis data. Cloud properties were analyzed using MERRA-2 for cloud occurrence and SEVIRI’s Optimal Cloud Analysis (OCA) product for effective droplet radius. The "Heavy Dust" case (18 August) featured a dust mixing ratio exceeding 600 µg/m³, confined by a strong temperature inversion at the 700 hPa level, while the "Less Dust" case (12 August) showed a peak of 300 µg/m³ with broader vertical dispersion due to weaker atmospheric stability.
Results indicate that heavy dust conditions, acting as CCN, produce fewer but larger cloud droplets, enhancing coalescence processes and facilitating warm rain formation. Conversely, less dusty conditions result in a higher number of smaller droplets, suppressing warm rain development. This study highlights the critical role of dust in modifying cloud microphysics, droplet size distributions, and precipitation dynamics, advancing the understanding of atmospheric processes in arid regions. |
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