Assessing Long-Term Stability of SMOS Zero-Baseline Antenna Temperature Using the Aquarius Antenna Temperature Simulator

The National Aeronautics and Space Administration´s Aquarius and the European Space Agency´s Soil Moisture and Ocean Salinity (SMOS) are satellite missions to make global L-band brightness temperature measurements. Aquarius uses a sophisticated antenna temperature simulator over oceans for the calibration of its brightness temperature measurements. In this investigation, the simulator was adapted to simulate the real aperture antenna temperature measured by the SMOS reference radiometers. It is found that the simulated antenna temperature is very close to the measured value. The analysis shows that the simulated antenna temperature can be utilized for SMOS calibration studies as an additional independent reference, as well as for investigating the consistency between SMOS and Aquarius brightness temperature measurements.