Use of satellite-derived emissivity to detect coalfire-related surface temperature anomalies in Jharia coalfield, India

Among natural geo-hazards, spontaneous combustion of coal is unique in nature but common in most coal-producing countries. Coalfires can occur in coal seams and stockpiles of coal at ambient temperature in certain conditions, e.g. those concerning coal type, exposed area and moisture content. Once started, coalfires are difficult to extinguish and sometimes cannot be controlled. In addition to burning millions of tonnes of coal, the fires have enormous negative impacts on local and global environments. In the field of coalfire study, remote sensing is used as a powerful tool to detect and monitor coalfires. Nevertheless, most remote-sensing coalfire studies are based on a fixed emissivity (0.95 or 0.96) which is contrary to the real representation of the Earth's surface. In this research, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER)-derived emissivity was used to detect coalfire-related surface anomalies in an Indian coal mining region. Later, the temperature anomalies detected were validated with ground truth data. Additionally, the ASTER-derived emissivity value was used to extract surface temperatures from Landsat Enhanced Thematic Mapper Plus (ETM+) thermal infrared (TIR) data.