利用GPS动态PPP技术求解海潮负荷位移

Determination of Ocean Tide Loading Displacement Parameters by GPS Kinematic PPP

受特殊海岸线及复杂海底地形的影响,目前发布的全球海潮模型在局部沿海地区差异较大,需利用其他大地测量手段直接测定沿海地区的海潮负荷位移参数。GPS技术因具有全天候、精度高、成本低等优势,已成为获取海潮负荷位移参数的有效手段。本文基于GPS技术监测测站三维位移变化的灵敏度高于监测48个海潮参数的灵敏度这一基本思想,改进了利用GPS精密单点定位(PPP)技术估计48个海潮调和参数的方法,直接逐历元求解三维海潮负荷位移变化,再利用调和分析方法提取主要潮波(M2、S2、N2、K2、K1、O1、P1、Q1)的海潮负荷位移建模参数(振幅与相位)。利用12个香港连续运行参考站(CORS)8年的GPS观测数据,计算各测站的海潮负荷位移建模参数。与传统方法比较,本文方法可有效加速K1潮波在东西方向的收敛。将GPS海潮负荷位移建模参数估值与中国近海海潮模型值比较,发现除S2、K2和K1潮波的均方根误差较大外,其他潮波的均方根误差均小于1.5mm。将香港2008—2014年验潮站数据反演的潮波参数与海潮模型值比较,结果表明:GPS与验潮站数据反演的潮波参数均与中国近海海潮模型及HAMTIDE2011.11A全球海潮模型符合较好,验证了GPS PPP反演海潮负荷位移的有效性。采用GPS PPP估计的8个潮波的振幅与相位值替换全球海潮模型中对应的潮波值,进行海潮负荷效应改正,可减弱GPS长时间序列中的半周年信号。

Due to irregular coastlines, special geological structures and complex submarine topographies, some global ocean tide models exhibit large differences in some specific areas. So that some other geodetic observations have to be used to estimate the ocean tide loading （OTL） under some circumstances as ＂time-dependent＂. GPS technique has the advantages of long-term continuous observations, high accuracy and low cost, and GPS precision point positioning （PPP） technique is sensitive to the change of the east, north and vertical component of a station. In this study, it improves that the method in which the 48 OTL displacement parameters estimated in GPS PPP. Then an improved method to estimate 3 time-dependent OTL displacement parameters precisely in PPP is proposed, and the amplitudes and phase lags of eight principal constituents are extracted by the harmonic analysis. 12 GPS stations＇ continuous observations in Hong Kong from 2006 to 2013 are used to determine three-dimensional OTL displacement by the PPP method. Through comparison of convergence results from static PPP, it is found that the convergence of K1 constituent determined by the method is accelerated in east component. Comparing the RMS misfits between the GPS derived results and the values from the OSU.CHINASEA.2010 ocean tide model, it is found that the constituents＇ RMS misfits are all less than 1.5 mm in horizontal and vertical directions, except for S2, K2 and K1. Moreover, by comparing the harmonic parameters estimated by GPS derived and tide gauge data with ocean tide models, it is found that the two different observations＇ results show a great agreement with OSU.CHINASEA.2010 and HAMTIDE2011.11A ocean tide models, which demonstrates that GPS is capable of determining OTL displacement parameters. Using GPS derived 8 constituents＇ displacements amplitudes and phase lags which were instead of the responding model values to correct OTL can weaken effect of the semiannual signal in GPS long period time series.