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1.
卫星激光测距（SLR）技术作为卫星精密定轨手段和轨道检核重要方法,激光反射器已经成为重力卫星和测高卫星等低轨卫星的基本载荷.经典的SLR台站坐标是使用动力学方法计算的,本文根据多颗低轨卫星（LEO）多历元的激光观测数据,采用几何方法开展地面SLR测站坐标计算.通过组建低轨卫星群实现对全球激光站的动态观测,为了合理配置不同低轨卫星间观测值权重,削弱低轨卫星群可能存在的系统性偏差,提出采用方差分量估计组合的最小二乘法进行解算.实测结果显示,解算出SLR台站坐标框架解与SLRF2014差异平均值在25.1 mm,外符合精度达到1~2 cm.该方法避免了复杂动力学模型,SLR台站坐标的几何计算方法既可以作为激光测站框架解算手段之一,同时将LEO卫星群作为空间并址站实现不同技术地球参考框架间的融合.  相似文献   

2.
The Earth center of mass (geocenter) time series with the sampling interval of one week are determined from Satellite Laser Ranging (SLR), Global Navigation Satellite System (GNSS) and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) observations. The 3D geocenter time series were projected onto XY, YZ and ZX planes of the International Terrestrial Reference Frame (ITRF), thus, three complex-valued time series can be analyzed for each observation technique. The signal to noise ratio in these geocenter time series is very small and detectable oscillations are rather broadband, however, the annual oscillation can be noticed in each one of them. The wavelet transform technique with the Morlet wavelet function was applied to compute the mean and spectra-temporal polarization functions from the prograde (positive periods) and retrograde (negative periods) spectra of the examined complex-valued time series. The sign of the polarization function determines turning direction in the elliptical motion. If this function is positive or negative for oscillation with a chosen period, then this oscillation is prograde or retrograde, respectively. To estimate the significance level of polarization functions, corresponding to time series data length, the Monte Carlo experiment was performed using complex-valued white noise data. In order to detect similarity between elliptic oscillations in two different time series the spectra-temporal wavelet semblance function was computed. This function reveals that in the XY equatorial plane there is phase agreement between retrograde annual oscillation for SLR and GNSS techniques, and between prograde annual oscillation for DORIS and two other techniques. To construct a model of geocenter motion from GNSS and SLR center of mass time series the wavelet based semblance filtering method was applied. Common oscillations in the analyzed time series are dominated by the annual oscillation with amplitude less than 5 mm.  相似文献   

3.
Tang  Geshi  Li  Xie  Cao  Jianfeng  Liu  Shushi  Chen  Guangming  Man  Haijun  Zhang  Xiaomin  Shi  Sihan  Sun  Ji  Li  Yongping  Calabia  Andres 《中国科学:地球科学(英文版)》2020,63(2):257-266
On September 20 th, 2015, twenty satellites were successfully deployed into a near-polar circular orbit at 520 km altitude by the Chinese CZ-6 test rocket, which was launched from the Tai Yuan Satellite Launch Center. Among these satellites, a set of 4 Cube Sats conform the atmospheric density detection and precise orbit determination(APOD) mission, which is projected for atmospheric density estimation from in-situ detection and precise orbit products. The APOD satellites are manufactured by China Spacesat Co. Ltd. and the payload instruments include an atmospheric density detector(ADD), a dual-frequency dualmode global navigation satellite system(GNSS) receiver(GPS and Beidou), a satellite laser ranging(SLR) reflector, and an S/Xband very long baseline interferometry(VLBI) beacon. In this paper, we compare the GNSS precise orbit products with colocated SLR observations, and the 3 D orbit accuracy shows better than 10 cm RMS. These results reveal the great potential of the onboard micro-electro-mechanical system(MEMS) GNSS receiver. After calibrating ADD density estimates with precise orbit products, the accuracy of our density products can reach about 10% with respect to the background density. Density estimates from APOD are of a great importance for scientific studies on upper atmosphere variations and useful for model data assimilation.  相似文献   

