Passive Microwave Remote Sensing of Soil Moisture, Biomass and Salinity

摘要

Passive remote sensing from space at the long wavelength end of the microwave spectrum (i.e. L-band, 1.4 GHz) is minimally affected by the atmosphere and provides information on important parameters of the surface such as soil moisture and ocean salinity that are important for understanding the hydrologic cycle, energy exchange with the atmosphere and ocean circulation. There is also evidence of a potential for remote sensing of biomass at L-band. The engineering challenges of putting long wavelength sensors in space with adequate resolution to meet even modest science requirements has slowed development of such systems. For example, to achieve soil moisture maps from space with 10 km resolution, requires antennas on the order of 20 meters in diameter in space. However, three L-band sensor missions are now being prepared for launch: SMOS, Aquarius and Hydros. They represent different approaches (technologies) for realizing remote at long wavelength from space.