共查询到20条相似文献，搜索用时 31 毫秒
1.
The continuous efforts on establishment and modernization of the geodetic control in Turkey include a number of regional geoid
models that have been determined since 1976. The recently released gravimetric Geoid of Turkey, TG03, is used in geodetic
applications where GPS-heights need to be converted to the local vertical datum. To reach a regional geoid model with improved
accuracy, the selection of the appropriate global geopotential model is of primary importance. This study assesses the performance
of a number of recent satellite-only and combined global geopotential models (GGMs) derived from CHAMP and GRACE missions’
data in comparison to the older EGM96 model, which is the underlying reference model for TG03. In this respect, gravity anomalies
and geoid heights from the global geopotential models were compared with terrestrial gravity data and low-pass filtered GPS/levelling
data, respectively. Also, five new gravimetric geoid models, computed by the Fast Fourier Transform technique using terrestrial
gravity data and the geopotential models, were validated at the GPS/levelling benchmarks. The findings were also compared
with the validation results of the TG03 model.
The tests showed that as it was expected any of the high-degree combined models (EIGEN-CG03C, EIGEN-GL04C, EGM96) can be employed
for determining the gravity anomalies over Turkey. In the west of Turkey, EGM96 and EIGEN-CHAMP03S fit the GPS/levelling surface
better. However, all the tested GGMs revealed equal performance when they were employed in gravimetric geoid modelling after
de-trending the gravimetric geoid model with corrector surface fitting. The new geoid models have improved accuracy (after
fit) compared to TG03. 相似文献
2.
Comparison of the qualities of recent global and local gravimetric geoid models in Iran 总被引：1，自引：0，他引：1
A number of regional gravimetric geoid models have recently been determined for the Iran area, and a common problem is to select the best model, e.g. for engineering applications. A related problem is that in order to improve the local geoid models, the selection of the best Global Geopotential Model (GGM) model for the region is essential, to be used in a combined solution from GGM and local gravimetric data. We discuss these problems by taking advantage of 260 GPS/levelling points as an external tool for validation of different global and local geoid models in the absolute and relative senses. By using relative comparisons of the height differences between precise levelling and GPS/geoid models we avoid possible unknown systematic effects between the different types of observables.The study shows that the combination of the newly released GRACE model (GGM02C) with EGM96 geoid model fits the GPS/levelling data in Iran with the best absolute and relative accuracy among the GGMs. Among the local geoid models, the newly gravimetric geoid model IRG04 agrees considerably better with GPS/levelling than any of the other recent local geoid models. Its rms fit with GPS/levelling is 55 cm. Hence, we strongly recommend the use of this new model in any surveying engineering or GPS/levelling projects in the area. 相似文献
3.
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). 相似文献
4.
G. Rodríguez-Caderot M. C. Lacy A. J. Gil B. Blázquez 《Studia Geophysica et Geodaetica》2006,50(4):619-631
This work focuses on the comparison between satellite-only and combined Global Geopotential Models (GGMs) derived from the
CHAMP and GRACE satellite missions with land gravity anomalies, geoid undulations provided by the gravimetric geoid ANDALUSGeoid2002
and GPS/levelling geoid undulations in Andalusia in order to find the GGM that best fits this area in order to be used in
a further geoid computation. The results show that the EIGEN-CG01C model or the combined models GGM02C/EIGEN-CG01C and ITG-CHAMP01E/EIGEN-CG01C
should be used. 相似文献
5.
Ali Kiliçoğlu Ahmet Direnç Hasan Yildiz Murat Bölme Bahadir Aktuğ Mehmet Simav Onur Lenk 《Studia Geophysica et Geodaetica》2011,55(4):557-578
Turkish regional geoid models have been developed by employing a reference earth gravitational model, surface gravity observations
and digital terrain models. The gravimetric geoid models provide a ready transformation from ellipsoidal heights to the orthometric
heights through the use of GPS/leveling geoid heights determined through the national geodetic networks. The recent gravimetric
models for Turkish territory were computed depending on OSU91 (TG-91) and EGM96 (TG-03) earth gravitational models. The release
of the Earth Gravitational Model 2008 (EGM08), the collection of new surface gravity observations, the advanced satellite
altimetry-derived gravity over the sea, and the availability of the high resolution digital terrain model have encouraged
us to compute a new geoid model for Turkey. We used the Remove-Restore procedure based on EGM08 and applied Residual Terrain
Model (RTM) reduction of the surface gravity data. Fast Fourier Transformation (FFT) was then used to obtain the residual
quasigeoid from the reduced gravity. We restored the individual contributions of EGM08 and RTM to the whole quasi-geoid height
(TQG-09). Since the Helmert orthometric height system is adopted in Turkey, the quasi-geoid model (TQG-09) was then converted
to the geoid model (TG-09) by making use of Bouguer gravity anomalies and digital terrain model. After all we combined a gravimetric
geoid model with GPS/leveling geoid heights in order to obtain a hybrid geoid model (THG-09) (or a transformation surface)
to be used in GPS applications. The RMS of the post-fit residuals after the combination was found to be ± 0.95 cm, which represents
the internal precision of the final combination. And finally, we tested the hybrid geoid model with GPS/leveling data, which
were not used in the combination, to assess the external accuracy. Results show that the external accuracy of the THG-09 model
is ± 8.4 cm, a precision previously not achieved in Turkey until this study. 相似文献
6.
