Preliminary calibration results of the HY-2B altimeter's SSH at China's Wanshan calibration site

Satellite altimeter needs to be calibrated to evaluate the accuracy of sea surface height data. The dedicated altimeter calibration field needs to establish a special calibration strategy and needs to evaluate its calibration ability. This paper describes absolute calibration of HY-2B altimeter SSH using the GPS calibration method at the newly Wanshan calibration site, located in the Wanshan Islands, China. There are two HY-2B altimeter passes across the Wanshan calibration site. Pass No. 362 is descending and the ground track passes the east of Dan'gan Island. Pass No. 375 is ascending and crosses the Zhiwan Island. The GPS data processing strategy of Wanshan calibration site was established and the accuracy of GPS calibration method of Wanshan calibration site was evaluated. Meanwhile, the processing strategies of the HY-2B altimeter for the Wanshan calibration site were established, and a dedicated geoid model data were used to benefit the calibration accuracy. The time-averaged HY-2B altimeter bias was approximately 2.12 cm with a standard deviation of 2.08 cm. The performance of the HY-2B correction microwave radiometer was also evaluated in terms of the wet troposphere path delay and showed a mean difference -0.2 cm with a 1.4 cm standard deviation with respect to the in situ GPS radiosonde.