Understanding day-night differences in dust activities over the dust belt of North Africa, the Middle East, and Asia

• Main Authors: Tindan, Jacob Zora-Oni, Jin, Qinjian, Pu, Bing
• Format: Text
• Language: English
• Published: 2022
• Subjects: Indian; Aerosol Robotic Network
• Online Access: https://doi.org/10.5194/acp-2022-490; https://acp.copernicus.org/preprints/acp-2022-490/

Utilizing the well-calibrated, high spectral resolution, and equal-quality-performance for day and night observations (9:30 a.m. and 9:30 p.m. equator passing time) of the Infrared Atmospheric Sounder Interferometer (IASI) products, this study investigates the day-night differences in dust activities over the dust belt of North Africa, the Middle East, and Asia. Both daytime and nighttime dust optical depth (DOD) at 10 microns shows high consistency with solar and lunar observations from AErosol RObotic NETwork (AERONET) sites across the dust belt, with correlation coefficients of 0.8–0.9 for most sites. IASI reveals significant (95 % confidence level) day-night differences in dust activities over the major dust sources within the dust belt. Annual mean daytime DOD at 9:30 a.m. is significantly higher than that of nighttime at 9:30 p.m. in the central to northern Sahara Desert, the central to eastern Arabian Peninsula and dust source regions in South and East Asia including the Taklamakan Desert, but lower over the southern Sahel to the Guinea Coast, and the central to southern Indian subcontinent. The magnitude of the day-night difference in DOD is larger and more significant in boreal winter and spring than other seasons. An analysis of 10 m wind fields and dust uplift potential using the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 (ERA5) suggests that the positive day-night differences in DOD over the central Sahara, the Middle East, and Asia are associated with enhanced dust emissions driven by stronger wind speed. Dust layer heights demonstrate negative day-night differences (i.e., lower daytime versus higher nighttime values) over dust source regions in the central Sahara, central Arabian Peninsula, and Asia, and positive height differences in the southern Sahel to the Guinea Coast, southern parts of the Arabian Peninsula, and large parts of the Indian subcontinent. The higher dust layer height over the Guinea Coast and the Indian subcontinent during daytime is associated with ...