首先基于半解析法建立了新的GRACE卫星K波段测量系统星间测速、GPS接收机轨道位置和加速度计非保守力误差联合影响累计大地水准面的误差模型;其次,基于各关键载荷精度指标的匹配关系,论证了误差模型的可靠性;最后,基于美国喷气动力实验室（JPL）公布的2006年的GRACE Level 1B实测误差数据,有效和快速地估计了120阶全球重力场的精度,在120阶处累计大地水准面的精度为18.368 cm,其结果和德国地学研究中心（GFZ）公布的EIGEN-GRACE02S全球重力场模型符合较好. 本文的研究为将来国际卫星重力测量计划（如GRACE Follow-On, 360阶）中高阶全球重力场模型精度的有效和快速估计提供了理论基础和计算保证. 相似文献
7.
R. Klees X. Liu T. Wittwer B. C. Gunter E. A. Revtova R. Tenzer P. Ditmar H. C. Winsemius H. H. G. Savenije 《Surveys in Geophysics》2008,29(4-5):335-359
When using GRACE as a tool for hydrology, many different gravity field model products are now available to the end user. The traditional spherical harmonics solutions produced from GRACE are typically obtained through an optimization of the gravity field data at the global scale, and are generated by a number of processing centers around the world. Alternatives to this global approach include so-called regional techniques, for which many variants exist, but whose common trait is that they only use the gravity data collected over the area of interest to generate the solution. To determine whether these regional solutions hold any advantage over the global techniques in terms of overall accuracy, a range of comparisons were made using some of the more widely used regional and global methods currently available. The regional techniques tested made use of either spherical radial basis functions or single layer densities (i.e., mascons), with the global solutions having been obtained from the various major processing centers. The solutions were evaluated using a range of computed statistics over a selection of major river basins, which were globally distributed and ranged in size from 1 to 6 million km2. For one of the basins tested, the Zambezi, additional validation tests were conducted through comparisons against a custom designed regional hydrology model of the region. We could not prove that current regional models perform better than global ones. Monthly mean water storage variations agree at the level of 0.02 m equivalent water height. The differences in terms of monthly mean water storage variations between regional and global solutions are comparable with the differences among only global or regional solutions. Typically they reach values of 0.02 m equivalent water heights, which seems to be the level of accuracy of current GRACE solutions for river basins above 1 million km2. The amplitudes of the seasonal mass variations agree at the sub-centimetre level. Evident from all of the comparisons shown is the importance that the choice of regularization, or spatial filtering, can have on the solution quality. This was found to be true for global as well as regional techniques. 相似文献
8.
This work presents a validation study of global geopotential models (GGM) in the region of Fagnano Lake, located in the southern Andes. This is an excellent area for this type of validation because it is surrounded by the Andes Mountains, and there is no terrestrial gravity or GNSS/levelling data. However, there are mean lake level (MLL) observations, and its surface is assumed to be almost equipotential. Furthermore, in this article, we propose improved geoid solutions through the Residual Terrain Modelling (RTM) approach. Using a global geopotential model, the results achieved allow us to conclude that it is possible to use this technique to extend an existing geoid model to those regions that lack any information (neither gravimetric nor GNSS/levelling observations). As GGMs have evolved, our results have improved progressively. While the validation of EGM2008 with MLL data shows a standard deviation of 35 cm, GOCO05C shows a deviation of 13 cm, similar to the results obtained on land. 相似文献
9.
