近海潮汐效应对上海地区精密定位的影响

针对全球海潮模型在不同沿海地区存在差异性以及在中国近海精度不高的问题,利用全球海潮模型FES2004和NAO99b计算上海地区(经纬度范围为120.85°E～122.2°E,30.6667°N～31.8833°N)S₂、M₂、K₁和O₁四个分潮的海潮负荷位移在垂直分量上的差异;并利用中国近海模型osu.chinasea.2010对全球海潮模型FES2004中相应的区域进行替换,计算近海效应对SHJZ站(上海金山)、SHJBS站(上海宝山)、SHAO站(上海佘山)以及DCMD站(上海崇明)四个测站精密定位的影响。结果表明:1) 全球海潮模型FES2004和NAO99b在上海地区存在较明显的差异,尤其是垂直分量,最大接近4 mm,且两个模型的差异随离海洋距离增大而减小;2) 利用修正前后的全球海潮模型FES2004经过计算分析得出,近海效应对上海地区GPS测站精密定位的影响达到5 mm,对测站垂直分量的位移影响从大到小分别是DCMD站(5.1 mm)、SHBS站(4.9 mm)、SHJS(4.2 mm)、SHAO(3.6 mm)。 

The Effect of Local Tide on Precision Positioning in Shanghai

In view of the differences of the global tidal model in different coastal areas and the poor accuracy of offshore in China,using the global tide models FES2004 and NAO99b to calculate the vertical component of the tidal load displacements of the four tide components S₂、M₂、K₁and O₁ in Shanghai (The range from 120.85 to 122.2 East longitude, 30.6667 to 31.8833 West latitude).In order to calculate the effect of local tide on the precise positioning of four stations of SHJZ station (Shanghai Jinshan), SHJBS station (Shanghai Baoshan), SHAO station (Shanghai Sheshan) and DCMD station (Shanghai Chongming), using the Chinese offshore model osu.chinasea.2010 to replace the corresponding region in the global tide model FES2004.The results show that: (1)There are obvious differences between the global tide models FES2004 and NAO99b in Shanghai, especially in the vertical components. The maximum is close to 4 mm, and the difference between the two models decreases with the distance from the ocean;(2)The influence of offshore effect on the precision positioning of GPS stations in Shanghai reaches 5 mm,and the influence on the vertical component of the station from big to small are DCMD station (5.1 mm), SHBS station (4.9 mm), SHJS (4.2 mm) and SHAO (3.6 mm) respectively.