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Validating global hydrological models by ground and space gravimetry

chinese Science Bulletin 2009年第9期54卷 1534-1542页

作者： zhou jiangcun1,2.3,{2.,2.& xu jianqiao1,2.1 institute of geodesy and geophysics, chinese academy of Sciences, wuhan 430077, china 2.Key Laboratory of dynamic geodesy, chinese academy of Sciences, wuhan 430077, china 3 Graduate University of chinese academy of Sciences, Beijing 100049, china institute of geodesy and {2. Chinese Academy of Sciences Wuhan 430077 China Key Laboratory of dynamic geodesy Chinese Academy of Sciences Wuhan 430077 China Graduate University of chinese academy of Sciences Beijing 100049 China

The long-term continuous gravity observations obtained by the superconducting gravimeters (SG) at seven globally-distributed stations are comprehensively analyzed. After removing the signals related to the Earth's tides and variations in the Earth's rotation, the gravity residuals are used to describe the seasonal fluctuations in gravity field. Meanwhile, the gravity changes due to the air pressure loading are theoretically modeled from the measurements of the local air pressure, and those due to land water and nontidal ocean loading are also calculated according to the corresponding numerical models. The numerical results show that the gravity changes due to both the air pressure and land water loading are as large as 100×10-9 m s-2.in magnitude, and about 10×10-9 m s-2.for those due to the nontidal ocean loading in the coastal area. On the other hand, the monthly-averaged gravity variations over the area surrounding the stations are derived from the spherical harmonic coefficients of the GRACE-recovered gravity fields, by using Gaussian smoothing technique in which the radius is set to be 600 km. Com-pared the land water induced gravity variations, the SG observations after removal of tides, polar mo-tion effects, air pressure and nontidal ocean loading effects and the GRACE-derived gravity variations with each other, it is inferred that both the ground- and space-based gravity observations can effec-tively detect the seasonal gravity variations with a magnitude of 100×10-9 m s-2.induced by the land water loading. This implies that high precision gravimetry is an effective technique to validate the re-liabilities of the hydrological models.

关键词：重力测量水文模型模型验证和空间地面重力变化季节性波动空气压力

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Study on characteristics of long-term gravity changes at wuhan station

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chinese Science Bulletin 2008年第13期53卷 2033-2040页

作者： xu jianqiao {2. jiangcun LUO ShaoCong sun heping Key Laboratory of Dynamic geodesy Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China

We consider the characteristics of long-term changes in non-tidal gravity and their implication to the local perturbations in barometric pressure and water storage and to the local vertical crustal movement using the long-term continuous gravity observations from a superconducting gravimeter (SG) at Wu-han station,together with the co-site measurements from a Global Positioning System (GPS) receiver and an absolute gravimeter FG5. The observation results indicate that there are obvious seasonal variations in the long-term gravity changes measured with the SG. About 70 percent of the whole sea-sonal changes come from the contribution of the local disturbances in air pressure and water storage,while over 95 percent of the annual changes are attributed to the loading effects of these environmental perturbations. Due to the absence of direct measurements of the local water storage,especially those of the underground water,the global assimilating models of land water LaD (Land Dynamics) and GLDAS (Global Land Data Assimilation System) cannot virtually describe the real hydrologic distur-bances around the station. The resulting gravity changes,which are simulated theoretically by means of convolution integration of the loading Green’s functions and water models LaD and GLDAS,show significantly time delay of about 55 days from those measured with the SG. Compared with the meas-urements of the absolute gravity with the FG5,the long-term drift rate of the SG is determined as about 17.13 nms-2.a. From the co-site GPS measurements,it is found that the local crust is slowly subsiding at a rate of 3.71±0.16 mm/a,and the related gravity variation is estimated as 13.88±0.2. nms-2.a. In other words,the ratio of the changes in gravity and altitude related to the local vertical crustal movement is about -37.41 nms-2.cm. It implies that a considerable mass adjustment may be associated with the local vertical crustal movement,and its dynamic mechanism should be investigated further.