4.
Space geodetic techniques (e.g., Global Positioning System, GPS and very long baseline interference, VLBI) have been widely used to determine the precipitable water vapor (PWV) for meteorology and climatology, which was verified by comparing with co-located independent technique observations. However, most of these comparisons have been conducted using only short-time spanning observations at several stations. The goal of this study is to identify and quantify the systematic errors between VLBI and GPS PWV estimates using a 5-year (2002–2007), PWV data set constructed from co-located measurements and radiosonde data as well. It has found systematic errors between VLBI and GPS PWV estimations from comparisons with long-term co-located GPS measurements. The total mean VLBI PWVs are systematically smaller than GPS estimates with 0.8–2.2 mm for all sites, but can be as much as 15–30%. The subdiurnal PWV variation magnitudes and long-term trends between VLBI and GPS are nearly similar, but the VLBI-derived PWV trends are systematically smaller than GPS estimates with about 0.1±0.02 mm/year. These systematic errors in PWV estimates between VLBI and GPS are probably due to technique own problems, different used elevation angles and co-location separation.  相似文献   

5.
近些年来，ＧＰＳ（全球定位系统）测量取得的进展是其测量精度已可与ＶＬＢＩ及ＳＬＲ相媲美，由于这样的发展及ＧＰＳ具有使用方便经济的特点，作为强有力的工具而被用于研究全球大地测量学及地球动力学，ＧＰＳ测量监测全球板块运动，监视海平面上升，建立地球（参考）框架等等。  相似文献   

6.
《Journal of Geodynamics》2006,41(4-5):494-501
We have processed all available DORIS data from all available satellites, except Jason-1 over the past 10 years (from January 1993 to April 2003). Weekly solutions have been produced for stations positions coordinates, geocenter motion and scale factor stability. We present here accuracy presently achievable for all types of potential geodetic products. Typically weekly stations positions can be derived with a repeatability of 1.0–1.5 cm using data from 5 satellites simultaneously, showing the significant improvement in precision that has been gained recently using the additional new DORIS satellites. As an example, we show how such new results can detect displacement from large magnitude earthquakes, such as the 2003 Denali fault earthquake in Alaska. Displacements of −5 cm in latitude and +2 cm in longitude were easily detected using the DORIS data and are confirmed by recent GPS determination. The terrestrial reference frame was also well be monitored with DORIS during this 10-year period. Other geodetic products, such as tropospheric corrections for atmospheric studies are also analyzed. Finally, we discuss here the possible advantages and weaknesses of the DORIS system as additional geodetic tool, in conjunction with the already existing GPS, VLBI and SLR services, to participate in an Global Geodetic Observing System (GGOS).  相似文献   

7.
A mathematical model used for determination of a local geoid model by combining airborne gravity disturbances and the Earth Gravitational Model 2008 (EGM08) is shortly reviewed. The precision of the estimated local geoid model of Taiwan is tested by its comparison with the “real” geoid at Global Satellite Navigation Systems (GNSS)/levelling points. The same comparison at GNSS/levelling points is done for the geoid evaluated only by using EGM08. Conclusions concerning a rate of improvement of the “global” geoid from EGM08 using the “local” geoid from airborne gravity data are presented.  相似文献   

8.
《Journal of Geodynamics》2006,41(4-5):436-449
In the interest of improving the performance and efficiency of space geodesy a diverse group in the US, in collaboration with IGGOS, has begun to establish a unified National Geodetic Observatory (NGO). To launch this effort an international team will conduct a multi-year program of research into the technical issues of integrating SLR, VLBI, and GPS geodesy to produce a unified set of global geodetic products. The goal is to improve measurement accuracy by up to an order of magnitude while lowering the cost to current sponsors. A secondary goal is to expand and diversify international sponsorship of space geodesy. Principal benefits will be to open new vistas of research in geodynamics and surface change while freeing scarce NASA funds for scientific studies. NGO will proceed in partnership with, and under the auspices of, the International Association of Geodesy (IAG) as an element of the Integrated Global Geodetic Observation System project. The collaboration will be conducted within, and will make full use of, the IAG's existing international services: the IGS, IVS, ILRS, and IERS. Seed funding for organizational activities and technical analysis will come from NASA's Solid Earth and Natural Hazards Program. Additional funds to develop an integrated geodetic data system known as Inter-service Data Integration for Geodetic Operations (INDIGO), will come from a separate NASA program in Earth science information technology. INDIGO will offer ready access to the full variety of NASA's space geodetic data and will extend the GPS Seamless Archive (GSAC) philosophy to all space geodetic data types.  相似文献   

