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Investigation of Dust Emission Paths Over Lake Urmia Local Dust Spots Using the HYSPLIT Model

Azimi, Fatemeh | 2019

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 52257 (09)
  4. University: Sharif University of Technology
  5. Department: Civil Engineering
  6. Advisor(s): Tajrishy, Masoud
  7. Abstract:
  8. At Lake Urmia (LU) greatest extent, it was the largest lake in the Middle East and the sixth-largest saltwater lake on Earth, with a surface area of approximately 5,200 km2. The lake has shrunk to 10% of its former size due to damming of the rivers that flow into it, and the pumping of groundwater from the surrounding area. Moreover, as the lake shriks its potentional to be a major dust sources increases. A Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model was used to investigate and track the extent of dust emission and aerosol concentration over Lake Urmia marginal dust spots in order to identify the affected and critical areas. Also, percent movement, propagation amplitude, and height were calculated for each spot. MODIS (Moderate Resolution Imaging Spectroradiometer) derived aerosol optical depth (AOD) images (MODIS/Terra+Aqua Land Aerosol Optical Thickness Daily L2G Global 1km SIN Grid V006-MCD19A2) along with synoptic stations ground data (wind speed and direction, visibility, and precipitation) confirmed the validity of the modeling. Results indicate the effect of wind in altitude on the overall particle motion and dust mass distribution. However, this diffusion carries a small concentration of suspended particles (generally less than ten micrograms per cubic meter). While the prevailing wind near the ground is easterly and north-easterly which carries aerosols to the west and south of the lake. Dispersal of dust in these regions occurs in the early hours of emission, so the particle height and expansion are low and the south and south-western parts of the lake experience high concentrations of particle matters, while the eastern and northern parts of the lake are less affected by local spots dust. Therefore, the health of the inhabitants of the eastern and northern parts of the lake, unlike the western and southern regions, is not very endangered. Also, spots on the south of the lake, due to its large area (140 km2), has a significant effect on increasing the concentration of suspended particulates in the basin, whereas emission from the focal spot is limited. Finally, by considering the active area (out of water body) of each hotspot during different years and examining its relationship with the lake level, it was found that south hotspot only depends on the water level of more than 1275 m. While most of the other hotspots areas are covered with water up to a level of 1272.5 m by decreasing in lake level, hotspots areas will quickly become active areas for dust particles
  9. Keywords:
  10. Urumieh Lake ; Dust Emission ; Air Particulate Matter ; Optical Depth ; Dust Sources ; Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT)Model

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