From UPSC perspective, the following things are important :
Prelims level : Aerosol Optical Depth (AOD)
Mains level : Combating urban air pollution in India
ISRO’s INSAT-3D & 3DR satellites are being used for assessment of air pollution.
Aerosol Optical Depth (AOD)
- Aerosol Optical Depth (AOD) is a quantitative estimate of the amount of aerosol present in the atmosphere, and it can be used as a proxy for surface Particulate Matter PM2.5 (particles smaller than 2.5 µm median diameter).
- AOD measures the extinction of a ray of light as it passes through the atmosphere.
How is AOD calculated?
- Using medium resolution Indian Remote Sensing (IRS) satellite data, stubble burned area maps are generated at the end of stubble burning activity in Kharif season.
- ISRO has been carrying out monitoring of stubble burning since 2015. The products generated are comparable to the NASA products.
- The Imager payload on-board ISRO’s INSAT-3D & 3DR satellites are used to monitor Aerosol Optical Depth (AOD).
Significance of AOD
- It is found that AOD, PM2.5 and PM10 concentrations are higher over Indo-Gangetic Plain covering parts of Delhi, Uttar Pradesh and Bihar during October and November.
- High concentration of these pollutants is seen originating from parts of Punjab and Haryana during stubble burning.
- Climatological study of satellite based fire occurrences and associated pollutant parameters reveal that fire occurrences increased by 4% over Punjab and Haryana region during Oct-Nov between 2003 and 2017.
- The model based analysis suggests that there is a high probability of transportation of smoke aerosols from Punjab & Haryana, towards down-wind regions of Delhi, Uttar Pradesh and Bihar.