One-Point Calibration for Soil Moisture Active/Passive (SMAP) L-band Microwave Radiometer

The SMAP microwave radiometer’s antenna temperature (TA) is computed from the radiometer outputs using a conventional two-point calibration method. The receiver gain and noise temperature which are calibrated via the internal reference load and internal noise diode, then TA is derived. In this work, the internal reference load is the only calibration source used and the receiver noise temperature is modeled. The performance of the one-point calibration is validated by comparing the calibrated TA, NEDT, and long-term calibration drifts to those of the conventional two-point calibration. In addition, the long-term stability of the internal noise source is also included.