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In this letter, we propose an approach based on the use of Sentinel-2 spectral indices and self-organizing map (SOM) to automatically map burned areas and burned severity. These analyses were performed on a test area in Chania, located in Crete, affected by a fire (around 200 ha) that occurred from July 13, 2018 to July 28, 2018. The investigated area is characterized by heterogeneous land cover types made up of natural and agricultural lands. To identify different levels of fire severity without using fixed thresholds, we applied SOM to the three spectral indices normalized difference vegetation index (NDVI), normalized burn ratio (NBR), and burned area index for sentinel (BAIS) used to enhance burned areas. This is a particular critical issue because fixed threshold values are generally not suitable for fragmented landscapes, vegetation types, and geographic regions different from those for which they were devised. To cope with this issue, the methodological approach herein proposed is based on three steps: 1) indices computation; 2) maps of the difference of the three indices computed using the data acquired from prefire and postfire occurrences; and 3) unsupervised classification obtained processing all the difference maps using the SOM. The obtained results were validated using an independent data set, which showed high correlation with satellite-based fire severity.

Since the mid-1980 s satellite remote sensing data have been used in forest fire monitoring for applications related to the diverse phases of fire management as, fire prevention, danger estimation, detection of active fires, estimation of fire effects (burned area mapping, fire severity estimation, smoke plumes, biomass losses, etc), post fire recovery, fire regime characterization, etc. Today satellite technologies can fruitfully support both research and operational activities for fire monitoring and management at different temporal and spatial scales and with cost effective tools. This paper provides a short overview of satellite remote sensing for forest fire danger estimation at different scale of observations.

This article is focused on the FIRESAT methodology developed for and funded by the Protezione Civile of the Basilicata Region. The fire monitoring system is based on satellite free of charge data and developed for the dynamic estimation of vegetation fire susceptibility and fire impact in forest and non-forestry ecosystems. The purpose of this fire risk system is the timely (daily) and detailed (from 1 km down to 30 m) monitoring of the vegetation and meteorological conditions which can affect the proneness of vegetation to fire. FIRESAT provides operational monitoring tools for a systematic forest fire management from risk estimation to fire severity mapping, including the estimation of fire damage on hydro-geological risk and vegetation fire resilience.