Self-Consistent Amplitude Calibration of Miras-SMOS

Using land-sea transitions as two-level targets, the gain parameter of the three Noise Injection Radiometers (NIR) installed in instrument MIRAS onboard ESA's SMOS satellite are independently estimated. The reference data for this calibration is the average antenna temperature measured simultaneously by the other MIRAS receivers operating as total power radiometers. Individually, the retrieved parameters show similar values to the nominal sky-calibrated ones, but long-term series of data reveal different seasonal behavior, suggesting that external maneuvers may have a non-negligible impact on the NIR front-end stability.