PhD Studentship - Exploiting InSAR Loop Closure for Monitoring Soil Moisture and Vegetation Dynamics

Changes in soil moisture and vegetation structure alter microwave scattering from the land surface, generating phase inconsistencies in Interferometric Synthetic Aperture Radar (InSAR) observations. These inconsistencies appear as non-zero phase around closed interferometric loops. Recent studies, including our ESA-funded research on InSAR phase bias, have demonstrated systematic relationships between loop closure and vegetation and land-surface conditions. However, the physical controls on these signals and their potential for quantitative environmental monitoring remain poorly understood. This PhD will investigate: (1) how soil moisture, vegetation water content and structural change influence InSAR loop closure; (2) whether their contributions can be separated; and (3) how sensitivity changes with radar wavelength and polarisation. Multi-temporal Sentinel-1 C-band observations will be combined with newly available NISAR L-band data to investigate these processes across contrasting vegetation and soil conditions. Forward modelling will be used to simulate how changes in soil and vegetation properties generate closure-phase signals, while inverse modelling will investigate whether these properties can be retrieved from the observations. Closure-phase time series will be analysed alongside backscatter and coherence and validated using independent soil-moisture, vegetation and meteorological observations. The Doctoral Researcher will have substantial flexibility to shape the project, including selecting study environments and developing physical, statistical or data-driven approaches for separating environmental contributions to closure phase. The supervisory team will provide hands-on training in InSAR processing, radar scattering, environmental Earth observation, scientific programming, geospatial data analysis, reproducible research and scientific communication. CASE partner SatSense Ltd will provide industrial co-supervision, access to operational InSAR expertise and datasets, and a three-month placement where the researcher will gain experience in large-scale processing, product development and validation. This academic-industry partnership will enable the researcher to test whether fundamental understanding of environmentally driven phase closure can ultimately be translated into scalable Earth observation products. Funding For eligible students the studentship will cover home tuition fees plus an annual tax-free stipend.