Root-zone soil moisture (RZSM) information is valuable in a wide range of applications, including weather forecasting, hydrological and land surface modeling, and agricultural production. However, there is still a lack of sensing information that adequately represents RZSM, especially with regard to longer periods and larger spatial scales. For example, active and passive microwave remote sensing observations for soil moisture are limited to the topsoil and can be influenced by land cover type. One option for RZSM…