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Spectral analysis of quasi-stationary sea surface topography from GRACE mission

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Science China Earth sciences 2005年第11期48卷 2040-2048页

作者： ZHANG Zizhan1.2.& LU Yang1.3.1.{1.,{1.,{2., China 2. graduate school of the{1., beijing 1.003., China 3. Unite Center for Astro-geodymics Research,{1., Shanghai 2.003., China 1. institute of geodesy and geophysics Chinese Academy of Sciences 430077 Wuhan China 2. {1. {1. of the{2. 100039 Beijing China 3. Unite Center for Astro-geodymics Research Chinese Academy of Sciences 200030 Shanghai China

During the last two decades satellite altimetry has offered an abundance of meas-urements of the sea surface resulting in the improvement of global mean sea surface height (MSSH) and marine geoid determination. On the other hand, with the launching of new genera-tion gravity satellites, some high accuracy long-wavelength gravity models are available. These breakthroughs give us a great opportunity for new estimation of quasi-stationary sea surface topography (QSST). In this paper, the new gravity model GGM01. derived from GRACE mission is briefly presented, and a new global high precision and high-resolution QSST is determined based on the GGM01. model and the global MSSH. The spectral features of the QSST esti-mated by GGM01. and EGM96 gravity model to degree/order {3.0 are discussed by spectral analysis. As a result, the QSST is mainly composed of long waves, medium waves partially and short waves scarcely, its power spectral structures are different between the zonal direction and the meridional direction, there are great differences between the two models, which maybe ex-plain why the ocean currents derived from the two gravity models by Tapley show different pat-terns.

关键词： quasi-stationary sea surface topography, mean sea surface height, GGM01. fast Fourier transform, spectral analysis

Validating global hydrological models by ground and space gravimetry

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

作者： ZHOU JiangCun1,2.3. SUN HePing1,2.& XU JianQiao1,2.1{3.,{1.,{2., China 2.key laboratory of dynamic geodesy,{1.,{2., China 3.{13. University of{1.,{1.}, China institute of {1. and {2. Chinese Academy of Sciences Wuhan 430077 China key {1. of {2. {3. Chinese Academy of Sciences Wuhan 430077 China graduate University of{1. 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 1.0×1.-9 m s-2.in magnitude, and about 1.×1.-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 1.0×1.-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

Sea level variations in the South China Sea inferred from satellite gravity,altimetry,and oceanographic data

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Science China Earth sciences 2012年第10期55卷 1696-1701页

作者： FENG Wei 1,2,ZHONG Min 1,3.& XU HouZe 1,3.1 State key laboratory of {1. and Earth’s {3.s,institute of {1. and geophysics,chinese academy of sciences,wuhan {1.},China 2 {1.} University of{1.},{1.} {1.},China 3.institute of geophysics,Huazhong University of Science and Technology,wuhan 43.074,China 1. State key {1. of {{3. and Earth’s dynamics Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. Institute of Geophysics Huazhong University of Science and Technology Wuhan 430074 China

Sea level variations(SLVs) can be divided into two major components:the steric SLV and the mass-induced *** two components of SLV in the South China Sea(SCS) are studied by using satellite altimetry,GRACE(Gravity Recovery and Climate Experiment) satellite gravity,and oceanographic data on annual and inter-annual *** the annual timescale,the geographic distribution of mass-induced SLV's amplitude jointly estimated from altimetry and the ECCO(Estimation of the Circulation and Climate of the Ocean) model agrees very well with that from *** observes obvious seasonal mass-induced SLV in the SCS with annual amplitude of 2.7±0.4 cm,which is consistent with the annual amplitude of 2.7±0.3.cm estimated from the steric-corrected *** the inter-annual timescales,the mean SLV in the SCS shows a large oscillation,which is mainly caused by the steric *** trend of mean SLV inferred from altimetry in the SCS is 5.5±0.7 mm/yr for the period of 1.93.2.09,which is significantly higher than the global sea level rise rate of 3.3.0.4 mm/yr in the same *** is no obvious trend signal in the mass-induced SLV detected from GRACE that indicates the water exchange between the SCS and its adjacent seas and land is in balance within the study period.

