Research On Calibration Method Of HY-2B Satellite Altimeter Based On Wanshan Calibration Field

Satellite altimeters have been utilized for oceanic observations for almost half a century since the launch of the first Skylab satellite,equipped with an altimeter sensor,in1973.These altimeters receive pulse echoes and measure the sea surface height,effective wave height,and backscatter of the ocean,allowing for the collection of diverse ocean dynamics information,such as currents,tides,seafloor topography,gravity fields,and sea surface wind speed.This has significantly contributed to the advancement of research in various fields,including geodesy,geophysics,and marine science,and has been one of the primary data sources for the development of oceanography in the 20 th century.As the echoes received by altimeters are influenced by various factors such as component aging,atmospheric conditions,sea state,and geophysical environment,there are instrument errors,ionospheric errors,tropospheric errors,sea state deviations,and geophysical errors in the data.Therefore,the data measured by the altimeter must be calibrated.To address this issue,exclusive and operational satellite altimeter calibration fields have been established internationally for operational satellite altimeters.The HY-2B satellite,launched in October2018,is the first Chinese satellite with an altimeter in operational operation,and its exclusive altimeter calibration field,the Wanshan radar altimeter calibration field,was basically completed in 2020.To accurately calibrate a satellite altimeter,high precision field observation equipment alone is insufficient.It requires exclusive absolute calibration algorithms suitable for the calibration field.Thus,in order to fully utilize the Wanshan radar altimeter calibration field,it is crucial to establish a proprietary calibration algorithm.The research goal of this thesis is to establish an exclusive calibration algorithm for the Wanshan calibration field to help the development of China’s marine satellite business.This thesis firstly conducted a comprehensive literature review on the calibration of satellite altimeter sea surface altitude both domestically and abroad.The study analyzed and summarized the field observation instruments,calibration algorithms,and calibration results of the four major operational altimeter calibration sites overseas.Secondly,this research focused on the absolute calibration technology based on the Wanshan calibration site,which included the establishment of the reference transfer,field data processing algorithm,and altimeter correction term data processing.The absolute calibration algorithm was established,and the influence of each error term in the absolute calibration of Wanshan radar altimeter was investigated.This study’s main research content and innovative contributions are as follows:(1)The framework system for absolute calibration of satellite altimeters was established through the review of the four major international operational calibration fields and domestic and foreign research on altimeter calibration technology.This research enabled the mastery of absolute calibration techniques for satellite altimeters,leading to the establishment of a framework system for satellite altimeter calibration based on tide gauge.(2)An exclusive tide gauge calibration algorithm was established for the Wanshan radar altimeter calibration site.By conducting a data study of the tide gauge on Tanpole Island in the Wanshan calibration site,algorithms for tide gauge reference transfer and tide gauge data processing were developed.The study also included the calibration of the HY-2B altimeter’s sea surface altimeter,and an algorithm for high precision inversion of satellite altimeter’s sea surface height was established at the Wanshan calibration site.(3)A study was conducted on the influence of error factors on the calibration of the Wanshan calibration site.The study was based on the absolute calibration of HY-2B altimeter sea surface height at the Wanshan calibration site.The ionospheric correction,dry troposphere correction,wet troposphere correction,sea state deviation correction,inverse atmospheric pressure correction,geodetic level,tide,and other factors affecting the calibration results were analyzed.The study aimed to obtain the error range of each influencing factor.