Analysis and calibration of microwave radiometer (RAD) on-aboard SZ-4 spacecraft

We analysed the performances of multi-channel microwave radiometer (RAD) on-aboard SZ-4 spacecraft launched at the end of 2002. Because RAD lacks of on-orbit external calibration, we put forward a vicarious external calibration scheme, i.e., we re-calibrated all RAD channels using the typical microwave emission targets on the surface of the Earth, the global open ocean and Amazon Rain Forest. We compared the re-calibrated brightness temperatures of RAD with in situ measurements obtained during the ground experiment carried in February, 2003.