Satellite-based soil moisture validation and field experiments; Skylab to SMAP
Résumé
Soil moisture remote sensing has reached a level of maturity that is now limited primarily by technology and funding. This is a result of extensive research and development that began in earnest in the 1970s and by the late 1990s had provided the basis and direction needed to support two dedicated satellite missions; Soil Moisture Ocean Salinity (SMOS) and Soil Moisture Active passive (SMAP). Field experiments have played a critical role in the development and implementation of these missions, as well as exploiting other satellites of opportunity. They continue to be of value in the validation and improvement of the soil moisture algorithms and products. Each of these experiments has involved at least two of the following four methodologies; tower, aircraft, satellite, and ground-based observations. Each methodology provides complementary information that expands the temporal or spatial information of the alternatives. The evolution, selected highlights, and lessons learned from these campaigns will be reviewed. Plans for upcoming SMAP post-launch field experiments will be presented.