9.
The provision of accurate models of Glacial Isostatic Adjustment (GIA) is presently a priority need in climate studies, largely due to the potential of the Gravity Recovery and Climate Experiment (GRACE) data to be used to determine accurate and continent-wide assessments of ice mass change and hydrology. However, modelled GIA is uncertain due to insufficient constraints on our knowledge of past glacial changes and to large simplifications in the underlying Earth models. Consequently, we show differences between models that exceed several mm/year in terms of surface displacement for the two major ice sheets: Greenland and Antarctica. Geodetic measurements of surface displacement offer the potential for new constraints to be made on GIA models, especially when they are used to improve structural features of the Earth’s interior as to allow for a more realistic reconstruction of the glaciation history. We present the distribution of presently available campaign and continuous geodetic measurements in Greenland and Antarctica and summarise surface velocities published to date, showing substantial disagreement between techniques and GIA models alike. We review the current state-of-the-art in ground-based geodesy (GPS, VLBI, DORIS, SLR) in determining accurate and precise surface velocities. In particular, we focus on known areas of need in GPS observation level models and the terrestrial reference frame in order to advance geodetic observation precision/accuracy toward 0.1 mm/year and therefore further constrain models of GIA and subsequent present-day ice mass change estimates.  相似文献   

10.
On precise orbit determination of HY-2 with space geodetic techniques   总被引：1，自引：1，他引：0  
As the first radar altimetric satellite of China, HY-2 requires the precise orbit determination with a higher accuracy than that of other satellites. In order to achieve the designed radial orbit with the accuracy better than 10 cm for HY-2, the methods of precise orbit determination for HY-2 with the centimeter-level accuracy based on space geodetic techniques (DORIS, SLR, and satellite-borne GPS) are studied in this paper. Perturbations on HY-2 orbit are analyzed, in particular those due to the non-spherical gravitation of the earth, ocean tide, solid earth tide, solar and earth radiation, and atmospheric drag. Space geodetic data of HY-2 are simulated with the designed HY-2 orbit parameters based on the orbit dynamics theory to optimize the approaches and strategies of precise orbit determination of HY-2 with the dynamic and reduced-dynamic methods, respectively. Different methods based on different techniques are analyzed and compared. The experiment results show that the nonspherical perturbation modeled by GGM02C causes a maximum perturbation, and errors caused by the imperfect modeling of atmospheric drag have an increasing trend on T direction, but errors are relatively stable on the other two directions; besides, the methods with three space geodetic techniques achieve the radial orbit with the precision better than 10 cm.  相似文献   

11.
In the past 30 years the Satellite Laser Ranging(SLR) technique has improved to a large extent, currently achieving a ranging precision down toa few millimeters. Moreover the growth in the size of the international network of SLR stations and therapidly growing constellation of geodetic target satellites make the SLR a well established technique for solidEarth studies and for the related Earth subsystem sciences. The long SLR observation history has become a veryimportant source of data for global and local changes detection and monitoring in many different fields.Tectonic plate motion, crustal deformation, post-glacial rebound and subsidence, Earth rotation, and polarmotion, time variations of the Earth's gravitational field, ocean tides modeling, center of mass of the totalEarth system monitoring, International Terrestrial Reference System (ITRS) maintenance are only themain applications in which the SLR technique plays a significant role. Plate boundary zones in whichdeformation is diffuse are in general geographical areas associated with high seismic and volcanic activity.A principal key to understand the geophysics of a plate boundary process is the detailed knowledge of the3-D kinematics. This work will focus on the relevant results of the Eurasian SLR subnetwork in termsof technological evolution and crustal deformation. A general overview of the Eurasian SLR stationperformance will be presented with particular reference to the state-of-the-art SLR observatory MLRO (Matera LaserRanging Observatory). The current tectonic deformations (velocity and strain-rate field) detectedby the Eurasian network and by the former WEGENER/MEDLAS campaigns will also be discussed.  相似文献   

