Uso de sensoriamento remoto via satélite na identificação de rastros de destruição por tornados em um evento de tempo severo no Rio Grande do Sul

The number of tornado reports in Brazil has increased in recent years; nevertheless, it is likely that many occurrences over uninhabited areas and/or during night time hours remain unconfirmed, especially in a country devoid of official surveys of damage caused by intense winds. This work follows previous initiatives addressing the employment of remote sensing via satellite to identify damage paths associated with tornadoes. The nocturnal event analyzed in this study took place in north-northeast Rio Grande do Sul state from the night hours of 7 June 2017 into early morning hours of the following day, and represents an example of the characterization of significant damage caused by tornadoes despite the lack of visual confirmation of the phenomenon. Images produced by low-orbit environmental satellites of the Landsat and Sentinel series are analyzed, as well as imagery made available by the commercial-purpose environmental satellites that comprise the data base of Google Earth software. To aid in the identification of damage inflicted to dense vegetation, the web tools Global Florest Change and Global Florest Watch, which employ objective methods to detect abrupt modifications in the vegetation cover, are also utilized. Based on these products, it was possible to identify seven tornado damage tracks for the nocturnal event of June 2017, ratifying the value added by remote sensing products in the confirmation of tornadic episodes.