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Developing systematic SAR backscatter tools for volcanic monitoring (VOLCSCATTER)



Synthetic Aperture Radar (SAR) backscatter can provide crucial information about the progression of a volcanic eruption,regardless of the time of day or environmental conditions (e.g., cloud coverage). SAR backscatter is dependent on the surface scattering properties, which can be altered during a volcanic eruption through the emplacement or removal of material. Monitoring backscatter changes through time, can therefore alert us to changes in volcanic activity, and understanding the impacts of a process and potential behaviour of future volcanic flows. SAR backscatter data is currently under-exploited for monitoring volcanic eruptions. Partly because the interpretation of backscatter signals can be challenging as they represent the interaction between multiple surface scattering properties (i.e., surface roughness, local gradient, and dielectric properties) produce by complex changes to the earth’s surface (e.g., lava flows, domes, pyroclastic density current etc.). Being able to better understand and quantify changes in backscatter related to variations within volcanic deposits can provide knowledge about changes to a volcanic eruption (e.g., effusion rate, dome stability, direction of travel) that can be decisive for communicating hazard and determining eruption response. High-resolution SAR data has demonstrated the potential backscatter for monitoring and understanding volcanic processes. These studies have generally concentrated on specific eruptions and satellite parameters (e.g., polarisation) to analyse the specific processes. To address key challenges highlighted by the volcano remote sensing community, VolcScatter will expand on these proof-of-concepts studies, through in-depth analysis of how the different satellite parameters and scattering properties affect the SAR backscatter signals over volcanic deposits, to develop analysis tools that are easily transferrable between eruptions and sensors. This will enable us to capitalise on the full potential of ESA’s Sentinel-1 dataset to develop an open-access products including (1) a SAR backscatter toolbox for volcano monitoring and (2) a web-based operational system to automatically map the extent of volcanic changes. The toolbox will provide key information about how best to apply the SAR backscatter data depending on the eruption and data available, what limitations and assumptions need to be considered and how to quantify these errors. Together, these tools will enable more widespread use of SAR backscatter and ESA’s Earth Observation capabilities for monitoring volcanic eruptions. SAR backscatter offers us with a unique opportunity to develop an operational monitoring tool using the extensive satellite based observing capacity provided through ESA and maximise the use of this dataset to address challenges within volcano monitoring.


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