Landsat–MODIS Assessment of Paddy Residue Burning in Northwestern India: District-Level Comparison of Burn-Affected Cropland During the 2021 Post-Monsoon Season

Abstract

Across northwestern India, a large part of the post-harvest agricultural fire activity is associated with paddy residue burning. The amount detected in regional satellite-based monitoring is not necessarily the same at different spatial resolutions, since smaller or fragmented burning areas may be represented differently. This study compares Landsat-derived probable burn-affected cropland with the MODIS MCD64A1 burnt-area product across seven validation districts in Punjab, Haryana and Rajasthan which focusing on the 2021 post-monsoon burning season within a comparison framework built from 2005 to 2025 data. Landsat Collection 2 surface reflectance imagery was processed using fixed pre- and post-burning seasonal composites to derive the Normalized Burn Ratio, Normalized Difference Vegetation Index, and their differenced forms, dNBR and dNDVI. A dNBR threshold of 0.65, established through long-term calibration against MODIS, was used to estimate probable burn-affected cropland for 2021. Landsat gave higher burn-area estimates than MODIS in all seven districts, despite this there is a difference between the two varied across the districts. Sangrur–Malerkotla showed the closest agreement, with Landsat and MODIS estimates of 2904.98 and 2795.59 km² respectively, a ratio of 1.039, the largest difference was observed in Sonipat, where the Landsat estimate was more than six times higher than the MODIS value. The seven district-level observations produced a strong positive correlation between the two products (Pearson's r = 0.949, R² = 0.900, p = 0.0011), consistent with the pattern observed in the larger 2005 to 2025 clean-record dataset (n = 120, r = 0.850, R² = 0.722). The largest differences between the two products were seen in districts outside the main Punjab burning belt. The findings of the study suggest that MODIS-based estimates of burning in this region may be lower in areas where agricultural fields are smaller and more fragmented, and that Landsat's finer spatial resolution captures a greater extent of probable burning activity than the coarser MODIS product resolves.