Investigating the rare phenomenon of dust in the southern shores of the Caspian Sea

Introduction: Climate change-driven droughts have intensified dust storms, expanding their impact to regions that previously experienced little to no dust. One such area is the southern shores of the Caspian Sea. Materials and methods: This study investigated three severe dust cases along the southern Caspian coast, originating from various sources both inside and outside of Iran. A combination of satellite data, reanalysis data, and numerical model outputs was analyzed. The dust surface concentration output from the WRF-Chem model’s 36- and 48-h forecasts was qualitatively compared with the dust patterns from MERRA2 reanalysis data. Results: Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) satellite data confirmed the presence of dust from near the surface to over 5 km in altitude, allowing dust to cross the Alborz range. Satellite imagery and Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model outputs revealed that dust over the southern Caspian coast originated from three sources: northern Iraq, central Iran, and western Turkmenistan. Comparing Weather Research and Forecasting (WRF)-Chem model outputs with reanalysis data demonstrated that the model accurately predicted dust events along the southern Caspian shores in all three cases, though its precision is not yet suitable for quantitative comparison. Conclusion: According to the results of this study, dust in the northern provinces of Iran is emitted from three dust sources in northern Iraq, central Iran, and Turkmenistan. Also, the WRF-Chem model has been able to predict the dust transport from these different dust sources to northern Iran. However, it can be stated that the accuracy of the outputs is still not suitable for quantitative comparison.