The stability test of radiometer

Either soil moisture or ocean salinity plays important role in globe water cycle. They are key parameters for monitoring the globe climate change [1]. Aperture Synthesis Microwave Imaging Radiometer will measure global sea surface salinity with 50-km spatial resolution, and the average monthly salinity accuracy aims at 0.1 psu (parts per thousand). This requires the radiometer has long-term calibration stability of <0.3K over 30 days. A special research was developed to achieve this objective. The research has addressed several areas including noise diode sensitivity versus temperature, L-band low-noise receiver performance under different test conditions and some components characterization which used in the Radiometer. Many of the research results and the calibration methods have been used to help to improve the performance of the radiometer.