Different methods for temperature and spectral emissivity retrieval over active fires from IR hyperspectral remotely sensed data

We have developed a theoretical model which allows us to retrieve the temperature of burning areas employing the thermal infrared spectral-radiance data gathered by the used sensor. The algorithm performs the temperature-emissivity separation by coupling together radiance data from a pair of neighbouring similar image pixels, which are assumed to have the same emissivity spectrum and independent temperatures. The characteristic uncertainty in the basic TIR equations is thus resolved using a double number of spectral measurements (radiance samples) for the temperature estimation. Results produced by this model have been compared with fire-front temperatures assessed utilising spectral data collected at short-wave infrared wavelengths between 1.99 mum and 2.48 mum. Moreover, we have also applied the GBE-method for retrieving the pixel temperature and spectral emissivity utilising TIR spectral data. In order to test the three considered methods, we have utilised a rare example of airborne hyperspectral image acquired over a natural active fire. This image was collected by the MIVIS operated on board of a Casa 212 airplane over the Alps (Italy). The paper shows the image acquired by the MIVIS sensor, the related processing and is completed with a theoretical discussion of the involved topics.