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1.
对ＧＥＯＳＡＴ测高卫星在中国近海区域（０°－３５°Ｎ,１０５°－１２７°Ｅ）以及１２７°－１３５°Ｅ内６个ＥＲＭ周期（１９８７年１月１日－４月１２日）的地球物理数据记录（ＧＤＲ）中的数据进行了编辑和预处理．根据卫星弧段的实际长度选取了混合轨道误差模型,并采用最小二乘技术对上升弧段与下降弧段交叠点处的不符值进行了平差计算．处理结果表明,所选用的方法可以大大地消除径向轨道误差的影响,使交叠点处的不符值由原来的５６ｃｍ（ＲＭＳ）降低到现在的２４ｃｍ（ＲＭＳ）在此基础上,构造出６个１°×１°的中国近海海平面及其平均海平面．该平面被称为＂测高大地水准面＂与美国Ｏｈｉｏ州立大学的ＯＳＵ９１Ａ重力场模型的大地水准面相比,两者具有同等量级的精度及一致的形态。 相似文献
2.
A. Kilicoglu 《Studia Geophysica et Geodaetica》2005,49(1):1-12
Approximately nine-year data from ERS1, ERS2 and TOPEX/POSEIDON (T/P) satellite altimetry missions have been used for the recovery of gravity anomalies over the Black Sea. The Corrected Sea Surface Height product of Aviso/Altimetry has been proven to be homogeneous after a cross-over adjustment. The Least Squares Collocation method was applied in a so-called remove-restore procedure. The residual geoid heights, obtained by subtracting EGM96 geoid heights from cross-over adjusted sea surface heights, were inverted to recover residual gravity anomalies in a grid structure over the Black Sea. Finally, EGM96 free air gravity anomalies were added to the predicted residual gravity anomalies to obtain the free air gravity anomalies. In order to check the consistency with respect to an external source, these computed free air gravity anomalies were compared to ship gravity observations, and to alternative satellite altimetry derived gravity anomalies. Comparisons with the observed gravity data yielded that external consistency of the gravity anomalies computed in this study is about 3 mGal for individual ship tracks. Overall external consistency in the test area is 4.8 mGal. Comparison with other satellite altimetry derived gravity anomalies presented a good agreement. 相似文献
3.
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
4.
A method for splitting sea surface height measurements from satellite altimetry into geoid undulations and sea surface topography is presented. The method is based on a combination of the information from altimeter data and a dynamic sea surface height model. The model consists of geoid undulations and a quasi-geostrophic model for expressing the sea surface topography. The goal is the estimation of those values of the parameters of the sea surface height model that provide a least-squares fit of the model to the data. The solution is accomplished by the adjoint method which makes use of the adjoint model for computing the gradient of the cost function of the least-squares adjustment and an optimization algorithm for obtaining improved parameters. The estimation is applied to the North Atlantic. ERS-1 altimeter data of the year 1993 are used. The resulting geoid agrees well with the geoid of the EGM96 gravity model. 相似文献
5.
JERRY C. RITCHIE THOMAS J. JACKSON JURGEN D. GARBRECHT EARL H. GRISSINGER JOSEPH B. MURPHEY JAMES H. EVERITT 《水文科学杂志》2013,58(5):403-416
Abstract Vertical surface properties of the landscape were measured using a laser altimeter mounted in a small twin-engine aeroplane. The laser altimeter makes 4000 measurements per second with a vertical recording precision of 0.05 m for a single measurement. These airborne laser measurements were analysed to provide information on topography, vegetation canopy and stream and gully cross-sections. Laser altimeter data were used to measure small (less than 0.20 m deep) and large gullies and stream cross-sections. Vegetation canopy heights, cover, structure and distribution were determined in studies in Texas and Arizona. Laser measurements of vegetation cover and height were significantly correlated with ground measurements made with line-intercept methods. While conventional ground-based techniques may be used to make all these measurements, airborne laser altimeter techniques allow the data to be collected in a quick and efficient way over large and inaccessible areas. The airborne laser altimeter data can also help quantify various land surface parameters needed for natural resource and landscape management or required by hydrological simulation models. Measurements of landscape properties over large areas provide a better understanding of landscape functions and can lead to the development of better management plans to conserve and improve the productivity of natural resources. 相似文献
6.
近海岸区域平均海面高在大地测量学、物理海洋学以及地球物理学研究中具有非常重要的意义.受各种条件的制约和限制，目前卫星测高技术主要应用于深海区域，在近海区域尤其是海岸线附近区域的应用几乎为空白.本文根据ERS-1测高卫星回波波形特征，采用五参数线性模型，由最小二乘拟合方法，对近海区域尤其是靠近海岸线附近的ERS-1测高波形数据进行波形重构.比较波形重构前、后解算平均海面高，表明波形重构技术不仅明显改善了解算近海海面高的精度，而且增加了近海测高海平面的分辨率，并使卫星测高有效观测延伸至海岸线附近.随后，本文利用波形重构后海面高数据构造了近海多年平均海平面，并对我国近海海平面特征进行了初步分析. 相似文献
7.
