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Investigation the Effects of Inversion on Tehran Air Quality Using Meteorological and Photochemical Models during Normal and High Concentrations Episodes

Shahbazi, Hossein | 2013

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 44582 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Hosseini, Vahid; Rashidi, Yousef
  7. Abstract:
  8. In this study, The Comprehensive Air Quality Model with extensions (CAMx model, v5.41), was used to model gas phase pollutants over Tehran modeling domain during two episodes of July 7th to July 13th and November 30th to December 6th, 2012. In the second episode due to very high concentration of pollutants caused by a combination of meteorological conditions and occurrence of an inversion, a forced holiday was imposed on the city-wide operations to protect the health of citizens. It was found that WRF/CAMx modeling system is a useful tool for the analysis of urban environmental problems and predicting critical conditions. The WRF simulation results for 2-m height temperature, 10-m height wind speed and direction agreed with measurements, especially during December 2012 episode. A comparison of CAMx model performance with observations shows that the model predicts the gaseous pollutant concentrations reasonably well in both episodes. The meteorological conditions were found to have significant impact on the level of pollutant concentrations. During July episode the values of temperature decrease with height from surface to 15 km above ground, but on December episode the values of temperature increase with height near surface and after that starts to decrease with height until about 12 km. Increasing near surface temperature in December episode is an indication of inversion occurrence during this episode. The comparison shows that during a temperature inversion, the gaseous pollutants accumulate mostly due to the absence of removal mechanisms such as advection. Gaseous pollutant concentrations increase dramatically during such episode which could lead to unhealthy and dangerous levels. The average concentration for all pollutants in December episode is significantly greater than those of July episode
  9. Keywords:
  10. Air Quality Modeling ; Meteorological Modeling ; CAMx Photochemical Model ; Meteorological Conditions ; Inversion ; Air Pollution ; Weather Research and Forecasting (WRF)Modeling System

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