Wildfires Temperature Estimation by Complementary Use of Hyperspectral PRISMA and Thermal (ECOSTRESS & L8)

This paper deals with detection and temperature analysis and of wildfires using PRISMA imagery. Precursore IperSpettrale della Missione Applicativa (Hyperspectral Precursor of the Application Mission, PRISMA) is a new hyperspectral mission by ASI (Agenzia Spaziale Italiana, Italian Space Agency) launched in 2019. This mission provides hyperspectral images with a spectral range of 400-2,500 nm and an average spectral resolution less than 12 nm and a spatial resolution of 30 m/pixel. This study focuses on the wildfire temperature estimation over the Bootleg Fire, US 2021. The analysis starts by considering the Hyperspectral Fire Detection Index (HFDI) which is used to analyze the informative content of the images, along with the analysis of some specific visible, near-infrared and shortwave-infrared bands. This first analysis is used as input to perform a temperature estimation of the areas with active wildfire. Surface temperature is retrieved using PRISMA radiance and a linear mixing model based on two background components (vegetation and burn scar) and two active fire components. PRISMA temperatures are compared with LST (Land Surface Temperature) products from NASA's ECOSTRESS and Landsat 8 which imaged the Bootleg Fire before and after PRISMA. A critical discussion of the results obtained with PRISMA is presented, followed by the advantages and limitation of the proposed approach. Plain Language Summary This work explores new opportunities for wildfire mapping and monitoring basing on recent technological achievements in the field of remote sensing and data analysis. The input data of this research study are provided by the new satellite PRISMA (Precursore IperSpettrale della Missione Applicativa, Hyperspectral Precursor of the Application Mission) from ASI (Agenzia Spaziale Italiana, Italian Space Agency). This spacecraft represents an innovative remote sensing mission for the observation of the Earth, as it provides images with a revolutionary quantity of spectral information which go far beyond the visible spectrum. Using PRISMA data, we study the Bootleg Fire during 2021 in the US, providing a descriptive analysis of the wildfire and a quantitative estimation of the temperatures achieved during the event. To confirm the results of our approach, we also compare the outcomes to the data provided by two other satellite missions: ECOSTRESS (ECOsystem Spaceborne Thermal Radiometer Experiment) and Landsat 8. Hence, a critical discussion of the results obtained with PRISMA is presented in order to report advantages and limitation of the proposed approach.