Active Microwave Sensors for Vegetation Water Content Estimation

Vegetation is a vital part of ecosystems globally and serves as a foundation for food and habitat for animal species. It plays a key role for the environment and the climate by producing oxygen, supporting the energy cycle, providing nutrients, improving water quality and contrasting flooding and land erosion. Its health is at the basis of human life and, therefore, it is important to explore new technologies to contribute for an enhanced monitoring of vegetation and provide a quality certification since it has a direct or indirect impact on human life. Vegetation monitoring can be made at different scales including spatial, spectral and temporal ones.In this study, a comprehensive overview of active microwave sensors useful to estimate the water content of vegetation is proposed. They include both synthetic aperture radar onboard o satellite platforms to monitor vegetation at the field level and proximity measurement radars to observe vegetation at the plant level. All this matter represents a preliminary study framed within the "Innovative technologies for non-invasive assessment of plant health condition to support precision farming (VEGETATION)" project, which aims at developing a low-cost multi-sensor prototype to be equipped on ground moving platforms to estimate the vegetation water content.