利用GPS观测中国大陆固体地球潮汐形变  

Determination of solid Earth tide displacements in China using GPS technique

作　　者：韩昆延 袁林果[1] 姜中山 由晓文 HAN KunYan;YUAN LinGuo;JIANG ZhongShan;YOU XiaoWen(Faculty of Geosciences and Engineering,Southwest Jiaotong University,Chengdu 611756,China;School of Geospatial Engineering and Science,Sun Yat-sen University,Zhuhai Guangdong 519082,China)

机构地区：[1]西南交通大学地球科学与工程学院,成都611756 [2]中山大学测绘科学与技术学院,广东珠海519082

出　　处：《地球物理学报》2024年第5期1746-1766,共21页Chinese Journal of Geophysics

基　　金：国家自然科学基金项目(42074021,41904015)资助。

摘　　要：利用中国陆态网242个GPS连续观测站超过10年的观测数据,采用精密单点定位静态方法获得了八个主要潮波的三维潮汐位移.与建模值对比结果表明,GPS观测潮汐位移的精度可达亚毫米级.进一步将GPS观测值与OTL(Ocean Tide Loading)建模值对比,除DTU10外其他七种海潮模型与GPS观测值之间一致性较好.综合考虑验潮站观测结果,最适合中国大陆M2、O1潮波OTL建模的海潮模型是TPXO9-Atlas,地球模型为PREM.本研究还发现,M2、O1潮波GPS观测值与建模值之间的残差存在明显的大尺度空间相关性,表明中国地区存在固体潮建模误差等系统误差.本文对198个离海岸线距离超过200 km的内陆站点的系统误差进行分析,改正系统误差后内陆站点东、北和垂直方向加权均方根误差(Weighted Root Mean Square,简称WRMS)分别为:0.04 mm、0.07 mm和0.11 mm(M2),0.05 mm、0.07 mm和0.11 mm(O1);44个沿海站点WRMS分别为:0.18 mm、0.27 mm和0.59 mm(M2),0.10 mm、0.16 mm和0.30 mm(O1).部分沿海站点仍存在较大残差,主要源于海潮负荷位移建模误差,除海潮模型外还包括海水密度、地球模型、上地幔和地壳模型等因素影响.本文首先使用最新WOA(World Ocean Atlas)18海洋数据集计算海水密度和可压缩性的影响,结果表明中国内地OTL建模对海水密度变化和可压缩性并不敏感.其次,软流圈滞弹性散耗效应可使半日潮软流圈的剪切模量降低约8.5%,周日潮软流圈的剪切模量降低约9.1%,考虑滞弹性散耗效应,M2、O1潮波垂直方向上残差最大可分别减小0.50 mm、0.25 mm.最后,本文利用GPS实测数据对四种三维地球模型进行了适用性评价,结果表明除USTC地球模型受沉积层影响外,其他三种地球模型都能有效提高GPS观测结果与理论建模结果的一致性;另外全球地壳模型CRUST1.0与GPS观测值之间的残差最小,说明中国大陆海潮负荷建模精度受地壳结构精度影响较大.本文研究结果�By analyzing the observation data of 242 continuous GPS stations over a period of more than 10 years,we apply the static method and obtain the tidal displacement parameters of the eight major tidal constituents.The comparison with theoretical modeling values demonstrates that the GPS observation accuracy of tidal displacements reaches sub-millimeter level.Comparisons are also analyzed between GPS observations and modeling,and reveal that the seven ocean tide models align well with GPS observations but the DTU10 model.The statistical observation results of tide gauge stations indicate that TPXO9-Atlas is the best ocean model for ocean tide load displacement modeling,and PREM is the most appropriate earth model.Moreover,the residuals between the observed values and the theoretical modeling values for M2 and O1 tides show evident long-wavelength,coherent spatial patterns over the region.The results of 198 inland stations over more than 200 km from the coastline are used to analyze the error of Solid Tide Modeling and other systematic errors.The statistical results show mismatches in the weighted root mean square(WRMS)of inland stations in east,north,and vertical are 0.04 mm,0.07 mm,and 0.11 mm by M2,while 0.05 mm,0.07 mm,and 0.11 mm by O1,respectively.The WRMS misfits of 44 coastal stations in the three directions are 0.18 mm,0.27 mm,0.59 mm by M2,while 0.10 mm,0.16 mm,and 0.30 mm by O1,respectively.Apparent residuals exist among some coastal stations,mainly due to the errors of OTL(Ocean Tide Loading)displacement modeling,such as ocean tide model,seawater density and Earth model.To address these issues,we first consider the effects of seawater density and compressibility based on the WOA18 ocean data set,and the results show that the OTL displacement modeling is not sensitive to the variation of seawater density and compressibility in China.Secondly,in the asthenosphere,the anelastic dispersion results in a reduction of the shear modulus of~8.5%(semidiurnal tide),~9.1%(diurnal tide),respectively.The model incorpora

关 键 词：GPS 固体潮 海潮负荷效应 地球模型 滞弹性散耗效应 

分 类 号：P228[天文地球—大地测量学与测量工程]