S<Subscript>2</Subscript> tide aliasing in GRACE time-variable gravity solutions     

J. L. Chen  C. R. Wilson  Ki-Weon Seo 《Journal of Geodesy》2009,83(7):679-687

Errors in high-frequency ocean tide models alias to low frequencies in time-variable gravity solutions from the Gravity Recovery and Climate Experiment (GRACE). We conduct an observational study of apparent gravity changes at a period of 161 days, the alias period of errors in the S₂ semidiurnal solar tide. We examine this S₂ alias in the release 4 (RL04) reprocessed GRACE monthly gravity solutions for the period April 2002 to February 2008, and compare with that in release 1 (RL01) GRACE solutions. One of the major differences between RL04 and RL01 is the ocean tide model. In RL01, the alias is evident at high latitudes, near the Filchner-Ronne and Ross ice shelves in Antarctica, and regions surrounding Greenland and Hudson Bay. RL04 shows significantly lower alias amplitudes in many of these locations, reflecting improvements in the ocean tide model. However, RL04 shows continued alias contamination between the Ronne and Larson ice shelves, somewhat larger than in RL01, indicating a need for further tide model improvement in that region. For unknown reasons, the degree-2 zonal spherical harmonics (C₂₀) of the RL04 solutions show significantly larger S₂ aliasing errors than those from RL01.  相似文献   

Alternative mission architectures for a gravity recovery satellite mission   总被引：4，自引：1，他引：3  

D. N. Wiese  W. M. Folkner  R. S. Nerem 《Journal of Geodesy》2009,83(6):569-581

Since its launch in 2002, the Gravity Recovery and Climate Experiment (GRACE) mission has been providing measurements of the time-varying Earth gravity field. The GRACE mission architecture includes two satellites in near-circular, near-polar orbits separated in the along-track direction by approximately 220 km (e.g. collinear). A microwave ranging instrument measures changes in the distance between the spacecraft, while accelerometers on each spacecraft are used to measure changes in distance due to non-gravitational forces. The fact that the satellites are in near-polar orbits coupled with the fact that the inter-satellite range measurements are directed in the along-track direction, contributes to longitudinal striping in the estimated gravity fields. This paper examines four candidate mission architectures for a future gravity recovery satellite mission to assess their potential in measuring the gravity field more accurately than GRACE. All satellites were assumed to have an improved measurement system, with an inter-satellite laser ranging instrument and a drag-free system for removal of non-gravitational accelerations. Four formations were studied: a two-satellite collinear pair similar to GRACE; a four-satellite architecture with two collinear pairs; a two-satellite cartwheel formation; and a four-satellite cartwheel formation. A cartwheel formation consists of satellites performing in-plane, relative elliptical motion about their geometric center, so that inter-satellite measurements are, at times, directed radially (e.g. parallel to the direction towards the center of the Earth) rather than along-track. Radial measurements, unlike along-track measurements, have equal sensitivity to mass distribution in all directions along the Earth’s surface and can lead to higher spatial resolution in the derived gravity field. The ability of each architecture to recover the gravity field was evaluated using numerical simulations performed with JPL’s GIPSY-OASIS software package. Thirty days of data were used to estimate gravity fields complete to degree and order 60. Evaluations were done for 250 and 400 km nominal orbit altitudes. The sensitivity of the recovered gravity field to under-sampled effects was assessed using simulated errors in atmospheric/ocean dealiasing (AOD) models. Results showed the gravity field errors associated with the four-satellite cartwheel formation were approximately one order of magnitude lower than the collinear satellite pair when only measurement system errors were included. When short-period AOD model errors were introduced, the gravity field errors for each formation were approximately the same. The cartwheel formations eliminated most of the longitudinal striping seen in the gravity field errors. A covariance analysis showed the error spectrum of the cartwheel formations to be lower and more isotropic than that of the collinear formations.  相似文献   

LEO星载GPS双向滤波定轨研究   总被引：1，自引：1，他引：0  

秦显平  杨元喜 《武汉大学学报(信息科学版)》2009,34(2)