Multivariate Prediction of Total Water Storage Changes Over West Africa from Multi-Satellite Data 总被引：1，自引：1，他引：0
Ehsan Forootan Jürgen Kusche Ina Loth Wolf-Dieter Schuh Annette Eicker Joseph Awange Laurent Longuevergne Bernd Diekkrüger Michael Schmidt C. K. Shum 《Surveys in Geophysics》2014,35(4):913-940
West African countries have been exposed to changes in rainfall patterns over the last decades, including a significant negative trend. This causes adverse effects on water resources of the region, for instance, reduced freshwater availability. Assessing and predicting large-scale total water storage (TWS) variations are necessary for West Africa, due to its environmental, social, and economical impacts. Hydrological models, however, may perform poorly over West Africa due to data scarcity. This study describes a new statistical, data-driven approach for predicting West African TWS changes from (past) gravity data obtained from the gravity recovery and climate experiment (GRACE), and (concurrent) rainfall data from the tropical rainfall measuring mission (TRMM) and sea surface temperature (SST) data over the Atlantic, Pacific, and Indian Oceans. The proposed method, therefore, capitalizes on the availability of remotely sensed observations for predicting monthly TWS, a quantity which is hard to observe in the field but important for measuring regional energy balance, as well as for agricultural, and water resource management. Major teleconnections within these data sets were identified using independent component analysis and linked via low-degree autoregressive models to build a predictive framework. After a learning phase of 72 months, our approach predicted TWS from rainfall and SST data alone that fitted to the observed GRACE-TWS better than that from a global hydrological model. Our results indicated a fit of 79 % and 67 % for the first-year prediction of the two dominant annual and inter-annual modes of TWS variations. This fit reduces to 62 % and 57 % for the second year of projection. The proposed approach, therefore, represents strong potential to predict the TWS over West Africa up to 2 years. It also has the potential to bridge the present GRACE data gaps of 1 month about each 162 days as well as a—hopefully—limited gap between GRACE and the GRACE follow-on mission over West Africa. The method presented could also be used to generate a near-real-time GRACE forecast over the regions that exhibit strong teleconnections. 相似文献
10.
The Gravity Recovery and Climate Experiment (GRACE) has been measuring temporal and spatial variations of mass redistribution within the Earth system since 2002. As large earthquakes cause significant mass changes on and under the Earth’s surface, GRACE provides a new means from space to observe mass redistribution due to earthquake deformations. GRACE serves as a good complement to other earthquake measurements because of its extensive spatial coverage and being free from terrestrial restriction. During its over 10 years mission, GRACE has successfully detected seismic gravitational changes of several giant earthquakes, which include the 2004 Sumatra–Andaman earthquake, 2010 Maule (Chile) earthquake, and 2011 Tohoku-Oki (Japan) earthquake. In this review, we describe by examples how to process GRACE time-variable gravity data to retrieve seismic signals, and summarize the results of recent studies that apply GRACE observations to detect co- and post-seismic signals and constrain fault slip models and viscous lithospheric structures. We also discuss major problems and give an outlook in this field of GRACE application. 相似文献
11.
Robert Tenzer Ismael Foroughi Lars E. Sjöberg Mohammad Bagherbandi Christian Hirt Martin Pitoňák 《Surveys in Geophysics》2018,39(3):313-335
In planetary sciences, the geodetic (geometric) heights defined with respect to the reference surface (the sphere or the ellipsoid) or with respect to the center of the planet/moon are typically used for mapping topographic surface, compilation of global topographic models, detailed mapping of potential landing sites, and other space science and engineering purposes. Nevertheless, certain applications, such as studies of gravity-driven mass movements, require the physical heights to be defined with respect to the equipotential surface. Taking the analogy with terrestrial height systems, the realization of height systems for telluric planets and moons could be done by means of defining the orthometric and geoidal heights. In this case, however, the definition of the orthometric heights in principle differs. Whereas the terrestrial geoid is described as an equipotential surface that best approximates the mean sea level, such a definition for planets/moons is irrelevant in the absence of (liquid) global oceans. A more natural choice for planets and moons is to adopt the geoidal equipotential surface that closely approximates the geometric reference surface (the sphere or the ellipsoid). In this study, we address these aspects by proposing a more accurate approach for defining the orthometric heights for telluric planets and moons from available topographic and gravity models, while adopting the average crustal density in the absence of reliable crustal density models. In particular, we discuss a proper treatment of topographic masses in the context of gravimetric geoid determination. In numerical studies, we investigate differences between the geodetic and orthometric heights, represented by the geoidal heights, on Mercury, Venus, Mars, and Moon. Our results reveal that these differences are significant. The geoidal heights on Mercury vary from ? 132 to 166 m. On Venus, the geoidal heights are between ? 51 and 137 m with maxima on this planet at Atla Regio and Beta Regio. The largest geoid undulations between ? 747 and 1685 m were found on Mars, with the extreme positive geoidal heights under Olympus Mons in Tharsis region. Large variations in the geoidal geometry are also confirmed on the Moon, with the geoidal heights ranging from ? 298 to 461 m. For comparison, the terrestrial geoid undulations are mostly within ± 100 m. We also demonstrate that a commonly used method for computing the geoidal heights that disregards the differences between the gravity field outside and inside topographic masses yields relatively large errors. According to our estimates, these errors are ? 0.3/+ 3.4 m for Mercury, 0.0/+ 13.3 m for Venus, ? 1.4/+ 125.6 m for Mars, and ? 5.6/+ 45.2 m for the Moon. 相似文献
12.
