CIRFA Seminar: Automatic detection of low-backscatter targets in the Arctic using Wide Swath Sentinel-1 imagery

WHEN: 10 November 2022, 14:00-15:00.

WHERE: CIRFA corridor or via Teams (Click here to join the meeting)

Dear CIRFA Team and friends, we welcome you to this week`s talk by Anca Cristea about Automatic detection of low-backscatter targets in the Arctic using Wide Swath Sentinel-1 imagery.

Dual-polarized Sentinel-1 imagery (a) HH (b) HV – processed with the proposed method to extract (c) segments and (d) the low backscatter low wind area. Edit of original figure from A. Cristea et. al “Automatic Detection of Low-Backscatter Targets in the Arctic Using Wide Swath Sentinel-1 Imagery,” in IEEE JSTARS, vol. 15, pp. 8870-8883, 2022.

Low backscatter signatures in Synthetic Aperture Radar (SAR) are characteristic to surfaces that are highly smooth and specular reflective of microwave radiation. In the Arctic, these typically represent newly formed sea ice, oil spills, and localized weather phenomena such as low wind or rain cells. Operational monitoring services use freely available SAR imagery from Sentinel-1 to monitor such phenomena. We have developed a detection method for low backscatter targets applicable to Sentinel-1 Extra Wide-Swath (EW) and Interferometric Wide (IW) SAR imagery.

Using intensity values coupled with incidence angle and Noise-Equivalent Sigma Zero (NESZ) information, the image segmentation method is able to detect low backscatter targets as one segment across sub-swaths. We use the Barents Sea as a test site due to the abundant presence of low backscatter targets with different origins, and of long-term operational monitoring services that help cross-validate our observations. Utilizing a large set of scenes acquired in the Barents Sea during the freezing season (November – April), we demonstrate the potential of performing large-scale operational monitoring of local phenomena with low backscatter signatures.