Comparative performance analysis of photochemical smog modeling systems for ozone simulation in Bangkok Metropolitan region | |
| Author | Pongsakorn Chaichai |
| Call Number | AIT Thesis no.EV-15-18 |
| Subject(s) | Photochemical smog--Mathematical models--Thailand--Bangkok Simulation methods |
| Note | A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Environmental Engineering and Management |
| Publisher | Asian Institute of Technology |
| Series Statement | Thesis ; no. EV-15-18 |
| Abstract | Photochemical smog models have become widely used to simulate complex processes of ozone formation and results are served as input for regulatory analysis to assess the effectiveness of control strategies. Since past decade, surface ozone levels in Bangkok Metropolitan Region (BMR) have gradually increased causing the photochemical smog pollution problem over the city. This study attempted to assess the suitability of a photochemical smog modeling system for simulate the surface ozone in BMR. The performance of three-dimensional (3D) photochemical grid models, CAMx and CMAQ, driven by the fifth-generation Penn State/National Center for Atmospheric Research mesoscale model (MM5) and the Weather Research and Forecasting (WRF) model, respectively, was assessed. BMR domain of 7000 km2 covering the southwest and northeast coordinate of 99.297, 12.445 and 102.085, 15.153 at grid resolution of 2 km was used in this study. The simulation period was March, August and November 2010. A comparative analysis of WRF and MM5 performance over BMR was conducted using the observation data from Thai Meteorological Department (TMD) and Pollution Control Department (PCD). Three physic scheme sets were used in each meteorological model to select a more suitable scheme set. The simulated meteorological conditions by WRF and MM5 agreed reasonably with the observations but with some differences. The simulated temperature by WRF model was more accurately resemble the observed than that from MM5. The difference in the performance was more clearly reflected in the statistical analysis which showed that the WRF model results were in better agreement with the observed than MM5 for Mean bias (MB) and Index of agreement (IOA) in the simulation of temperature, wind speed, wind direction and relative humidity. The scatter plots also showed the better agreements of the results by WRF compared to MM5 in several stations for all simulated months. The photochemical grid modeling, CAMx and CMAQ, used the emission input data that AIT-PTT project compiled from existing and newly developed emission inventories for the domain. Emission input data was regridded from 1 km2 resolution to 6 km2 and 2 km2 resolutions for the simulation using the meteorological field inputs generated by WRF. The results from both CAMx and CMAQ models were comparatively evaluated using the observed ozone concentrations from 13 PCD monitoring stations. Both models results showed high ozone in surrounding areas of Bangkok, particularly in the Northern part. The spatial distribution of simulated ozone by CAMx was more consistent with the emission and meteorological fields than that from CMAQ. The simulation results of both models underestimated surface ozone in BMR for the dry months, while overestimated results can be observed in the wet month. When evaluated against the US EPA criteria only UPA and MNBE statistical measure of some stations met the suggested criteria. A better performance was obtained for the dry months by both models. Further development and refinement of emission input data is required to improve the simulation results. The physics schemes of both WRF and MM5 should be carefully screened to select the most suitable for the tropical meteorology conditions of BMR. |
| Year | 2015 |
| Type | Thesis |
| School | School of Environment, Resources, and Development (SERD) |
| Department | Department of Energy and Climate Change (Former title: Department of Energy, Environment, and Climate Change (DEECC)) |
| Academic Program/FoS | Environmental Engineering and Management (EV) |
| Chairperson(s) | Nguyen, Thi Kim Oanh; |
| Examination Committee(s) | Shim, Shang-Gyoo;Shrestha, Sangam;Thawach Chatchupong; |
| Scholarship Donor(s) | Royal Thai Government Fellowship; |
| Degree | Thesis (M.Sc.) - Asian Institute of Technology, 2015 |