National height reference systems have conventionally been linked to the local mean sea level, observed at individual tide gauges. Due to variations in the sea surface topography, the reference levels of these systems are inconsistent, causing height datum offsets of up to ±1–2 m. For the unification of height systems, a satellite-based method is presented that utilizes global geopotential models (GGMs) derived from ESA’s satellite mission Gravity field and steady-state Ocean Circulation Explorer (GOCE). In this context, height datum offsets are estimated within a least squares adjustment by comparing the GGM information with measured GNSS/leveling data. While the GNSS/leveling data comprises the full spectral information, GOCE GGMs are restricted to long wavelengths according to the maximum degree of their spherical harmonic representation. To provide accurate height datum offsets, it is indispensable to account for the remaining signal above this maximum degree, known as the omission error of the GGM. Therefore, a combination of the GOCE information with the high-resolution Earth Gravitational Model 2008 (EGM2008) is performed. The main contribution of this paper is to analyze the benefit, when high-frequency topography-implied gravity signals are additionally used to reduce the remaining omission error of EGM2008. In terms of a spectral extension, a new method is proposed that does not rely on an assumed spectral consistency of topographic heights and implied gravity as is the case for the residual terrain modeling (RTM) technique. In the first step of this new approach, gravity forward modeling based on tesseroid mass bodies is performed according to the Rock–Water–Ice (RWI) approach. In a second step, the resulting full spectral RWI-based topographic potential values are reduced by the effect of the topographic gravity field model RWI_TOPO_2015, thus, removing the long to medium wavelengths. By using the latest GOCE GGMs, the impact of topography-implied gravity signals on the estimation of height datum offsets is analyzed in detail for representative GNSS/leveling data sets in Germany, Austria, and Brazil. Besides considerable changes in the estimated offset of up to 3 cm, the conducted analyses show that significant improvements of 30–40% can be achieved in terms of a reduced standard deviation and range of the least squares adjusted residuals. 相似文献
13.
GOCE, Satellite Gravimetry and Antarctic Mass Transports 总被引：1，自引：0，他引：1
Reiner Rummel Martin Horwath Weiyong Yi Alberta Albertella Wolfgang Bosch Roger Haagmans 《Surveys in Geophysics》2011,32(4-5):643-657
In 2009 the European Space Agency satellite mission GOCE (Gravity Field and Steady-State Ocean Circulation Explorer) was launched. Its objectives are the precise and detailed determination of the Earth’s gravity field and geoid. Its core instrument, a three axis gravitational gradiometer, measures the gravity gradient components V xx , V yy , V zz and V xz (second-order derivatives of the gravity potential V) with high precision and V xy , V yz with low precision, all in the instrument reference frame. The long wavelength gravity field is recovered from the orbit, measured by GPS (Global Positioning System). Characteristic elements of the mission are precise star tracking, a Sun-synchronous and very low (260 km) orbit, angular control by magnetic torquing and an extremely stiff and thermally stable instrument environment. GOCE is complementary to GRACE (Gravity Recovery and Climate Experiment), another satellite gravity mission, launched in 2002. While GRACE is designed to measure temporal gravity variations, albeit with limited spatial resolution, GOCE is aiming at maximum spatial resolution, at the expense of accuracy at large spatial scales. Thus, GOCE will not provide temporal variations but is tailored to the recovery of the fine scales of the stationary field. GRACE is very successful in delivering time series of large-scale mass changes of the Antarctic ice sheet, among other things. Currently, emphasis of respective GRACE analyses is on regional refinement and on changes of temporal trends. One of the challenges is the separation of ice mass changes from glacial isostatic adjustment. Already from a few months of GOCE data, detailed gravity gradients can be recovered. They are presented here for the area of Antarctica. As one application, GOCE gravity gradients are an important addition to the sparse gravity data of Antarctica. They will help studies of the crustal and lithospheric field. A second area of application is ocean circulation. The geoid surface from the gravity field model GOCO01S allows us now to generate rather detailed maps of the mean dynamic ocean topography and of geostrophic flow velocities in the region of the Antarctic Circumpolar Current. 相似文献
14.