关键词：超导重力计潮汐引力气压水储存量

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Application of superconductive gravity technique on the constraints of core-mantle coupling parameters

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Science china Earth Sciences 2012年第2期55卷 513-520页

作者： CUI XiaoMing sun heping {2. jianqiao zhou jiangcun institute of geodesy and {2. Chinese Academy of SciencesWuhan 430077China Key Laboratory of Dynamic geodesy Chinese Academy of SciencesWuhan 430077China Graduate University of chinese academy of Sciences Beijing 100049China

The parameters, i.e. the Period and the Quality factor, of the Earth's free core nutation (FCN) are closely related to the dissipative coupling between the core and the mantle. Based on the FCN parameters obtained from the actual observations and theoretical simulation, significantly constrained in this study were several key parameters near the core-mantle boundary (CMB), related to the core and mantle coupling, including viscosity at the top of liquid core, conductivity at the bottom of the mantle, and dynamic ellipticity of the CMB. In order to choose high quality observations from global stations of the superconducting gravimeters (SG) on the Global Geodynamics Project (GGP) network, we adopted two criteria, the standard deviations of harmonic analysis on tidal observations and the quality of the FCN parameters calculated with the observations from single station. After the mean ocean tidal effects of the recent ocean tidal models were removed, the FCN parameters were retrieved by stacking the tidal gravity observations from the GGP network. The results were in a good agreement with those in the recent research by using the SG and/or the VLBI observations. Combined with an FCN theoretical model deduced by angular momentum method, the viscous and electromagnetic coupling parameters near the CMB were evaluated. Numerical results indicated that the viscosity at the top of the liquid core was in the range from 6.6×102.to 2.6×103 Pa·s, which was in good agreement with those obtained from the Earth's nutation, the FCN and variations in the length of day (LOD). The conductivity at the bottom of the mantle should be as large as 2.6×106-1.0×107 S m-1 to match the FCN quality factors from the actual observations. The dissipative coupling had a little influence of 1-2.sidereal days for the FCN period.

关键词： SG observations free core nutation core-mantle boundary viscosity conductivity dynamic ellipticity

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Co-seismic change in ocean bottom topography:Implication to absolute global mean sea level change

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geodesy and Geodynamics 2019年第3期10卷 179-186页

作者： jiangcun zhou {2. sun jianqiao xu Xiaodong Chen Xiaoming Cui State Key Laboratory of geodesy and Earth’s Dynamics Institute of Geodesy and GeophysicsChinese Academy of SciencesWuhan430077China University of chinese academy of Sciences Beijing 100049China

Earthquakes perturb both the ocean bottom topography due to displacements of sea floor and the geoid due to mass redistribution, which induces the relative sea level(RSL) change. However, the relative global mean sea level(GMSL) change is zero in that sea water mass is conserved. But the absolute GMSL change is not zero because earthquakes displace total ocean mass with respect to the Earth’s center of mass(CM) which remains unchanged after an earthquake. This displacement, i.e. the absolute GMSL change, may be detectable by altimetry since the satellites are orbiting around CM. In this paper, we proposed a method to estimate co-seismic absolute GMSL change caused by earthquakes based on the point dislocation theory for a spherically symmetric, non-rotating, elastic and isotropic(SNREI) *** change can be directly connected to the perturbation of ocean bottom topography. We first computed co-seismic displacements as well as the change in geo-potential and solved the sea level equation to validate the insignificance of the oceans’ feedback, i.e. the loading effect due to RSL change, to co-seismic displacements. The results imply that the loading effect due to RSL change is negligible on displacements while is considerable on geoid. We then computed the absolute GMSL change caused by co-seismic vertical and horizontal displacements by making use of the integrated Green’s function method. The numerical results show that a large earthquake may raise the absolute GMSL by magnitude of sub-millimeter and the recent three large events cause GMSL to rise about one millimeter, in which the contribution from horizontal displacement is non-negligible.

