The unusual stubble burning season of 2020 in northern India: a satellite perspective

We analysed nine years (2012-2019) of fire observations from the Visible Infrared Imaging Radiometer Suite (VIIRS) onboard the Suomi-NPP satellite to assess the post-monsoon crop stubble burning activities over northern India. The 2020 fire season (September-November) was analysed extensively, and spatiotemporal trends were examined. Our analysis indicates that about 60% of post-monsoon fires occurred in the state of Punjab, followed by Madhya Pradesh (11%), Haryana (4%), and Uttar Pradesh (3%). The year 2020 saw the greatest fire activity in Punjab and across the country since 2016. Over the nine years, Punjab did not show any systematic trends in fire activities, whereas Haryana and Madhya Pradesh demonstrated an overall decreasing (45% lower in 2020 compared to the 2012-2019 mean) and increasing (185% more in 2020 compared to 2012-2019 mean) trends, respectively. The high fire occurance in the Punjab are related to high percentage of crop area with specific variety of rice, which produces high straw load and mature in shorter time. The increase in Madhya Pradesh is directly related to an increase in rice crop planting area over the years, whereas the decrease in Haryana is related to changes in crop residue management. The uncertainty analysis in this paper shows that over a given region, day-to-day variability in fire counts can have sampling biases due to changing satellite viewing geometry. Furthermore, long-term trends can also be impacted by the reduced sampling of satellite fire detections under cloudy conditions. However, large scale spatiotemporal analysis of fires in this area provides crucial and well sought-after information for crop fire control and air quality management in north India. The district level analysis for the four states signifies the critical information that satellites can provide for identifying hotspots and planning regionally focused mitigation strategies to curb pollution from crop burning fires.