本文首次利用解析法有效快速估计了将来GRACE（Gravity Recovery and Climate Experiment） Follow-On地球重力场的精度. 第一,基于功率谱原理分别建立了新的GRACE Follow-On卫星激光干涉星间测量系统星间速度、GPS接收机轨道位置和轨道速度以及加速度计非保守力误差影响累计大地水准面的单独和联合解析误差模型. 第二,利用提出的GRACE卫星关键载荷匹配精度指标和美国喷气推进实验室（JPL）公布的GRACE Level 1B实测精度指标的一致性,以及估计的GRACE累计大地水准面精度和德国波兹坦地学研究中心（GFZ）公布的EIGEN-GRACE02S地球重力场模型实测精度的符合性,验证了本文建立的解析误差模型是可靠的. 第三,论证了GRACE Follow-On卫星不同关键载荷匹配精度指标和轨道高度对地球重力场精度的影响. 在360阶处,利用轨道高度250 km、星间距离50 km、星间速度误差1×10-9m/s、轨道位置误差3×10-5m、轨道速度误差3×10-8m/s和非保守力误差3×10-13m/s2,基于联合解析误差模型估计累计大地水准面的精度为1.231×10-1 m. 本文的研究不仅为当前GRACE和将来GRACE Follow-On地球重力场精度的有效快速确定提供了理论基础和计算保证,同时对国际将来GRAIL（Gravity Recovery and Interior Laboratory）月球卫星重力测量计划的成功实施具有重要的参考意义. 相似文献
15.
Roelof Rietbroek Mathias Fritsche Christoph Dahle Sandra-Esther Brunnabend Madlen Behnisch Jürgen Kusche Frank Flechtner Jens Schröter Reinhard Dietrich 《Surveys in Geophysics》2014,35(6):1267-1283
We investigated two ‘gap-filler’ methods based on GPS-derived low-degree surface loading variations (GPS-I and GPS-C) and a more simple method (REF-S) which extends a seasonal harmonic variation into the expected Gravity Recovery and Climate Experiment (GRACE) mission gap. We simulated two mission gaps in a reference solution (REF), which is derived from a joint inversion of GRACE (RL05) data, GPS-derived surface loading and simulated ocean bottom pressure. The GPS-I and GPS-C methods both have a new type of constraint applied to mitigate the lack of GPS station network coverage over the ocean. To obtain the GPS-C solution, the GPS-I method is adjusted such that it fits the reference solution better in a 1.5 year overlapping period outside of the gap. As can be expected, the GPS-I and GPS-C solutions contain larger errors compared to the reference solution, which is heavily constrained by GRACE. Within the simulated gaps, the GPS-C solution generally fits the reference solution better compared to the GPS-I method, both in terms of spherical harmonic loading coefficients and in terms of selected basin-averaged hydrological mass variations. Depending on the basin, the RMS-error of the water storage variations (scaled for leakage effects) ranges between 1.6 cm (Yukon) and 15.3 cm (Orinoco). In terms of noise level, the seasonal gap-filler method (REF-S) even outperforms the GPS-I and GPS-C methods, which are still affected by spatial aliasing problems. However, it must be noted that the REF-S method cannot be used beyond the study of simple harmonic seasonal variations. 相似文献
16.
Free-Air Anomalies (FAA) for the Norwegian marine area including some parts of the North Sea, the Norwegian Sea and the Barents
Sea are computed from satellite altimetry data. A total of 84 cycles of ERS2 along-track data, 25 cycles of ENVISAT along-track
data and high density ERS1 data during its geodetic mission are used. The new geopotential model from the Gravity Recovery
and Climate Experiment (GRACE) mission, GGM02S (Tapely et al., 2005) is used to compute the long wavelength contributions
of the geoid and the FAA. To correct data for mean dynamic topography, the available Levitus climatology model (Levitus and
Boyer, 1994) is used. Corrected data are then used to compute along-track gradients in each cycle-pass to suppress the orbital
and the atmospheric errors below the noise level of the altimeter. Resulted gradients are then stacked and the east-west and
the north-south components of the deflection of verticals are computed where ascending and descending tracks meet each other.
