Investigation of atmospheric particles in Urmia Lake region using a hand-held sun-photometer

Abstract

Urmia Lake is a hypersaline lake in Northwest Iran. Regions inside its water catchment area experience frequent dust events. We are reporting the results of a two-year measurement campaign using a Calitoo sunphotometer, alongside synoptic measurements, satellite data, and atmospheric models. The monthly mean aerosol optical thickness (AOT) demonstrates a seasonal pattern, with fine particles prevailing in the winter and coarse particles being dominant during the summer months. Approximately 69% and 10% of the measurements indicate urban-industrial pollution and dust as the primary atmospheric particle types in the region, respectively. On the remaining days, a combination of the aforementioned aerosol types prevails as the dominant atmospheric particle composition. An in-depth analysis of a specific dust event unveiled a 24-hour delay between the peak AOT and the subsequent increase in particulate matter. Furthermore, the HYSPLIT model’s backward trajectory analysis depicted the transport of a dust plume from Mesopotamia to Urmia Lake, inducing alterations in AOT, mass concentrations, and visibility.