12.
Satellite laser ranging (SLR) has proven avery efficient method for contributingto the tracking of altimetric satellites anddetermining accurately their orbitalthough hampered by the non-worldwide coverageand the meteorologicalconditions. Indeed, in some cases it is the onlymethod available to determinethe satellite orbit (e.g., the orbits of the ERS-1and Geosat-Follow-On missions).Moreover, any operational and non-weather dependenttechniques, like GPS,DORIS, PRARE, can exhibit systematic errors inpositioning and orbitography. Acomparison with SLR results allows to evidence sucherrors and vice versa. Fordoing that, two different approaches for determiningprecise orbits can beconsidered: one based on global orbit determination,the other on a short-arctechnique used to locally improve a global orbitdetermined by another trackingtechniques, such as DORIS or GPS. We can thusvalidate a global orbit andachieve orbit quality control to a level of2 to 3 centimeters at present and expectto achieve a level of 1 to 2 centimeters inthe near future. Errors induced bystation coordinates or by the gravity field(geographically correlated errors, forexample) can be estimated from SLR tracking data.Colocation experiments withdifferent techniques in the same geodetic siteplay also a key role to ensure preciserelationships between the geodetic referenceframes linked to each technique. Inparticular, the role of the SLR technique is tostrengthen the vertical component(including velocity) of the positioning, whichis crucial for altimetry missions.The role of SLR data in the modelling of the firstterms of the gravity field has finally to be emphasized,which is of primary importance in orbitography,whatever the tracking technique used.Another application of SLR technology is thesatellite altimeter calibration. Examples of past calibrationand future experiments are given, including theaccuracy we can expect from the Jason-1 and EnviSatspace oceanography missions.  相似文献   

13.
《Journal of Geodynamics》2006,41(4-5):414-431
Towards the end of the 19th century, geodetic observation techniques allowed it to create geodetic networks of continental size. The insight that big networks can only be set up through international collaboration led to the establishment of an international collaboration called “Central European Arc Measurement”, the predecessor of the International Association of Geodesy (IAG), in 1864. The scope of IAG activities was extended already in the 19th century to include gravity.At the same time, astrometric observations could be made with an accuracy of a few tenths of an arcsecond. The accuracy stayed roughly on this level, till the space age opened the door for milliarcsecond (mas) astrometry. Astrometric observations allowed it at the end of the 19th century to prove the existence of polar motion. The insight that polar motion is almost unpredictable led to the establishment of the International Latitude Service (ILS) in 1899.The IAG and the ILS were the tools (a) to establish and maintain the terrestrial and the celestial reference systems, including the transformation parameters between the two systems, and (b) to determine the Earth's gravity field.Satellite-geodetic techniques and astrometric radio-interferometric techniques revolutionized geodesy in the second half of the 20th century. Satellite Laser Ranging (SLR) and methods based on the interferometric exploitation of microwave signals (stemming from Quasars and/or from satellites) allow it to realize the celestial reference frame with (sub-)mas accuracy, the global terrestrial reference frame with (sub-)cm accuracy, and to monitor the transformation between the systems with a high time resolution and (sub-)mas accuracy. This development led to the replacement of the ILS through the IERS, the International Earth Rotation Service in 1989.In the pre-space era, the Earth's gravity field could “only” be established by terrestrial methods. The determination of the Earth's gravitational field was revolutionized twice in the space era, first by observing geodetic satellites with optical, Laser, and Doppler techniques, secondly by implementing a continuous tracking with spaceborne GPS receivers in connection with satellite gradiometry. The sequence of the satellite gravity missions CHAMP, GRACE, and GOCE allow it to name the first decade of the 21st century the “decade of gravity field determination”.The techniques to establish and monitor the geometric and gravimetric reference frames are about to reach a mature state and will be the prevailing geodetic tools of the following decades. It is our duty to work in the spirit of our forefathers by creating similarly stable organizations within IAG with the declared goal to produce the geometric and gravimetric reference frames (including their time evolution) with the best available techniques and to make accurate and consistent products available to wider Earth sciences community as a basis for meaningful research in global change. IGGOS, the Integrated Global Geodetic Observing System, is IAG's attempt to achieve these goals. It is based on the well-functioning and well-established network of IAG services.  相似文献   

