On the exploitation of L-band DInSAR products retrieved through the SAOCOM-1 constellation for the investigation of natural and anthropogenic hazards.

Differential Synthetic Aperture Radar Interferometry (DInSAR) is a well-known technique that allows the investigation of surface displacements affecting large areas on the Earth, in both natural and anthropogenic hazard scenarios, with limited costs and with a centimeter to millimiter accuracy. In the last decades the effectiveness of the satellite DInSAR technology for ground deformation analyses, and its crucial role in emergency scenarios, have been largely demonstrated, thus pushing the space agencies to develop new space-borne SAR systems. In particular, important investments on the development of L-band SAR systems are ongoing, with the forthcoming missions of ESA (ROSE-L), JAXA (PALSAR-3) and NASA-ISRO (NISAR), as well as the already operating SAOCOM-1 and PALSAR-2 systems clearly showing the relevance of these sensors, particularly for what attains their DInSAR applications. Indeed, it is worth to remark that the L-band DInSAR interferograms are effective in maintaining coherence for a long period over rather vegetated areas and in various cases of snow/ice covered zones, thus allowing to overcome the typical limitations of higher frequency systems, operating at C- and/or X-band, which, in the above scenarios, typically guarantee sufficient coherence only for a few weeks.

In this work, we present the first results achieved by processing stripmap L-band SAR images acquired by the Argentinian SAOCOM-1 constellation. In particular, we show some algorithmic developments made for an efficient DInSAR exploitation of stripmap SAOCOM-1 images. These improvements can play a significant role in different scenarios as for creating a national scale L-band ground motion service and for civil protection purposes, thanks to the potential capability to provide, in several portions of Earth, systematic space-borne L-band products with a revisit time, typically, of 24 days that can be reduced down to 8 days. Finally, we present the surface displacement maps and time-series retrieved through the Parallel Small BAseline Subset (P-SBAS) processing chain, properly adapted to process the SAOCOM-1 images, over some selected areas of interest, which involve both volcanic hazard contexts (Campi Flegrei caldera and Etna and Stromboli volcano in Italy), and fast-/slow-moving hydrogeological phenomena (Zeri, Tuscany region and Garessio, Piemonte region, in Italy).

The activities of this work were carried out within the project referred to as DInSAR-3M, funded by the Italian Space Agency (ASI), which is aimed at generating, through advanced DInSAR methodologies, surface deformation time series and mean velocity maps, spatially and temporally dense, for the multi-scale analysis of natural and anthropogenic phenomena.