Calibration of sentinel-3a altimeter in dan'gan island, china

The Sentinel-3A (S3A) altimeter flies over the Dan'gan island (ascending Pass 309), which was located at the south of Guangdong province, China. The sea level was measured using float type water level gauge and aquatrak 5003 acoustic tide gauge to calibrate the sea surface height (SSH) of altimeters. The EGM 2008 geoid and NAO.99Jb tide model was used for geoid and tidal differences between the in-situ equipment and the footprints of the altimeter in this study. The bias of S3A altimeter was +7.8 +/- 28.9 mm in synthetic aperture radar (SAR) mode, and +16.0 +/- 38.4 mm in Low resolution mode (PLRM). The results agree well with other calibration sites. The static GNSS stations were also used for validation of microwave radiometers (MWR) in three campaigns. The wet troposphere correction derived from ECMWF and microwave radiometer product minus static GNSS stations were +11.2 +/- 11.6 mm and +4.4 +/- 12.9 mm, with correlation of 0.980 and 0.979.