Spaceborne High Precision Sea Surface Salinity Remote Sensing by Interferometric Radiometry

The global sea surface salinity (SSS) can be accomplished by means of the L-band microwave radiometers from space, such as European Space Agency's SMOS (soil moisture and ocean salinity) and NASA's Aquarius/SAC-D. However, the microwave imaging radiometer using aperture synthesis in SMOS mission suffers from various errors and unexpected in-orbit phenomena, which degrade SSS accuracy. To further improve SSS accuracy, a full polarization aperture synthesis microwave radiometer (FPASMR) has been proposed for China's next-generation Haiyang satellite program with two important improvements, which is composed by an L- and X-band aperture synthesis radiometer (ASR) with two dimensions. One important improvement is that the sea surface roughness and sea surface temperature are simultaneously measured by the full polarization X-band ASR, and another important improvement is that the microwave-optical receiving technology and in-orbit thermal control subsystem are employed to improve the stability of the FPASMR for reducing visibility phase errors. The system of the FPASMR is introduced in terms of L-band subsystem, X-band subsystem, and the calibration subsystem. The main specifications of the FPASMR are analyzed in terms of field of view, angular resolution, and radiometric sensitivity. In addition, the FPASMR calibration is also introduced. The FPASMR demonstrator has also been developed and a series of experiments is performed to assess the performance of the FPASMR demonstrator and the improvements in the FPASMR.