In-orbit Calibration and Validation of HY-2B Altimeter Using an Improved Transponder

Caiyun Wang, Mingsen Lin, Chaofei Ma, Ke Xu, Peng Liu, Te Wang, Bo Mu, Jinbiao Zhu, Wei Guo
2021 IEEE Journal of Selected Topics in Applied Earth Observations and Remote Sensing  
HY-2B (Haiyang) is the follow-on mission to HY-2A, the Chinese first sea satellite for oceanography, launched in Oct 2018. The main payloads onboard are similar to HY-2A. For the altimeter, an in-orbit calibration mode was designed to achieve higher calibration precision. An improved transponder was built and deployed for the calibration campaign. The purpose of the paper is to describe the in-orbit calibration and validation of HY-2B altimeter based on an improved transponder. A signal-rebuilt
more » ... transponder was developed and employed in HY-2A altimeter calibration. It played an important role in quantitative analysis of HY-2A altimeter data products. For HY-2B altimeter, a newly-designed calibration mode was added, and an improved transponder was built. It has some advantages over the previous one in the rebuilt signal forms and modulation ways. Two calibration campaigns were carried out, in April 2019 and October 2020 at different sites. In the two campaigns, the precision of the altimeter range calibration is obtained less than 1 cm. For further validation and assessment to the result, a comparison between HY-2B and Jason-3 was performed in term of SSH (Sea Surface Height) on the tens of cross track points in the open ocean. The comparison result shows high degree of accuracy and stability of HY-2B altimeter instrument. In China's next five-year plan (2021-2025), many more transponders and related calibration facilities would be installed in the ocean calibration fields, serving a variety of different satellite altimetry missions. Index Terms-HY-2B altimeter, in-orbit calibration, validation, improved transponder, integration.
doi:10.1109/jstars.2021.3111922 fatcat:oy2sku6qijdfxl35gtyx76gcmu