关键词： Point dislocation theory SNREI earth Sea level equation Absolute GMSL Ocean bottom topography

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Characteristics of tidal gravity changes in Lhasa,Tibet,china

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chinese Science Bulletin 2012年第22期57卷 2586-2594页

作者： xu jianqiao CHEN XiaoDong {2. jiangcun sun heping State Key Laboratory of geodesy and Earth＇s Dynamics Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077China

Tidal gravity changes arise from the response of the solid Earth to the tidal forces of the sun,Moon and planets close to the Earth,and are a comprehensive reflection of the structure and distribution of physical properties of the Earth's *** a result,observations of tidal gravity changes are the basis of studies on other global and/or regional dynamic *** characteristics of tidal gravity changes in the region of the Tibetan Plateau were investigated through continuous gravity measurements recorded with a superconducting gravimeter (SG) installed in Lhasa over a *** contrast measurements with a spring gravimeter LaCoste-Romberg ET2. at the same site,the gravity observations in Lhasa were scaled to the international tidal gravity reference in ***,the scale factor of the SG was determined accurately as-777.358 ± 0.136 nm s-2.-1,which is about 2.2. less than the value provided by the *** results indicate that the precision of the tidal gravity observations made with the SG in Lhasa was very *** standard deviation was 0.459 nm s-2.and the uncertainties of for the four main tidal waves (i.e.O 1,K 1,M 2.and S 2. were better than 0.006%.In addition,the observations of the diurnal gravity tides had an obvious pattern of nearly diurnal *** a result,it is affirmed that the Lhasa station can provide a local tidal gravity reference for gravity measurements on the Tibetan Plateau and its surrounding *** loading effects of oceanic tides on tidal gravity observations in Lhasa are so weak that the resulting perturbations in the gravimetric factors are less than 0.6%.However,the loading effects of the local atmosphere on either the tidal or nontidal gravity observations are significant,although no seasonal variations were *** removal of the atmospheric effects,the standard deviation of the SG observations in Lhasa decreased obviously from 2.009 to 0.459 nm *** removed the loading effects of ocea

关键词：超导重力仪潮汐变化拉萨国际重力潮汐基准青藏高原地区重力潮汐观测重力观测中国

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Research Progress in Surface and Marine Gravimetry

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测绘学报:英文版 2023年第3期6卷 19-32页

作者： heping sun Lifeng BAO Shi CHEN Xiaoming CUI Qianqian LI Lulu JIA {2. xu jiangcun zhou Minzhang HU Yiqing ZHU Xiaodong CHEN Lin WU Jiancheng HAN Honglei LI Miaomiao ZHANG Linhai WANG Innovation academy for Precision Measurement Science and Technology Chinese Academy of SciencesWuhan 430077China State Key Laboratory of geodesy and Earth’s Dynamics Innovation Academy for Precision MeasurementUniversity of Chinese Academy of Sci-encesBeijing 100049China institute of geophysics China Earthquake AdministrationBeijing 100081China Beijing Baijiatuan Earth Sciences National Observation and Research Station Beijing 100095China institute of Seismology China Earth-quake AdministrationWuhan 430071China Second Monitoring Center China Earthquake AdministrationXi’an 710054China

Gravity field is the most basic physical field generated by the material properties of the Earth *** reflects the spatial distribution,movement and change of materials determined by the interaction and dynamic process inside the *** the years,a variety of technical means have been used to detect the Earth’s gravity field and supported numerous studies on the global change,resource detection,geological structure movement,water resources change and other related fields of *** is part of the progress in surface and marine gravimetry obtained by chinese geodesy scientists from {2.9 to 2.2. from the following aspects,including:①Continuous gravity network in chinese mainland;②Application of superconducting gravity measurement;③Network adjustment for continental-scale gravity survey campaign and data quality control;④Regional time-variable gravity field and its application;⑤Research progress on novel technologies for gravity inversion;⑥Research progress on marine gravity field determination;⑦Application research on marine gravity field.

关键词： surface and marine gravimetry time-variable gravity field geodynamics gravity inversion

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利用谱元法计算SNREI地球的表面负荷变形

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地球物理学报 2019年第7期62卷 2382-2393页

作者：廖彬彬徐建桥孙和平周江存中国科学院测量与地球物理研究所大地测量与地球动力学国家重点实验室武汉430077 中国科学院大学北京100049

谱元法作为一种基于变分原理的数值方法,已经成为地球动力学数值模拟的重要手段.本文旨在对Martinec(2.00)正演模拟表面负荷问题的谱-有限元方法进行改进.简单地介绍了谱元法计算负荷边值问题的相关理论,并推导了中性分层液体中的平衡... 详细信息

