摘要
The Global Navigation Satellite System–Acoustic(GNSS-A)combined positioning technique extends geodetic networks into the seafoor.Currently,GNSS-A can achieve static seafoor positioning accuracy at centimeter level.However,in practical operations,substantial time,manpower,fnancial and instrument resources are required to measure in situ Sound Speed Profles(SSPs).This paper evaluates the feasibility of GNSS-A with alternative SSPs instead of in situ measurements.The GNSS-A positioning using three diferent SSPs are compared:the Munk empirical profle,the profles from the HYbrid Coordinate Ocean Model(HYCOM)global ocean analysis product,and the in situ profles.Compared with the in situ profle,the Munk SSP has little impact on the GNSS-A horizontal position(0.6 cm in root-mean-square,RMS)but introduces a large systematic error in the vertical position(10.3 cm in RMS),and the impact on the displacement velocity is at the mm/a level.When the HYCOM profle is substituted for in situ profles,the impact on GNSS-A positioning is only 0.2 cm in the horizontal and 2.9 cm in the vertical,and the impact on displacement velocity is at the sub-mm/a level in the horizontal and mm/a level in the vertical.The HYCOM global ocean analysis SSPs can largely serve as a cost-efective substitute for in situ profles in GNSS-A seafoor positioning,which is especially applicable to GNSS-A measurements using unmanned surface vehicles,for which full-depth SSP measurements are difcult.Therefore,when SSPs are selected,appropriate decisions should be made on the basis of specifc GNSS-A application needs and conditions.
基金
supported by the Science and Technology Innovation Project Funded by Laoshan Laboratory(LSKJ202205102)
the Basic Scientifc Fund for National Public Research Institutes of China(2022S03)
the National Key Research and Development Program of China(2020YFB0505805)
the National Natural Science Foundation of China(42004030)
the Shandong Provincial Natural Science Foundation(ZR2023QD179).
