Study of the Extent of Contribution of Regional Stubble Burning to the Air Pollution in Delhi-National Capital Region

摘要

The issue of extreme episodic air pollution events in the Delhi-National Capital Region (NCR), India, during the month of November has been of concern for the last few years. Recent studies have used satellite observations and transport models, which indicate movement of smoke from stubble burning regions in Punjab and Haryana towards Delhi. Quantification of contribution of these emissions to the air pollution in Delhi, however, remains uncertain. In the present study, a similar attempt was made, and measurements are reported from 16 ground-based continuous air quality monitoring stations (CAAQMS) in the Delhi-NCR for the years 2016 and 2017. Time series PM_(2.5) ground measurements were compared with the total Fire Radiative Power (FRP) from Moderate Resolution Imaging Spectroradiometer (MODIS) onboard Terra and Aqua satellites for the airshed for Delhi-NCR. To quantify the smoke contribution from the fire pixels to the Delhi-NCR, the Navy Aerosol Analysis Prediction System (NAAPS) smoke data were used. NAAPS simulations show that the smoke aerosol contribution to Delhi-NCR from stubble burning was ～5-10 μg/m~3 during the pollution episodic days in 2016. NAAPS results along with the PM_(2.5) measurements at Ludhiana, Punjab, indicate that the stubble burning emissions may contribute 33- 66 μg/m~3 to the PM_(2.5) at Delhi depending on wind conditions and emission levels at the source. The predominant aerosols over the study area during the episodic period were verified to be absorbing in nature. Limited meteorological data indicated low temperatures and high relative humidity conditions during the episodic events.