Climatology and circulation classification of Saharan dust over Bulgaria

The Sahara is the largest hot desert in the world and produces more aeolian soil dust than any other desert. Saharan dust significantly impacts climate, biogeochemical, and hydrological processes. Additionally, Saharan dust strongly affects air quality and human health. As a result, it is important to monitor the frequency and the transport patterns of dust outbreaks. In this work, it is found that for the 10 years (2011–2020), there are a total of 365 days with Saharan dust transport over Bulgaria, with the number of days per year being between 16 and 53. The monthly climatology shows that the month with the largest number of days is March. The rarest transport of Saharan dust over Bulgaria is observed during the summer months. An objective classification of the atmospheric circulation on days with Saharan dust transport to Bulgaria is made for the period 2011–2019. Two objective circulation classifications — GrossWetter Types and Jenkinson–Collison Type with 26 types were used. The main circulation types with the transport of Saharan dust are associated with the development of Mediterranean cyclones and the transport of air masses from the south-southwest. A case study of Saharan dust intrusion into Bulgaria was made for the period from 25 to 27 March 2020. The specific synoptic conditions that lead to the transport of Saharan dust are discussed.