??????????????о??????????GPS?????λ?????

??о??????????????????GPS??λ?????????????????????????GPS?????λ????????????????????????????????GPS??????????????????????????NAO99b????????FES2004????????????????????GPS??λ?????GPS????????????????????????GPS????????λ??????????????????????????4??5??????????????????U??????????????E??N????????????????????????GPS????????????С??1 cm???????????NAO99b??FES2004??????????????????С?????????????????1???????????

EFFECT OF OCEAN TIDE LOADING ON GPS PRECISE POSITIONING BASED ON DIFFERENT OCEAN TIDE MODELS

In order to study the regular effect of ocean tide loading on GPS positioning in different regions, this paper deduces and analyzes the effect formula of ocean tide loading on GPS stations positioning.On this basis, through example of the GPS stations in Jiangsu and Xi’an, the NAO99b and FES2004 ocean tide model which are inversed with T/P altimetry data, are synthetically adopted to calculate the effect of ocean tide loading on GPS positioning and baselines. The results show that the magnitude of the effect on GPS positioning of offshore stations is up to centimeter, which is 4-5 times as large as that of inland stations. And the effect of ocean tide loading on U direction is much larger than E,N directions and the effect difference on GPS baselines in different areas is less than 1 cm. From the comparison of NAO99b and FES2004 ocean models we know the effect of the two models have little difference in the inland, but on the coast the difference is large, which is 1 cm or more.