Assessment of correlation between InSAR coherence and multispectral indices for soil moisture monitoring

Multispectral remote sensing has been widely used in surface water studies, including detection and monitoring of surface water dynamics, vegetation water content, peatland and wetland conditions, and soil moisture. Conversely, there is a limited number of research contributions on the potential applications of radar remote sensing and interferometric coherence in soil moisture monitoring. Addressing this gap, this study aims to investigate the relationship between radar data and selected spectral indices, with the purpose of joint monitoring of soil moisture changes. Furthermore, a quality index allowing for an a-priori assessment of the applicability of this combined methodology is proposed. The analysis is based on open access imagery acquired between 2019 and 2023 by ESA Copernicus Sentinel-1 and Sentinel-2 missions. The study focuses on two case study sites in Italy and Poland. The results indicate a significant correlation (0.70) between the two remote sensing datasets, highlighting the potential use of SAR coherence in soil moisture studies with both a stand alone and a joint procedure.