Remote Sensing of Surface Soil Moisture: A Comprehensive Review of Retrieval Methods and Satellite Products

Abstract

Soil moisture (SM) is a key parameter in surface water and energy cycles, playing a vital role in agriculture, hydrology, and atmospheric science. Remote sensing (RS) has been widely applied in SM retrieval, yet most existing reviews focus on individual data sources or specific methodologies, lacking a systematic pathway from retrieval principles to product applications, which poses a barrier for early-stage researchers. To address this gap, this study provides a comprehensive review of commonly used SM retrieval models based on different RS data sources, including optical, thermal infrared, active microwave, passive microwave, and multi-source approaches. Their underlying principles, assumptions, advantages, and limitations are critically examined. In parallel, key specifications of major satellite-based SM products, such as spatial-temporal resolution, coverage, and data accessibility, are summarized and compared. By integrating methodological explanations with product characterization, this review serves as a practical reference for researchers entering the field, facilitating informed decisions in SM retrieval applications.