介绍了目前常用的LEO(low Earth orbiter)星载GPS定轨方法,分析了LEO星载GPS双向滤波定轨方法与其他几种主要定轨方法的区别.从卫星运动方程和星载GPS非差定轨观测方程出发,给出了LEO星载GPS双向滤波定轨方法的原理,采用自行研制的定轨软件对两颗GRACE(gravity recovery and climate ex-periment)卫星进行了定轨试验,通过与JPL(Jet Propulsion Laboratory)轨道的对比及KBR(k-band rangingsystem)观测数据的外部检核发现:①双向滤波定轨技术不仅能显著提高单向滤波开始阶段的定轨精度,而且可以从整体上提高卫星的定轨精度;②LEO星载GPS双向滤波定轨方法切实可行,相应的星载GPS定轨软件对GRACE卫星定轨精度在径向、沿轨方向和法向优于5 cm.  相似文献   

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陈巍  申文斌  李进  韩建成 《大地测量与地球动力学》2009,29(3):119-124

??????????????λ???????????????????????????????仯?????????С????????????????GRACE????????????????λ????????????????е??????????????????????????????????????????????????????????????????????????????????????仯???????????????????????????????????????????????????????????????????6?????????????  相似文献   

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匡翠林 《大地测量与地球动力学》2009,29(4):88-92

???????л??????????????????ж???????????????????????????????????????????????????????????????????????????????????????????ж???????????????о???????????CHAMP??GRACE????????顣??????????÷????????????????????????????????????????????????????????????????????????????????  相似文献   

����GRACE�����������������������ļ���   总被引：8，自引：3，他引：5  

郑伟  许厚泽  钟敏  员美娟  周旭华  彭碧波 《大地测量与地球动力学》2009,29(5):89-93

???????????????????????????????????????????PEM??????С????Э????????LSM????????120??GRACE???????????????????????????1??????????JPL??????GRACE???????????????????????120?????????PEM??LSM???????????λ?????????5.192??10^-10????6.633??10^-10????2????????PEM??LSM???120?????????λ???????????1?GFZ??????EIGEN-GRACE02S???????????????????????????????????????????PEM??LSM????????????????????????Ч???3?????????PEM??LSM?????????????λ????????????????????????????????????????????????????????????120??GRACE???????????????????  相似文献   

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匡翠林  刘经南  赵齐乐 《大地测量与地球动力学》2009,29(2):121-125

?о???????漰????GPS?????????????????CHAMP??GRACE????GPS???????????????????????????????????????????????????????????????????PANDA??????????????????????????????????????????????ν???????????????????????????????????????????????  相似文献   

Constraining the geometry and volume of the Barents Sea Ice Sheet          下载免费PDF全文

Samuel B. Kachuck  Lawrence M. Cathles 《第四纪科学杂志》2018,33(5):527-535

  相似文献   

Recent hydrological behavior of the East African great lakes region inferred from GRACE,satellite altimetry and rainfall observations   总被引：1，自引：0，他引：1  

Mélanie Becker  William LLovel  Anny Cazenave  Andreas Güntner  Jean-François Crétaux 《Comptes Rendus Geoscience》2010,342(3):223-233

We have jointly analysed space gravimetry data from the GRACE space mission, satellite altimetry data and precipitation over the East African Great Lakes region, in order to study the spatiotemporal variability of hydrological parameters (total water storage, lake water volume and rainfall). We find that terrestrial water storage (TWS) from GRACE and precipitation display a common mode of variability at interannual time scale, with a minimum in late 2005, followed by a rise in 2006–2007. We argue that this event is due to forcing by the strong 2006 Indian Ocean Dipole (IOD) on East African rainfall. We also show that GRACE TWS is linked to the El Niño-Southern Oscillation cycle. Combination of the altimetry-based lake water volume with TWS from GRACE over the lakes drainage basins allows estimating soil moisture and groundwater volume variations. Comparison with the WGHM hydrological model outputs is performed and discussed.  相似文献   

卫星重力测量数据处理软件系统的设计     

张兴福  沈云中  胡雷鸣 《测绘科学技术学报》2006,23(6):393-395

介绍了自主开发的卫星重力测量数据处理软件--GRASTAR,给出了该软件的整体设计框架和功能.该软件主要采用动力学法实现,应用CHAMP卫星和GRACE卫星的观测数据反演地球重力场模型.利用模拟方法验证了该软件的正确性,并利用GRASTAR处理了126 d的CHAMP卫星数据,解算出直到40阶次重力场模型的初步结果.  相似文献