Assessment of Spire GNSS-R Based Soil Moisture Products: A Comparative Analysis with In-Situ and Other Satellite-Based Datasets 

  Soil moisture, a critical parameter influencing various environmental processes, is a key focus in Earth observation. This study evaluates and validates Spire's GNSS-R-based soil moisture products, presenting an innovative retrieval methodology capturing spatiotemporal dynamics with enhanced precision.   Leveraging extensive observations from Spire's GNSS-R and NASA’s CYGNSS (Cyclone Global Navigation Satellite System) satellites, our assessment involves a comprehensive comparison and validation of Spire's soil moisture data. Ground truth measurements from ISMN (International Soil Moisture Network) provide a crucial benchmark, while concurrent validation with established satellite-derived soil moisture products such as SMAP (Soil Moisture Active Passive) and ESA-CCI (Climate Change Initiative for Soil Moisture) ensures a robust understanding of Spire's GNSS-R products' performance across diverse regions.  The insights gained from this comparative study not only contribute to the validation of Spire's products but also provides perspectives on the strengths and limitations of distinct soil moisture measurement techniques.