Monitoring coal fires using remote sensing

Recent studies on ice cores from Greenland and Antarctica have proven that atmospheric temperature and CO2 content follow a regular 100,000-year cycle of change, and that these two quantities are closely related. It was also found that the recent increase of CO2 in the atmosphere exceeds the values extrapolated from historical data. Other than industrialization and rapid urbanization, natural hazards such as wild fires, spontaneous coal fires, and leakage from hydro-carbon reservoirs contribute to atmospheric CO2 increase. Coal fires, both underground and at surface, are a serious problem in most coal-producing countries. In the 1960s, the United States was the first country to use remote sensing as a tool for coal fire detection. A good number of space- and airborne thermal remote sensing sensors have since come into use. Multi-spectral spaceborne thermal remote sensing data can be employed to detect coal fire-related hot spots. For a better understanding of coal fire dynamics, it is necessary to quantify fire front propagation. Multi-spectral/multitemporal spaceborne remote sensing (using satellites such as Landsat TM, ETM+, and ASTER) can be used for this purpose by indicating direction and velocity of propagation. In the present study, different thermal infrared images were acquired for a fire zone in Wuda Coal Mining Area (Inner Mongolia Autonomous Region, P.R. China), and processed so as to allow detection and monitoring of coal fire hot spots and their spatial variation over time. The data sets were geo-corrected and could be overlaid up to pixel level. Fire locations as predicted in controlled model simulations showed a partial overlap with the hot spots detected in the area. In a second study, radiative transfer models were used to identify CO2 absorption bands with a view to facilitating remote sensing-based detection of CO2 emissions from coal fires.