MICROMETEOROLOGY, MIXING HEIGHT AND AIR POLLUTION SIMULATION IN A WESTERN GHATS VALLEY, INDIA

Abstract

The study was carried out with objectives to ascertain the micrometeorology, mixing height, and air pollutants simulation in a Western Ghats valley of India. This valley area had number of industries and a gas based combined cycle power plant (CCPP) of 4080 MW capacity is also proposed. The wind speed and directions, ambient air temperature, and humidity were assessed with the help of a weather monitoring station. The mixing height was estimated with the help of minisonde system. The air pollutants simulation was assessed for complex terrain (valley) with baseline data collection and impact assessment by Gaussian Dispersion Model based Industrial Source Complex Version 3. During night time calm condition prevails (99%), whereas; during 24 hours wind from north direction was the prevailing one followed by north-west. Diurnal variation in mixing height was recorded with maximum (903 m) during afternoon (2.30 pm). In case of sulphur dioxide (SO2) release from the proposed CCPP the 24-hourly ground level concentration was 468 µg/m3 whereas, for oxides of nitrogen (NOX) it was 281 µg/m3. Due to the prevailing micrometeorological and mixing height conditions the pollutants from the proposed CCPP will get build up and may result into air pollution episodes and photochemical smog formation. To prevent the build-up of air pollutants increasing the stack height (>250 m) of CCPP and reducing the NOx concentration in flue gas to 25 ppm, limitation/restriction of total design capacity of proposed project, and  optimize the different combinations of these options may be attempted. 

Key Words: Air pollutants simulation, Micrometeorology, Mixing height, Valley, Western Ghats

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