Effect Dynamic Stability of Atmospheric Boundary Layer on Plume Downward Flux Emitted from Daura Refinery Stacks

Abstract

The vertical motion of air that enhances or restricts the atmospheric turbulence through atmospheric boundary layer is known as "atmospheric stability", in which any movement of atmospheric components such as water vapor, aerosols, etc. are affected by the atmospheric stability. The aim of this research is to test the effect of atmospheric boundary layer stability on the amount of downward aersols flux at 10um (PM10) emission from stacks of Daura refinery, and estimated of deposition dust aerosols PM10 amount in area around the Daura refinery. In this study, hourly atmospheric stability based on similar theory of Monin-Obukhov length is calculated from archived data of the European Center for Medium Range Weather Forecast, and deposition velocity (Vd) for PM10 that is emitted from stacks Daura Refinery is calculated using the stability parameter (L). PM10 concentration is estimated according to the Gaussian model, which is used along with deposition velocity at this partical size in order to produce downward sedimentation flux (Fp) at distances 1000, 5000 and 10000 m from stack point sources emission. Results show that areas located to the south and southeast of the refinery receive large amounts of deposited flux values through stable weather conditions, where the accumulated PM10 amounts during one month have recorded 1.5 million μg /m2.s in January at a distance of 1000 m from refinery center stacks, while this amount reaches 532 million μg/m2.s during July due to the high emission rates resulting from burning fuel oil during July. The percentages of PM10 sedimentation decreased with the distance from the refinery to 1712 and 322839 μg /m2.s at a distance 10 km from the refinery in January and July, respectively. According to this method, the accumulated amount of PM10 in square meters can be estimated at any time, if atmospheric stability conditions and the domain of wind direction are known.