engleski

The aspects of numerical simulations on desert dust outbreaks over the Adriatic Sea; influence of Asian and African deserts

Airborne mineral dust is one of the most important factors in air quality and climate change. While the Saharan dust related transport towards European countries is well investigated and documented, there is less research of the advection from Asian deserts. Here, we provide the simulations of the two dust outbreaks in Croatia ; one of ‘typical’ Saharan origin and other with sources toward the east (i.e., the Caspian Sea). In both cases, the WRF-Chem model was applied to simulate the dust emission, transport and deposition. In the first case, the increase of PM10 hourly values was observed over the Adriatic coast in September 2015. Although the model does not capture the convective processes detected by the NASCube methode, it exhibits a good agreement with AOD observed at AERONET stations in the Mediterranean and with PM10 at air quality stations in Adriatic. The main mechanism was found to be a NLLJ morning breakdown over sources in Algeria and Tunisia. In the second case, the untypically extreme dust outbreak was observed over the Balkan region from 27 to 30 March 2020. The anticyclone north of Croatia and cyclone over Anatolia formed a strong pressure gradient driving a transport from desert sources east to the Caspian Sea. However, the PM10 chemical and morphological (SEM analyses) composition at the site in the northern Adriatic indicate mainly the presence of the Saharan dust. Preceding the Asian dust advection, the presence of Saharan dust transport towards Balkan driven by Sharav cyclone was observed. The model shows high correlation with PM10 hourly values from regional air quality stations but it underestimates the observations. Modelling results indicate the transport from Asia was below ~2 km, while the Saharan was up to ~8 km amsl. The mixing of the Asian and Saharan dust plume over Balkan was favoured by subsidence due to anticyclonic high pressure conditions, and it is the most plausible explanation for the observed PMs chemical and morphological results.

dust transport ; WRF ; Saharan dust, Aral

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