14.
Global Navigation Satellite Systems (GNSS) are very useful tools to study the ionosphere. Nevertheless, the precision of the usual dual frequency total electron content (TEC) monitoring technique is affected by code delays (hardware and multipath), and is therefore limited. This paper introduces a TEC monitoring technique based on triple frequency GPS and Galileo measurements. The three steps of this technique are validated on triple frequency simulated data. In fact, as it is not affected by code delays, the precision of the reconstructed TEC is improved in regards with the dual frequency technique.  相似文献   

15.
基于单站多系统的GNSS硬件延迟估算方法及其应用   总被引：1，自引：0，他引：1       下载免费PDF全文
随着全球导航卫星系统（Global Navigation Satellite Systems,GNSS）的不断发展,中国地区单个GNSS接收站在一个时刻可以接收到超过30颗GNSS卫星的信号,这为单站GNSS硬件延迟估算方法的研究提供了有利条件.本文首先通过GNSS硬件实验,分析了不同温度条件下GNSS系统硬件延迟的变化特征,研究结果显示：当温度快速变化时,硬件延迟变化比较剧烈,变化幅度可达12.53 TECU（1 TECU=10 16el·m-2）;在恒温条件或室温条件下,硬件延迟变化比较缓慢,变化幅度在1.00 TECU左右.在GNSS系统硬件延迟实验的基础上,充分利用单站多星观测的特点,提出了一种基于单站多系统的GNSS硬件延迟的估算方法——单站三角分解与差分消元法,并将该方法应用于河北保定站2015-2017年GNSS系统硬件延迟的求解中.通过对估算的GNSS系统硬件延迟进行分析显示：单站三角分解与差分消元法具有计算速度快、独立性好的特点;在北斗系统上硬件延迟的求解效果优于GPS、GLONASS系统,硬件延迟求解的结果整体上比利用欧洲定轨中心全球电离层地图校正的结果大2.50~3.00TECU左右;同时,该方法在消除GNSS系统硬件延迟后,获得的垂直总电子含量（Total Electron Content,TEC）能较好地反映电离层TEC的周日变化、日出增强、半年变化、年变化和春秋分不对称性等特征.  相似文献   

16.
The advances in satellite navigation and positioning technology and the worldwide establishment of continuous-tracking stations have greatly promoted the development and application of the high-precision Global Navigation Satellite System (GNSS). GAMIT/GLOBK, as a popular high-precision GNSS data-processing software, has been widely used in monitoring crustal deformation, tsunami, iceberg, etc. Based on the basic observations and various geophysical models processed by GAMIT/GLOBK, we analyze the influence of the correction of applied geophysical models, and describe the techniques of parameter estimation and accuracy assessment. In addition, taking the present crustal movement in the Chinese mainland and the MW7.8 earthquake in Nepal as examples, we discuss the applications of GAMIT/GLOBK in crustal deformation monitoring and its future prospect.  相似文献   

