Modeling some Dispersion Characteristics of Saline Particles from Urmia Lake Bed Based on near Surface Atmospheric Currents

Desiccation of Urmia Lake in the last two decades and saline dust emission from its dry bed has become an environmental crisis in the northwest of Iran. The main purpose of this study is the modeling of the deposition rate, transport pathway and emission height of saline dust over Urmia Lake based on near surface winds.

In this regard, observed severe winds around the lake were analyzed. Subsequently, by matching of strong winds with MODIS satellite AOD products, a number of dust storms generated over Urmia Lake were selected and then storm generation date and location determined. In next step the HYSPLIT model was run in forward mode for 18 hours. To assess the model results, its outputs were compared with synoptic maps.

Results showed that although strong winds are possible from all directions, but the prevailing directions are from the south, southwest and north respectively. Modeling results showed that saline dust diffusion is possible in all directions, and also transporting pathway, deposition rate and mixed layer height of saline dust can be different in terms of surface winds characteristics and especially upper levels atmospheric currents. Based on the results the emission path of the salt dust is more in line with upper levels winds, and raising particles may be emitted a distance of ~200 kilometers in 18 hours. Eventually, raising top height of saline particles could up to 4000 meters according to the intensity of ascending fluxes.