GRACE/GOCE扩展重力场模型确定我国1985高程基准重力位的精度分析  

Evaluation of the GRACE/GOCE Global Geopotential Model on estimation of the geopotential value for the China vertical datum of 1985

作　　者：赫林[1] 褚永海[1,2] 徐新禹[1,2] 张腾旭 HE Lin;CHU YongHai;XU XinYu;ZHANG TengXu(School of Geodesy and Geomatics,Wuhan University,Wuhan 430079,China;Key Laboratory of Geospace Environment and Geodesy,Ministry of Education,Wuhan 430079,China)

机构地区：[1]武汉大学测绘学院,武汉430079 [2]武汉大学地球空间环境与大地测量教育部重点实验室,武汉430079

出　　处：《地球物理学报》2019年第6期2016-2026,共11页Chinese Journal of Geophysics

基　　金：国家重点研发计划(2016YFB0501702);国家自然科学基金(41774010);高分辨率对地观测系统重大专项支持项目;广西空间信息与测绘重点实验室开放基金(16-380-25-33、15-140-07-19)资助

摘　　要：高精度高程基准重力位的确定往往依赖于高精度全球重力场模型,其对全球和区域高程基准的高精度统一非常关键,GRACE、GOCE卫星重力计划极大地提高了全球重力场模型中长波的精度.本文首先对GRACE/GOCE卫星重力场模型的内符合和外符合精度进行讨论分析,结果说明卫星重力模型的截断误差影响可达到分米级水平,在确定高程基准重力位时该影响不可忽略.利用EGM2008模型扩展GRACE/GOCE卫星重力场模型至2190阶,可有效减弱卫星重力模型的截断误差影响,但不同模型扩展时的最优拼接阶次不同,其中DIR-1、DIR-5模型对应的最优拼接阶次分别为180阶和220阶,以GPS水准数据检验,扩展模型在中国区域的精度均优于18cm.最后,基于最优拼接阶次获得的扩展重力场模型对我国1985高程基准重力位进行了估计,DIR-5和TIM-5模型对应数值分别为62636853.47m^2·s^-2和62636853.49m^2·s^-2,精度均为1.51m^2·s^-2;发现在中国区域模型大地水准面与GPS/水准数据的差值存在微弱的系统性倾斜,东西向倾斜约为9cm,南北向倾斜约为1.4cm,考虑倾斜改正后基于DIR-5和TIM-5模型估计我国1985高程基准重力位的精度提高了0.16m^2·s^-2.The accuracy of the geopotential value of the vertical datum is usually relies on the high-precision Global Geopotential Models (GGMs),which are critical for high-precision uniformity of global and regional vertical datums or height systems.The advent of the GOCE and GRACE missions during the last decade have brought significant improvement in modelling of the low-frequency or rather medium-frequency part of the Earth′s static gravity field.The GRACE/GOCE GGMs are extended from the degree and order n max +1 to 2190 using EGM2008 in order to evaluated the effect of the omission error on the computed geopotential value of the China vertical datum of 1985,and the effect of the GRACE/GOCE GGMs omission error is at dm-level for China.The effect of the GRACE/GOCE GGMs omission error on the geopotential can be effectively reduced by extending the model with the high-resolution gravity field model EGM2008 and the optimal extend degree and order is difference based on the difference GRACE/GOCE GGMs,for example,the extend degree and order is 180 and 220 for DIR-1 and DIR-5.The GRACE/GOCE GGMs extended by the EGM2008 with the optimal extend degree and order provide a significant,compared to EGM2008,improvement in the comparisons with the GPS/Levelling data,by as much as 18 cm,in terms of the standard deviation.The W LVD 0 determined for the China local vertical datum was 62636853.47 m^2·s^-2 and 62636853.49 m^2·s^-2 for DIR-5 and TIM-5,and the accuracy both are 1.51 m^2·s^-2.Lastly,the spatial tilts found in the levelling network can be modeled with a 2-parameter bias corrector model,the east-west tilt is about 9 cm,and the north-south tilt is about 1.4 cm.Based on the DIR-5 or TIM-5 models,the accuracy of the geopotential value of the 1985 is improved about 0.16 m^2·s^-2.

关 键 词：GRACE/GOCE重力场模型 GPS/水准 截断阶次 倾斜 高程基准重力位 

分 类 号：P223[天文地球—大地测量学与测量工程]