17.
This work intends to determine if low-cost surveying techniques based on recreational echosounders can be used to perform nearshore bathymetry for analysing evolution of coastal sectors. For that purpose, two hydrographic surveying techniques were compared, i.e. (1) a real-time kinematic differential global positioning system (RTK-DGPS) synchronised with a single beam echosounder with real-time tidal elevation correction and (2) a low-cost recreational echosounder-chartplotter system using Global Navigation Satellite Systems (GNSS) with real-time European Geostationary Navigation Overlay Service (EGNOS) augmentation services and depth values post-processed using measured sea level. Two bathymetric data sets were obtained, one by each method, for the same area and survey lines at an ebb tidal delta (Tavira Inlet, Ria Formosa Portugal). Vertical differences were determined assuming no morphological variations between surveys. Results showed that depth elevation differences between bathymetric surfaces were of 0.10?±?0.16 m, slightly higher but within the same order of the error attributable to the used interpolator (0.00?±?0.11 m, triangular surface fitting). The differences between surveys performed with two different equipment sets and using different methodologies for correcting water elevations are very small both quantitative and qualitatively. Those differences can be diminished by improving the tidal level correction and uncertainties associated to different tidal slopes throughout the survey area. Pitch/roll corrections performed with low-cost GPS receivers would be also a valuable addition to the accuracy and precision of the method. It is then concluded that navigation with EGNOS augmentation services and sounding devices ten times cheaper than combined RTK-DGPS with single beam echosounders allow to measure and monitor accurately the nearshore bathymetry.  相似文献   

18.
毫米级地球参考框架的构建   总被引：4，自引：0，他引：4       下载免费PDF全文
本文指出了最新的国际地球参考框架ITRF（International Terrestrial Reference Frame）2005已不能满足当今毫米级地球动态变化监测的需要.提出了利用ITRF2005、SBL/GGFC（Special Bureau for Loading/Global Geophysical Fluids Center）和GRACE（Gravity Recovery and Climate Experiment）等卫星的最新成果,构建毫米级地球参考框架的方案,介绍了对其两个关键问题：地壳非线性运动特征∑RΔXiR(t)和地球质心运动ΔX0(t)的空间技术（GPS,VLBI,SLR和GRACE）监测和地球物理因素模制的方法和一些初步结果,并对目前建立和实现毫米级地球参考框架存在的问题和所能达到的精度进行了初步评估.  相似文献   

19.
The present article is written in response to the recent call of the United Nations for the enhanced international cooperation of different countries on global geodesy to build the Global Geodetic Reference Frame (GGRF). It reviews historical landmarks in the development of the State Geodetic Reference Frame on the territory of Russia over the last two centuries. It discusses major steps in creating the Russian terrestrial reference frame by both the ground-based and space geodesy methods relying upon the satellite observation techniques. Currently the State Geodetic Reference Frame undergoes a radical improvement in order to effectively implement the potential of modern satellite technologies through the use of the Global Navigation Satellite Systems (GNSS). We outline the current status of the National Geodetic Network in Russia, its hierarchical structure and accuracy. We pay a particular attention to the high-precision State Geodetic Coordinate System (GSK-2011), created simultaneously along with the global reference-ellipsoid, and designed for various types of users to conduct the land surveying and mapping in Russia. We also present the geocentric coordinate system (PZ-90.11) used for navigating space missions, solving various problems of global geodesy, and supporting the continuous operation of GLONASS.  相似文献   

20.
The local tie vector, which connects the different space geodetic techniques at a co-located site, plays an important role in the realization of the International Terrestrial Reference Frame (ITRF). This paper presents a new method to determine the tie vector between the GNSS and very long baseline interferometry tracking points. The parameters of the local tie vector and the axes offsets are introduced into constraint equations. The parameters are then resolved using the 3D constrained least squares adjustment. With the surveying data collected at two different sites (Kunming and Urumqi) in China, the proposed method can precisely determine the local tie vectors in a geocentric frame. The root mean square error (RMSE) is (1.2, 2.3 and 1.5 mm) and (1.0, 1.5 and 1.4 mm) for the three coordinate components at the sites in Kunming and Urumqi, respectively. The offset between the primary and secondary axes of the VLBI telescopes is estimated to be 7.5 mm in Kunming’s site and 4.0 mm in Urumqi’s site, and the corresponding RMSE is 1.8 mm and 2.0 mm for the two sites, respectively.  相似文献   

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