谱元法作为一种基于变分原理的数值方法,已经成为地球动力学数值模拟的重要手段.本文旨在对Martinec(2.00)正演模拟表面负荷问题的谱-有限元方法进行改进.简单地介绍了谱元法计算负荷边值问题的相关理论,并推导了中性分层液体中的平衡方程以及其对应的弱形式解.在地球半径方向上,采取高阶样条函数作为负荷解的基函数,并利用高斯-勒让德方法进行数值积分.均质地球模型数值试验表明,相较于Martinec的方法,本文方法可以有效地加快数值解的收敛速度.最后,利用PREM模型计算了SNREI地球的负荷勒夫数.数值计算结果表明本文方法的收敛性和稳定性都非常好.本文方法获得的负荷勒夫数与采用传统龙格-库塔积分方法获得的结果相对误差在0.01%的量级.

关键词：谱元法弱解中性分层流体 SNREI地球负荷勒夫数

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核幔耦合对地球自由核章动的激发影响

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地球物理学报 2018年第9期61卷 3584-3591页

作者：崔小明孙和平徐建桥周江存陈晓东中国科学院测量与地球物理研究所大地测量与地球动力学国家重点实验室武汉430077 中国科学院大学北京100049

地球自由核章动(FCN)是地幔与液核相互作用的重要动力学现象,其激发机制涉及地表流体层、地幔和地核等圈层之间的耦合,此前研究多利用地表流体层角动量数据单独研究其对FCN的激发,对核幔耦合的影响考虑不足.本文基于角动量守恒理论分析... 详细信息

地球自由核章动(FCN)是地幔与液核相互作用的重要动力学现象,其激发机制涉及地表流体层、地幔和地核等圈层之间的耦合,此前研究多利用地表流体层角动量数据单独研究其对FCN的激发,对核幔耦合的影响考虑不足.本文基于角动量守恒理论分析了核幔耦合对FCN周期及振幅的影响,并结合多个大气及海洋角动量函数时间序列首次估算了核幔耦合在FCN激发过程中的贡献.结果表明核幔耦合对FCN周期产生的固定和时变影响对FCN激发的作用均不可忽视,尤其时变影响可达几十个微角秒,对于进一步解释FCN时变特征非常重要;核幔耦合对FCN振幅的直接影响是地表流体层的激发与实测FCN不相符的主要原因,黏滞、电磁和地形等耗散耦合的存在对地表流体的激发振幅有67%左右的减弱效果.

关键词：自由核章动核幔耦合地表流体层激发

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基于谱-有限元法的SNERI地球模型固体潮形变计算

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大地测量与地球动力学 2020年第4期40卷 425-431页

作者：张惠康徐建桥廖彬彬孙和平陈晓东周江存中国科学院测量与地球物理研究所大地测量与地球动力学国家重点实验室武汉市430077 中国科学院大学北京市100049

基于谱-有限元法计算一个球型、非自转、完全弹性、各向同性(SNERI)的地球固体潮形变,其中地球固体部分潮汐形变的弱解用哈密顿变分原理给出,液核部分的弱解采用静态中性分层的流体近似。计算过程中把SNERI地球进行等间距球层剖分,球面... 详细信息

基于谱-有限元法计算一个球型、非自转、完全弹性、各向同性(SNERI)的地球固体潮形变,其中地球固体部分潮汐形变的弱解用哈密顿变分原理给出,液核部分的弱解采用静态中性分层的流体近似。计算过程中把SNERI地球进行等间距球层剖分,球面上对解函数和试探函数采用球谐展开,径向上采用线性插值。比较数值计算结果与同质地球模型的解析解结果得出,1km径向等距剖分即可获得10-8精度量级的低阶Love数。基于PREM地球模型的计算结果表明,谱-有限元法计算的固体潮2.3阶Love数与Runge-Kutta法的计算值差异在10-4量级;与武汉台超导重力仪8个主潮波的实测重力潮汐因子相比,本方法计算的理论重力潮汐因子相差平均约0.15%。研究结果说明,谱-有限元法具有较好的收敛性与较高的计算精度,比传统Runge-Kutta法更适用于高精度地计算复杂地球模型的固体潮形变。

关键词：谱-有限元法 SNERI地球模型固体潮 PREM地球模型 Love数计算

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