关键词： altimetry GRACE ECCO the South China Sea sea level variation

Variation properties of ionospheric eclipse factor and ionospheric influence factor

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Progress in Natural Science:Materials International 2005年第6期15卷 573-576页

作者： ZHAO Chunmei 1.2.*, YUAN Yunbin1. OU Jikun1.and CHEN Jinping3.1.{1.,{1.,{2., China 2. graduate school of{1., beijing 1.003., China 3. Department of Precision Instrument and Mechanology, Tsinghua University, beijing 1.0084, China) institute of {1. and {2. Chinese Academy of Sciences Wuhan 430077 China graduate {1. of{2. Beijing 100039 China Department of Precision Instrument and Mechanology Tsinghua University Beijing 100084 China

The concepts and calculation methods of ionospheric eclipse factor (IEF) and ionospheric influence factor (IFF) are further illustrated. The temporal and spacial variation properties of IEF and IFF are studied, which shows that the properties are influenced by the geographic position and season. The possibility of improving the precision of using GPS data to determine ionospheric delay based on the above variation properties is also analysed.

关键词： GPS ionospheric eclipse factor ionospheric influence factor

The gravitational gradient tensor’s invariants and the related boundary conditions

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Science China Earth sciences 2010年第5期53卷 781-790页

作者： YU JinHai1,2.3.& ZHAO DongMing4 1 College of Earth Science, graduate University of{1.,{2., China 2.3.,{1., wuhan 430077, China 3.State key laboratory of Astronautic dynamics, Xi’an 710043. China 4 Zhengzhou institute of Surveying and Mapping, Zhengzhou 450052. China 1. College of Earth Science Graduate University of Chinese Academy of Sciences Beijing 100049 China2. Institute of Geodesy and Geophysics Chinese Academy of Sciences Wuhan 430077 China3. State Key Laboratory of Astronautic Dynamics Xi’an 710043 China4. Zhengzhou Institute of Surveying and Mapping Zhengzhou 450052 China

Here we report new approaches of recovering the Earth gravitational field from GOCE (Gravity field and steady-state Ocean Circulation Explorer) gradiometric data with the help of the gradient tensor’s invariants. Our results only depend on GOCE satellite’s position and gradiometry, in other words, they are completely independent of the satellite attitude. First, starting from the invariants, linearization models are established, which can be referred as the general boundary conditions on the satellite’s orbit. Then, the spherical approximation expressions for the models are derived, and the corresponding solving methods for them are discussed. Furthermore, considering effects of J2.term, the spherical approximation models are improved so that the accuracies of the boundary conditions can be theoretically raised to O ( J 2.2.T), which is approximately equivalent to O(T2.. Finally, some arithmetic examples are constructed from EGM96 model based on the derived theories, and the computational results illustrate that the spherical models have accuracies of 1.-7 and the order recovering the gravitational field can reach up to 2.0, and the models with regard to effect of J2.term have accuracies of 1.-8 and the order can reach up to 2.0.

关键词： the Earth’s gravitational field gravitational gravidiometry tensor’s invariant

Interactions between hotspots and the Southwest Indian Ridge during the last 90 Ma:Implications on the formation of oceanic plateaus and intra-plate seamounts

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Science China Earth sciences 2011年第8期54卷 1177-1188页

作者： ZHANG Tao 1,2.3.4,LIN Jian 5 & GAO JinYao 3.4 1 institute of geodesy and geophysics,{1. {2. of sciences,wuhan 430077,China 2.graduate University of chinese academy of sciences,beijing 1.0049,China 3.The Second {1.} of Oceanography,State Oceanic Administrator,Hangzhou 3.0012.China 4 key {1.} of Submarine Geosciences,State Oceanic Administrator,Hangzhou 3.0012.China 5 Department of Geology and {1.},Woods Hole Oceanographic Institution,Woods Hole,MA 02.43.USA 1. institute of geodesy and geophysics Chinese Academy of Sciences Wuhan 430077 China2. Graduate University of Chinese Academy of Sciences Beijing 100049 China3. The Second Institute of Oceanography State Oceanic Administrator Hangzhou 310012 China4. Key Laboratory of Submarine Geosciences State Oceanic Administrator Hangzhou 310012 China

This study investigates the relationship between the hotspot-ridge interaction and the formation of oceanic plateaus and seamounts in the Southwest Indian *** first calculated the relative distance between the Southwest Indian Ridge (SWIR) and relevant hotspots on the basis of models of plate reconstruction,and then calculated the corresponding excess magmatic anomalies of the hotspots on the basis of residual bathymetry and Airy *** results reveal that the activities of the Marion hotspot can be divided into three main phases:interaction with the paleo-Rodrigues triple junction (73.6-68.5 Ma),interaction with the SWIR (68.5-42.7 Ma),and intra-plate volcanism (42.7-0 Ma).These three phases correspond to the formation of the eastern,central,and western parts of the Del Cano Rise,*** magnitude and apparent periodicity of the magmatic volume flux of the Marion hotspot appear to be dominated by the hotspot-ridge *** periodicity of the Marion hotspot is about 2. Ma,which is much longer than that of the Hawaii and Iceland hotspots (about {3. Ma).