Three geopotential models (OSU91A, GEM-T3, and GRIM4-C2), available in 1991, have been compared in several ways. The models have been differenced to find the geoid undulation difference are on the order of 1 m in land areas and 30 cm in ocean areas with extreme differences reaching 6 m. The models were also evaluated, augmented by higher degree terms, when necessary, through comparisons with undulations at Doppler and GPS positioned stations. The undulation difference at the Doppler stations was ± 1.57 m with no significant difference between models. Using 4 GPS test areas, differences were seen between the various models. A final comparison was made between geoid undulations implied by a Geosat 17 day cycle and undulations from the three models. The OSU91A model performed best having a difference standard deviation of ±34 cm. 相似文献
8.
C.M. Green K.M.U. Fletcher S. Cheyney G.J. Dawson S.J. Campbell 《Geophysical Prospecting》2019,67(6):1611-1619
This paper reviews the impacts of new satellite altimeter data sets and new technology on the production of satellite gravity. It considers the contribution of the increased data volume, the application of new altimeter acquisition technology and the potential for future developments. Satellite altimeter derived gravity has provided gravity maps of the world's seas since the 1980s, but, from 1995 to 2010, virtually all improvements were in the processing as there were no new satellite data with closely spaced tracks. In recent years, new data from CryoSat-2 (launched in 2010) and the geodetic mission of Jason-1 (2012–2013) have provided a wealth of additional coverage and new technology allows further improvements. The synthetic aperture radar mode of CryoSat-2 uses a scanning approach to limit the size of the altimeter sea surface footprint in the along-track direction. Tests indicate that this allows reliable data to be acquired closer to coastlines. The synthetic aperture radar interferometric mode of CryoSat-2 uses two altimeters to locate sea-surface reflection points laterally away from the satellite track. In a study to generate gravity for freshwater lakes, this mode is found to be valuable in extending the available satellite coverage. The AltiKa altimeter uses higher frequency radar to provide less noisy sea-surface signals and its new orbit mode gives potential for further improvements in satellite gravity. Future developments include the potential for swath mapping to provide further gravity improvements. 相似文献
9.
This paper presents a survey of recent work on the gravimetric geoid. The gravity models considered are those published in the past few years by the Goddard Space Flight Center (GSFC), the Smithsonian Astrophysical Observatory (SAO) and the Ohio State University (OSU). Comparisons and analyses have been carried out through the ose of detailed gravimetric geoids which we have computed by combining the above-mentioned models with a set of 26 000, 1ox1o mean free air gravity anomalies. The accuracy of the detailed gravimetric geoid computed using the most recent Goddard Earth Model (GEM-6) in conjunction with the set 1ox1o mean free air gravity anomalies is assessed at 2 m on the continents of North America, Europe And Australia, 2 to 5 m in the North-East Pacific and North Atlantic areas and 5 to 10 m in other areas where surface gravity data are sparse. Rms differences between this detailed geoid and the detailed geoids computed using the other satellite gravity fields in conjunction with same set of surface data range from 3 to 7 m. The maximum differences in all cases occurred in the Southern Hemisphere where surface data and satellite observations are sparse. These differences exhibited wavelengths of approximately 30o to 50o in longitude. Detailed geoidal heights were also computed with models truncated to 12th degree and order as well as 8th degree and order. This truncation resulted in a reduction of the rms differences to a maximum of 5 m. Comparisons have been made with the astrogeodetic data of Rice (United States), Bomford (Europe), and Mather (Australia) and also with geoidal heights from satellite solutions for geocentric station coordinates in North America and the Caribbean. 相似文献
10.
中国海及邻域重力场特征及其构造解释 总被引：7，自引：3，他引：7
利用中国海及邻域 2’× 2’由Seaset,Geosat,ERS 1及TOPEX/POSEIDON等卫星测高资料解算的自由空气重力异常 ,结合ETOPO5全球海底地形资料计算了中国海及邻域布格重力异常 ,并反演了得到了中国海及邻域地壳厚度 .经对重力异常特征进行分析 ,讨论了重力异常与大地构造及其活动的相关性 . 相似文献
11.
利用测高数据的一次差分计算海域垂线偏差，有效降低了动力海面地形和系统残差对垂线偏差的影响；然后根据扰动场元间的协方差函数是具有各态历经性的平稳随机函数这一特征，提出了利用垂线偏差精确逼近海域大地水准面的协方差函数. 而海域大地水准面的精确确定，为从测高数据中精确分离动力海面地形提供了条件. 本文还利用Topex/Poseidon、ERS 1/2测高数据计算了全球海域大地水准面和动力海面地形，证明了本文所述方法是科学合理的. 相似文献
12.
