X- and Ku-Band SAR Backscattering Signatures of Snow-Covered Lake Ice and Sea Ice

• Published in: Remote Sensing
• Main Authors: Katriina Veijola, Juval Cohen, Marko Mäkynen, Juha Lemmetyinen, Jaan Praks, Bin Cheng
• Format: Article in Journal/Newspaper
• Language: English
• Published: MDPI AG 2024
• Subjects: remote sensing; synthetic aperture radar; sea ice; snow; Science; Q; Northern Finland; Sea ice
• Online Access: https://doi.org/10.3390/rs16020369; https://doaj.org/article/8acda113c2cf450e9f44e28e8a79af94

In this work, backscattering signatures of snow-covered lake ice and sea ice from X- and Ku-band synthetic aperture radar (SAR) data are investigated. The SAR data were acquired with the ESA airborne SnowSAR sensor in winter 2012 over Lake Orajärvi in northern Finland and over landfast ice in the Bay of Bothnia of the Baltic Sea. Co-incident with the SnowSAR acquisitions, in situ snow and ice data were measured. In addition, time series of TerraSAR-X images and ice mass balance buoy data were acquired for Lake Orajärvi in 2011–2012. The main objective of our study was to investigate relationships between SAR backscattering signatures and snow depth over lake and sea ice, with the ultimate objective of assessing the feasibility of retrieval of snow characteristics using X- and Ku-band dual-polarization (VV and VH) SAR over freshwater or sea ice. This study constitutes the first comprehensive survey of snow backscattering signatures at these two combined frequencies over both lake and sea ice. For lake ice, we show that X-band VH-polarized backscattering coefficient ( <semantics> σ o </semantics> ) and the Ku-band VV/VH-ratio exhibited the highest sensitivity to the snow depth. For sea ice, the highest sensitivity to the snow depth was found from the Ku-band VV-polarized <semantics> σ o </semantics> and the Ku-band VV/VH-ratio. However, the observed relations were relatively weak, indicating that at least for the prevailing snow conditions, obtaining reliable estimates of snow depth over lake and sea ice would be challenging using only X- and Ku-band backscattering information.