Finally, the inverse Vening-Meinesz formula is implemented on the gridded deflections to compute FAA. Results are then compared
with available marine and airborne data. Standard deviations of ± 4.301 and ± 6.159 mGal in comparison with airborne and marine
FAA were achieved. Thereafter, the derived anomalies are combined with marine and airborne FAA together with the land FAA
to compute a fine resolution geoid for Norway and the surrounding marine areas. This geoid is evaluated over sea and land
with the synthetic geoid (the geoid derived from the mean sea surface by subtracting the mean dynamic topography) and Global
Positioning System (GPS)-levelling and the standard deviations of the differences are ± 20.9 and ± 12.8 cm respectively.
ali.soltanpour@ntnu.no, hossein.nahavandchi@ntnu.no, kourosh.ghazavi@ntnu.no 相似文献
17.
Presently, two satellite missions, Gravity Recovery and Climate Experiment (GRACE) and Gravity field and steady-state Ocean Circulation Explorer (GOCE), are making detailed measurements of the Earth’s gravity field, from which the geoid can be obtained. The mean dynamic topography (MDT) is the difference between the time-averaged sea surface height and the geoid. The GOCE mission is aimed at determining the geoid with superior accuracy and spatial resolution, so that a more accurate MDT can be estimated. In this study, we determine the mean positions of the Antarctic Circumpolar Current fronts using the purely geodetic estimates of the MDT constructed from an altimetric mean sea surface and GOCE and GRACE geoids. Overall, the frontal positions obtained from the GOCE and GRACE MDTs are close to each other. This means that these independent estimates are robust and can potentially be used to validate frontal positions obtained from sparse and irregular in situ measurements. The geodetic frontal positions are compared to earlier estimates as well as to those derived from MDTs based on satellite and in situ measurements and those obtained from an ocean data synthesis product. The position of the Sub-Antarctic Front identified in the GOCE MDT is found to be in better agreement with the previous estimates than that identified in the GRACE MDT. The geostrophic velocities derived from the GOCE MDT are also closer to observations than those derived from the GRACE MDT. Our results thus show that the GOCE mission represents an improvement upon GRACE in terms of the time-averaged geoid. 相似文献
18.
1 Introduction Large-scale mass redistribution, or temporal varia- tion of mass within the Earth system, the driving force of interactions between solid Earth and geophysical fluids envelope (i.e., atmosphere, ocean, and hydro- sphere), is an important geophysical process critical to human life. Most of the interactions between solid Earth and the atmosphere/oceans happen at seasonal and inter-annual time scales. One important contribu- tor of mass redistribution at seasonal and inter-annual … 相似文献
19.
Hydrological Signals Observed by the GRACE Satellites 总被引：3，自引：1，他引：2
R. Schmidt F. Flechtner U. Meyer K.-H. Neumayer Ch. Dahle R. König J. Kusche 《Surveys in Geophysics》2008,29(4-5):319-334
20.
本文利用卫星重力反演与模拟软件ANGELS系统(ANalyst of Gravity Estimation with Low-orbit Satellites)对低低跟踪模式的重力卫星的关键载荷精度指标进行了深入分析.模拟结果表明:(1)对短弧长积分法而言,在低低跟踪模式的关键载荷精度指标中,重力场反演精度对星间距离变率精度最为敏感;(2)通过对目前在轨运行GRACE的载荷指标进行分析,发现轨道数据的误差主要影响重力场的低阶部分(约小于25阶),较高阶次部分(约大于26阶)主要受星间距离变率的误差限制;(3)如果下一代低低跟踪模式的重力卫星的目标之一是把重力异常反演精度较GRACE提高约10倍,则在保持轨道高度和GRACE相同的前提下,轨道、星间距离变率和星载加速度计等关键载荷指标需要达到的最低精度分别约为2cm、10nm·s-1和3.0×10-10 m·s-2;(4)轨道精度和混频误差将是影响下一代低低跟踪模式重力卫星重力场恢复能力进一步提高的主要制约因素,距离变率精度和加速度计精度存在盈余. 相似文献