The accuracy of determining the Molodensky normal heights using geopotential models has been investigated. On the basis of geopotential model JGM-3/OSU91A the Molodensky normal heights can be computed with an accuracy of about ±35 cm at the GPS sites in the central part of Europe. On the basis of JGM-3/OSU91A improved the accuracy becomes higher, about ±14 cm. 相似文献
13.
14.
《Journal of Atmospheric and Solar》1999,61(16):1197-1203
The global ionospheric total electron content maps (GIMs) provide integrated electron densities between the ground and the GPS satellite altitude (20,200 km). Satellite altimeter ionospheric delay corrections require integrated electron densities between the ground and altimeter satellite altitude. In the case of the Geosat Follow-On (GFO) spacecraft, flying at 800 km, we estimated that using GIM TEC data alone, up to a 2 cm path delay can be introduced into the GFO measurements for high solar activity period by not taking into account the electron content above this altitude. Furthermore, the GIMs can have errors of 20–30 TECU in low latitudes for high solar activity in areas where there is little GPS data (such as over the oceans). In this paper, we describe the results of ingesting GIM TEC data into the International Reference Ionosphere model (IRI-95) to mitigate these two effects. 相似文献
15.
16.
Sea surface height and transport stream function of the South China Sea from a variable-grid global ocean circulation model 总被引：8，自引：0，他引：8
The study on the South China Sea (SCS) circulation has a history of more than 40 years. Nevertheless, the SCS circulation is not fully understood compared with the Bohai Sea, Yellow Sea and East China Sea (ECS). Many numerical studies on the SCS circulati… 相似文献
17.
Summary The High-Tatra mountains are situated in the northern part of the Carpathian bend covering an area of about 335 km2 some peaks being high more than 2600 m above sea level. In the said mountain region there are 100 small lakes in heights from 1100 m up to 2200 m above sea level. A detailed mapping of lakes has been carried out using the ground mapping technique “photogrametry” and measurements of depths have been done by ultra-sound. On the base of two examples it may be observed from the obtained results that the stability of lakes, blocked by moraines, may be easily damaged the final consequence being then the extinction of toe lake. Another example describing an interesting water bilan of a lake without inflow and outflow, of a height of 1346 m, is also given. The average precipitation falling down on the lake surface is 933 mm. From this quantity 374 mm evaporate back into the atmosphere. The water level of the lake increases annually by 210 mm in average. The remaining quantity of water seeps into the ground. 相似文献
18.
南极冰盖冰雪质量变化反映了全球气候变化,并且直接影响着全球海平面变化.ICESat测高卫星的主要任务之一就是要确定南北两极冰盖的质量变化情况并评估其对全球海平面变化的影响.本文利用2003年10月至2008年12月的ICESat测高数据,针对南极DEM分辨率有限的特殊性,通过求解坡度改正值,解决重复轨道地面脚点不重合的问题,计算了南极大陆(86°S以北区域,后文所述南极冰盖均不包括86°S以南区域)在这5年里的冰雪质量变化情况,得到东南极冰盖的质量变化为-18±20Gt/a,西南极-26±6Gt/a,南极冰盖的冰雪质量变化为-44±21Gt/a,对全球海平面上升的影响约为0.12mm·a~(-1).解算结果表明,南极冰盖质量亏损主要集中在西南极阿蒙森海岸附近冰川以及东南极波因塞特角区域. 相似文献
19.
Time‐lapse seismic surveying has become an accepted tool for reservoir monitoring applications, thus placing a high premium on data repeatability. One factor affecting data repeatability is the influence of the rough sea‐surface on the ghost reflection and the resulting seismic wavelets of the sources and receivers. During data analysis, the sea‐surface is normally assumed to be stationary and, indeed, to be flat. The non‐flatness of the sea‐surface introduces amplitude and phase perturbations to the source and receiver responses and these can affect the time‐lapse image. We simulated the influence of rough sea‐surfaces on seismic data acquisition. For a typical seismic line with a 48‐fold stack, a 2‐m significant‐wave‐height sea introduces RMS errors of about 5–10% into the stacked data. This level of error is probably not important for structural imaging but could be significant for time‐lapse surveying when the expected difference anomaly is small. The errors are distributed differently for sources and receivers because of the different ways they are towed. Furthermore, the source wavelet is determined by the sea shape at the moment the shot is fired, whereas the receiver wavelet is time‐varying because the sea moves significantly during the seismic record. 相似文献
20.
Melting of continental ice sheets and glaciers, changes in ocean circulation pattern and in sea level, variations of surface and ground water levels and river discharge, glacial-isostatic adjustment, mantle convection and tectonics, all this causes transport and (re-) distribution of mass inside the Earth and at its surface. Equipped with precise sensor systems, gravity field and altimeter satellites observe these mass-transport processes. During 2006–2012, the German Research Association DFG had established the SPP 1257, ‘Mass distribution and Mass Transport in the Earth System’ as a coordinated research programme to facilitate integrated analysis of these data, to improve our knowledge about several transport processes within the Earth system and to investigate their interactions. This special issue reports about the findings of the first 4 years within the programme. 相似文献