关键词： Southwest Indian Ocean hotspot-ridge interaction magmatic volume flux oceanic plateaus seamounts

The diurnal variations, semiannual and winter anomalies of the ionospheric TEC based on GPS data in China

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Progress in Natural Science:Materials International 2005年第1期 57-61页

作者： HUO Xingliang 1,2.*, YUAN Yunbin 1, OU Jikun 1, WEN Debao 1,2.and LUO Xiaowen 1,2.1. {3. laboratory of {2. geodesy, institute of geodesy and geophysics, chinese academy of sciences, wuhan 430077, China 2. graduate school of chinese academy of sciences, beijing 10003., China) key laboratory of {1. {3.，institute of {3. and geophysics，chinese academy of sciences，wuhan {1.}，China graduate {1. of{2.，{3. 1.003.，China key laboratory of {1. {3.，institute of {3. and geophysics，chinese academy of sciences，wuhan {1.}，China

With the spherical harmonic (SH) function model and the dual frequency GPS P code phase data from the Crustal Movement Observation Network of China (CMONOC) during the period from year 2.00 to 2.02. time series of total electron content (TEC) in the area of China is calculated. The diurnal variations, semiannual, and winter anomalies of the ionosphere in the area of China are analyzed and discussed, especially according to the results of year 2.01.

关键词： Global Positioning System spherical harmonic function model total electron content semiannual anomaly winter anomaly.

Partial continuation model and its application in mitigating systematic errors of double-differenced GPS measurements

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Progress in Natural Science:Materials International 2005年第3期 54-59页

作者： GUO Jianfeng 1,2 ˇˇ ,OU Jikun 1 and REN Chao 1 (1.key laboratory of Geo{1.s,{3. of geodesy and geophysics,chinese academy of sciences,wuhan430077,China 2.{1.} {1.} of the{1.},{1.}10003.,China) key laboratory of Geo{2.s，{3. of geodesy and geophysics，chinese academy of sciences，wuhan 430077，China graduate {1. of the{2.，{3. 1.003.，China key laboratory of Geo{2.s，{3. of geodesy and geophysics，chinese academy of sciences，wuhan 430077，China

Based on the so-called partial continuation model with exact finite measurements,a new stochastic assessment procedure is *** every satellite pair,the temporal correlation coefficient is estimated using the original double-differenced(DD)GPS *** then,the Durbin-Watson test is applied to test specific hypothesis on the temporal correlation *** the test is not significant with a certain significant level,a data transformation is *** transformed measurements are free of time *** purpose of illustration,two static GPS baseline data sets are analyzed in *** experimental results demonstrate that the proposed procedure can mitigate effectively the impact of systematic errors on DD GPS measurements.

关键词： partial continuation model systematic errors GPS double-differenced measurements.

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模拟研究卫-卫跟踪中星间隔的选择问题

天文学报 2005年第1期46卷 62-69页

作者：周旭华吴斌许厚泽彭碧波中国科学院测量与地球物理研究所动力大地测量重点实验室

从两个方面讨论了低轨卫星在做卫-卫跟踪(SST)观测时,星间隔的选择问题. 1.用地球重力位系数作为扰动量,比较该扰动引起的不同间隔的SST星间距离和速度变化大小. 2.用随机误差为1.m／s的星间速度变化作为模拟观测量,恢复不同间隔的 ... 详细信息

从两个方面讨论了低轨卫星在做卫-卫跟踪(SST)观测时,星间隔的选择问题. 1.用地球重力位系数作为扰动量,比较该扰动引起的不同间隔的SST星间距离和速度变化大小. 2.用随机误差为1.m／s的星间速度变化作为模拟观测量,恢复不同间隔的地球重力位系数,并做精度评估.两种结果表明,适当增大SST间隔对求解重力场有利, 但无限制增大无实际意义,对于选定高度为42. km卫星,在作SST观测时,星间隔不宜超过690km.此模拟方法及结果对我国确定重力卫星指标有着重要意义.

关键词： SST 重力位地球模拟观测重力卫星重力场低轨卫星间隔扰动系数