Qian, YG; Kong, XS (2012). A method to retrieve subpixel fire temperature and fire area using MODIS data. INTERNATIONAL JOURNAL OF REMOTE SENSING, 33(16), 5009-5025.
Methods for retrieving subpixel fire temperature and fire area have been developed over several years, but the retrieval accuracies of these methods require further improvement. In this study, a channel of the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor centred at 2.1 mu m and associated with the MODIS 4.0 2.1 mu m channel is used to retrieve the temperature and area of fires. To test the feasibility of using the 2.1 mu m channel for retrieval, the fire contribution ratios of MODIS 2.1, 4.0 and 11.0 mu m channels are first examined using simulated surface radiance. Considering the difficulties in obtaining real-time validation data and in evaluating the retrieval accuracies, simulated MODIS data are used for this study. A modified method, which combines MODIS 2.1 and 4.0 mu m channels, is introduced and described in detail. Compared with the traditional method, which utilizes a combination of 4.0 and 11.0 mu m channels (Dozier 1981), the results show that the 2.1 mu m channel is more sensitive to active fires and the large area of fires than the 11.0 mu m channel, but is less sensitive to smouldering fires and small fires. The modified method that we propose has better performance and higher accuracy in active fires (temperature >= 800 K) and in large fires (area >= 0.5%). However, the traditional method is more accurate for smouldering fires and small fires. Finally, a sensitivity analysis is performed to estimate the uncertainty in assessing fire temperature and area. Experimental results indicate that under realistic conditions (fire temperatures of approximately 1000 K and a fire fractional area greater than 0.005), the retrieval errors for fire temperature and fire area are +/- 35 K and 20%, respectively.