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.

In recent years, dust events in Iraq become very frequent due to its emission from active local dust sources or transportation from abroad. This study aims to identify dust sources in Iraq for the period (1st January, 2005 to 31 December, 2016) using mean of monthly mean of the aerosol optical properties including Deep Blue Aerosol Optical Depth(DB-AOD), Deep Blue Angstrom Exponent(DB-AE) and UV Positive Absorption Aerosol Index(AAI) acquired from space borne instruments including MODerate resolution Imaging Spectroradiometer (MODIS) for both Aqua and Terra, Multiangle Imaging SpectroRadiometer (MISR) and Ozone Monitoring Instrument (OMI), considering the dust aerosols having values of AOD>0.5, AE<0.5 and AI>0.7 based on the predefined thresholds. The results show that Al-Jazira and the southern region of Iraq considered as significant dust sources most of the year, with the absence of active dust sources in December, January, October and November. While spring and summer months show many active dust sources in the Alluvial plain, western plateau, southern and southeastern parts of Iraq with high AOD, low AE and high AAI especially in April, May, June and July. MISR/AOD shows lower values of MODIS-DB in Iraq along months of the years, which could be due to the insufficient coverage over dust regional sources compared to MODIS.

A series of huge wildfires occurred in some regions of Lebanon in mid-October 2019, when the region witnessed a heat wave with high averages of minimum and maximum temperatures, accompanied by dry weather conditions. This study aimed to investigate the weather pattern that predominated over Lebanon between 10 and 18 October 2019, and to study the weather factors that ignited and spread the fire in several places. The study focused on the Chouf district, in Mount Lebanon Governorate, which witnessed the most severe wildfire outbreak, based on ERA5 atmospheric reanalysis data at the surface and upper levels between 10 and 18 October 2019. It was found that the existence of an atmospheric blocking system over the region for many days was the main factor in the creation of the dry and extremely hot weather, and that the breakdown of the ridge ignited the fire, reinforcing the wildfire’s intensity and spreading fire patches to other regions.